Latest reference questions for pressure vessel design assessment

Thread Content

Reference Questions for Assessment I. Fill-in-the-blank questions: 1. Low-pressure reaction vessels and storage vessels containing flammable media or media with moderate toxicity are classified as Class II pressure vessels. Article 6, Paragraph 2 of the Code: There is a pressure vessel with a maximum operating pressure of 670 mmHg vacuum, a design pressure of 0.15 Mpa, and its vessel category is \"No Category\". According to Article 2, Section 3 of the Pressure Vessels Regulations, the minimum number of inspection ports for pressure vessels is as follows: for 3000 mm ≤ Di ≤ 500 mm, 2 manholes are required; for 500 mm ≤ Di ≤ 1000 mm, 1 access hatch or 2 manholes are required; for Di > 1000 mm, 1 access hatch or 2 manholes are required. 4. Pressure vessels that meet one of the following conditions may not require inspection holes: Article 46, 1) of the Pressure Vessels Regulations – pressure vessels with an inner diameter of 300 mm or less. 2) The pressure vessel is equipped with a removable head, cover plate, or other type of lid that can be opened and closed, and its dimensions are not smaller than those of the specified inspection holes. 3) No corrosion or minor corrosion, requiring inspection and cleaning. 4) Pressure vessels for refrigeration units. 5) Heat exchanger. 5. Medium-pressure storage vessels containing flammable media or media with moderate toxicity, for which the PV product is ≥ 10 MPa·m3, are classified as Class III pressure vessels. Article 6.6 of the Code: For pressure vessels of Category II that are used to contain flammable media, the butt joints of reaction pressure vessels and storage pressure vessels must undergo 100% radiographic (RT) or ultrasonic (UT) inspection. Article 85, Clause 7 of the Pressure Vessels Code: Carbon steel and low-alloy steel sheets used for manufacturing pressure vessel shells shall be subject to ultrasonic testing on a sheet-by-sheet basis if they meet one of the following conditions: Article 14, Clause 1 of the Pressure Vessels Code – Pressure vessels that contain media with an extreme or highly hazardous toxicity level. 2) Pressure vessels with a maximum operating pressure of 10 MPa or greater. 3) Containers filled with liquefied petroleum gas and containing a hydrogen sulfide concentration greater than 100 mg/L. 8. The design, manufacture, installation, use, inspection, repair, and modification of pressure vessels shall all be carried out in strict accordance with the provisions of the Pressure Vessel Regulations. Article 4, Paragraph 9 of the Code: Pressure vessels (storage vessels or mobile pressure vessel tanks) used to hold mixed liquefied petroleum gas at normal temperatures shall undergo overall heat treatment in a furnace. Article 73, Paragraph 10 of the Pressure Vessels Regulations: The Pressure Vessels Regulations apply to pressure vessels that meet all of the following conditions: Article 2, Paragraph 1 of the Pressure Vessels Regulations – a pressure of 0.1 Mpa or higher (excluding hydrostatic pressure) ； 2) The inner diameter (for non-circular cross-sections, this refers to the largest dimension of the cross-section) is greater than or equal to 0.15 m, and the volume (V) is greater than or equal to 0.025 m3 ； 3) The medium is a gas, a liquefied gas, or a liquid with a maximum operating temperature equal to or higher than its standard boiling point. 11. According to the relevant regulations, the safety accessories for pressure vessels include: safety valves, rupture disc devices, emergency shut-off devices, pressure gauges, level gauges, temperature measuring instruments, and safety interlock devices for quick-opening pressure vessels. Article 2, Paragraph 12 of the Code: The Code sets out the basic requirements for the quality supervision and safety inspection of pressure vessels. Article 5, Clause 13 of the Code: In the case of welded joints that have been inspected using partial radiographic or ultrasonic testing and in which unacceptable defects are found, the inspection length shall be increased at both ends of such defects by an amount equal to 10% of the length of that welded joint, with this increased length being no less than 250 mm. If any unacceptable defects remain, a 100% inspection of that welded joint is conducted. GB150, Clause 10.8.5.1, item 14: The Code stipulates that when it is not possible to provide inspection holes due to special circumstances, the following requirements must be met simultaneously: 1) 100% non-destructive testing (RT or UT) of each longitudinal and circumferential weld ； Article 47, paragraph 2 of the Code requires that the calculated thickness be indicated on the design drawings, and thickness measurements should be carried out regularly during the service life of the pressure vessel or during inspections ； 3) Correspondingly shorten the inspection cycle. 