Pressure Vessel Design Review Question Bank (Short Answer Questions 2/3)

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4-364 To conduct a welding procedure qualification, a preliminary welding procedure specification must first be prepared in accordance with the requirements of the design documents and the manufacturing processes. (A) A. Correct B. Incorrect 4-365 Welding procedure qualification test pieces (ABCD). A. Welding should be carried out simultaneously with the tube section at the extended portion of the longitudinal weld of the tube section. B. It should be performed by welding workers with proficient skills within the organization. C. Equipment from the organization should be used for welding. D. It should be carried out by the same welder who welded the container. 4-366 A qualified welding process refers to those indicated in a qualified welding procedure qualification report, among the general welding procedure qualification factors and specific welding procedure qualification factors (ABC). A. Important factors B. Secondary factors C. Supplementary factors NB/T47014 – Page 25 explains the specialized welding procedure qualification factors specified in the NB/T47014 standard.  4-367 Important factors refer to the welding procedure qualification factors that affect (A). A. Mechanical properties and bending capacity of the welded joint; B. Mechanical properties and bending capacity of the base metal in the heat-affected zone; C. Impact toughness of the welded joint; D. Impact toughness of the base metal in the heat-affected zone. Explain the factors specific to welding procedure qualification as specified in standard NB/T47014. 4- The 368 supplementary factor refers to the welding procedure qualification factor that affects (C). A. Mechanical properties and bending capacity of the welded joint B. Mechanical properties and bending capacity of the base material C. Impact toughness of the welded joint D. Impact toughness of the base material. Explain the factors specific to welding procedure qualification as specified in standard NB/T47014. 4-369 For shielded metal arc welding, the following options represent secondary factors among the specialized welding procedure qualification factors: (ACDE). A. Changing the type of crack formation; B. Reducing the preheating temperature by more than 50°C below the value required for qualification; C. Adding additional welding positions compared to those used in the qualification tests; D. Switching from manual welding to automatic welding; E. Changing the post-weld heating temperature and holding time between the end of welding and the subsequent heat treatment. Briefly describe the specialized qualification rules for various welding methods regarding butt joints and fillet joints as specified in standard NB/T47014. 4-370 For the specific evaluation rules for various welding methods, whenever any one of (A) is changed, a new welding procedure qualification is required. (Minor factors do not need to be re-evaluated.) A. Major factors B. Minor factors C. Additional factors D. Major factors and additional factors Page 38, 4-371 Welding materials include welding wire, electrodes, welding strips, and flux; gases, electrodes, and gaskets do not belong to welding materials. ×A. Correct B. Incorrect. Based on the basic understanding of welding materials and the principles for selecting them, complete the following questions: 4- The welding materials for pressure vessels should comply with the requirements of NB/T47018. √A. Correct B. Incorrect Briefly describe the specific evaluation rules for various welding methods in standard NB/T47014, regarding the process evaluation of butt welds and fillet welds. 4- For the specific evaluation rules applicable to various welding methods, when any additional factor is added or changed, tests can be conducted using impact toughness specimens corresponding to that added or changed factor. ( √) A. Correct B. Incorrect Based on a basic understanding of welding materials and the principles for selecting them, complete the following questions: 4-374 Regarding the principles for selecting welding materials, which of the following statements is correct? BCDA. It is necessary to ensure that the mechanical properties of the weld metal are less than or equal to the limits specified for the base material, or meet the technical requirements outlined in the design documents. B. When necessary, it shall be ensured that other properties of the weld metal, such as corrosion resistance requirements, are not lower than the corresponding requirements of the base material. C. Appropriate welding materials, combined with sound welding procedures, are necessary to ensure that the properties of the welded joint remain in line with the specifications outlined in the design documents and the requirements for operation even after going through the manufacturing process. D. The manufacturing (installation) unit shall be familiar with the welding properties of the welding materials; welding materials used for pressure vessels should be based on welding tests or practical experience. Briefly describe the specific evaluation rules for various welding methods regarding the process qualification of butt welds and fillet welds in standard NB/T47014. 4-375 For the specific evaluation rules for various welding methods, when (B) is increased or changed, it is not necessary to conduct a new welding procedure qualification, but it is required to prepare a new pre-welding procedure document. A. Important factors B. Secondary factors C. Supplementary factors D. Important factors and supplementary factors 4-376 The requirements for sampling and processing of tensile test specimens for welding tests are (ACD). Page 41 A. The weld bead excess on the sample should be removed by mechanical means so that it is level with the base material ； B. When sampling, cold working methods must be used ； C. Cold leveling of the specimen is permitted before removing the weld bead excess height ； D. It allows for the creation of specimens by avoiding welding defects and imperfections. Please briefly describe the method for preparing tensile test specimens according to standard NB/T47014. According to standards 3774-377NB/T47014, tensile tests shall be conducted using full-thickness specimens. ( ) A. Correct B. Incorrect Answer: Incorrect Explanation: NB/T47014-2014, clause 6.1.5.    Please briefly describe the method for preparing tensile test specimens according to standard NB/T47014. If the 3784-378 tensile test specimen fractures on the base metal outside the weld or fusion line, its tensile strength value () can be considered to indicate that the test meets the requirements. A. The minimum tensile strength of the base material as specified by the standard. B. Not less than 95% of the minimum tensile strength of the base material specified by the standard. C. The maximum tensile strength of the base material as specified by the standard. D. Not less than 95% of the maximum tensile strength of the base material specified by the standard. Answer: B. Explanation: According to NB/T47014-2014, clause 6.4.1.5.4(d).      The welding materials referred to in standards 3794-379NB/T47015 include (). A. Welding rods, welding wires, welding strips B. Flux C. Gas D. Electrodes E. Padding Answer: ABCDE Explanation: NB/T47015-2014, clause 3.2.1.      Complete the following questions in accordance with the general welding procedures specified in standard NB/T47015. The weld positions specified in the 3804-380NB/T 47015 standards are divided into ( ). A. Flat weld B. Vertical weld C. Horizontal weld D. Overhead weld Answer: ABCD Explanation: NB/T47015-2014, Clause 3.3.     Complete the following questions in accordance with the general welding procedures specified in standard NB/T47015. 3814-381 NB/T47015 stipulates that when selecting welding materials, it is necessary to ensure that the mechanical properties and other characteristics of the weld metal are the same as or similar to those of the base material. ( ) A. Correct B. Incorrect Answer: Incorrect Explanation: NB/T47015-2014, clause 3.2.2.      Briefly describe, according to the NB/T47015 standard, which welds need to be evaluated and found to be compliant in accordance with the NB/T47014 standard. 3824-382 According to standard NB/T47015, for which of the following welds is it required that the welding process be evaluated and deemed compliant in accordance with standard NB/T47014? A. Welds of pressure-bearing components ； B. Welds welded to the compressed components ； C. Provisional welding of welds in A and B; D. Surfacing and repair welding on the surface of compressed components. Answer: ABCD. Explanation: NB/T47015-2014, clause 3.4.1.      Before using welding materials, the following preparatory steps are correct: 3834-383 Before using welding materials, the wire must have any oil or rust removed from it. The shielding gas for welding should be kept dry. A. Correct B. Incorrect Answer: Correct Explanation: NB/T47015-2014, clause 4.2.1.     Briefly describe, according to the NB/T47015 standard, which welds need to be evaluated and found to be compliant in accordance with the NB/T47014 standard. 3844-384: It is a horizontal pressure vessel. Which of the following welds require a welding procedure qualification in accordance with NB/T47014? ( ) A. Welds corresponding to welding joints of classes A, B, C, and D; B. Welds corresponding to welding joints of classes B and E; C. Repair welds on the surfaces of cylinders, heads, or nozzles; D. Welds between the saddle bottom plate and the gusset plates. Answer: ABC. Explanation: NB/T47015-2014, clause 3.4.1.      Before using welding materials, the following preparation steps are correct: Electrodes and fluxes packaged in vacuum packaging (3854-385) must be redried in accordance with the specifications outlined in the product instructions; after drying, they can be placed in an insulated box at a temperature of 100°C to 150°C for later use. A. Correct B. Incorrect Answer: Incorrect Explanation: NB/T47015-2014, clause 4.2.2.     Briefly describe, according to the NB/T47015 standard, which welds need to be evaluated and found to be compliant in accordance with the NB/T47014 standard. For surfacing welding of pressurized components in 3864-386, only a welding procedure qualification in accordance with NB/T47014 is required; the welders performing this work do not need to pass the assessments specified in TSG Z6002 \"Rules for the Assessment of Welding Operators for Special Equipment\". ( ) A. Correct B. Incorrect Answer: Incorrect Explanation: NB/T47015-2014, clause 3.4.2.      Before using welding materials, the correct preparatory steps are as follows: For electrodes with a drying temperature of over 350°C, as per 3874-387, the cumulative number of drying cycles should not exceed a certain limit. A. 2 times B. 3 times C. 4 times D. 5 times Answer: B Explanation: NB/T47015-2014, clause 4.2.2.      Regarding the post-weld heat treatment of welded joints, is the following statement correct: Welded joints specified in 3884-388 and below require post-weld heat treatment. A. Low-alloy steel weldments with high sensitivity to cold cracking. B. Weldments prone to reheat cracking. C. Weldments under high constraint. D. Aluminum weldments. Answer: AC. Explanation: NB/T47015-2014, clause 4.5.1.      Regarding the post-weld heat treatment of welded joints, is the following statement correct: The 3894-389 post-weld heat treatment can be carried out within a short period after welding; the heat treatment temperature is generally between 200°C and 350°C, and the holding time depends on the heat treatment temperature and the thickness of the weld metal, being usually not less than 30 minutes. A. Correct B. Incorrect Answer: Incorrect Explanation: NB/T47015-2014, clause 4.5.3.      Regarding the post-weld heat treatment of welded joints, is the following statement correct: If stress-relief heat treatment is carried out immediately after welding, post-weld heat treatment is not necessary. A. Correct B. Incorrect Answer: Correct Explanation: NB/T47015-2014, clause 4.5.4.      Regarding welding repairs, is the following statement correct: For welds that require welding repairs, which of the following preparatory tasks must be carried out? 3914-391 A. Remove defects B. Analyze the causes of defects C. Prepare repair procedure documents D. Non-destructive testing. Answer: ABC. Explanation: NB/T47015-2014, clause 3.7.      Regarding welding repairs, is the following statement correct: For the areas 3924-392 that require repair, grooves should be prepared; the shape and size of these grooves must prevent the occurrence of welding defects and facilitate the work of the welder. A. Correct B. Incorrect Answer: Correct Explanation: NB/T47015-2014, clause 3.7.3.      Regarding welding repairs, is the following statement correct: When performing repairs on welds specified as 3934-393, if preheating is required, the preheating temperature should not be higher than that used for the original weld. A. Correct B. Incorrect Answer: Correct Explanation: NB/T47015-2014, clause 3.7.4.      Briefly describe the factors to be considered when determining the shape and dimensions of welding grooves according to standard NB/T47015. The 3944-394 welding method affects the weld groove; changing the welding method requires a new weld procedure qualification, and therefore changing the weld groove also necessitates a new weld procedure qualification. ( ) A. Correct B. Incorrect Answer: Incorrect Explanation: NB/T47014-2014, clause 6.2.2 and Table 6.      Regarding the methods for preparing welding grooves and the precautions to take, are the following statements correct? 3954-395: Regarding the methods for preparing welding grooves, which of the following options are correct? A. Carbon steel and strength-grade low-alloy steels with a minimum standard tensile strength of not more than 540 MPa can have their grooves prepared either by hot working or by cold working methods ； B. Hot working methods should be given priority for heat-resistant low-alloy steels and strength-oriented low-alloy steels with a minimum standard tensile strength of greater than 540 MPa. C. Hot working methods should be given priority for high-alloy steels. D. Cold working methods should be preferentially used for heat-resistant low-alloy steels and strength-oriented low-alloy steels with a minimum standard tensile strength of greater than 540 MPa. Answer: AD. Explanation: NB/T47015-2014, Clause 4.3.      Regarding the methods for preparing welding grooves and the precautions to be taken, is the following statement correct: For 3964-396, the surface of the groove and the areas surrounding it (measured from the edge of the groove; approximately 10 mm on each side for manual arc welding, and approximately 20 mm on each side for submerged arc welding, plasma arc welding, and gas shielded welding) must be cleaned of water, rust, oil, slag, and other harmful impurities. A. Correct B. Incorrect Answer: Correct Explanation: NB/T47015-2014, clause 4.3.3.      Regarding the methods for preparing welding grooves and the precautions to take, is the following statement correct: The sides of the grooves in 3974-397 stainless steel should be properly protected to prevent welding spatter from adhering to them. A. Correct B. Incorrect Answer: Correct Explanation: NB/T47015-2014, clause 4.3.4.      Briefly describe the factors to be considered when determining the shape and dimensions of welding grooves according to standard NB/T47015. 3984-398: To determine the type and dimensions of the welding groove, which of the following factors need to be considered? ( ) A. Welding method B. Type and thickness of base material C. Weld filler metal and its amount, to avoid defects D. Reduce welding deformation and residual stress E. Facilitate welding protection and make it easier for welders to work. Answer: ABCDE Explanation: NB/T47015-2014, clause 3.5.2.      Briefly describe the factors to be considered when determining the shape and dimensions of welding grooves according to standard NB/T47015. 3994-399 For the welding of composite materials, what measures can be taken to reduce the dilution rate of the weld metal at the transition zone? ( ) A. Choose welding materials with higher Cr and Ni contents than those used in double-layer stainless steel. B. Select appropriate welding groove shapes and dimensions. C. Use suitable welding methods and techniques. D. Perform post-weld heat treatment. Answer: BC. Explanation: NB/T47015-2014, clause 9.1.3.   According to the provisions on heat treatment in standard NB/T47014, complete the following questions. According to the provisions on heat treatment in standard NB/T47014, complete the following questions. For 4-400 carbon steels and low-alloy steels, heat treatment processes below (C) °C, and for high-alloy steels, heat treatment processes below (D) °C, are not considered to be post-weld heat treatment. A.500 B.350 C.490 D.315 Answer: CD Explanation: Refer to NB/T47015-2011, page P105, clause 4.6.1. Follow the provisions regarding heat treatment in standard NB/T47014 to answer the following questions. For the welding of 4-401 non-compressed elements with compressed elements, the thickness for post-weld heat treatment is taken as ( ). A. Thickness of the compressed element B. Thickness of the non-compressed element C. Thickness of the weld at the joint D. The greater value between the thickness of the compressed element and that of the non-compressed element. Answer: C. Explanation: According to NB/T47015-2011, page 105, clause 4.6.2.4(f), and in accordance with the provisions regarding heat treatment in NB/T47014 standard, complete the following questions. 4- For Pressure Vessel 402, whose medium is liquid ammonia, if defects are found in the welds after heat treatment, post-weld heat treatment must be carried out on the repaired areas after the welds are repaired. ( ) A. Correct B. Incorrect Answer: Correct Explanation: NB/T47015-2011, page P109, clause 4.7.1(a). In accordance with the regulations on welding procedures for stainless steel composite plates specified in the NB/T47015 standard, complete the following questions. 4- Which of the following statements regarding the welding of stainless steel composite plates is correct? ( ) A. When welding stainless steel composite plates, it is generally advisable to weld the base layer first and then the cladding layer. B. When preparing the groove for composite steel plates, cold working methods must be used. C. Spot welding is only allowed on the base material. D. When preheating is required for the base layer or the coating layer, the total thickness of the composite panel should be used as the thickness parameter for determining the preheating temperature. Answer: CD. Refer to NB/T47015-2011, P120, clauses 9.1.4.1, 9.1.5.1, 9.1.5.3, and 9.1.6.1 for the explanation. Cold working methods are recommended for groove preparation. The welding sequence for stainless steel generally starts with welding the base layer, followed by the transition layer, and finally the overlay layer. This question lacks a transition layer.    According to the provisions on the welding procedures for stainless steel clad plates in standard NB/T47015, complete the following questions. 4-404 Carbon steel or low-alloy steel welding materials shall not be used for welding on the cladding base metal, transition welds, or cladding welds. ( ) A. Correct B. Incorrect Answer: Correct Explanation: According to clause 9.1.6.2 on page P120 of NB/T47015-2011, and in line with the welding procedures specified in this standard for stainless steel composite plates, complete the following questions. 4-405 Which of the following statements regarding the post-weld heat treatment of austenitic stainless steel clad plate containers is correct? A. Welding post-heat treatment should be avoided as much as possible for austenitic stainless steel composite plates. B. The specifications for welding post-heat treatment should be determined based on the total thickness of the composite plate. C. For pressure vessels made of stainless steel composite plates with a cladding layer of 06Cr13, welding post-heat treatment shall be carried out in accordance with the requirements of that cladding layer. D. For equipment with high requirements for resistance to intergranular corrosion, if heat treatment after welding is required for the base layer, it is advisable to apply the cladding layer after the heat treatment. Answer: A B. According to clause 9.1.8 of NB/T47015-2011 P120, for C: pressure vessels made of stainless steel composite plates with a cladding layer of 06Cr13, if austenitic stainless steel welding materials are used to weld the cladding layer and no post-weld heat treatment is required for the base material, then post-weld heat treatment can be omitted; otherwise, post-weld heat treatment shall be carried out in accordance with the requirements of the cladding material. D: For equipment with high requirements for resistance to intergranular corrosion, if post-weld heat treatment is required for the base layer, it is advisable to apply the cladding cover layer after the heat treatment.   4- The material of the welding test specimens for product 406 should have (        ) with the material of the pressure-bearing equipment components it represents. A. Same standards B. Same grade C. Same specifications (thickness, outer diameter) D. Same furnace number E. Same heat treatment condition Answer: ABCE Explanation: NB/T47016-2011, Clause 3.2 According to the provisions of the NB/T47016 standard regarding product welding specimens, complete the following questions. The welded test pieces of the plate-shaped products for the longitudinal joints of section 4-407 shall ( ). A. Place it at the extended portion of its weld seam. B. Weld it simultaneously with the tube section it represents. C. Weld it during the welding process of the pressure-bearing equipment component it represents. D. Weld it after the welding of the tube section is completed. Answer: AB. Explanation: According to clause 3.4a of NB/T47016-2011, in accordance with the standards regarding welded test pieces for products, complete the following questions. 4- The welded test pieces of product 408 do not need to undergo heat treatment along with the container, provided that measures are taken to ensure that they are heat-treated using the same process as the container. ( ) A. Correct B. Incorrect Answer: Correct Explanation: Article 9.1.2.3 of GB/T150.4-2011.      According to the provisions on test specimens in standard NB/T47016, complete the following questions. 4-409 Which of the following statements regarding the welding of test pieces is correct? A. When the welded joints under test are subjected to different welding processes, the welding process and conditions applied to the test specimens should be identical to those of the corresponding welded joints; a welding process that results in higher mechanical properties should be selected for preparing the test specimens. B. The test specimens are prepared in accordance with the specially prepared welding procedure documents. C. The test piece code, work order number or pressure equipment identifier, and material code shall be specified in the welding documents. D. The test piece shall have welding records. Answer: BCD. According to clauses 3.5.1, 3.5.3, and 3.5.4 of NB/T 47016-2011, when the welded joints under inspection are produced using different welding processes, the welding process and conditions applied to the test specimens must be identical to those used for the corresponding welded joints. A welding process that results in lower mechanical properties should be selected for preparing the test specimens.     