15. When the wall thickness of pressure vessels is ≤38 mm, their butt joints shall be inspected by radiography ； When radiation detection cannot be used due to structural reasons or other factors, recordable ultrasound detection is permitted. Article 86, paragraph 16 of the Code stipulates that when selecting materials for pressure vessels, in addition to considering mechanical properties and bending strength, compatibility with the medium must also be taken into account. The phosphorus content (as determined by melting analysis, the same applies hereafter) of steel dedicated for pressure vessels should not exceed 0.03%, and the sulfur content should not exceed 0.02%. Article 11, Paragraph 17 of the Regulatory Standards: Low-pressure vessels containing extremely hazardous or highly hazardous media, with a PV product of 0.2 MPa·m3 or greater, shall be classified as Category III pressure vessels. Article 6, Paragraph 18 of the Regulations: The quality and specifications of the materials used for pressure vessels shall comply with the relevant ** standards and industry standards. Article 10, Clause 19 of the Code specifies that the non-destructive testing methods for pressure vessels include radiography (RT), ultrasonic testing (UT), magnetic particle testing (MT), penetrant testing (PT), and eddy current testing, among others. Article 83, Paragraph 20 of the Code: For pressure vessel nozzles with a nominal diameter of 250 mm or more, the requirements for non-destructive testing of the butt joints are the same as those for the welded joints of the vessel’s main body. Article 88, Paragraph 21 of the Code: The proportion of non-destructive testing for butt weld joints of pressure vessels is generally set at 100% or ≥20%. For ferritic steel cryogenic vessels, the proportion of local non-destructive testing should be greater than or equal to 50%. Article 84, Paragraph 22 of the Code: The pressure testing of pressure vessels is divided into hydraulic testing and pneumatic testing. Article 94, Paragraph 23 of the Regulations on Pressure Vessels: The periodic inspections of pressure vessels include external inspection, internal and external inspection, and pressure test. Article 132, Paragraph 24 of the Regulations: Based on the principle of operation in the production process, pressure vessels are classified into reaction pressure vessels, heat exchange pressure vessels, separation pressure vessels, and storage pressure vessels. Appendix 1, Item 25 of the Code: The discharge capacity of safety valves and rupture discs must be greater than or equal to the safe discharge capacity of the pressure vessel. Article 145, Paragraph 26 of the Code: The pressure for the airtightness test is the design pressure of the pressure vessel. Article 101, Paragraph 27 of the Code: The Code classifies pressure vessels according to their design pressure as follows: Low pressure: For vessels with oval end caps where P1 is ≤ 0.1 MPa, the effective thickness should be not less than 0.3%. GB150 7.2.1 Clause 106: When steel is used at temperatures equal to or below -200°C, a Charpy (V-notch) low-temperature impact test must be conducted as specified; austenitic stainless steels can be exempted from such impact tests when used at temperatures of ≥-196°C. GB150 4.1.7 Clause 107: When making openings in the transition area of oval or butterfly head shapes, the center line of such openings should be perpendicular to the surface of the head. GB150 8.2.4 Clause 108: Welded joints of categories A, B, and C for low-temperature pressure vessels shall all adopt a fully penetrative weld structure. Before welding low-temperature pressure vessels, a welding procedure qualification in accordance with JB4708 shall be carried out, including low-temperature Charpy impact tests on the welds and heat-affected zones. According to Appendix C3.3/C4.2.1109 of GB150, when local inspection is permitted for the butt joints of low-temperature pressure vessels, the inspection length shall be not less than 50% of the length of each welded joint, and shall also be not less than 250 mm. According to Appendix C4.6.2110 of GB150, low-temperature pressure vessels must have sufficient flexibility in their structural design; the structure should be as simple as possible to minimize constraints ； Avoid excessive temperature gradients ； Sudden changes in the structural shape should be avoided as much as possible to reduce local high stresses ； The end of the take over should be polished into a round corner. GB150 Appendix C3.2111: Shocks for low-temperature pressure vessels must be equipped with gaskets and must not be welded directly to the vessel shell. GB150 Appendix C3.2112: Heat treatment in pressure vessel manufacturing is divided into two categories: overall heat treatment and local heat treatment. 113. The steel used for the pressure-bearing components of low-temperature pressure vessels must be killed steel; for shell plates with a thickness greater than 20 mm, ultrasonic testing shall be carried out on each plate, and they must meet the Class III requirements specified in JB/T4730.3-2005. GB150 Appendix C2.1114: For low-temperature pressure vessels that require 100% radiographic or ultrasonic testing, their T-joints, butt welds, and fillet welds must all undergo 100% magnetic particle or penetrant testing. The welds connecting the compressed elements to the non-compressed elements also require 100% magnetic particle or penetrant testing. GB150 Appendix C2.1115: For pressure vessels consisting of two pressure chambers, the test pressures for each of these chambers shall be specified on the drawings, and the stability of adjacent shell walls under those test pressures shall be checked. 116. According to the GB150 standard, the longitudinal welds of the manway section on pressure vessels shall be of Class A welds, while the welds between the manway flange and the manway section shall be of Class B or Class C welds. According to clause 10.1.6 of GB150 and item 117, GB151-1999 \"Shell and Tube Heat Exchangers\" applies to parameters with a nominal diameter of DN ≤ 2600 mm and a nominal pressure of PN ≤ 35 MPa. According to clause 118 of GB151 1.2, the method specified in GB151 for calculating the heat exchange area takes the outer diameter of the heat exchange tubes as a basis; after deducting the length of the tubes that extend inward, the outer surface of the tube bundle is determined. According to GB151 3.7.1 clause 119, the common arrangements of heat exchange tubes are regular triangles, angled regular triangles, squares, and angled squares. The center-to-center distance between heat exchange tubes is generally not less than 1.25 times the outer diameter of those tubes. GB151 5.6.3 Clause 1 2 0: In the connection between heat exchange tubes and tube sheets, forced expansion fitting is applicable for a design pressure of 4 MPa ； Design temperature 300 ℃ ； There is no severe vibration during operation, no excessive temperature changes, and no significant stress corrosion. GB151 5.8.2.1 Clause 121: In the connection between the heat exchange tubes and the tube sheet, the minimum expansion length for expansion joints should be the nominal thickness of the tube sheet minus 3 mm, or the smaller of that value and 50 mm. GB151 5.8.2.3 Clause 122: In the connection between heat exchange tubes and tube sheets, the use of expansion welding is applicable when high sealing performance is required ； Withstand vibration or fatigue loads ； There is gap corrosion ； Applications where a composite tube sheet is used. GB151 5.8.4.1 Clause 123: When the shell side of a horizontal heat exchanger contains a single-phase clean fluid, the gaps in the baffle plates should be arranged horizontally, up and down ； In horizontal heat exchangers, condensers, and reboilers, where the fluid in the shell side is in a gas-liquid mixture or contains solid particles, the gaps in the baffle plates should be arranged vertically left and right, with liquid inlets provided at the lowest point of the baffle plates. GB151 5.9.1 Clause 124. The three short-circuit prevention structures recommended by the GB151 standard are: bypass baffle ； Pipe baffle ； Middle baffle. According to GB151, clause 5.13.125, a Class I tube bundle for heat exchangers refers to one that uses non-ferrous metal tubes, stainless steel tubes, as well as steel tubes of high precision grades ； Grade II tube bundles refer to the use of steel pipes with a standard precision grade. 126. GB151 stipulates that austenitic stainless steel welded pipes that meet the requirements of these regulations can be used as heat exchange tubes, but they shall not be used in applications involving extremely hazardous media ； The design pressure is not greater than 6.4 MPa ； The operating temperature is the same as that of seamless pipes of the corresponding steel grade. According to clause 4.4.2, item 127 of GB151, when the design temperature is 300°C or higher, butt-welded flanges should be used for the connection fittings. For heat exchangers in which it is not possible to use the connection fittings or interfaces for venting and draining, vent ports should be installed at the highest points of the tube side and shell side, and drain ports at the lowest points; the minimum nominal diameter of these ports is 20 mm. GB151 5.4.2 Clause 128: The minimum spacing between baffle plates shall generally be not less than 1/5 of the inner diameter of the cylinder, and not less than 50 mm. According to GB151 5.9.5.2, clause 129: For tube boxes and floating head covers made of carbon steel or low-alloy steel, as well as those with lateral openings that exceed 1/3 of the cylinder’s inner diameter, stress-relief heat treatment shall be carried out after welding; the sealing surfaces of the equipment flanges should be processed after this heat treatment. GB151, Clause 6.8, Item 130: External pressure and vacuum heat exchangers shall be pressure-tested under internal pressure. 