According to the provisions on test specimens in standard NB/T47016, complete the following questions. The welding of 4-410 product weld specimens can be carried out by welders who are not involved in welding the components of that pressure-bearing equipment, but the same conditions, procedures, and welding techniques as those used for welding the container must be employed. ( ) A. Correct B. Incorrect Answer: Incorrect. Explanation: According to clause 9.1.2.3 of GB/T150.4-2011, the test piece shall be welded by the welder who is responsible for welding that container, using the same conditions, procedures, and welding techniques as those employed for welding the actual container.      4-411 What markings should be applied to welding test pieces? (       ) A. Test piece code B. Material identification number C. Welder’s code D. Work order number or pressure equipment identifier. Answer: ABC. Explanation: According to NB/T47016-2011, page 152, clause 3.10, and in line with the provisions of standard NB/T47042 regarding saddles, questions 4–412 can be answered as follows: For horizontal containers, the saddles can be exempted from strength verification provided that the conditions specified in NB/T47065.1 are met. ( ) A. Correct B. Incorrect Answer: Correct Explanation: According to clause 6.1.3 of NB/T47042-2014, regarding post-weld heat treatment in the standard NB/T47015 \"Welding Code for Pressure Vessels\", is the following statement correct? 4-413 Purpose of post-weld heat treatment. A. Improve the properties of the welded area. B. Restore the mechanical properties of the material. C. Eliminate welding residual stresses. D. Improve the mechanical properties of the material. Answer: AC. Explanation: According to Article 4.6 on post-weld heat treatment in the NB/T47015-2011 standard, page 105, regarding NB/T47015 \"Code for Welding of Pressure Vessels\", is the following statement correct? 4-414 Post-weld stress-relief heat treatment involves heating the welded area or a part of it to a temperature above the metal’s phase transition point for a certain period of time, followed by uniform cooling. A. Correct B. Incorrect Answer: Incorrect. Explanation: According to clause 4.6 of NB/T47015-2011, P105, it is necessary to heat to a sufficiently high temperature below the metal’s phase transition point.     Regarding post-weld heat treatment in the NB/T 47015 standard \"Welding Code for Pressure Vessels\", is the following statement correct: Heat treatment processes at temperatures below 490°C for 415 carbon steel and low-alloy steel, and at temperatures below 315°C for high-alloy steel, are not considered to be post-weld heat treatment. A. Correct B. Incorrect Answer: Correct Explanation: According to clause 4.6.1 of NB/T47015-2011P105, and in line with the requirements for saddles specified in standard NB/T47042, answer the following questions 4–416. Which of the following statements regarding saddles is correct? A. When selecting the material for a saddle, factors such as the design temperature and ambient temperature of the container, as well as economic considerations, should be taken into account. B. The design temperature of the saddle should be determined by taking into account both the design temperature of the container and the ambient temperature. C. The saddle gasket welded to the cylinder should be compatible with the cylinder material. D. Generally, the minimum safety factor for the allowable stress of carbon steel and low-alloy steel saddle materials is 1.5. Answer: ABCD. According to clauses 5.4.1 and 5.4.2(a) of NB/T 47042-2014, which of the following conditions must be met simultaneously for the saddle pad to serve a reinforcing purpose? 4-417 A. The nominal thickness of the gasket plate is ≥ 0.6 times the nominal thickness of the cylinder. B. The nominal thickness of the gasket plate is ≥ the nominal thickness of the cylinder. C. The width of the gasket plate is not less than the effective width of the cylinder. D. The cover angle of the gasket plate is not less than the cover angle of the saddle plus 12°. E. The cover angle of the gasket plate is greater than the cover angle of the saddle plus 6°. Answer: ACD. Explanation: Note in clause b of Article 7.7.4.1.1 of NB/T47042-2014. In accordance with the provisions on saddles in standard NB/T47042, answer questions 4–418 regarding large-diameter, thin-walled horizontal vessels: when arranging saddles, it is necessary to ensure that the distance A from the center line of the saddle to the tangent line of the head is as small as possible; the purpose of this is ( ). A. Less than or equal to 0.2 LB. Less than or equal to 0.5 RAC. The absolute values of the bending moments at the supports and between the two supports are equal D. Utilize the reinforcing effect of the end cap on the cylinder. Answer: BD. Explanation: According to Article 6.1.2 of NB/T47042-2014, in accordance with the provisions regarding saddle gussets in the NB/T47042 and NB/T47065.1 standards, answer the following questions 4–419: The conditions under which a saddle gusset exerts a reinforcing effect are met simultaneously when ( ). A. The nominal thickness of the saddle pad is greater than or equal to the nominal thickness of the cylinder. B. The nominal thickness of the saddle pad is greater than or equal to 0.6 times the nominal thickness of the cylinder. C. The width of the saddle pad shall be greater than or equal to the effective width of the cylinder. D. The cover angle of the shimming plate should be no less than the cover angle of the saddle plus 12°. Answer: BCD. Explanation: See note in clause b of section 7.7.4.1.1 of NB/T 47042-2014.      4- What factors are related to the effective width of the cylinder at the support of the 420 horizontal vessel? A. Nominal thickness of the cylinder B. Width of the support base plate C. Axial width of the support D. Width of the support web E. Average radius of the cylinder Answer: ACE Explanation: According to Article 7.6 on page 83 of NB/T47042-2014, the effective width b2 of the cylinder is given by b2 = b + 1.56 * (Ra * δn)^0.5. In accordance with the provisions regarding saddle-type support base plates in the NB/T47042 and NB/T47065.1 standards, complete the following questions. 4-421: When the container requires heat treatment, the saddle-type support base plate should be welded to the container before the heat treatment is carried out. ( ) A. Correct B. Incorrect Answer: Correct Explanation: NB/T47065.1-2018, P32, Article 7.9 – Regarding the saddle gaskets for horizontal containers, the following statement is correct: When the gasket for horizontal containers can serve a reinforcing purpose, it has an impact on the following types of stresses. A. Axial stress in the cylinder B. Tangential shear stress in the cylinder C. Circumferential stress in the cylinder D. Horizontal tensile stress in the saddle web Answer: CD Explanation: NB/T47042-2014, clauses 7.7.4 and 7.8.1; also see clause 22.6.2 on page P221 of the \"Tutorial\". The enhanced version has an impact on σ5, σ6, and σ9; in particular, σ6 decreases significantly. At this point, σ’6 is referred to as the controlling stress ； Increasing the saddle wrap angle can reduce the axial and tangential stresses in the cylinder at the saddle plane.     4-423 In which of the following situations should a saddle support use a pad-mounted structure? ( ) A. The effective thickness of the container cylinder is less than or equal to 3 mm. B. The circumferential stress at the saddle support of the container cylinder exceeds the specified value. C. The container cylinder requires heat treatment. D. The temperature difference between the container cylinder and the saddle support is greater than 200°C. E. The material of the container cylinder does not have the same or similar chemical composition and performance parameters as those of the saddle support. Answer: A, B, C, D, E. Explanation: NB/T47065.1-2018, Page 32, Clause 8.3. In accordance with the requirements of NB/T47042 standard, answer the following question: 4-424. From a stress perspective, what angle is better to use for the saddle support of horizontal containers? A. 120° B. 135° C. 147° D. 150° Answer: D Explanation: Training Manual for Pressure Vessel Design Engineers – Vessel Construction Techniques, P221. According to clause 22.6.2 of standard NB/T47042, complete the following question: 4-425. What stresses are affected by the size of the saddle angle of horizontal vessels? A. Axial stress at the saddle plane B. Axial stress at the mid-section of the cylinder C. Tangential shear stress at the saddle plane D. Circumferential stress at the saddle plane Answer: A, D Explanation: Training Manual for Pressure Vessel Design Engineers – Vessel Construction Techniques, P221, Section 22.6.2, 4-426. Fixed supports should generally be installed at the end of horizontal vessels where the pipe diameters are larger and the number of pipes is greater; this is done to reduce the effects of thermal stress resulting from the expansion or contraction of the cylinder due to temperature changes. A. Correct B. Incorrect Answer: Correct Explanation: Pressure Vessel Engineer Training Manual – Vessel Construction Techniques, P207. According to Clause 22.1 of standard NB/T47042 regarding the calculations for vessels and saddles, complete the following questions. 4-427 Which stresses are affected by the saddle pad? ( ) A. σ1, σ2 B. σ3, σ4 C. σ5, σ6 D. σ9 Answer: C, D Explanation: NB/T47042-2014, Page 97 – Table 10, calculation formulas. In accordance with the provisions of the NB/T47042 standard regarding the calculation of containers and saddles, complete the following questions. 4-428 The checking calculations for horizontal vessel saddles include ( ). A. Calculation and verification of horizontal tensile stress in the web B. Calculation and verification of compressive stress in the saddle C. Calculation and verification of stress on the anchor bolts due to earthquakes D. Calculation and verification of stress on the saddle floor Answer: A, B, C Explanation: NB/T47042-2014, pages P93/P94/P95, clauses 7.8.1/7.8.2/7.8.3. In accordance with the provisions of NB/T47042 standard regarding the calculation of containers and saddles, complete the following questions. 4-429 When calculating the horizontal tensile stress in the saddle web, how should the effective width of the gusset plate be determined when it serves a reinforcing role? ( ) A. Based on the actual width of the shimming plate, b4; B. Based on the effective width of the cylinder, b2; C. Based on the width of the saddle; D. The larger value between the actual width of the shimming plate, b4, and the effective width of the cylinder, b2. Answer: B. Explanation: According to clause 7.8.1.2.b) of NB/T47042-2014, P93, and in accordance with the design calculations for horizontal containers specified in this standard, the following question needs to be addressed: In the stress verification for a double-saddle horizontal container model 4-430, which stresses need to be checked at the cylinder sections at the supports? A. Axial stresses σ1, σ2 B. Axial stresses σ3, σ4 C. Tangential shear stress τ D. Circumferential stresses σ5, σ6 Answer: B, C, D Explanation: NB/T47042-2014, pages P86/P87/P90, clauses 7.7.2.2.2/7.7.3/7.7.4. According to the NB/T47041 standard, what loads should be considered in the design of towers? 4-431 What are the main loads acting on tower-type vessels under operating conditions? (   ) A. Internal pressure, external pressure, or maximum pressure difference ； B. The weight of the medium contained within the tower (including internal components and packing, etc.). C. The gravitational load due to auxiliary equipment as well as insulation materials, linings, pipes, ladders, platforms, etc. D. The static pressure of the liquid column. E. Wind loads and seismic loads. Answers: A, B, C, D, E. Explanation: According to NB/T47041-2014, clause 4.2.4, and the design calculation regulations for horizontal tanks specified in NB/T47042, complete the following task: In the stress verification of double-saddle horizontal tanks, regardless of whether the cylinder is reinforced or not, the axial stresses σ3 and σ4 caused by pressure and axial bending moments occur at the highest and lowest points respectively on the cross-section of the cylinder. A. Correct B. Incorrect Answer: Incorrect Explanation: According to clause 7.7.2.2.2 of NB/T47042-2014, P86, and in line with the design calculation requirements for horizontal vessels specified in this standard, the following issue needs to be addressed: 4-433. The magnitude of the circumferential stress in a horizontal vessel with double saddles, as well as the location of the point where the maximum stress occurs, are influenced by factors such as whether there are reinforcement rings on the saddle surfaces and their positions. A. Correct B. Incorrect Answer: A Explanation: NB/T47042-2014, page P89, 7.7.4, or the Training Manual for Pressure Vessel Design Engineers – Vessel Construction Techniques, page 215, 22.4.5. According to standard NB/T47041, what loads should be considered during the design of towers? 4-434 How to consider the effects of wind and earthquakes during hydraulic testing? ( ) A. 25% wind bending moment + 100% seismic bending moment, plus 100% wind bending moment; the larger of these values shall be taken. B. Include both 25% wind bending moment and 100% seismic bending moment. C. Include 30% wind bending moment; no seismic bending moment shall be considered. D. Ignore the effects of wind and seismic forces. Answer: C. Explanation: Training Manual for Pressure Vessel Design Engineers – Vessel Construction Techniques, P252. Please analyze the characteristics of horizontal vessels with two supports and those with multiple supports, and answer the following question: 4-435. It is preferable to use three or more supports for the saddle support of horizontal vessels. A. Correct B. Incorrect Answer: Incorrect Explanation: NB/T47042-2014, Pages 81-82, Clause 6.1.4, item 4-436: The stress characteristics of horizontal vessels supported by multiple saddles (under the condition that the installation tolerances are met) are as follows: A. The load-bearing capacity of each individual support is low. B. The reaction forces are distributed evenly. C. The stress in the vessel’s cross-section is low. D. The load-bearing capacity of each individual support is high. E. The reaction forces are not distributed evenly. F. The stress in the vessel’s cross-section is high. Answer: A, C, E. Explanation: Questions and Answers on the Design of Chemical Pressure Vessels, Page 86, Clause 4.2.68: According to the NB/T47041 standard, what loads should be considered during the design of towers? 4-437 When checking the axial stress of a cylinder during a hydrostatic test, which masses above the calculation section should be taken into account? ( ) A. Shell and internal components B. Insulation, escalators, platforms C. Auxiliary equipment and eccentric masses D. Hydrostatic pressure of the liquid column E. Lining Answer: A, B, C Explanation: NB/T47041-2014, Page 43, Clause 7.11.1.1, 4-438 When the loads and support positions are symmetrical, the stress characteristics of a horizontal vessel supported by double saddles are as follows: A. The bearing capacity of each individual support is low B. The reaction forces are distributed evenly C. The stress in the cylinder section is low D. The bearing capacity of each individual support is high E. The reaction forces are not distributed evenly F. The stress in the cylinder section is high Answer: B, D, F Explanation: Please analyze the factors that affect the circumferential compressive stress in the cylinder at the saddle locations, and answer the following question: 4-439 When the circumferential compressive stress in the cylinder at the saddle locations does not meet the required criteria, which of the following measures can help reduce this stress? A. Increase the wrap angle of the saddle. B. Adjust the spacing between saddles so that A ≤ 0.5R. C. Increase the width of the saddle. D. Increase the thickness of the cylinder. E. Add reinforcing gussets. F. Install reinforcing rings within the plane of the saddle. Answer: A, B, C, E, F. Explanation: Training manual for pressure vessel design engineers – Container construction technology 22.4.54-440. When the circumferential compressive stress on the cylinder at the saddle location does not meet the required criteria, which of the following measures should be adopted first to reduce this stress? A. Increase the wrap angle of the saddles. B. Adjust the spacing between the saddles so that A ≤ 0.5R. C. Increase the width of the saddles. D. Increase the thickness of the cylinder. E. Add reinforcing gussets. F. Install reinforcing rings within the plane of the saddles. Answers: A, B, C, E, F. Explanation: Training manual for pressure vessel design engineers – Vessel construction technology 22.4.5. Please analyze the factors that affect the circumferential compressive stress at the saddles and answer the following questions: 4-441. The reinforcing rings of horizontal vessels should be a complete ring or a structure equivalent to a complete ring; the connection structure between these reinforcing rings and the shell must comply with the relevant provisions of GB/T150.3. A. Correct B. Incorrect Answer: Correct Explanation: Follow the principle of dual saddle mounting for horizontal containers to complete the following questions. 4-442 What are the principles for arranging the supports of a horizontally mounted vessel with two supports, at position A (where A is the distance from the centerline of the saddle to the tangent line of the head)? A. A should be as large as possible and equal to or greater than 0.5RA, but it should not be greater than 0.2LB. A should be as small as possible and equal to or less than 0.5RA, and it should not be greater than 0.2LC. A should be as large as possible and equal to or greater than 0.5RA, or equal to or greater than 0.2LD. A should be as small as possible and equal to or less than 0.5RA, or equal to or greater than 0.2L. Answer: B. Explanation: NB/T47042-2014, Page 81, Clause 6.1.2 – According to the principles for the double-saddle arrangement of horizontal containers, complete the following tasks. 4-443 Select an appropriate value for A so that the head acts as a reinforcement for the cylinder, thereby reducing the axial stress and tangential shear stress in the area of the saddle section, as well as the circumferential stress at the corners of the saddle and at the edges of the saddle reinforcement plates. A. Correct B. Incorrect Answer: Incorrect Explanation: Training manual for pressure vessel design engineers – Vessel construction technology 22.6.1. Based on the double saddle layout principle for horizontal vessels, complete the following tasks. 4-444 When A=0.2L, the maximum bending moment across the container’s span is equal to the bending moment at the support sections (in terms of absolute value), resulting in the minimum absolute value of the bending stress that determines the container’s thickness. A. Correct B. Incorrect Answer: Incorrect Explanation: Training Manual for Pressure Vessel Design Engineers (Old Version), P398 22.1 Complete the following questions based on the principles for arranging the saddles of horizontal vessels. 4-445 Horizontal vessels use saddle supports; when the supports are welded to the vessel, one of them should be able to slide or roll on the foundation. A. Correct B. Incorrect Answer: Correct Explanation: NB/T47042-2014, Page 81, Clause 6.1.1, item 4-446: On which side of the container’s nozzles should the fixing supports for double-saddle horizontal containers be installed? (      ) A. The side with more container nozzles B. The side with fewer container nozzles C. There is no restriction; any of the above options is acceptable. Answer: A. Explanation: According to the principles for arranging the saddles of horizontal containers, complete the following questions. 4- 447 Three-saddle support equipment; the arrangement of the supports should be as follows. A. Fixed at one end, with sliding motion at the middle and other end; B. Fixed at both ends, with sliding motion in the middle; C. Sliding motion at both ends, fixed in the middle; D. No restrictions, any of the above options is acceptable. Answer: C. Explanation: According to the requirements for the arrangement of flange bolt holes specified in standard GB/T150, complete the following question: 4-448. How should the flange bolt holes be arranged relative to the main axis or vertical line of the shell? A. Centered B. At the mid-span C. Unrestricted Answer: B Explanation: GB/T150.4 6.5.6 In accordance with the requirements for the placement of flange bolt holes specified in the GB/T150 standard, complete the following question: For a flange with bolt holes that are centered, as it is connected to external pipes, the bolts bear the external loads more evenly, which also facilitates the tightening process. A. Correct B. Incorrect Answer: B Explanation: GB/T150.4 6.5.6 – For towers with a diameter of 4–450, a conical shell is the preferred choice for the skirt shell, as it can withstand greater stresses and allows for more anchor bolts to be used. (      ) A. Correct B. Incorrect Answer: B Explanation: According to page 18 of the NB/T47041 standard, regarding the requirements for the placement of flange bolt holes as specified in GB/T150, answer the following question: 4-451 If the bolts are located on the center line below the pipe connection, leakage can lead to corrosion and rusting, and it becomes difficult to remove these bolts. A. Correct B. Incorrect Answer: A Explanation: Page 266 of \"Design of Chemical Pressure Vessels – Methods, Problems, and Key Points\". According to standard NB/T47041, explain when a conical skirt shell should be used for towers. 4- 452 According to the NB/T47041 standard, when a conical skirt is used for the skirt shell of a tower, the half-cone apex angle should not exceed ( ). A. 10° B. 12° C. 15° D. 20° Answer: C Explanation: NB/T47041 6.2.1 Based on the calculation formulas related to horizontal containers, complete the following question: 4- 453 In horizontal containers, the physical meaning of K1 and K2 in the formulas for calculating the axial stresses σ3 and σ4 at the saddle portion of the cylinder is the degree to which the load-bearing capacity of the cylinder above the saddle is reduced due to deformation caused by the applied loads. A. Correct B. Incorrect Answer: A Explanation: Page 213 of the \"Training Manual for Pressure Vessel Design Engineers\". Using the relevant calculation formulas for horizontal vessels, solve the following problem: 4-454 When the cylinder is not reinforced at the saddle plane, what is the relationship between K1, K2, and the change in the saddle angle? A. K1 and K2 are constant values that do not change as the angle of the saddle changes. B. K1 and K2 increase as the angle of the saddle increases. C. K1 and K2 decrease as the angle of the saddle increases. D. As the angle of the saddle increases, K1 and K2 first increase to a certain value and then gradually decrease. Answer: B. Explanation: According to Table 2 in NB/T47042, and using the relevant calculation formulas for horizontal vessels, complete the following task: 4-455. By installing reinforcement rings on the saddle plane, or by arranging the saddle in an appropriate manner so that the head can reinforce the cylinder, it is possible to prevent the cylinder from deforming and becoming flattened at the saddle plane. A. Correct B. Incorrect Answer: A Explanation: According to page 213 of the \"Training Manual for Pressure Vessel Design Engineers\", and in line with standard NB/T47041, explain when a conical skirt shell should be used for towers. 4- 456 In which of the following situations should a conical skirt shell be considered for use with the tower? ( ) A. The design calculations require a large number of anchor bolts; it is difficult to arrange them in a cylindrical pattern, and it is necessary to maintain a certain spacing between the anchor bolts ； B. There are many pipe openings inside the skirt shell, and the piping layout is quite dense ； C. The thickness of the skirt shell is sufficient, but the design calculations require an increase in the sectional moment of inertia of the skirt shell ； D. The tower is subject to significant wind loads, which causes the concrete foundation beneath the skirt base ring to experience compressive stresses that exceed its allowable limits; therefore, it is necessary to reduce the compressive stresses acting on the top surface of the foundation. Answer: ACD. Explanation: See page 18 of NB/T 47041. According to TSG 21-2016 \"Regulations on the Safety Technical Inspection of Fixed Pressure Vessels\", answer questions 4-457. TSG 21-2016 was formulated by combining seven existing regulations. A. Correct B. Incorrect Answer: A Explanation: Preface to TSG21-2016 In accordance with the provisions regarding pressure tests in GB/T 150 standard, complete the following questions. 4- 458 Which of the following are the purposes of a voltage withstand test? ( ) A. Assess the overall strength, stiffness, and stability of the container ； B. Check the density of the welded joint ； C. Verify the sealing performance of the sealing structure ； D. Eliminate or reduce welding residual stresses and the peak stresses in local discontinuities ； E. It has a closing effect on microcracks, blunting their tips. Answer: ABCDE. Explanation: According to the “Training Manual for Pressure Vessel Design Engineers” 19.1.1, based on TSG 21-2016 “Safety Technical Supervision Regulations for Fixed Pressure Vessels”, answer question 4-459. Which of the following regulations make up TSG 21-2016? A. TSG R0004-2009 “Safety Technical Supervision Regulations for Fixed Pressure Vessels” B. TSG R0001-2004 “Safety Technical Supervision Regulations for Non-Metallic Pressure Vessels” C. TSG R0003-2007 “Safety Technical Supervision Regulations for Simple Pressure Vessels” D. TSG R0002-2005 “Safety Technical Supervision Regulations for Ultra-High Pressure Vessels” E. “Regulations on the Registration and Management of Boilers and Pressure Vessels” F. TSG R5002-2013 “Rules for the Management of Pressure Vessel Use” G. TSG R7001-2013 “Rules for Periodic Inspections of Pressure Vessels” H. TSG R7004-2013 “Rules for Supervisory Inspections of Pressure Vessels”. Answer: ABCDFGH. Explanation: Preface to TSG 21-2016. Based on TSG 21-2016 “Safety Technical Supervision Regulations for Fixed Pressure Vessels”, answer question 4-460. Starting from the date of implementation of TSG 21-2016, the seven existing regulations were simultaneously repealed. A. Correct B. Incorrect Answer: B Explanation: Preface to TSG21-2016 In accordance with the classification regulations for pressure vessels specified in TSG 21-2016, complete the following question: 4-461 Which of the following media belong to Group 1 media? A. Chemical media with extreme toxicity hazards B. Chemical media with moderate toxicity hazards C. Chemical media with high toxicity hazards D. Explosive media E. Liquefied gases Answer: ACDE Explanation: TSG21-2016 Appendix A1.1 According to the classification regulations for pressure vessels in TSG 21-2016, complete the following question: 4-462 The classification of pressure vessels is related to which of the following factors? A. Medium grouping B. Design temperature C. Design pressure D. Volume Answer: ACD Explanation: Appendix A of TSG21-2016 According to the classification regulations for pressure vessels outlined in TSG 21-2016, complete the following question: 4-463 The classification of multi-chamber pressure vessels should be based on the highest category among all the pressure chambers; this highest category shall be used for the management of such multi-chamber devices. Design and manufacturing requirements shall be specified according to the category of each individual pressure chamber. A. Correct B. Incorrect Answer: A Explanation: TSG21-2016 Appendix A1.3.2 – Regarding the loads to be considered in pressure vessel design, is the following statement correct? 4-464 What loads must be considered in the design of pressure vessels? A. Internal pressure B. External pressure C. Maximum pressure difference D. Hydrostatic pressure of a liquid column less than 5% of the design pressure Answer: ABC Explanation: TSG21-2016 3.1.8 Regarding the loads to be considered in the design of pressure vessels, is the following statement correct? 4- 465 When necessary, the design of pressure vessels should also take into account the following loads: the weight of the equipment itself, the weight of the contents inside, the weight of accessories, wind loads, seismic loads, thermal expansion, and the reaction forces at the supports. A. Correct B. Incorrect Answer: A Explanation: TSG21-2016 3.1.8 Regarding the loads to be considered in pressure vessel design, is the following statement correct? 4- 466 The design of pressure vessels should not take into account pipe thrust, impact loads, and lifting forces. A. Correct B. Incorrect Answer: B Explanation: TSG21-2016 3.1.8      In accordance with the provisions regarding pressure tests in GB/T150 standard, complete the following questions. 4- 467 How is the test pressure for hydraulic testing determined? ( ) A. Hydrostatic test for pressure vessels under internal pressure, B. Hydrostatic test for pressure vessels under internal pressure, C. Hydrostatic test for pressure vessels under external pressure, D. Hydrostatic test for pressure vessels under external pressure. Answer: AD. Explanation: GB/T150.1 4.6.2. According to TSR 21-2016 \"Regulations on the Safety Supervision of Fixed Pressure Vessels\", the scope of application applies to the vessel body itself; safety accessories and instruments are not included within this scope. A. Correct B. Incorrect Answer: B Explanation: According to TSG21-2016 1.64-469, for a vessel made of 15CrMoR with a nominal wall thickness of 24 mm, a design temperature of 525°C, and a design pressure of 2.0 MPA, the allowable stresses as specified in GB/T 150.2 are given in the table below. The appropriate hydrostatic test pressure for this vessel is ( ). A.7.20MPAB.6.33MPAC.3.57MPAD.3.14MPA Answer: C Explanation: According to the definition in GB150.1-2011, clause 4.6, for pressure vessels covered by the regulations set out in TSR 21-2016 \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\", the scope of application is determined as follows. For question 4-470, the option that does not belong to the actual structure of a pressure vessel is A: the welding groove surface of the first circumferential weld that connects the pressure vessel to external pipelines or devices. B. The end face of the first threaded joint in the threaded connection. C. The first flange sealing surface of the flanged connection. D. The first sealing surface for connections using dedicated fittings or pipes. E. Pressure cover for the opened part of the pressure vessel and its fasteners. F. Supports such as lugs and legs welded to pressure vessels. G. Welded joints connecting non-compressed components to the pressure vessel body Answer: AG Explanation: According to TSG 21-2016 1.6.1, for pressure vessels governed by the TSR 21-2016 \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\", the scope of application is determined as follows. Complete question 4-471: Regarding the main compressed components within a pressure vessel body, which of the following statements is correct? A. The cylinder body (including sections with varying diameters), spherical shell plates, shell plates of non-spherical vessels, end caps, flat lids, etc., are considered compressed components ； B. The tube sheet and expansion joints of the heat exchanger are primary pressure-bearing components, while the heat exchange tubes are not primary pressure-bearing components. The bolts of C.M36 are not primary compression members. D. Nozzles and pipe flanges with a nominal diameter of 250 mm or more are considered primary pressure-bearing elements. Answer: AD. Explanation: According to TSG 21-2016 1.6.1 and the provisions on air barriers in NB/T 47041, complete the following questions. 4-472 When the lower head of the tower shell ( ) is greater than or equal to ( ), an air barrier should be installed at the upper part of the skirt, near the head. A. Operating temperature B. Design temperature C. 350°C D. 400°C Answer: BD Explanation: According to NB/T 47041-2014, section 6.5.3, and the regulations regarding air barriers in NB/T 47041, complete the following questions. 4-473 An air barrier should be installed at the upper part of the skirt, near the head. The purpose of installing this air barrier is ( ). A. Ensure that the air inside and outside the air barrier does not come into direct contact, in order to avoid heat exchange between them. B. The air inside the air barrier remains relatively stationary, acting like an insulating layer. C. Prevent excessive temperature gradients at the junction between the skirt shell and the head. D. Avoid fatigue damage to the welds at the connection between the skirt shell and the head due to excessive temperature stress. Answers: ABD. Explanation: According to NB/T 47041-2014 standard, Section 3 – Structure, 5: The function of the air barrier is to ensure that the air inside and outside it does not come into direct contact, thereby minimizing heat exchange; moreover, the air inside the air barrier remains relatively stationary, functioning like an insulating layer. When the operating temperature of a tower-type vessel (or its bottom) is high or varies significantly, the air within the air-insulating ring is heated. Conversely, this air also heats the metal in the connected areas, resulting in a smaller variation in the temperature of the metal walls in those areas and thereby increasing the number of cycles to which the equipment can withstand before suffering fatigue damage. Please complete the following questions regarding the material selection for spherical tanks. 4-474 When spherical tanks are made of high-strength steel, those properties of the material should be given special consideration. A. Corrosion resistance B. Weldability C. Toughness D. High-temperature performance Answer: BC Explanation: \"Technical Questions and Answers on Spherical Storage Tanks\" (1) Weldability can be expressed by the highest Vickers hardness Hmax in the weld heat-affected zone, or by the carbon equivalent (Ceq) related to this value. Ceq = C + Mn/6 + Si/24 + Ni/40 + Cr/5 + Mo/4 + V/14 (%) There is a relationship between Ceq and Hmax as follows: Hmax = (666 × Ceq + 40) ± 40. When conducting weldability tests on high-strength steels, it is necessary to carry out tests on carbon equivalent, the highest hardness of the weld seam, and weld bend resistance. If the carbon equivalent does not meet the requirements of this specification, a test for the maximum hardness of the weld shall be conducted. When neither of the above two tests meets the requirements of this specification, a weld bead bending test shall be conducted. The various tests are carried out in sequence; if one of them is successful, it can be concluded that this steel is qualified. In recent years, companies such as Ito Seikatsu have proposed, on a experimental basis, using the weld crack sensitivity index Pc to estimate the likelihood of weld cracks occurring. Pc = C + Si/30 + Mn/20 + Cu/20 + Ni/60 + Cr/60 + Mo/15 + V/10 + 5B (%). (2) Regarding toughness, generally speaking, the higher the strength of steel, the lower its toughness; it becomes more brittle and is at risk of brittle fracture. Therefore, high-strength steels are required to possess good toughness. In accordance with the regulations in NB/T 47041 regarding gas barriers, complete the following questions. 4-475 By adopting a gas barrier ring structure, fatigue failure of the welds between the skirt shell and the head caused by excessive temperature difference stress can be definitely avoided. ( ) A. Correct B. Incorrect Answer: B Explanation: According to the NB/T 47041-2014 standard, Section 3 – Structure, point 5 states that the presence of a gas barrier structure does not necessarily prevent the welding joints from being affected by thermal stress, nor does it guarantee that their strength meets the required standards. It can only be said that this structure **reduces the impact of thermal stress, thereby helping to ensure the proper operation of the equipment to a certain extent. In accordance with the provisions of GB/T 150 standard regarding the design calculations for cylinders under external pressure, complete the following questions. 4-476 The coefficient A is the value at critical instability of the outer pressure cylinder. A. Circumferential strain B. Axial strain C. Circumferential stress D. Axial stress Answer: A Explanation: Technical Q&A P35 2-47 According to the provisions of GB/T 150 standard for the design and calculation of pressure vessels under external pressure, complete the following questions. 4-477 For a cylinder, which of the following parameters is related to coefficient A? ( ) A. Cylinder diameter B. Cylinder thickness C. Calculated length of the cylinder D. Cylinder material Answer: ABC Explanation: According to GB 150.3-2011 4.3.2.1 and the provisions of the GB/T 150 standard regarding the design calculations for cylinders under external pressure, complete the following questions. 4-478 GB/T 150.3: When calculating pressure vessels with internal and external pressures, for thin-walled cylinders, ( ) is used as the dividing criterion. A. L/Do ≥ 10 B. L/Do ≥ 20 C. Do/δe ≥ 20 D. Do/δe ≥ 10 Answer: C Explanation: According to GB150.3-2011 4.3.2 and the provisions in GB/T 150 regarding the design calculations for external pressure on elliptical heads, complete the following questions. 4-479 When designing an elliptical head under external pressure, external pressure checks shall be performed separately on the middle part of the head and at the folded edges. ( ) A. Correct B. Incorrect Answer: B Explanation: According to Section 10.2.4 of the 19th edition of the Engineer Training Manual, and in line with the provisions of GB/T 150 regarding the design calculations for external pressure on elliptical heads, complete the following questions. 4-480 Under external pressure, the stresses generated at the bottom edge and in the transition zone of an elliptical head are ( ). A. Circumferential tensile stress B. Circumferential compressive stress C. Longitudinal tensile stress D. Longitudinal compressive stress Answer: A Explanation: Engineer Training Manual, 19th edition, 10.2.4 2 According to the provisions of GB/T 150 regarding the design calculations for external pressure on elliptical heads, complete the following questions. 4-481 The thickness calculation for convexly curved elliptical end caps under compressive loads should employ the design method for pressure vessels with spherical shapes. For such elliptical end caps, the equivalent external radius Ro is given by Ro = K1Do, where K1 is a coefficient determined by the ratio of the long and short axes of the ellipse. When K = ( ), it refers to a standard elliptical end cap. A.1 B.0.9 C.2 D.1.5 Answer: B. Explanation: Refer to GB 150.3-2011, section 5.3.3, Table 5-2. Please complete the following questions regarding the material selection for spherical tanks. 4-482 Under normal circumstances, the higher the strength of steel, the lower its toughness, and there is a risk of brittle fracture; therefore, high-strength steel is required to have good toughness. A. Correct B. Incorrect Answer: A Explanation: Comprehensive Book on Chemical Equipment Design – Spherical Vessels and Large Storage Tanks, Chapter 2, Section 1. Please answer the following questions regarding the material selection for spherical vessels. 4-483 The weldability of materials can be evaluated using parameters such as carbon equivalent and weld crack sensitivity index. A. Correct B. Incorrect Answer: A Explanation: Comprehensive Book on Chemical Equipment Design – Spherical Vessels and Large Storage Tanks, Chapter 2, Section 1, 1-5. Based on the causes and characteristics of weld cracks in spherical vessels, complete the following questions. 4-484 The following factors may cause cracks in the welds of spherical tanks. A. Microcracks exist in the material. B. Preheating before welding. C. Deterioration of the material in the weld and heat-affected zone. D. High welding restraint. E. Contact with stress-corrosion inducing media. F. Multi-layer welding. Answer: ACDE. Explanation: Engineer Training Manual, 19th edition, 16.1.3 1. Based on the causes and characteristics of cracks in spherical tank welds, complete the following questions. 4-485 Spherical tanks manufactured from materials prone to delayed cracking shall await at least several hours after welding is completed before non-destructive testing of the weld joints can be carried out. A. 24h B. 36h C. 48h D. 12h Answer: B Explanation: According to GB 12337-2014 8.6.2.2, and based on the causes and characteristics of cracks in spherical tank welds, complete the following questions. 4-486 Spherical tanks with a tendency to stress corrosion should undergo stress-relief heat treatment after welding. A. Correct B. Incorrect Answer: A Explanation: According to GB 12337-2014, clause 8.8.3, and the provisions on design loads for spherical tanks in GB/T12337-2014, complete the following questions: 4-487. Which loads should be considered in the calculation of spherical tank shells? A. Internal pressure B. External pressure C. Frictional force D. Hydrostatic pressure of the liquid column. Answer: ABD. Explanation: According to GB 12337-2014, clause 3.8.2, and the provisions regarding design loads for spherical tanks in GB/T12337-2014, complete the following questions: Wind load and seismic load are considered short-term loads, and they can be ignored when calculating the strength of spherical tanks. A. Correct B. Incorrect Answer: B Explanation: According to GB 12337-2014, clause 3.8.2, and the provisions regarding design loads for spherical tanks in GB/T12337-2014, complete the following questions: 4-489. Since spherical tanks have support structures such as struts and reinforcement plates, local stresses are generated at the points where these structures connect to the tank shell; therefore, it is necessary to conduct strength calculations for the stresses at the lowest points of connection between the struts and the tank shell. A. Correct B. Incorrect Answer: A Explanation: According to the principles of rational design for flange connections as specified in GB 12337-2014 6.11, address the following question: In a properly designed flange, the gasket load should be kept as （ ） as possible, and the diameter of the bolt circle should be kept as （ ） as possible. A. Large, large B. Large, small C. Small, large D. Small, small Answer: D Explanation: Engineer Training Manual, 19th edition, 12.8 According to the reasonable design principles for flange connections, complete the following question: 4-491 A proper flange design should ensure that the axial, circumferential, and radial stresses are close to the corresponding allowable stresses. A. Correct B. Incorrect Answer: B Explanation: According to the principles of rational design for flange connections as specified in GB 150.3-2011 7.5.3.4, address the following question: The ratio of the taper of the flange neck to the dimensions of the flange ring only affects the appearance of the flange; it does not affect its strength. A. Correct B. Incorrect Answer: B Explanation: Increasing the size of the flange cone reduces its rotational stiffness, which in turn increases its load-bearing capacity. As a result, the boundary forces and moments between the cone and the flange ring increase; specifically, the boundary forces and moments at the end of the cone increase. This leads to an increase in axial bending stress. However, since the bending resistance of the cone is proportional to the square of its thickness, this ultimately results in a decrease in the axial bending stress of the cone. Boundary forces: an increase in torque leads to an increase in the radial bending moment acting on the inner edge of the flange, which in turn results in an increase in the radial bending stress of the flange ring. As the radial bending moment on the inner edge of the flange increases, the support provided by the flange ring increases, which reduces deflection; consequently, the hoop stress decreases. Please answer the following questions related to stress corrosion: 4-493 Stress corrosion cracking is a type of failure that occurs in metals under the combined action of compressive stress and a corrosive environment (along with certain temperature conditions). A. Correct B. Incorrect Answer: B Explanation: Engineer Training Manual – Basic Knowledge, Components, P97. Please answer the following questions related to stress corrosion: 4-494 The medium that is most likely to cause stress corrosion in Q345R is A. Chloride ions B. Alkaline solutions C. Chlorides combined with steam D. Wet hydrogen sulfide. Answer: D Explanation: 4-495 The medium that is most likely to cause stress corrosion in S30408 is ( ). A. Chloride ions B. Alkaline solution C. Chlorides combined with steam D. Wet hydrogen sulfide. Answer: A. Explanation: For the design and load analysis of spherical tank supports in 4-496, the following statement is correct: A. The components of the spherical tank supports must have sufficient strength and stiffness to withstand various loads acting on the spherical tank. B. The welds connecting the spherical tank supports to the sphere shell must have sufficient welding length and strength, and measures must be taken to reduce stress concentration. C. The static load acting on the pillar is mainly gravitational load. D. The dynamic loads acting on the pillar are mainly wind loads and seismic loads. Answer: AB. Explanation: Based on the design principles of spherical tank supports, complete the following questions. 4-497 The anchor bolt holes provided on the bottom plate of the spherical tank support should be horizontally oriented oval holes, to facilitate adjusting the verticality of the support as well as its movement during the overall heat treatment of the spherical tank. A. Correct B. Incorrect Answer: A Explanation: According to page 17 of the GB 12337 -2014 standards, complete the following questions based on the design principles for spherical tank supports.  For spherical tanks specified with post-weld heat treatment in 4-498, foundation shims should be embedded in the foundation surface. A. Correct B. Incorrect Answer: A 4-499 According to the GB/T 12337-2014 standard, when calculating the thickness of spherical shells, how should negative deviations in the thickness of the steel be handled? ( ). A. In accordance with the regulations of steel standards ； B. When the negative deviation in the thickness of the steel is not greater than 0.3 mm, it can be ignored ； C. When the negative deviation of the steel thickness is not greater than 0.3 mm and does not exceed 6% of the nominal thickness, it can be ignored ； D. When determining the nominal thickness, the negative deviation in steel thickness can be ignored ； E. When determining the nominal thickness, the negative deviation in steel thickness must be taken into account ； Answer: C. Explanation: According to Article 3.8.3.2 of GB 12337-2014, which deals with the structure and material selection of spherical tank supports, determine whether the following statements are correct. For spherical tanks storing cryogenic media with a capacity of 4–500, it is advisable to use segmented support columns. A. Correct B. Incorrect Answer: A Explanation: From the book on chemical equipment design – Spherical tanks and large storage tanks, 2005, page 37 – determine whether the following statements regarding the structure and material selection of spherical tank supports are correct. When segmental struts are used in 4-501, the upper segment of the strut typically accounts for (  ) of the total height of the strut. A. 10%～20% B. 20%～30% C. 30%～40% D. 40%～50% Answer: C Explanation: Comprehensive Book on Chemical Equipment Design – Spherical Vessels and Large Storage Tanks, 2005, p. 37. Regarding the structure and material selection of spherical vessel supports, are the following statements correct? Vent holes are provided on pillar 4-502 to prevent the pillar from bursting due to increased pressure caused by the thermal expansion of gases inside it in case of a fire. A. Correct B. Incorrect Answer: A Explanation: Chemical Equipment Design, Volume on Spherical Vessels and Large Storage Tanks, 2005, pages 384-503. The corrosion margin for a certain spherical vessel is 2 mm, and the negative deviation in the thickness of the steel plate is 0.3 mm. The calculated thickness of the upper spherical shell is 43.96 mm. Determine the thinnest nominal thickness that can be used for this upper spherical shell. A. 46mm B. 47mm C. 48mm D. 52mm Answer: A Explanation: The nominal thickness equals the calculated thickness plus the corrosion allowance plus the negative deviation; however, when the negative deviation is not more than 0.3mm and does not exceed 6% of the nominal thickness, it can be ignored. In what conditions should Q345R spherical shell steel plates with a thickness of 4-50440mm be used? ( ) A. Hot rolling B. Normalizing C. Quenching D. Quenching and tempering Answer: B Explanation: According to clause 4.2.3 of GB 12337-2014, and in line with the NB/T 47042 standard, the characteristics of multi-support horizontal containers are described. 4-505 Which of the following descriptions is correct? （ 　） A. When the L/Di ratio is very large, in order to avoid severe deformation of the cylinder and excessive stress caused by an overly large span between supports, it is possible to consider using three or more supports. B. Whether it is a two, three, or multiple saddle configuration, there must be only one fixed support. C. The middle support of the three supports should be treated as a fixed end. D. The reinforcement ring can effectively reduce the stress conditions at the saddle area. Answer: ABCD. Explanation: A – JB/T4731-2005, Definition 4.2; B – Container construction technology, P207; C – Container construction technology, P207; D – NB/T47042-2014, 6.3.34-506. For horizontal containers with three saddles, it is necessary to impose restrictions on () in order to avoid the additional support forces that arise as well as the extra bending moments generated within the container. A. Irregularity of the foundation B. Vertical error existing between two adjacent saddles during installation C. Uneven settlement of the foundations of two adjacent saddles D. Horizontal error existing between two adjacent saddles during installation. Answer: C. Explanation: Container construction technology, page 207; according to standard NB/T 47042, the characteristics of horizontal containers with multiple supports are outlined. In the design of horizontal vessels with multiple supports, when A=0.207L (where L is the distance between the tangents to the vessel shell), the absolute value of the bending stress that determines the vessel thickness is minimized. ( ) A. Correct B. Incorrect Answer: B Explanation: In the flange connections of pressure vessels subjected to internal pressure, what type of load acts on their bolts? A. Tension B. Pressure C. Shear force D. Bending moment Answer: AD Explanation: To prevent the two plates from sliding relative to each other, the friction force required is F2 = μ × N; μ is the coefficient of static friction between the two plates. N- The normal force provided by n pairs of bolts and nuts. (        ) A. Correct B. Incorrect Answer: B Explanation: On a plate with bolt holes, the plate is fixed to a foundation using bolts. If a force F2 is applied at one of the end faces of the plate, perpendicular to the contact surface between the plate and the foundation, such that the plate is on the verge of sliding, then the formula for the force P exerted on each bolt is (   ), where F1 is the frictional force generated between the plate and the foundation when a bolt is tightened, n is the number of bolts, and μ is the maximum static friction coefficient between the plate and the foundation. A. P = F1/n B. P = F2/(\mu n) C. P = F2/n D. P = F2/μ. For pressure vessels with a cylindrical body and a head connected together, briefly describe where failure occurs first. 4-511 Theoretically, the areas of stress concentration are calculated assuming that the material is within ( ). A. Elasto-plastic region B. Elastic region C. Plastic region Answer: B Explanation: Theoretically, stress concentrations are calculated assuming that the material is in the elastic region; however, when a pressure vessel fails, the material is already in the plastic region, no longer satisfying the conditions of elastic theory. Stress is then redistributed according to plasticity laws, and the point where the stress is highest is no longer at the joints. So first, the failure occurs not at the joint itself, but at a point a certain distance away from the junction between the head and the cylinder. When a 4-512 pressure vessel fails, the material at the site of failure is in (       ) state, and it no longer meets the conditions of (       ). A. Plastic region B. Elastic region C. Elastic theory D. Plastic theory Answer: AC Explanation: Theoretically, stress concentrations are calculated assuming that the material is in the elastic region; however, when a pressure vessel fails, the material is already in the plastic region, no longer satisfying the conditions of elastic theory. Stress is then redistributed according to plasticity laws, and the point where the stress is highest is no longer at the joints. Therefore, the condition under which the formula for calculating the safe discharge capacity of the 4-515 safety valve – which is located not at the connection point but at a distance from it, at the junction between the head and the cylinder {Ws = (A*C*Kf*Pd) / (Kb*13.16*^0.5), unit: Kg/h} – holds true is (      ). A. Pb/Pd＜B (sonic expansion) B. Pb/Pd=B (sonic expansion) C. Pb/Pd≤B (sonic expansion) D. Pb/Pd≥B (sonic expansion) Answer: C Explanation: Kb —— back pressure correction coefficient, dimensionless. A — Area of the safety valve throat passage, mm2. Z — Compressibility coefficient of the gas in the vented state, dimensionless. Td — temperature of the gas in the vented state, K. M — molecular weight of the gas, kg/kmol. Kf——Rated discharge coefficient of the safety valve (structural characteristic coefficient), dimensionless. Pd——gas discharge pressure, MPA A. 516 When the structure of the safety valve remains unchanged, the back pressure and the discharge pressure Pd stay constant, but the discharge medium is replaced with another one, which parameters in the formula for calculating the safe discharge capacity of the safety valve {Ws = (A*C*Kf*Pd) / (Kb*13.16*^0.5), unit: Kg/h} remain unchanged (indicated by symbols)? Why? A.Kb remains unchanged, as the back pressure and discharge pressure Pd remain constant ； B.Kb remains unchanged, as the structure of the safety valve has not changed ； C.Kf remains unchanged, as the structure of the safety valve has not changed ； D. A remains unchanged, as the structure of the safety valve has not changed ； Answer: A, C, D. Explanation: Briefly describe the factors related to the determination of the allowable stress of materials. The allowable stress value for material 4-517 is determined by (   ). A. Material B. Plate thickness range C. Design temperature D. Safety factor Answer: A, B, C, D Explanation: The allowable stress of a material is primarily determined by the material’s yield strength or tensile strength, as well as the safety factor. The yield strength and tensile strength of materials are dependent on temperature and material thickness. 4- The allowable stress value for material 518 is determined by ( ). A. Nominal thickness B. Calculated thickness C. Effective thickness D. Design thickness Answer: A Explanation: Calculated thickness refers to the thickness obtained through calculation using formulas.  The design thickness refers to the sum of the calculated thickness and the corrosion allowance. The nominal thickness is the design thickness plus the negative deviation of the steel plate thickness, rounded up to the standard specification thickness for the steel material. Effective thickness refers to the nominal thickness minus the corrosion allowance and the negative deviation of the steel thickness. Based on the definition of thicknesses above, the nominal thickness is the greatest thickness. The allowable stress of the material is selected based on its thickness and design temperature. From the allowable stress table for materials, it can be seen that for the same material, the greater the thickness, the lower the allowable stress. Briefly describe the factors related to the determination of the allowable stress of materials. Answer: When designing and calculating pressure vessels of type 4-519, designers only need to carry out design checks based on the nominal thickness of the shell; there is no need to consider the cutting thickness, which is left to the manufacturer’s discretion. ( ) A. Correct B. Incorrect Answer: B Explanation: When the cutting thickness is adjusted precisely, the allowable stress of the material may decrease. The classification of pressure vessels: 4-520. Ultra-high pressure vessels refer to those with a design pressure greater than 10.0 MPa. A. True B. False Answer: B Explanation: TSG 21-2016 (P103), Article A3. Ultra-high pressure vessels refer to pressure vessels with a design pressure of 100 MPa or higher. Pressure vessels are classified into grades 4–521; high-pressure vessels are those with a design pressure of 10 MPa or higher. A. Correct B. Incorrect Answer: B Explanation: TSG 21-2016 (P103), Article A3. Ultra-high pressure vessels refer to pressure vessels whose design pressure is greater than or equal to 10 MPa and less than 100 MPa. Pressure vessels are classified into four pressure grades: 4 – 522. Which of the following statements is incorrect? A. Pressure vessels with a design pressure of less than 1.6 MPa are low-pressure vessels. B. Pressure vessels are classified into four pressure grades based on their design pressure: low-pressure, medium-pressure, high-pressure, and ultra-high-pressure. C. Pressure vessels with a design pressure greater than 100.0 MPa are ultra-high pressure vessels. D. Pressure vessels with a design pressure of less than 0.1 MPa are low-pressure vessels. Answer: A and D. Explanation: TSG 21-2016 (P103), Clause A3 – Requirements for the roundness of external pressure cylinders and internal pressure cylinders. 4-523 After welding external pressure vessels, it is not necessary to use an arc gauge to check their roundness. A. Correct. B. Incorrect. Answer: B. Explanation: GB/T150.4 (P326), Clause 6.5.11 – Requirements for the roundness of external pressure cylinders and internal pressure cylinders. 4-524 According to GB/T150, which statement regarding the roundness of cylinders is correct? A. The roundness requirements for external pressure cylinders are stricter than those for internal pressure cylinders. B. The roundness requirements for internal pressure cylinders are stricter than those for external pressure cylinders. C. The roundness requirements for internal pressure cylinders and external pressure cylinders are the same. D. Neither internal pressure cylinders nor external pressure cylinders have any requirements regarding roundness. Answer: A. Explanation: GB/T150.4 (P326), Clause 6.5.11. 4-525 The reason why the stability safety factor for external pressure vessels is higher than that for internal pressure vessels is: ( ). A. External-pressure vessels are more important than internal-pressure vessels. B. External-pressure vessels require the installation of external pressure reinforcement rings. C. Improving the resistance to instability is necessary to compensate for manufacturing errors. D. The calculated length of the cylinder in external-pressure vessels is greater than that in internal-pressure vessels. Answer: C. Explanation: The stability safety factor refers to the factor that provides resistance against instability under external pressure. The determination of the stability safety factor for externally pressurized vessels depends mainly on two factors: 1. The reliability of the calculation formulas ； 2. The roundness requirements for the cylinder that can be ensured during the manufacturing process. The series of curve families in Figure 4-2, “Curve of external pressure strain coefficient A”, in GB/T150.3—2011 for external pressure instability consist of vertical and inclined parts, representing respectively which two types of external pressure instability modes: A. Axial instability and circumferential instability; B. Oblong cylinders and short cylinders; C. Flat-end cover instability and cylinder instability; D. Head instability and cylinder instability. Answer: B. Explanation: The critical pressure of cylinders under external pressure can be expressed as Pcr = KE(δe/Do)3, where K is related to δe/Do and L/Do within the cylinder. In the graph, the horizontal axis A represents ε, while the vertical axis is L/Do; thus, different values of δe/Do result in a set of curves, and therefore this graph is applicable to long and short cylinders made of various metals. For external pressure instability 4-527, according to Figure 4-2 “Curve A of external pressure strain coefficient” in GB/T150.3—2011, which of the following statements is correct? A. The external pressure stability of short cylinders is independent of the cylinder’s length. B. The external pressure stability of long cylinders is independent of the cylinder’s length. C. The external pressure stability of both short and long cylinders is independent of the cylinder’s length. D. The external pressure stability of both short and long cylinders is dependent on the cylinder’s length. Answer: B. Explanation: The critical pressure for cylinders under external pressure can be expressed as Pcr = KE(δe/Do)3, where K is a value related to δe/Do and L/Do within the cylinder. In the graph, the horizontal axis A represents ε, while the vertical axis is L/Do; thus, different values of δe/Do result in a set of curves, and therefore this graph is applicable to long and short cylinders made of various metals. As can be seen from the graph, the straight segments of the different Do/δe curves perpendicular to the horizontal axis indicate that the critical pressure is independent of the vertical axis L/Do, which corresponds to an oblong cylinder. During external pressure instability or circumferential instability from 4 to 528 weeks, the wavenumber of short cylinders is 2, while that of long cylinders is ≥3. A. True B. False Answer: B Explanation: According to the Bresse formula, when the length-to-diameter ratio of a cylinder increases to a certain level and instability occurs, two wave patterns appear; moreover, the critical pressure for instability is independent of the length. Cylinders of this type are referred to as long cylinders. (Training Manual for Pressure Vessel Design Engineers) The welding joint coefficient 4-529 in the formula for calculating the thickness of internal-pressure cones – which welding joint coefficient refers to here? A. Circumferential welding joints of the cone shell B. Longitudinal welding joints of the cone shell C. Butt joints between the larger end of the cone shell and the cylinder D. Butt joints between the smaller end of the cone shell and the cylinder Answer: B Explanation: The welding joint coefficient for a cone shell refers to the coefficient applicable to joints subjected to circumferential membrane stresses; it is thus the coefficient for the longitudinal welds of the cone shell. When determining the thickness of the reinforced section at the large end of the conical shell using the welding joint coefficient 4-530, the corresponding welding joint coefficient to be used is: A. The circumferential welding joint coefficient between the conical shell and the large-end cylinder; B. The longitudinal welding joint coefficient of the conical shell; C. The longitudinal welding joint coefficient of the large-end cylinder; D. The minimum value among the above three; E. The maximum value among options A, B, and C. Answer: A. Explanation: The welding joint coefficient applicable to the reinforced section at the large end of the conical shell refers to the joint coefficient of the circumferential weld connecting the conical shell and the cylinder. When determining the thickness of the reinforced section at the smaller end of the conical shell using the welding joint coefficient 4-531, the corresponding welding joint coefficient to be used is: A. The longitudinal welding joint coefficient of the conical shell; B. The longitudinal welding joint coefficient of the cylinder at the smaller end; C. The circumferential welding joint coefficient between the conical shell and the cylinder at the smaller end; D. The minimum value among the above three; E. The maximum value among options A, B, and C. Answer: C. Explanation: For the reinforced section at the smaller end of the conical shell, it refers to the welding joint coefficient of all those welds that are subjected to circumferential local membrane stresses at the junction between the conical shell and the cylinder, and the smallest value among these coefficients is taken. Therefore, this weld joint coefficient includes the joint coefficients for the longitudinal welds of the conical shell, the longitudinal weld of the cylinder, and the joint weld between the small end of the conical shell and the cylinder connection ring, with the smallest value being adopted. For the optimized design of flanges 4-532, which of the following measures can be taken to achieve this goal? A. Increase the number of studs B. Decrease the number of studs C. Increase the diameter of the studs D. Decrease the diameter of the studs Answer: A, D Explanation: For the optimized design of flanges 4-533, increasing the diameter of the circle around which the screw holes are distributed, increasing the number of studs, increasing the diameter of the studs, and controlling the width of the gaskets can all contribute to an optimized design of the flange. A. Correct B. Incorrect Answer: B Explanation: For the optimized design of flanges 4-534, decreasing the diameter of the circle around which the screw holes are distributed, decreasing the number of studs, decreasing the diameter of the studs, and controlling the width of the gaskets can all help to optimize the flange design. A. Correct B. Incorrect Answer: B Explanation: Reducing the number of studs and their diameter reduces the area of the bolts. In the calculation of the torque on the flange, the lever arm for each load is the distance from that load to the center of the bolt. Therefore, reducing the diameter of the circle around which the bolts are located can effectively decrease the lever arms involved in calculating the torque on the flange; however, it is necessary to ensure that the specifications and quantity of bolts are appropriate. When the required diameters of the bolt circles in the circumferential and radial directions for the selected bolts are close to each other, the diameter of the bolt circle reaches its minimum value, which represents the most optimal configuration. Intergranular corrosion in stainless steel 4-535: From the perspective of raw materials, increasing the carbon content in the steel can prevent intergranular corrosion in stainless steel. A. True B. False Answer: A Explanation: Measures to prevent intergranular corrosion: 1. Solution treatment ； 2. Reduce the carbon content in steel ； 3. Add stabilizing carbide elements. Intergranular corrosion in stainless steel 4-536: From the perspective of raw materials, adding stabilizing elements to the steel can prevent intergranular corrosion in stainless steel. A. True B. False Answer: A Explanation: Measures to prevent intergranular corrosion: 1. Solution treatment ； 2. Reduce the carbon content in steel ； 3. Add stabilizing carbide elements. Intergranular corrosion occurs in stainless steel 4-537. Which of the following statements regarding intergranular corrosion in stainless steel is correct? A. When stainless steel is exposed to an environment prone to intergranular corrosion, a corrosion margin should be considered. B. Stainless steel should not be used in environments where intergranular corrosion can occur. C. Solvent treatment can prevent intergranular corrosion in stainless steel. D. When stainless steel is exposed to an environment prone to intergranular corrosion, post-weld heat treatment should be carried out. Answer: C. Explanation: Measures to prevent intergranular corrosion: 1. Solvent treatment ； 2. Reduce the carbon content in steel ； 3. Add stabilizing carbide elements. 538 Creep failure is one of the main forms of failure in externally pressurized vessels. A. True B. False 539 Failure caused by insufficient strength is one of the main forms of failure in externally pressurized vessels. A. Correct B. Incorrect. Failure modes of pressure vessels under external pressure 540: The failure modes that should be given special attention for pressure vessels under external pressure include: A. Fatigue failure B. Failure due to insufficient strength C. Corrosion failure D. Instability E. Creep failure. Methods of forming convex heads 541: Whole-plate forming is the only method for manufacturing convex heads. A. Correct B. Incorrect. Methods of forming convex heads 542: Splitting the head into sections and then welding them together is not allowed as a method for forming convex heads. A. Correct B. Incorrect. Methods of forming convex heads 543: The common methods for forming convex heads include: A. Forming after assembling the plates first B. Spin-forming of heads C. Whole-plate forming D. Stamping of heads E. Splitting into sections and then welding them together. Heat treatment of pressure vessels 544: Post-weld stress relief heat treatment is the only type of heat treatment required for pressure vessels. A. Correct B. Incorrect. Heat treatment of pressure vessels 545: The heat treatment methods used in the manufacturing of carbon steel pressure vessels include: A. Solution treatment B. Heat treatment to restore mechanical properties C. Stabilization treatment D. Normalizing treatment E. Dehydrogenation treatment. Heat treatment of pressure vessels 546: Heat treatment of pressure vessels can generally be divided into post-weld stress relief heat treatment, heat treatment to improve mechanical properties, and intermediate heat treatment. A. Correct B. Incorrect. Flange types 547: The correct statements regarding flange types are: A. Based on their degree of integrity, flanges can be classified as slip-on flanges and butt-welded flanges. B. Based on their degree of integrity, flanges can also be classified as necked flanges and plate flanges. C. Based on their degree of integrity, flanges can further be classified as narrow-face flanges and wide-face flanges. D. Slip-on flanges are not considered integral flanges. Flange types 548: Loose flanges should be calculated as if they were integral flanges. A. Correct B. Incorrect. Flange types 549: Flanges of any type must not be calculated as if they were integral flanges. A. Correct B. Incorrect. Product welding specimens 550: For pressure vessels containing toxic substances and having Class A longitudinal welds, product welding specimens must be prepared for each vessel according to GB/T150 requirements. A. Correct B. Incorrect. Product welding specimens 551: For pressure vessels made of 12Cr2Mo1VR, product welding specimens must be prepared according to GB/T150 requirements. A. Correct B. Incorrect. Product welding specimens 552: For pressure vessels with Class A longitudinal welds, GB/T150 requires that product welding specimens be prepared for each vessel in the following cases: A. Low-temperature vessels B. Ultra-high-pressure vessels C. Steel vessels whose material properties are improved or restored through heat treatment during manufacturing D. High-pressure vessels E. Vessels with a maximum allowable working pressure specified in the design. 553: The maximum allowable working pressure of a vessel is the highest operating pressure that the vessel can experience during normal operation. A. Correct B. Incorrect. Maximum allowable working pressure 554: The maximum allowable working pressure of a vessel is determined by calculating the thickness of each pressure-bearing element, taking into account all the loads acting on those elements, and then selecting the minimum value among them. A. Correct B. Incorrect. 555: Which of the following steps are used to determine the maximum allowable working pressure of a vessel? ( ) A. Determining the appropriate temperature and selecting the allowable stress for the relevant material B. Determining the loads acting on each pressure-bearing element C. Determining whether there are openings in each pressure-bearing element D. Calculating the nominal thickness of each pressure-bearing element to ensure it meets the design requirements E. Considering the effective thickness of each pressure-bearing element along with the requirements mentioned in A and B, and calculating the maximum pressure that each element can withstand, then selecting the minimum value. Low-temperature vessels 556: The correct statements regarding low-temperature vessels are: A. When a vessel is operating under low-temperature and low-stress conditions, it does not need to be treated as a low-temperature vessel. B. When a vessel is operating under low-temperature and low-stress conditions, it should be treated as a low-temperature vessel. C. Low-temperature and low-stress conditions apply to 12Cr2Mo1VR. D. Low-temperature and low-stress conditions do not apply to bolt materials. Low-temperature vessels 557: Low-alloy steel pressure vessels with a design temperature of -20°C or lower are considered low-temperature vessels. A. Correct B. Incorrect. Low-temperature vessels 558: Austenitic stainless steel vessels with a design temperature of below -196°C are considered low-temperature vessels. A. Correct B. Incorrect. Durability strength and creep strength 559: The average value of the durability strength of a material after 100,000 hours of operation at the design temperature is considered the durability strength of that material at that temperature. A. Correct B. Incorrect. Durability strength and creep strength 560: The correct statements regarding allowable stress are: A. The allowable stress for aluminum and aluminum alloys is independent of the material’s durability strength. B. The allowable stress for carbon steel and low-alloy steel is independent of the material’s durability strength. C. The allowable stress for copper and copper alloys is independent of the material’s durability strength. D. The allowable stress for nickel and nickel alloys is independent of the material’s durability strength. 4-561: According to GB/T150, the allowable stress of a material depends only on the tensile strength and yield limit specified in the material standard. A. Correct B. Incorrect. Answer: B. The allowable stress value is the allowable value for the overall tensile stress in a thin film. It is determined for materials that have been successfully used in practice, by dividing their mechanical properties (σb, σs, σD, σn) by the corresponding safety factors (nb, ns, nD, nn). This value depends not only on the material’s tensile strength and yield strength but also on its high-temperature fatigue strength and high-temperature creep strength. Explanation: Page 37 of the interpretation of GB/T 150.1-2014 – I. Determination of the coefficient for the basic allowable stress of materials; Page 9 of the interpretation of GB/T 150-1989 – IV. Basis for determining the ultimate allowable stress. ✔Quality Plan 4-562: During the manufacturing of pressure vessels, the manufacturing unit shall prepare a quality plan for such vessels. A. Correct B. Incorrect Answer: A. Clause 4.1.4 of TSG 21-2016: Quality Plan (1) Before manufacturing pressure vessels, the manufacturing unit shall develop a comprehensive quality plan in accordance with these regulations; such a plan shall include, as a minimum, the control points for the manufacturing processes of the vessels or pressure-bearing components, as well as the inspection items to be carried out. Explanation: Clause 4.1.4(1) of TSG 21-2016 ✔4-563 The quality plan for the manufacture of pressure vessels is essentially the inspection plan for such equipment ； For those requiring type testing, the quality plan also includes the details of the type testing. A. Correct B. Incorrect Answer: A. Clause 4.1.4 of TSG 21-2016: Quality Plan (1) Before manufacturing pressure vessels, the manufacturing unit shall formulate a comprehensive quality plan (inspection plan) in accordance with these regulations; such a plan shall include, as a minimum, the control points for the manufacturing process of the vessels or pressure-bearing components, as well as the inspection items to be carried out. 6.2 In manufacturing inspection, item (6) of 6.2.1.1.1 requires a type test report for the product undergoing type testing. Explanation: Clause 4.1.4(1) of TSG 21-2016 ； Clause 6.2.1.1.1(6) of TSG 21-2016.      ✔Quality Plan 4-564: The main contents of the manufacturing quality plan prepared by the pressure vessel manufacturing unit include: A. Control points for the manufacturing process of the vessel or pressure components; B. Inspection items for the vessel or pressure components; C. Construction drawings; D. Strength calculation reports; E. Risk assessment reports. Answer: A, B. Clause 4.1.4 of TSG 21-2016: Quality Plan (1) Before manufacturing pressure vessels, the manufacturing unit shall formulate a comprehensive quality plan (inspection plan) in accordance with these regulations; such a plan shall include, as a minimum, the control points for the manufacturing process of the vessels or pressure-bearing components, as well as the inspection items to be carried out. Drawing documents (construction drawings, strength calculation reports, risk assessment reports) should also serve as the basis for inspection. Explanation: Clause 4.1.4(1) of TSG 21-2016.      ✔Determination of the hydrostatic test pressure for fixed-tube-sheet heat exchangers 4-565 When determining the hydrostatic test pressure for the tube bank of a fixed-tube-sheet heat exchanger, which pressure-bearing components need to be considered? A. Tube sheet B. Tube bank shell C. Partition plates D. Nozzles E. Heat exchange tubes Answer: A, B, D, E. Analysis: All pressurized components of the pipe train should be considered. Note 2 to 4.6.2.2 of GB/T 150.1-2011. ✔Determination of the hydrostatic test pressure for fixed-tube-sheet heat exchangers 4-566 Which of the following steps are related to determining the hydrostatic test pressure for the tube bank of a fixed-tube-sheet heat exchanger? A. Determine the allowable stresses for the main pressure-bearing components and fasteners at the design and test temperatures, and select the smaller value of t/B. Decide whether a leak test is necessary/C. Ensure that the value of t is not lower than the minimum of the allowable stresses determined by the tensile strength and yield strength of each material/D. Calculate the test pressure pT = 1.15p/t/E. Calculate the test pressure pT = 1.25p/t Answer: A, C, E. The test pressure for the hydraulic test is PT=1.25p/t. When the materials used for the various main pressure-bearing components of the container, such as cylinders, heads, nozzles, equipment flanges (or manway flanges), and their fasteners, are different, the minimum value among the p/t ratios of the materials of these components shall be adopted ； t should not be lower than the minimum value of the allowable stresses determined by the tensile strength and yield strength of the respective materials. Explanation: GB/T 150.1-2011, clause 4.6.2.2 a), b), and notes 2 and 3. ✔Determination of the hydraulic test pressure for fixed-tube-sheet heat exchangers 4-567: When determining the hydraulic test pressure for the tube bank of a fixed-tube-sheet heat exchanger, this value must not be less than the hydraulic test pressure for the shell side. A. Correct B. Incorrect Answer: B.  The pressure testing sequence for a fixed-tube-sheet heat exchanger is to first perform pressure testing on the shell side, while simultaneously checking the tube ends ； Proceed with the pipe side pressure test. The hydrostatic test pressure for the tube side and the shell side is determined based on their respective design pressures; when the design pressure of the tube side is lower than that of the shell side, a normal testing procedure can be followed ； When the design pressure of the tube side is higher than that of the shell side, the joint pressure testing shall be carried out in accordance with the specifications in the drawings or as agreed upon by both the supplier and the buyer. Some increase the test pressure in the shell side to match that of the tube side, while others conduct an ammonia leakage test after pressuring the shell side. Explanation: Clause 4.6.2 of GB/T 150.1-2011, and clauses 8.13.2 and 8.13.6 of GB/T 151-2014.    ✔For pressure vessels whose standard minimum tensile strength of the material specified in conditions 4-568 of the empirical design method is less than 540 MPa, it is entirely possible to carry out empirical design in accordance with GB/T 150-2011. A. Correct B. Incorrect Answer: B. To carry out comparative empirical design, the following three conditions must be met simultaneously: 1 Pressure vessels that cannot be designed in accordance with GB/T 150.3 ； Pressure vessels whose standard minimum tensile strength of the material is less than 540 MPa ； 3 Pressure vessels with a medium level of toxicity of the filling medium or below. It is incorrect to say that design can be based on comparative experience simply by meeting one condition. Explanation: GB/T 150.1-2011, Clause D.1.3. ✔For condition 4-569 of the comparative empirical design, containers in which the medium contained has a toxicity level of moderate or lower can certainly be designed using GB/T150-2011 for comparative empirical purposes. A. Correct B. Incorrect Answer: B. To conduct a comparative empirical design, the following three conditions must be met simultaneously: 1. Pressure vessels that cannot be designed in accordance with GB/T 150.3 ； 2. Pressure vessels whose standard minimum tensile strength of the material is less than 540 MPa ； 3. Pressure vessels with a medium level of toxicity of the filling medium or below. It is incorrect to say that design can be based on comparative experience simply by meeting one condition. Explanation: GB/T 150.1-2011, Clause D.1.3. ✔For condition 4-570 of comparative empirical design, the correct statements regarding comparative empirical design are as follows: A. Pressure vessels that cannot be designed in accordance with GB/T150.3 should be subjected to comparative empirical design using GB/T150-2011. B. The vessel under comparative empirical design and the reference vessel may have different or dissimilar structures. C. The design unit shall obtain the certification documents regarding the safe use of the reference vessel, as well as the design documents provided by the user. D. Vessels undergoing comparative empirical design do not need to meet the requirements of the Code for Pressure Vessels. Answers: A, C. GB/T 150.1-2011 stipulates that for comparative empirical design, the following three conditions must be met simultaneously: 1. Pressure vessels that cannot be designed in accordance with GB/T 150.3 ； 2. Pressure vessels whose standard minimum tensile strength of the material is less than 540 MPa ； 3. Pressure vessels with a medium level of toxicity of the filling medium or below. The design unit shall obtain the certification documents and design files provided by the user regarding the safe use of the reference container. The Solid Content Regulations stipulate that comparable empirical design methods must undergo a technical review in accordance with Article 1.9 of the Solid Content Regulations. Explanation: GB/T 150.1-2011, clauses D.1.3 and D.1.4. Clause 3.1.5 of TSG 21-2016.  ✔Determination of impact energy for welded joints 4-571. Which of the following statements regarding impact tests on welded joints is correct? A. Only welded joints of low-temperature pressure vessels require impact testing. B. Welded joints of austenitic stainless steel vessels do not need to undergo impact testing. C. The temperature for the impact test should not be higher than the temperature specified in the standards. D. Impact tests on welded joints of low-temperature vessels should not include the heat-affected zone. Answer: C. NB/T4716-2011 Clause 5.1 ； It is stipulated that when the relevant codes, standards, and design documents for pressure-bearing equipment require impact tests on welded joints, impact tests must be conducted on the welded specimens of the products. Clause 6.3: Impact Tests – The impact tests on welded joints include the weld area and the heat-affected zone ； When the impact test temperature is not specified in the design documents (drawings) or relevant technical documents, the impact test temperature shall not be higher than the lowest designed metal temperature of the pressure-bearing equipment. Explanation: Clause 5.1 of NB/T4716-2011 ； 6. 3 items: Impact test and Table 4. ✔The impact energy of welded joints is specified as 4-572. The impact absorption energy of welded joints made from carbon steel and low-alloy steel plates used in pressure vessels shall not exceed the values given in Table 1 of GB/T150.2. A. True B. False Answer: B. The acceptable criterion for the impact test of welded joints according to standard NB/T4716-2011 is not less than that specified in Table 4 ； Table 1 in GB/T 150.2-2011 is almost identical to Table 4 in NB/T4716-2011. Explanation: Clause 6.3.4(b) of NB/T4716-2011, Table 4 of NB/T4716-2011, and Table 1 of GB/T 150.2-2011. ✔Determination of the impact energy of welded joints 4-573: For materials whose minimum standard tensile strength increases with thickness, when determining the impact absorption energy of their welded joints, the highest value of Rm for that steel should be used to calculate the impact absorption energy value. A. Correct B. Incorrect Answer: A. As specified in Table 1 of GB/T 150.2-2011, for steels whose Rm value decreases as the thickness increases, the impact energy value is determined based on the Rm value corresponding to the minimum thickness range of that steel; in other words, the impact absorption energy value is determined using the highest Rm value of that steel. Explanation: Note in Table 1 of GB/T 150.2-2011. ✔Supply condition of carbon steel and low-alloy steel plates 4-574: Q345R, which is used for the inner liners of multi-layer containers, should be used in the normalized state. A. Correct B. Incorrect Answer: A. GB/T 150.2-2011 stipulates that Q245R and Q345R, used for the inner cylinders of multi-layer containers, shall be used in the normalized state. Explanation: According to clause 4.1.4 a) of GB/T 150.2-2011, carbon steel and low-alloy steel plates in supply states 4–575 should be used in the normalized state for Q245R materials with shell thicknesses greater than 30 mm. A. Correct B. Incorrect Answer: B. GB/T 150.2-2011 stipulates that Q245R and Q345R used for shells with a thickness greater than 36 mm should be used in the normalized state. Explanation: GB/T 150.2-2011, clause 4.1.4 b). ✔Supply conditions for carbon steel and low-alloy steel plates 4-576 Which of the following carbon steel and low-alloy steel plates should be used in the normalized state? A. Q345R used for shells with a thickness greater than 36 mm. B. Steel plates used for containers that contain stress-corrosion-causing media. C. Q245R used for the inner liners of multi-layer containers. D. Steel plates used for containers that hold highly toxic media. E. Q245R and Q345R with a thickness greater than 50 mm, used for other pressure-bearing components such as flanges, tube sheets, and flat covers. Answer: A, C, E. GB/T 150.2-2011 stipulates that Q245R and Q345R used for the inner cylinders of multi-layer vessels shall be used in the normalized state ； Q245R and Q345R used for shell thicknesses greater than 36 mm should be used in the normalized state ； Q245R and Q345R with a thickness greater than 50 mm, used for other compressed components (flanges, tube sheets, flat covers, etc.), should be used in the normalized state. Explanation: GB/T 150.2-2011, clause 4.1.4, items a), b), c).      ✔4-577 Containers holding extremely toxic hazardous media are subjected to ultrasonic testing, sheet by sheet, using carbon steel or low-alloy steel plates. A. Correct B. Incorrect Answer: B. TSG21-2016 stipulates that for containers with a thickness of 12 mm or more that are used to hold highly toxic substances, the steel plates used must be in the normalized state. Less than 12mm, no need. Explanation: Clause 2.2.1.4.1(1) of TSG21-2016.    ✔4-578 Ultrasonic testing of carbon steel or low-alloy steel plates used for containers in wet hydrogen sulfide stress corrosion environments is carried out sheet by sheet. A. Correct B. Incorrect Answer: B. TSG21-2016 stipulates that for steel plates used in containers intended for use in a wet hydrogen sulfide stress corrosion environment, where the thickness is 12 mm or greater, these plates must be used in their normalized state. Less than 12mm, no need. Explanation: Clause 2.2.1.4.1(2) of TSG21-2016.    ✔Ultrasonic testing of carbon steel and low-alloy steel plates 4-579 Which of the following are factors that determine that carbon steel or low-alloy steel plates used for containers should be subjected to ultrasonic testing on a sheet-by-sheet basis? A. Thickness of the steel B. Type of material C. Condition in which the material is supplied D. Operating pressure of the container E. Inner liner of multi-layer containers Answer: A, B, E. According to TSG 21-2016 2.2.1.4 for ultrasonic testing of steel plates and GB/T 150.2-2014 4.1.8, the thickness of the steel, the type of material, and the inner cylinder of multi-layer containers are all factors that determine whether carbon steel or low-alloy steel plates used for containers should be subjected to ultrasonic testing on a sheet-by-sheet basis. Explanation: Clause 2.2.1.4 of TSG 21-2016, Clause 4.1.8 of GB/T 150.2-2014, and Table 3. ✔For forged parts made of carbon steel and low-alloy steel with grades 4–580, the design pressure of the container can be used as a factor in determining the grade of those forged parts. A. True B. False Answer: B. Clause 6.1.3 of GB/T 150.2-2014 stipulates that the selection of Grade III or Grade IV forgings is not determined by design pressure factors. Explanation: Clause 6.1.3 of GB/T 150.2-2014. ✔The design temperature of a vessel can be used as a factor in determining the forging grade 4-581 for carbon steel and low-alloy steel plates in that vessel. A. True B. False Answer: A. Clause 6.1.3 of GB/T 150.2-2014 stipulates that for low-temperature carbon steel and low-alloy steel forgings with a design temperature below -20°C and a nominal thickness greater than 200 mm, Grade III or Grade IV forgings shall be selected. Explanation: GB/T 150.2-2014, clause 6.1.3 (d).     ✔4-582 What factors are considered in determining the grade of carbon steel and low-alloy steel forgings? A. The shape and purpose of the forging B. The nominal thickness of the forging C. The impact energy value of the forging D. The operating conditions to which the forging will be subjected E. The minimum standard tensile strength value of the forging Answer: A, B, D, E.  Clause 6.1.3 of GB/T 150.2-2014 specifies the conditions for selecting the grades of carbon steel and low-alloy steel forgings.    Explanation: Clause 6.1.3 of GB/T 150.2-2014.  ✔Tensile testing and impact energy values for stud blank materials: 4-583. If the tensile testing and impact energy values for carbon steel and low-alloy steel stud blank materials are not satisfactory, such materials must be discarded and cannot be used again. A. True B. False Answer: B. Clause 7.1.3 of GB/T 150.2-2014 specifies that when the tensile test results or impact energy values for carbon steel and low-alloy steel stud blanks are unsatisfactory, 2 additional tensile specimens and 3 additional impact specimens shall be taken from the same blank for retesting ； The batch of blanks deemed unqualified can be re-heat-treated in accordance with the provisions of 7.1.2. ✔4-584 If the tensile test results and impact energy values for the raw materials of carbon steel and low-alloy steel studs are not satisfactory, their original heat treatment requirements should be changed and they should be reheated before being tested again. A. Correct B. Incorrect Answer: B. According to clauses e), f), and g) of 7.1.3 in GB/T150.2-2011, the answer is correct. Tensile tests and impact energy values for stud blank materials: 4-585. When the tensile test results and impact energy values of carbon steel and low-alloy steel stud blank materials do not meet the required standards, reasonable measures that can be taken include: A. If the application scenario for the studs is not demanding, the acceptance criteria can be appropriately lowered. B. Since studs are not subjected to compressive forces, they can still be used regardless of whether the test results of the blank materials are satisfactory or not. C. Replacing them with materials of higher strength. D. Subjecting them to heat treatment again according to the original requirements, and conducting tests on new samples in accordance with the standard requirements. Answer: D. According to clause 7.1.3(g) of GB/T150.2-2011, the answer is correct. 4-586. Factors that need to be considered when selecting fasteners for pressure vessels include: All of the following. A. The temperature range suitable for the fasteners. B. The compatibility between bolts and nuts. C. The toxicity of the material contained within the vessel. D. The minimum requirements regarding impact energy absorption. E. The chemical composition requirements for the fastener materials. Answer: ABCDE. Explanation: Per clause 7.1 of GB/T150.2-2011. HG/T 20613-2009 4 Materials. Verification per clause 3.2.5 of TSG 21-2016: 4–587 correct answers. The factors to be considered when selecting fasteners for pressure vessels include: (Select all): A. Temperature requirements for impact testing; B. Strength and plasticity requirements of the fasteners; C. Presence of flammable or explosive substances contained within; D. Requirements for non-destructive testing of the fasteners; E. Requirements regarding the thread type of the fasteners. Answer: ABCDE. Explanation: Based on Table 2 in clause 4.4.1 of GB/T150.1-2011 ； Articles 7.1 and 7.2 of GB/T150.2-2011, and Article 4 on materials in HG/T 20613-2009 ； A and B must be chosen. According to clause 3.2.5 of TSG 21-2016, special-grade high-strength studs must be used for containers holding liquefied petroleum gas and similar substances; therefore, option C should be chosen. In accordance with clause 6.7.3 of GB/T 150.4-2011, studs with a nominal diameter greater than M36 shall undergo surface inspection ； According to Clause 4 of NB/T 47027-2012, studs for flanges with a nominal pressure of 4.0 MPa or higher are required to undergo MT testing; therefore, D should be selected. According to clause 7.1.7 of GB/T 150.3-2011, fine-thread threads should be used when the nominal diameter of the bolt is greater than M48 mm; per clause C.5.2(c) of JB4732-1995 (confirmed in 2005), V-shaped threads are required for the studs in fatigue-resistant containers, hence option E should be chosen. Verification: The correct answer. Factors to consider when selecting fasteners for pressure vessels: 4-588. These factors include: A. Requirements regarding the machining precision of the fasteners; B. Requirements regarding the method of tightening the fasteners; C. The category of the vessel; D. Requirements for non-destructive testing of the fasteners; E. Requirements regarding the surface treatment of the fasteners. Answer: A, B, D, E. Explanation: HG/T 20613-2009 specifies restrictions on the use of commercial-grade fasteners. According to clause 6.7.3 of GB/T 150.4-2011, studs with a nominal diameter greater than M36 must undergo surface inspection ； According to Article 4 of NB/T 47027-2012, studs for flanges with a nominal pressure of 4.0 MPa or higher are required to undergo MT testing; therefore, D should be determined based on the category of the pressure vessel, as well as the medium and pressure involved. The relationship between volume and pressure is significant in this context. The choice of fasteners is not directly determined by the category of the pressure vessel – for pressure vessels in Category 3, high-strength bolts of specialized grades are usually selected, and this decision is based on factors such as the medium inside the vessel, rather than its category ； Therefore, there is no need to choose C. Verification: The answer is correct. Strain-hardened austenitic stainless steel – 4-589. When the operating temperature is below -100°C, strain-hardened austenitic stainless steel studs cannot be used. A. Correct B. Incorrect. Answer: B. Explanation: GB/T 150.2, clause 7.2.5(b). Verification: The answer is correct. Strain-hardened austenitic stainless steel 4-590: When the operating temperature does not exceed 50°C and the bolt size is not larger than M48, strain-hardened austenitic stainless steel studs can be used. A. Correct B. Incorrect Answer: B Explanation: GB150.2 Table 18. Verification: The answer is correct. Strain-hardened austenitic stainless steel 4-591: What precautions should be taken when using strain-hardened austenitic stainless steel studs? A. The operating temperature must not exceed 50°C. B. When the operating temperature is below -100°C, the impact absorption energy of the material must be at least 41 J. C. When the operating temperature is below -196°C, the impact absorption energy of the material must be at least 41 J. D. The tensile and impact tests must meet the standard requirements. E. The size of the studs. Answer: A, B, D, E Explanation: GB150.2 7.2.5b). Verification: The answer is correct. 4-592: The calculated length of a pressure vessel under external pressure is independent of the position of its support lines. A. Correct B. Incorrect Answer: Choose B. Verification: The answer is correct. For a cylindrical shell under external pressure, line 4-593 can be used as a support line if reinforcing angle steel is installed at either the larger or smaller end of the cone-shaped shell. A. Correct B. Incorrect Answer: Choose B. Explanation: According to Note 4.3.1 in GB/T 150.3-2011, it is necessary to calculate to ensure that the reinforcing angle steel has sufficient moment of inertia before such a section can be used as a support line. Verification: The correct answer is 4 – 594. Which of the following definitions of the support line in a cylinder under external pressure is correct? A. The support line refers to the area where a reinforcing ring is present on the cylinder wall. B. The support line refers to the reinforced section at the smaller end of the conical portion. C. The support line refers to the reinforced section at the larger end of the conical portion. D. The support line refers to the area where the cross-sectional thickness is sufficient to ensure that the stresses under external pressure meet the strength requirements. Answer: Choose D. Explanation: According to clause 4.3.1 of GB/T 150.3-2011. Verification: The answer is correct. Failure modes of elliptical and butterfly heads 4-595: Under internal pressure, only strength failure can occur in butterfly heads. A. True B. False Answer: B Explanation: According to page 121 of the GB/T 150-2011 standard, the compressive stresses on butterfly heads under internal pressure can cause elastic instability. Verification: The answer is correct. Failure modes of elliptical and butterfly heads 4-596: Under internal pressure, elliptical heads may experience elastic instability as a failure mode. A. True B. False Answer: Choose A. Explanation: According to page 120 of the GB/T 150-2011 standard, the compressive stresses on elliptical heads under internal pressure can lead to elastic instability. Verification: The answer is correct. Failure modes of elliptical and butterfly heads 4-597. The failure modes of elliptical and butterfly heads under internal pressure include: A. Fatigue failure B. Strength failure C. Corrosion failure D. Elastic instability failure. Answer: BD. Explanation: In addition to strength failure, elliptical and butterfly heads under internal pressure can also experience elastic instability failure. Explanation of GB/T 150-2011 standards, pages 120 and 121: Under internal pressure, the compressive stresses on elliptical and butterfly heads can cause elastic instability. Verification: The answer is correct. The meaning of f1 and f2 in the calculation of conical shells 4-598: In the calculation of conical shells, f1 refers to the axial force per unit length of circumference generated by wind loads at the larger end of the conical shell, in addition to pressure loads. A. True B. False Answer: B Explanation: Verification based on the symbol definitions in GB/T150.3P123 – the answer is correct. The meaning of f1 and f2 in the calculation of conical shells 4-599: In the calculation of conical shells, f1 refers to the axial force per unit length of circumference generated by seismic loads at the smaller end of the conical shell, in addition to pressure loads. A. True B. False Answer: B Explanation: Verification based on the symbol definitions in GB/T150.3P123: The answer is correct. 4-600 Which of the following statements regarding the definitions and calculation formulas for f1 and f2 in the analysis of conical shells is correct? A. f1 is the axial force per unit length of circumference generated at the large end of the conical shell due to external loads, in addition to pressure loads. B. f2 refers to the axial force per unit length of circumference generated at the small end of the conical shell due to internal pressure. C. f2 is the axial force per unit length of circumference generated at the small end of the conical shell due to external loads, in addition to pressure loads. D. f1 is the axial force per unit length of circumference generated at the large end of the conical shell due to internal pressure. E. The calculation formulas are as follows: FL or FS – the axial force at the large end or small end of the conical shell ； M – Bending moment at the larger end of the conical shell; N – Bending moment at the smaller end of the conical shell ； For the radius at the larger or smaller end of an RL or RS-cone shell, f1 = FL/(2πRL) + M/(πRL2), and f2 = FS/(2πRS) + N/(πRS2). Answer: A C. Explanation: Verification based on the symbol definitions in GB/T150.3P123 – the answer is correct. Characteristics of hybrid spherical shell structures 4-601: Hybrid spherical shell structures combine the characteristics of both ( ) and ( ). In such structures, except for the plates at the poles, all other parts are made of ( ) spherical shell plates. A. Spherical head, circular cylinder, spherical head, circular cylinder B. Spherical head, circular cylinder, football petal type, orange segment type C. Tower-type equipment, leg-type supports, spherical head, circular cylinder D. Football petal type, orange segment type, football petal type, orange segment type Answer: Choose D. Analysis: “Training Manual for Pressure Vessel Engineers” 24.1 Verification: The answer is correct. Features of hybrid spherical shell structures 4-602: Compared to the segmental type, the advantage of hybrid spherical shell structures is higher material utilization, shorter weld lengths, and a reduced number of shell plates; therefore, they are particularly suitable for small spherical tanks. A. Correct B. Incorrect Answer: B. Analysis: “Training Manual for Pressure Vessel Engineers” 24.1 Verification: The answer is correct. Features of hybrid spherical shell structures 4-603: The disadvantage of hybrid spherical shell structures is that, due to the presence of two types of shell plates, assembly and alignment are more complicated; there are still Y-shaped joints, and high precision in manufacturing is required. A. Correct B. Incorrect Answer: A. Analysis: Section 24.1 of the \"Training Manual for Pressure Vessel Engineers\" discusses the hybrid spherical shell structure, which features two types of shell plates – football-petal type shell plates, and Y-shaped joints at the connections between these plates and orange-petal type shell plates. This indeed makes assembly and alignment more complicated, and it requires a high level of precision in manufacturing; therefore, the answer is correct. Key points in shell plate design 4-604: When designing shell plates, their geometric dimensions should be kept as small as possible to save material. Meanwhile, taking into account the characteristics of the shell, each shell plate must be unique and not interchangeable. A. Correct B. Incorrect Answer: B. Analysis: “Training Manual for Pressure Vessel Engineers” 24.2 Verification: The answer is correct. Key points in shell plate design 4-605: When designing shell plates, the longitudinal welds on adjacent strips need not be offset from each other, but the weld layout should be even in order to reduce assembly stresses, constriction stresses, and residual stresses. A. Correct B. Incorrect Answer: B.  Analysis: “Training Manual for Pressure Vessel Engineers” 24.2 Verification: The answer is correct. Key points in shell plate design 4-606: When designing shell plates, which of the following factors should be considered? A. Selecting appropriate steel plate specifications to improve material utilization. B. Using as few different specifications as possible to ensure good interchangeability. C. The structural design of the tie rods. D. The material used for the connections. E. It is necessary to take into account the capacity of the press and lifting equipment. Answer: ABE. Explanation: According to the “Training Manual for Pressure Vessel Engineers”, section 24.2 – Verification: The answer is correct. The connection between the pillars and the spherical shell as specified in GB/T 12337 is of type ( ). A. Butt welding B. Lap welding C. V-shaped pillar support D. Tangential or secant equatorial pillar support. Answer: D. Explanation: According to GB/T 12337-2014 (P23), 5.3.14–608, the advantages of the connection method specified in this standard are: A. It allows for more support legs to be used. B. The load is distributed evenly, resulting in good elasticity and the ability to withstand thermal expansion. C. It is easy to install, simple to construct, easy to adjust, and convenient for on-site operation and maintenance. D. It requires less material. E. It is suitable for tanks of various sizes. Answers: B, C, E. Explanation: As stated in GB/T 12337-2014 (P15), clause 3. 4-609 The disadvantages of tangential or secant equatorial pillar support are: A. Poor load-bearing capacity. B. Difficult to install. C. High center of gravity, leading to poor stability. D. Not easy to transport. Answer: C. Explanation: As stated in GB/T 12337-2014 (P15), clause 3. 4-610 Which of the following are part of the design requirements for the main bolts of high-pressure equipment? A. The blanks for these bolts should undergo 100% UT testing and meet the grade I requirements specified in NB/T 47013.3. B. Fine-threaded bolts can be used if necessary, with the root portion rounded off. C. The surface roughness of the bare portion of the bolt should be at least Ra 1.6 ； The Ra value of the threaded portion should be no less than 3.2D. After processing, the studs should undergo treatments such as phosphating or blueing. E. After processing, 100% MT testing must be carried out, and the results must meet the requirements of grade I as specified in NB/T47013.3. Answers: ABCDE. Explanation: “Comprehensive Book on Chemical Equipment Design – High-Pressure Vessels” (P157), Chapter 5, Section 4; & HG/T 21573.2-95 “Large-Diameter Double-End Studs”, 4-611. Which of the following statements regarding the main bolts used in high-pressure equipment are correct? A. The manufacturing precision of the studs should meet the requirements of grade A as specified in GB/T 3103.1. B. The strength, impact energy absorption capacity, and elongation after fracture of the material should comply with the provisions in GB/T150.2. C. The chemical composition of the material should meet the requirements specified in GB/T150.2. D. The minor diameter of the thread on the stud should be smaller than the outer diameter of the bare shaft portion. E. The threads should be manufactured using the rolling method. Answers: A, B, C, E. Explanation: “Comprehensive Book on Chemical Equipment Design – High-Pressure Vessels” (P157), Chapter 5, Section 4; & HG/T 21573.2-95 “Large-Diameter Double-End Studs”, 4-612. Technical requirements for main bolts used in high-pressure equipment: The hardness of the bolt material should be about 30HB higher than that of the component it is screwed into, and about 30HB lower than that of the nut. A. Correct. B. Incorrect. Answer: B. Explanation: “Comprehensive Book on Chemical Equipment Design – High-Pressure Vessels” (P157), Chapter 5, Section 4, 4-613. Technical requirements for 07MnNiMoDR steel spherical tanks: For 07MnNiMoDR steel spherical tanks, if the steel plate manufacturer does not have any experience in using such steel plates in pressure vessels, it still needs to pass a technical review in accordance with the provisions of TSG21-2016. A. Correct. B. Incorrect. Answer: A. Explanation: GB/T 12337-2014 (P11), 4.1.7. 4-614. Technical requirements for 07MnNiMoDR steel spherical tanks: For 07MnNiMoDR steel spherical tanks with a thickness greater than 36 mm, an additional set of impact tests taken at half the thickness of the steel plate can be conducted; the requirements regarding the impact energy value are specified in the design documents. A drop hammer test can be performed additionally. The tests are conducted in accordance with GB/T and 6803, using P-2 type specimens; the acceptance criteria for the temperature at which no plastic transformation occurs (NDT) shall be specified in the design documents. A. Correct B. Incorrect Answer: A Explanation: According to GB/T 12337-2014 (P13~14), sections 4.2.5 and 4.2.64–615, for 07MnNiMoDR steel spherical tanks, which of the following technical requirements apply? A. The surface of the gas-cut grooves should be inspected using magnetic particle or penetrant testing; magnetic particle testing is preferred. B. Each heat-treated steel plate must undergo tensile testing and Charpy V-notch impact testing. When the thickness is greater than 16 mm, ultrasonic testing shall be carried out on each plate in accordance with NB/T 47013.3, with a grade of I being considered acceptable. C. When the thickness of the welded joint exceeds 32 mm, post-weld heat treatment to remove hydrogen must be carried out immediately. D. 100% radiographic or ultrasonic inspection must be performed on all spherical tank butt welds. If the thickness of its welded joint is greater than 36 mm, a combined inspection shall be carried out. E. After the pressure test, a leakage test shall be conducted. F. After cleaning the back side, 100% magnetic particle testing in accordance with NB/T 47013.4 or 100% penetrant testing in accordance with NB/T 47013.5 must be performed; the acceptance level shall be no lower than Grade I. Answer: A, B, C, D, F. Explanation: GB/T 12337-2014 – 8.6.4 & 4.2.4 & 8.3.4.7 & 8.6.5 (The acceptance level specified in option B is Grade T1) ； In option D, the thickness of the weld joint is 20 mm). According to TSG 21-2016, which of the following statements is correct? A. The weld joints between the nozzles (flanges) of pressure vessels that are directly exposed to flame heating and the vessel’s shell should have a fully penetrated structure. B. The weld joints between the nozzles (flanges) of pressure vessels and the vessel’s shell should have a fully penetrated structure. C. According to TSG 21-2016, the weld joints between the nozzles (flanges) of low-temperature pressure vessels and the vessel’s shell should have a fully penetrated structure. D. According to TSG 21-2016, the weld joints between the nozzles (flanges) of Class III pressure vessels and the vessel’s shell should have a fully penetrated structure. Answer: A, C, D. Explanation: TSG 21-2016 – 3.2.2.24-617. According to TSG 21-2016, the weld joints between the nozzles (flanges) of pressure vessels that are subject to pneumatic testing or combined pneumatic and hydraulic testing must have a fully penetrated structure. A. Correct B. Incorrect Answer: A Explanation: According to TSG 21-2016 – 3.2.2.24-618, the joints between the nozzles (flanges) of steel pressure vessels and the vessel shell should be designed with a fully penetrated structure under the following conditions: A. Pressure vessels in which the medium is explosive, or whose toxicity poses an extremely high or high level of hazard. B. Low-alloy steel pressure vessels whose minimum standard tensile strength is greater than 540 MPa. C. Pressure vessels for which fatigue analysis has been conducted. D. When the designer deems it necessary. Answer: A, C, D Explanation: TSG 21-2016 – 3.2.2.24-619 The design pressure refers to the highest pressure applied at the top of the vessel; together with the corresponding design temperature, it serves as the loading condition, and this value must be at least equal to the operating pressure. A. Correct B. Incorrect Answer: A Explanation: TSG 21-2016——3.1.9.14-620 The design pressure refers to the pressure used to determine the thickness of a component at the corresponding design temperature; it includes the hydrostatic pressure of liquid columns but does not include other additional loads. A. Correct B. Incorrect Answer: B Explanation: According to TSG 21-2016——3.1.9.14-621 regarding the determination of design pressure and calculated pressure, the following statement is incorrect. A. For a container composed of two or more pressure chambers, when determining the calculated pressure for the common components, the maximum pressure difference between adjacent chambers should be taken into account. B. When determining the calculated pressure for a pressure vessel subjected to external pressures, the maximum possible pressure difference between the inside and outside under normal operating conditions should be taken into account. C. For containers holding liquefied gases, in the absence of reliable insulation measures, the design pressure shall be determined based on the highest temperature that the medium inside the container may reach under operating conditions, within the specified filling coefficient range. D. When determining the shell thickness of a vacuum vessel, the design pressure is based on the external pressure it must withstand. Answer: C. Explanation: GB/T 150.1-2011 – 4.3.34-622 defines the calculated thickness as the thickness obtained by using the corresponding formulas specified in the standard. For external pressure components, it refers to the minimum thickness that meets the stability requirements. A. Correct B. Incorrect Answer: B Explanation: GB/T 150.1-2011——3.1.104-623 The design thickness refers to the sum of the calculated thickness, the corrosion allowance, and the negative deviation of the material thickness. A. Correct B. Incorrect Answer: B Explanation: GB/T 150.1-2011——3.1.114-624 The following statement is incorrect: A. The nominal thickness refers to the design thickness plus the amount of thinning that occurs during shaping, rounded up to the standard thickness specified for the steel material. B. The minimum forming thickness refers to the minimum thickness required after the compression component is formed to meet the design specifications. C. The effective thickness refers to the nominal thickness minus the corrosion allowance and the negative deviation of the material thickness. D. The additional material thickness refers to the sum of the material’s corrosion margin and the negative deviation from the material thickness. Answer: A. Explanation: According to GB/T 150.1-2011 – 3.1 and GB/T150-2011, for carbon steel and low-alloy steel pipes, when the operating temperature is ≤ -20°C, what requirements must be met regarding the allowable grades of steel, their condition of use, and the minimum operating temperature? Answer: The chemical composition of 4-62509MnD and 09MnNiD low-temperature steel pipes should satisfy P≤0.025% and S≤0.012%. A. Correct B. Incorrect Answer: B Explanation: According to Appendix A of GB/T 150.2-2011 – A.3.2 & A.3.34–4626 regarding the use of 09MnD steel pipes, the incorrect practice is using them in the normalized state. B. The wall thickness shall not exceed 8 mm. C. Minimum impact test temperature: -45°C. D. Meet the relevant requirements of GB9948. Answer: C. Explanation: According to Appendix A—A.3.24-627 of GB/T 150.2-2011 regarding the use of 09MnNiD steel pipes, the incorrect practice is using them in a quenched and tempered state. B. The wall thickness shall not exceed 8 mm. C. Minimum impact test temperature: -70°C. D. Meet the relevant requirements of GB9948. Answer: A. Explanation: According to Appendix A of GB/T 150.2-2011 – A.3.3, for forged parts made of 16MnD and 09MnNiD steels, when the operating temperature is below -20°C, GB/T 150-2011 specifies requirements regarding their heat treatment conditions and the minimum temperature for impact testing. Answer: Steel grade, standard for steel pipes, wall thickness under service conditions (mm), impact test temperature (°C): 16MnD – GBT 6479-2000, normalized; ≤40–400. 9MnNiD – GBT 150.2-2011, Appendix A, normalized; ≤8–70. For cylindrical, ring-shaped, or bowl-shaped forgings used in container shells or heads, grade IV forgings must be selected. A. Correct B. Incorrect Answer: B Explanation: GB/T 150.2-2011——6.1.3. 4-629 Regarding the use of 16MnD forgings, the incorrect option is A. Using it in the normalized state. B. The wall thickness shall not exceed 300 mm. C. Minimum impact test temperature: -40°C. D. The maximum operating temperature is 350°C. Answer: D. Explanation: GB/T 150.2-2011 – Table 94-630; regarding the use of 09MnNiD forgings, the incorrect option is A: using them in a quenched and tempered state. B. The wall thickness shall not exceed 250 mm. C. Minimum impact test temperature: -70°C. D. The maximum operating temperature is 300°C. Answer: B, D. Explanation: According to GB150.2, page P60, under what circumstances should post-weld heat treatment be carried out on heat exchanger tube boxes? 4-631: Composite plate tube boxes cannot undergo post-weld heat treatment. A. Correct B. Incorrect Answer: B 4-632. In which of the following situations should the heat exchanger tube sheet undergo post-weld heat treatment? A. Tube sheets made of chromium-molybdenum steel. B. Tube boxes designed for temperatures below -45°C. C. Tube boxes with stress corrosion. D. The medium is a highly toxic tube box. Answer: A, C, D. Explanation: According to GB150, page P331, item 4-633, under what circumstances should heat treatment after welding be carried out on heat exchanger tube boxes made of carbon steel or low-alloy steel? A. Tube box with segmented diaphragms. B. Tube banks with lateral openings whose diameter exceeds 1/3 of the inner diameter of the cylinder. C. Floating head covers made of carbon steel and low-alloy steel. D. Tube boxes that require pressure testing. Answer: A, B. Explanation: For low-alloy steel bolts as specified on page P106 of GB151, when the operating temperature is below -20°C, GB/T150-2011 sets requirements regarding their operating conditions and the minimum testing temperature. The minimum operating temperature for studs made of 4-634, 35 steel, 40MnB, 40MnVB, and 40Cr steel is all 0°C. A. Correct B. Incorrect Answer: A Explanation: On page P67, item 4-635 of GB150, regarding the use of 30CrMoA studs, the incorrect statements are (      ). A. For use in quenched and tempered condition. B. When used at the lower operating temperature limit, the diameter shall not exceed M64. C. Minimum impact test temperature: -70°C. D. At a service temperature of -50°C, the chemical composition shall be P≤0.020% and S≤0.010%. Answer: B, C, D. Explanation: According to GB150, page P66, item 4-636, regarding the use of 35CrMoA studs, the incorrect statements are (      ). A. For use in quenched and tempered condition. B. When used at the lower operating temperature limit, the diameter shall not exceed M64. C. Minimum impact test temperature: -70°C. D. At a service temperature of -50°C, the chemical composition shall be P≤0.020% and S≤0.010%. Answer: B, D. Explanation: Page P66 of GB150 discusses the common failure forms and modes of pressure vessels. 4-637: Common failure modes of pressure vessels include A. Strength failure: The vessel undergoes excessive plastic deformation or rupture under load. B. Stiffness failure: The container undergoes excessive elastic deformation, resulting in difficulties in transportation and installation or a loss of its normal operational capacity. C. Stable failure: Under load, the shape of the container changes suddenly, resulting in a loss of its functional capacity. D. Explosion Answer: A B C D 4-638. Which failure modes are taken into account in the technical specifications of the GB/T150 standard? A. Brittle fracture. B. Ductile fracture. C. Transportation collision injuries. D. Elastic or plastic instability. E. Creep fracture. Answer: A B D E Explanation: According to the GB150-2011 standard, page P14, item 4-639 – based on the process and mechanism of corrosion, into which categories can corrosion-induced failure be divided? A. Physical corrosion. B. Chemical corrosion. C. Electrochemical corrosion. D. Uniform corrosion. E. Local corrosion. Answer: A B C Explanation: According to the GB150-2011 standard, page P14 outlines the selection of materials for studs used in low-temperature applications. 640. When the operating temperature is below -100°C, there are no suitable carbon steel and low-alloy steel stud materials specified in GB/T150-2011. A. Correct B. Incorrect Answer: A4-641. The minimum operating temperature for austenitic steel studs is -196°C. A. Correct B. Incorrect Answer: B Explanation: On page 642 of GB150 P69, regarding the use of high-alloy steel studs, the incorrect statement is that the minimum operating temperature for S42020 steel studs is 0°C. B. High-alloy steel studs are always in a solution-treated state when in use. The allowable stress of C.S30408 stud steel bars increases after strain strengthening treatment. After strain strengthening of the steel rods for D.S30408 studs, low-temperature impact tests shall be conducted when the operating temperature is below -100°C. Answer: B. Explanation: GB150, page P69, covers elliptical end caps. 4-643: K represents the ratio of the long axis to the short axis of the elliptical head. When K=2, it is a standard elliptical head. A. Correct B. Incorrect Answer: B. 644. The shape factor K for an elliptical head represents the ratio of the maximum stress on the elliptical head to the primary circumferential membrane stress in the butt-welded cylinder. A. Correct B. Incorrect Answer: A Explanation: According to the GB150-2011 standard, page P120, item 4-645, regarding elliptical heads, the following statement is incorrect: A. The ratio of the long axis to the short axis of a standard elliptical head is 2. B. The spliced head shall undergo non-destructive testing prior to shaping. C. The effective thickness of a standard elliptical head shall be not less than 0.3% of the inner diameter of the head. D. The thickness calculation for convexly pressed elliptical end caps should employ the external pressure spherical shell design method. Answer: B C. Explanation: Page P38 of TSG21-2016 – connection methods between heat exchange tubes and tube sheets. 4-646: Strength expansion joining is not suitable for situations prone to stress corrosion. A. Correct B. Incorrect Answer: A Explanation: GB151-2014, page P25, item 647 – What are the connection methods between heat exchange tubes and tube sheets? A. Strength expansion jointing. B. Strength welding. C. Brazing. D. Strengthening of seal weld expansion. E. Inner hole welding. Answer: A B D E. Explanation: GB151-2014, page P28, item 4-648 – What are the connection methods for heat exchange tubes and tube sheets in applications subject to vibration and crevice corrosion? A. Strength expansion jointing. B. Strength welding. C. Strength welding with expansion fitting. D. Strengthening of seal weld expansion. E. Inner hole welding. Answer: C D E regarding the external pressure cylinder stiffening ring. 4-649: The reinforcement ring can be placed inside or outside the container; it must encircle the circumference of the cylinder entirely, with no unsupported length of the shell. A. Correct B. Incorrect Answer: B. For 4-650, continuous welding or intermittent welding can be used between the reinforcement ring and the cylinder. When the reinforcing ring is placed outside the container, the total length of the intermittent welds on each side of the reinforcing ring shall be not less than 1/3 of the outer circumference of the cylinder. A. Correct B. Incorrect Answer: B Explanation: GB150-2011, Page P106, 4-651. What is the purpose of installing reinforcement rings on cylinders under external pressure? A. Reducing the calculated length of a cylinder under external pressure. B. Improve the cylinder’s capacity to withstand external pressure. C. Reducing the cylinder wall thickness saves steel and lowers costs. D. Improve cylinder strength to prevent failure due to internal pressure. E. It can also serve as a thermal insulation support ring. Answer: A B C E. 4-652: External pressure flanges can be calculated as if they were internal pressure flanges, but the bolt area needs to be considered only in its tightened state. A. Correct B. Incorrect Answer: A Explanation: On page P197 of GB150-2011, into how many types are flanges in GB/T150.3-2011 classified according to their degree of integrity? What are the characteristics of each type? 4-653 Arbitrary flanges are to be calculated as integral flanges, and cannot be calculated as slip flanges. A. Correct B. Incorrect Answer: B Explanation: According to Article 7.4.4 of GB150.3-2011, into how many types are flanges classified in GB/T150.3-2011 based on their degree of integrity? What are the characteristics of each type? 4-654 Which of the following statements are incorrect? A. Flanges are classified into four types based on their degree of integrity: loose flanges, integral flanges, arbitrary flanges, and reverse flanges. B. Loose flange: The flange fails to connect effectively with the container or pipe, and does not possess the same structural strength as an integral connection. C. Integral flange: The flange, the flange neck, and the container or pipe fitting can be effectively connected to form an integral structure. D. The loose flange with a neck can be calculated as a single flange. Answer: A. Explanation: According to Article 7.4.4 of GB150.3-2011, how are common heat treatment methods classified based on different heat treatment objectives? 4-655 Depending on the objectives of heat treatment, what are the common heat treatment methods used in pressure vessel manufacturing? A. Post-weld heat treatment. B. Annealing treatment. C. Heat treatment to restore the mechanical properties of the material. D. Heat treatment to improve the mechanical properties of materials. E. Dehydrogenation treatment. Answer: A C DE. Explanation: According to Section 8 of GB150.4-2011, how are common heat treatment methods classified based on different heat treatment objectives? The thickness for determining whether post-weld heat treatment is required in 4-656 refers to the thickness of the steel plate. A. Correct B. Incorrect Answer: B Explanation: GB150.4-2011, Clause 8.2: 4-657 Under what circumstances is post-weld heat treatment required? ( ) A. Vessels indicated in the diagram as being subject to stress corrosion. B. Carbon steel and low-alloy steel containers used to hold media with extremely or highly hazardous toxicity. C. Chromium-molybdenum steel containers of any thickness. D. Vessels made of 16MnDR with a shell thickness of 20 mm or more. E. Pressure vessels designed for temperatures below -45°C. Answer: A B C Explanation: Clause 8.2.2 of GB150.4-2011 – Characteristics of reverse flanges. 4-658 Reverse flange refers to a flange whose flange ring is located on the inside of the cylinder. A. Correct B. Incorrect Answer: A Explanation: \"Training Manual for Pressure Vessel Design Engineers – Basic Knowledge: Components\", Page 285, Section 12.3.1 Characteristics of reverse flanges. 4-659 When the ratio of the flange inner diameter to the flange outer diameter is greater than 0.5, a flat cover with large holes and the cylinder connected to it can be regarded as reverse flanges, and designed using the principles applicable to flanges. A. Correct B. Incorrect Answer: B Explanation: According to Article 7.6.1 of GB150.3-2011, the characteristic of a reverse flange is that the ratio of the inner diameter to the outer diameter of the flange should be greater than or equal to 0.5. 4-660 Which of the following statements is incorrect? A. External pressure flanges can be calculated as internal pressure flanges. B. The overall flange requires stiffness calculation. C. Loose flanges require stiffness calculation. D. The stiffness of arbitrary flanges needs to be calculated. Answer: C D. Explanation: Articles 7.5.3.5 and 7.5.4 of GB150.3-2011 specify the requirements for local heat treatment as per GB/T150-2011. For welding joints of classes 4-661B, C, D, and E, local heat treatment is permitted. A. Correct B. Incorrect Answer: A Explanation: According to Article 8.2.6.5 of GB150.4-2011, the joint where a 4-662 spherical head is connected to a cylinder is classified as a Type A welding joint; local heat treatment is not permitted in such cases. A. Correct B. Incorrect Answer: B Explanation: Table 3 of GB150.2-2011 – Requirements for local heat treatment as specified in GB/T150-2011. 4-663 Which of the following statements is incorrect? A. Coal-fired furnaces must not be used for post-weld heat treatment. B. For overall heat treatment, only the method of overall heating in a furnace can be used. C. Segmented heat treatment, with the repeated heating length being no less than 1500 mm. D. Local heat treatment is permitted at the defect repair area. Answer: B. Explanation: According to Article 8.2.6 of GB150.4-2011, what are the common types of flange sealing surfaces for pressure vessels in the range of 4–664? (      ) A. Protruding plane. B. Concave and convex surfaces. C. Tenon and mortise surfaces. D. Torus. Answer: A B C D. Explanation: From \"Training Manual for Pressure Vessel Design Engineers – Basic Knowledge: Components\", Page 286, Section 12.4: Flange seal face types. 4-665 flanges with ribbed and tenon-groove surfaces have good sealing performance, and gaskets are not easily squeezed out of the sealing surface. A. Correct B. Incorrect Answer: A Explanation: \"Training Manual for Pressure Vessel Designers\" – compiled by Sinopec, Question 3-72: Flange seal surface types. 4-666 flat flange gaskets are prone to being squeezed out of the sealing surface. It is difficult to replace the tenon-and-socket flange gasket. A. Correct B. Incorrect Answer: A Explanation: \"Training Manual for Pressure Vessel Designers\" – compiled by Sinopec, Question 3-72: A pressure vessel with a design temperature of -20°C. When the cylinder material is Q245R, the required nominal thickness is 24 mm ； When the cylinder material is Q345R, the required nominal thickness is 20 mm. Under the above circumstances, how should Q245R and Q345R be used? Both 4-667Q245R and Q345R should undergo low-temperature impact tests at -20°C. A. Correct B. Incorrect Answer: B Explanation: Table 3 of GB150.2-2011 – 4-668Q245R should be used in the normalized state. A. Correct B. Incorrect Answer: A Explanation: Table 3 of GB150.2-2011 – A pressure vessel with a design temperature of -20°C. When the cylinder material is Q245R, the required nominal thickness is 24 mm ； When the cylinder material is Q345R, the required nominal thickness is 20 mm. Under the above circumstances, how should Q245R and Q345R be used? In what conditions can 4-669Q345R be used? A. Hot-rolled state. B. Controlled rolling condition. C. Normalized state. D. Normalizing followed by tempering. Answer: ABC. Explanation: According to Table 3 of GB150.2-2011, when welding dissimilar-thickness butt joints ranging from 4 to 670, the thickness for post-weld heat treatment shall be that of the thicker component. A. Correct B. Incorrect Answer: B Explanation: GB150.4-2011, Clause 8.2.1 – When welding non-compressed components to compressed components, the thickness for post-weld heat treatment shall be that of the compressed component. A. Correct B. Incorrect Answer: B Explanation: GB150.4-2011, Clause 8.2.1 – When welding the nozzles to the shell in 4-672, which factor is unrelated to the thickness of the post-weld heat treatment? A. Shell thickness. B. Thickness of the necking zone. C. Reinforcement ring thickness. D. Thickness of the fillet weld joint. Answer: All 4 options are relevant. Explanation: GB150.4-2011, Clause 8.2.1 – Connection between long-neck butt-welded flanges and butt-cylinders. The straight edge section of flange 4-673 can be thinned, as long as its thickness remains at least equal to that of the butt cylinder after thinning. A. Correct B. Incorrect Answer: B Explanation: \"Training Manual for Pressure Vessel Designers\" – compiled by Sinopec, Question 3-144: Connection of a long-neck welded flange to a butt-welded cylinder. After thinning the straight-flange section 4-674, it must be ensured that the axial bending stress at the thinned end does not exceed the allowable value. The thinned straight edge section can be considered as a conical neck for calculation. A. Correct B. Incorrect Answer: A Explanation: \"Training Manual for Pressure Vessel Designers\" – compiled by Sinopec, Question 3-144: Connection of a long-neck welded flange to a butt-welded cylinder. 4-675 Which of the following statements are correct? A. Long-neck butt-weld flanges must have straight edge sections. B. The stress on the straight flange section is the same as that on the cylinder. C. The straight edge section of the flange is subjected to both internal pressure and flange torque. D. Long-neck butt weld flanges do not allow patch welding. Answer: C. Explanation: From the \"Training Manual for Pressure Vessel Designers\" compiled by Sinopec, question 3-144 – Calculation of reinforcement for openings according to GB/T150-2011. In the calculation of equal-area reinforcement such as 4-676, the effective reinforcement range should be taken as the larger of the theoretically calculated value and the actual value. A. Correct B. Incorrect Answer: B Explanation: Clause 6.3.5.1 in GB 150.3-2011 deals with the calculation of reinforcement for openings as per GB/T150-2011. 4-677 Reinforcement range along the longitudinal direction of the shell: Determined based on the attenuation range of local stress concentration at the edge of a hole in a large flat plate under uniform tensile loading. A. Correct B. Incorrect Answer: B Explanation: Definition on Page 145 of GB 150.3-2011; calculation for reinforcement due to openings in GB/T150-2011. What issues should be considered when performing hole reinforcement using the analysis methods specified in GB/T150-2011 for 4-678? A. When performing joint reinforcement opening, the number of nozzles shall not exceed two. B. There are requirements for the ratio of the material’s yield strength to its tensile strength. C. There are requirements for the reinforcement length of the housing and connectors. D. There are requirements for the fillet size of the fillet weld between the cylinder and the nozzle. E. There are requirements for the radius of curvature of the inner wall at the joint end. Answer: B, C, D, E. Explanation: According to 6.6.14–679 in GB 150.3–2011, when designing flanges, it is necessary to keep the gasket load as low as possible; in other words, the narrower the gasket, the better. A. Correct B. Incorrect Answer: A Explanation: Petrochemical Engineering Design 2000,17(2) Technical Analysis of Pressure Vessel Strength Design (IV) Principles and Methods for the Rational Design of Pressure Vessel Flanges ； In 12.84-680 of Page 297 in the 2019 edition of \"Pressure Vessel Design_Engineer Training Manual_Basic Knowledge – Components\", it is stated that in flange design, the diameter of the circle centered on the bolts should be kept as small as possible, so as to result in a minimal flange torque. A. Correct B. Incorrect Answer: A Explanation: Petrochemical Engineering Design 2000,17(2) Technical Analysis of Pressure Vessel Strength Design (IV) Principles and Methods for the Rational Design of Pressure Vessel Flanges ； Section 12.8 on the design of flanges and gaskets, found on Page 297 of the 2019 edition of \"Pressure Vessel Design_Engineer Training Manual_Basic Knowledge – Components\". 4-681 What is the effect of flange cone dimensions on flange stress? A. Increasing the size of the flange taper neck increases its rotational stiffness, which in turn raises its load-bearing capacity; as a result, the boundary forces and boundary moments between the taper neck and the flange ring increase. B. Increasing the size of the flange cone neck increases the radial bending stress of the flange ring, while decreasing its hoop stress. C. Increasing the flange taper size does not change the stress level in the flange ring. D. Reducing the height of the flange cone neck helps to fully utilize the strength properties of the larger and smaller ends of the cone neck. Answer: A, B, D. Explanation: Petrochemical Engineering Design 2000,17(2) – Technical Analysis of Pressure Vessel Strength Design (IV): Principles and Methods for the Rational Design of Pressure Vessel Flanges ； Standard 12.9~12.10GB12337 in Page 297 of the 2019 edition of \"Pressure Vessel Design_Engineer Training Manual_Basic Knowledge – Components\", outlines the regulations regarding the selection and installation of safety accessories and auxiliary equipment for spherical tanks. 4-682 For spherical tanks containing explosive liquefied gases, at least 2 safety valves shall be installed, and the discharge capacity of each safety valve must meet the requirement for the maximum discharge capacity of the tank in the event of an accident. A. Correct B. Incorrect Answer: A Explanation: GB 12337-2014, section B.2.2 of the GB12337 standard, specifies the requirements regarding the selection and installation of safety accessories and auxiliary facilities for spherical tanks. 4-683 Regarding the safety accessories and auxiliary facilities of spherical tanks, the following statements are incorrect. A. A settlement measurement plate should be welded to each pillar of the spherical tank, at the same height. B. The number of grounding devices should be at least half of the number of spherical tank supports, and not less than 2. C. For spherical tanks containing liquid hydrocarbons, the supports shall be equipped with a fire-resistant layer, whose fire resistance rating shall be no less than 1.5 hours. D. When two or more safety valves are installed at a single connection port of a spherical tank, the cross-sectional area of that connection port shall be no less than the sum of the inlet cross-sectional areas of the safety valves. E. Emergency shut-off devices shall be installed at the inlet and outlet of storage tanks with extremely high or high toxicity, or those containing liquid hydrocarbons. Answer: B, C. Explanation: GB 12337-2014, specifically clauses B.10 and B.8.1, outlines the regulations regarding the selection and installation of safety accessories and auxiliary facilities for spherical tanks. 4-684 Which of the following statements are correct? A. For spherical tanks containing liquid hydrocarbons or media with an extremely high, high, or moderate level of toxicity, a conduit must be installed at the outlet of the discharge device; this conduit is used to direct the discharged medium to a safe location where it can be properly disposed of. B. Spherical tanks used to store liquefied gases that are explosive and have an extremely high level of toxicity and are highly hazardous shall be equipped with local and remote level gauges, as well as high-level alarms and interlocks for extremely high levels. C. The level gauge should be installed in a location where it is easy to observe; otherwise, additional auxiliary facilities should be provided. The highest and lowest safe liquid levels on the level gauge should be clearly marked. D. The installation location of the safety valve should allow operators to easily observe and clean it, and it should be protected from adverse effects such as radiant heat, freezing, or vibration. E. For pressure gauges used with corrosive or highly viscous media, a buffer device that isolates the medium should be installed between the pressure gauge and the spherical tank. Answer: A, B, C, E. Explanation: Sections B.2.4, B.5.6, B.5.7, and B.4.2.3 of GB 12337-2014 contain the regulations regarding the manufacturing and structural design of low-temperature spherical tanks. 4-685 Each low-temperature spherical tank shall undergo post-welding overall heat treatment prior to the pressure test. A. Correct B. Incorrect Answer: B Explanation: Clause E.4.3 of GB 12337-2014 outlines the regulations regarding the manufacturing and structural design of low-temperature spherical tanks. 4-686 For each low-temperature spherical tank, product welding specimens shall be prepared, and for each tank two product welding specimens shall be made for vertical welding, flat welding, and overhead welding. A. Correct B. Incorrect Answer: A Explanation: Sections E.4.4 and 8.9.1.1.3 of GB 12337-2014 contain the relevant provisions regarding the manufacturing and structural design of low-temperature spherical tanks. What factors should be fully considered in the design of 4-687 low-temperature spherical tanks? A. Use high-strength steel, and the structure should be as simple as possible to reduce restraints. B. Avoid creating excessive temperature gradients. C. Sudden changes in structural shape should be avoided as much as possible to reduce local stresses. D. The connection between the pipe fitting and the shell should have a smooth transition, with the inner wall at the end of the pipe fitting being rounded. Answer: B, C, D. Explanation: Standard GB 12337-2014, section E.3, specifies the relevant requirements for the welding of spherical tanks. 4-688 Welding materials should be kept, dried, and distributed by a designated person, with the number of drying cycles should not be less than 2. A. Correct B. Incorrect Answer: B Explanation: Clause 8.3.3.1 of standard GB 12337-2014 specifies the requirements regarding the welding of spherical tanks. When performing 4-689 tack welding and welding with fixtures, the requirements for welders can be lower than those for spherical shell welding. A. Correct B. Incorrect Answer: B Explanation: Clause 8.3.3.3 of standard GB 12337-2014 specifies the relevant requirements for the welding of spherical tanks. 4-690 Welding on spherical tanks is prohibited when any of the following conditions exist in the welding environment and no effective protective measures are in place. A. The wind speed is greater than 10 m/s during shielded metal arc welding. B. The wind speed during gas shielded welding is greater than 2 m/s. C. Relative humidity greater than 90%. D. Rain and snow environments. E. The surface temperature is below -20°C. Answer: A, B, C, D. Explanation: Clause 8.3.1.1 of standard GB 12337-2014 specifies the requirements regarding steel plates used for spherical shells. 4-691 Which of the following steel plates is not commonly used for spherical shells? A.Q345RB.15CrMoRC.09MnNiDRD.07MnNiMoDR Answer: B Explanation: Table 4 in 4.2.1 of GB 12337-2014 outlines the requirements for steel plates used in spherical shells, as specified by this standard. 4-692 The factors that affect the welding quality of spherical tanks include. A. Welding environment, wind speed, temperature, humidity, etc. B. Shell material, thickness. C. Welding process. D. Product welding test pieces. E. The competence of welders. Answer: A, C, E. Explanation: Clause 8.3 of the GB 12337-2014 standard specifies the requirements for steel plates used in spherical shells. 4-693 Regarding the thickness of a spherical shell, which of the following statements are correct? A. For steel plates in the quenched and tempered condition with a shell thickness greater than 36 mm, an additional set of impact tests taken at 1/2 of the plate thickness can be conducted. B. The thickness of the steel plate used for the spherical shell should not exceed 50 mm. C. When the shell thickness is greater than 50 mm, an analytical design method can be used to reduce the thickness. D. In accordance with the standards, for carbon steel and low-alloy steel plates with a shell thickness of 55 mm, each heat-treated plate shall be subjected to tensile testing and Charpy V-notch impact testing. E. The steel plates for low-temperature spherical tanks shall be in normalized or quenched and tempered condition. Answer: A, B, C, E. Explanation: GB 12337-2014, sections 4.2.5, 4.2.2, 4.1.8, and E.2.1.1 relate to high-pressure vessels. For the shells of single-layer high-pressure vessels, carbon steel and low-alloy steel plates with a thickness of ≥12 mm shall be ultrasonically inspected one by one. A. Correct B. Incorrect Answer: A Explanation: Table 3 in 4.1.8 of GB 150.2-2011 pertains to high-pressure vessels. 4-695 High-voltage equipment all requires the preparation of product welding specimens. A. Correct B. Incorrect Answer: B Explanation: 9.1.1.1 in GB 150.3-2011 pertains to high-pressure vessels. 4-696 Regarding the common sealing types for high-pressure vessels, which of the following statements are correct? A. Metal flat gasket sealing, which belongs to forced sealing. B. Tapered seal, which belongs to the semi-self-tightening seal type. C. Octagonal gasket seals and elliptical gasket seals belong to the category of radially self-tightening seals. D. Wood seal is an axially self-tightening seal. E. Kazari seal is a self-tightening seal. Answer: A, B, C, D, E. Explanation: Appendix C of GB 150.3-2011 deals with high-pressure vessels. All 4-697 high-pressure vessels require 100% RT testing. A. Correct B. Incorrect Answer: B Explanation: 10.3.1 in GB 150.3-2011 pertains to high-pressure vessels. 4-698 High-pressure vessels made of carbon steel and low-alloy steel all require post-weld heat treatment. A. Correct B. Incorrect Answer: B Explanation: According to Appendix 8.2.24-699 of GB 150.3-2011, the following statements are incorrect. A. When the ratio K of the outer diameter (D0) to the inner diameter (Di) is greater than 1.2, it is a thick-walled vessel. B. The wall thickness calculation formula used in engineering is the mean diameter formula, which is applicable under the condition that K ≤ 1.5. C. Thick-walled cylinders subjected to three-directional stresses: circumferential, axial, and radial, with the axial stress being uniformly distributed throughout the wall thickness. D. The circumferential and radial stresses in a thick-walled cylinder are non-linearly distributed across the wall thickness; under internal pressure, the outer wall experiences the greatest stress while the inner wall experiences the least. Answer: C. Explanation: The distribution is uniform only in the axial direction; see Figure SY3-1 on page 107 of the GB/T150 specifications. Answer: D. Explanation: The circumferential stress is higher on the inner wall, while the radial stress is 0 at the outer wall. See Figure SY3-1 on page 107 of the GB/T150 specifications. Regarding pressure vessels used for storing liquefied gases at normal temperatures, the determination of the design pressure is specified in TSG 21-2016 “Safety Technical Regulations for Fixed Pressure Vessels”. 4-700 Pressure vessels for storing liquefied gases at normal temperatures shall have a design pressure determined based on the operating pressure at the specified temperature. A. Correct B. Incorrect Answer: A Explanation: Article 3.1.9.3 of TSG21-2016, the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\" issued under TSG 21-2016, addresses the determination of design pressure for pressure vessels used for storing liquefied gases at normal temperatures.  4-701 The operating pressure of pressure vessels for storing mixed liquefied petroleum gas at normal temperatures is determined to be not less than the actual saturated vapor pressure of the components in the mixed liquefied petroleum gas at 50°C. A. Correct B. Incorrect Answer: A Explanation: Article 3.1.9.3 of TSG21-2016, the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\" issued under TSG 21-2016, addresses the determination of design pressure for pressure vessels used for storing liquefied gases at normal temperatures.  4-702  Which of the following statements is incorrect? A. In the absence of insulation, when the saturated vapor pressure of the mixed liquefied petroleum gas at 50°C is not higher than that of isobutane at 50°C, the saturated vapor pressure of isobutane at 50°C shall be used. B. When heat insulation is available, if the saturated vapor pressure of the mixed liquefied petroleum gas at 50°C is higher than that of isobutane at 50°C but not higher than that of propane at 50°C, the saturated vapor pressure of propane at 50°C shall be used. C. In the absence of insulation, when the saturated vapor pressure of the mixed liquefied petroleum gas at 50°C is higher than that of propane at 50°C, the saturated vapor pressure of ethylene at 50°C is used. Answer: C. Explanation: According to Table 3-2 of TSG21-2016, the answer should be A; this relates to the oblong holes on the bottom plate of the sliding saddle for horizontal containers. 4-703 When the container foundation is concrete, a foundation pad should be placed under the bottom plate of the sliding end saddle. A. Correct B. Incorrect Answer: A Explanation: According to clause 8.5, item 4-704 of NB/T47065-2018, under the same conditions, when the material of the housing for the sliding end saddle of a thermally expandable device is austenitic stainless steel versus chromium-molybdenum steel, the longer oval hole length is required for the former. A. Correct B. Incorrect Answer: A Explanation: JB/T4732-1995 (confirmed in 2005), Appendix G, Table G-6: Coefficient of thermal expansion – Stainless steel is higher than that of chromium-molybdenum steel, regarding the oblong holes in the bottom plate of the sliding end saddle for horizontal vessels. 4-705 The length of the oval hole in the bottom plate of the sliding end saddle of a horizontal vessel is related to which of the following factors? A. Linear expansion coefficient of the container shell material. B. The temperature difference between the operating temperature and the ambient temperature. C. The distance between the fixed-end saddle and the sliding-end saddle. D. Container tangent length. Answer: A, C, D. Explanation: The length of the oblong hole is determined by the degree of expansion of the equipment itself. The answer should be ABC; certainly, the temperature difference is related to the environmental conditions as well as the reinforcement structure of the oil tank. Complete the following questions.  4-706 The reinforcement of openings in the shell can be achieved through two structural approaches: reinforcement rings or integral reinforcement. ( ) A. Correct B. Incorrect Answer: A Explanation: According to clauses 6.3.1 and 6.3.2 of GB/T150.3-2011 regarding reinforcement structures, complete the following questions.  4-707 Which of the following belong to overall reinforcement of pressure vessels? () A. Increasing the thickness of the shell B. Increasing the thickness of the reinforcement rings C. Using thick-walled pipes D. Using reinforced forgings Answer: A, C, D Explanation: According to clause 6.3.2.2 of GB/T150.3-2011 regarding reinforcement structures, complete the following questions. 4-708 The conditions that must be met for using reinforcement rings include ( ). A. The minimum allowable tensile strength of low-alloy steel is less than 540 MPa. B. The diameter of the opening in the nozzle is less than one-third of the diameter of the cylinder. C. The thickness of the reinforcement ring does not exceed 1.5 times the nominal thickness of the shell. D. The nominal thickness of the shell does not exceed 38 mm. Answer: A, C, D. Explanation: According to clause 6.3.2.1 of GB/T150.3-2011, the stress on the foundation bolts of towers, the calculation methods, and the safety factors are discussed.  4-709 The safety factor of the tower foundation bolts is lower than that of the flange bolts in ordinary equipment. （）A. Correct B. Incorrect Answer: A Explanation: According to standard NB/T47041-2014, Section II – Materials (page 17), the anchor bolts of a tower structure are subjected to the greatest stress on their windward side, with this stress being distributed linearly around the entire circumference. When the first bolt fails, the stress is redistributed among the remaining bolts; as a result, the container does not collapse immediately. In contrast, the bolts of a flange experience equal stress, with all bolts bearing the load at the same time, so the failure of even one bolt can lead to serious accidents. It can also be seen that the bolts of the tower are allowed to undergo plastic deformation, whereas the bolts of the flanges must remain within the elastic range and are not permitted to deform to avoid leakage and failure; therefore, the bolts of flanges are mostly controlled based on their yield strength. Explain the stress on the tower foundation bolts, the calculation methods, and the safety factor.  4-710 What are the methods for calculating the foundation bolts of towers? () A. Wöhman method B. Taylor method C. Limit load method D. Euler method. Answer: A, B, C. Explanation: As stated in clauses 5.1, 5.2, and 5.3 of standard NB/T47041-2014. 4-711 Which of the following statements about the foundation bolts of towers are correct? () A. The stress is evenly distributed. B. The stress is unevenly distributed. C. Plastic deformation is allowed. D. Plastic deformation is not allowed. Answer: B, C. Explanation: According to NB/T 47041-2014, Section II – Materials (page 17), the answer is the same as that for question 709. Per GB150.1-2011, when it is required that a safety valve be installed on a device and a gas-tightness test is also necessary, explain briefly how to determine the setting pressure of the safety valve. 4-712 For pressure vessels equipped with overpressure relief devices such as safety valves and burst discs, if a gas-tightness test is required in the design, the designer shall specify the maximum allowable operating pressure for that pressure vessel. （）A. Correct B. Incorrect Answer: A Explanation: According to Article 3.1.18 of TSG 21-2016 and the provisions of GB150.1-2011, when it is required that a device be equipped with a safety valve and a gas-tightness test is also necessary, this article explains how to determine the setting pressure of the safety valve. 4-713 According to Appendix B of GB/T150.1-2011, the allowable deviation of the set pressure of a safety valve should not exceed ( ). A. ±3% of the set pressure or ±0.015 MPa, whichever is smaller; B. ±3% of the set pressure or ±0.015 MPa, whichever is larger; C. ±3% of the operating pressure or ±0.015 MPa, whichever is smaller; D. ±3% of the operating pressure or ±0.015 MPa, whichever is larger. Answer: B. Explanation: As specified in Appendix B, section 4.6 of GB/T150.1-2011. 4-714 When a device is equipped with a safety valve and also needs to undergo a leak test, which of the following options represents the correct order for the set pressure values of the safety valve? A. Safety valve setting pressure > Maximum allowable operating pressure > Airtightness test pressure B. Maximum allowable operating pressure > Airtightness test pressure > Safety valve setting pressure C. Maximum allowable operating pressure > Safety valve setting pressure > Airtightness test pressure Answer: C Explanation: According to Appendix B3 of GB/T150.1-2011, explain the purpose of creating notches in the shell at the weld joint where the tower vessel is welded to the lower head, as well as the minimum length required for the tower vessel’s sections. 4-715 When the lower head of the tower shell is fabricated by joining multiple plates, a notch should be provided in the skirt shell at the joint welds. （）A. Correct B. Incorrect Answer: A Explanation: According to NB/T47041 -2014, clause 6.4, item 4-716, when the lower head of a tower is constructed by joining multiple plates together, what are the purposes of making notches in the shell at the joints between these plates? （）A. To prevent overlap of the welds and their heat-affected zones during welding B. To ensure the reliability of the weld connections C. To avoid a decrease in the mechanical properties of the material at the connection points D. To prevent sudden changes in the structure Answer: A Explanation: As stated in NB/T47041 -2014, under Section 3 on Structure, clause 4, explain the purposes of making notches in the shell at the joints where the tower and its lower head are welded, as well as the minimum length required for the tower’s cylindrical sections. 4-717 To avoid the accumulation of heat-affected zones, when assembling the cylinder of a pressure vessel, the length of any individual cylinder section must not be less than (). A.100mm B.200mm C.300mm D.400mm Answer: C Explanation: GB/T150.4-2011 6.5.5(c) briefly describes the reasons for controlling the deflection of tower vessels in NB/T 47041.  4-718 When the H/D ratio of a tower-type vessel is greater than 15 and the height H is greater than 30 m, it is necessary to consider controlling the deflection at the top of the tower. （）A. Correct B. Incorrect Answer: B Explanation: According to NB/T 47041 7.6.2, taking into account the effect of lateral wind loads, for carbon steel and low-alloy steel tower-type vessels, the nominal thickness of the skirt shell should not be less than (). A. 3mm B. 5mm C. 6mm D. No requirement Answer: C Explanation: Clause 6.2.1 of NB/T 47041 outlines the reasons for controlling the deflection of control towers as specified in NB/T 47041.  4-720 The hazards associated with excessive deflection in towers include the following: () A. Impact on the tower’s operational performance B. Increased wind load C. Prone to leaks at pipeline flanges D. Effect on the overall safety of the equipment E. Compromise to the safety of maintenance personnel. Answer: A, C, D, E. Explanation: Controlling the deflection at the top of the tower is necessary to ensure the efficiency of the tray system and the stability of the operational process; additionally, the additional bending moments caused by deflection as well as the safety of maintenance workers must also be taken into consideration. However, controlling the deflection at the top of the tower is a challenging issue. Based on numerous calculation results, it is easier to meet the deflection control requirements for towers with large diameters and low heights, while it is more difficult to achieve such control for towers with small diameters or tall shapes. 4-721 To improve the stress conditions and enhance the load-bearing capacity, the connection between the skirt shell and the tower shell can adopt a butt joint style; the inner diameter of the skirt shell should be equal to the inner diameter of the lower head of the connected tower shell. （）A. Correct B. Incorrect Answer: A Explanation: According to clause 6.3.2, item 4-722 of NB/T 47041, for the butt welding of cylinders with different wall thicknesses, when the difference in thickness is significant, in order to reduce the additional bending moments and stresses generated, it is theoretically necessary to use （）。 A. Inner diameter alignment B. Mean diameter alignment C. Outer diameter alignment Answer: B Explanation: Briefly describe the principles and reasons for aligning the tower skirt with the lower head. 4-723 The main methods for reducing local stresses in structures are ( ) A. Rational structural design B. Use of high-strength materials C. Reduction of local loads transmitted by attachments D. Minimization of defects in the structure Answer: A Explanation: NB/T47041, page 19. Briefly describe the phenomena, causes, and prevention methods of hydrogen embrittlement and hydrogen corrosion. 4-724 Hydrogen embrittlement refers to the phenomenon of weakening of the material during operation (including the base metal and welded joints). ( ) A. Correct B. Incorrect Answer: Correct Explanation: Page 189 of the Engineering Training Manual, Volume 2, briefly describes the phenomena, causes, and prevention methods of hydrogen embrittlement and hydrogen corrosion. 4-725 The occurrence of hydrogen corrosion is related to which of the following factors: ( ) A. Certain hydrogen partial pressure B. High temperature C. Failure to carry out post-welding hydrogen removal treatment D. Inappropriate material selection. Answer: ABCD. Explanation: As described on page 189 of the Engineering Training Manual, Volume 2, the phenomena, causes, and prevention methods of hydrogen embrittlement and hydrogen corrosion are outlined. 4-726 The methods for preventing hydrogen embrittlement mainly include the following aspects ( ) A. Ensuring that the welding electrodes or flux are dry during welding B. Preheating the joint area before welding C. Conducting hydrogen removal treatment immediately after welding D. When selecting materials for design, using Nelson curves to choose appropriate materials based on the hydrogen partial pressure in the medium and the design temperature. Answer: ABCD