131. The common connection methods between heat exchange tubes and tube sheets include welding, expansion bonding, and a combination of expansion bonding and welding. GB151, Clause 5.8, Item 132: The thickness of the tube sheet shall be: the calculated thickness of the tube sheet (not less than the specified minimum thickness), plus the greater of the corrosion allowance for the shell side or the depth of the structural grooves, plus the greater of the corrosion allowance for the tube side or the depth of the partition groove. GB151 5.7 Clause 133: In GB151–1999, the principles for arranging ear-type supports on heat exchangers are as follows: when the nominal diameter DN is ≤800 mm, at least 2 supports must be installed, and they should be arranged symmetrically; when DN > 800 mm, at least 4 supports must be installed, and they should be distributed evenly. GB151 5.20.2 Clause 134: When installing a stacked heat exchanger, the distance from the bottom plate of the upper heat exchanger support to the equipment’s centerline should be at least 5 mm less than the distance from the sealing surface of the pipe flange to the equipment’s centerline. GB151 5.20.3 Clause 135: The hardness value of the heat exchange tube material should generally be lower than that of the tube sheet material. GB151 5.8.2.2 Clause 136: The butt joints of gasketed tube sheets shall be subject to 100% radiographic or ultrasonic inspection, with the radiographic inspection meeting Grade II as specified in JB/T4730.2-2005, and the ultrasonic inspection meeting Grade I as specified in JB/T4730.2-2005. GB151 6.4.1 Clause 137: In a fixed-tube-sheet heat exchanger without expansion joints, under the pressure (positive pressure) in the shell side, the axial stress on the tubes is tensile, while the axial stress on the shell is compressive. 138.JB4710-92 is applicable to self-supporting steel tower vessels with a height of more than 10 meters and a height-to-diameter ratio of more than 5. JB/T4710 1.1 Clause 139: When the carbon content in stainless steel is 0.03% < C < 0.08%, it is referred to as low-carbon stainless steel, and the symbol “0” is indicated before the steel grade” ； When the carbon content in stainless steel is C≤0.03%, it is referred to as ultra-low carbon stainless steel, and the symbol “00” is indicated before the steel grade. 140. The current measures to improve the intergranular corrosion resistance of austenitic stainless steels mainly include solution treatment, reducing the carbon content in the steel, and adding elements that stabilize carbides. 141. The main mode of failure for pressure and vacuum vessels is stability failure ； The main mode of failure for low-temperature pressure vessels is brittle failure. 142. The minimum thickness of the shell after processing is the thickness specified to meet the stiffness requirements during manufacturing, transportation, and installation. 143. When selecting the pressure rating for a pressure vessel flange, it should be taken into account that the pressure rating of the vessel flange must be no lower than the allowable operating pressure of the flange material at the operating temperature ； The pressure rating of the container flange in the vacuum system should be no less than 0.6 MPa. HG20583 3.1.4 Clause 144: When the design temperature of the tower bottom is greater than ? °C or less than ? °C, a short section made of the same material as that used for the tower bottom should be installed at the upper part of the skirt cylinder. 145. The material of the tower foundation bolt seats should generally be the same as that of the skirt cylinder. When the ambient temperature is above 0°C, Q235 is generally used as the material for anchor bolts; when the ambient temperature is below or equal to 0°C, Q345 is usually chosen. II. Multiple-choice Questions 1. The Pressure Vessel Code is applicable when A is greater than or equal to 0.1 MPa ； The inner diameter (for non-circular cross-sections, this refers to the largest dimension) is 0.15 m or greater, and the volume is D m3 or greater ； The medium is a gas, a liquefied gas, or a liquid with a maximum operating temperature equal to or higher than its standard boiling point. A) Maximum operating pressure B) Design pressure C) Nominal pressure D) 0.025 E) 0.022. Pressure vessels with an inner diameter of 0.15 m or more and a volume of D m3 or more fall under the jurisdiction of the \"Regulations on Pressure Vessels\". A) 0.015 B) 0.01 C) 0.0025 D) 0.025. A container that holds highly hazardous media, with a maximum operating pressure of 0.2 MPa and a volume of 0.1 m3, should be classified as a Class B pressure vessel. A) Class I B) Class II C) Class III 4. The design pressure of the tube side of a heat exchanger is -0.1 MPa; the fluid in this side is a highly hazardous gas. The design pressure of the shell side is 0.3 MPa, and the fluid there is steam. To which class of pressure vessel does this heat exchanger belong? A. A) Class I B) Class II C) Class III 5. Vertical buffer tank, with a maximum operating pressure of 1.6 MPa, an operating temperature of 280°C, a total volume of 6 m3, and the medium being superheated steam. Its category is B. A) Class I B) Class II C) Class III 6. Medium-pressure reaction vessels containing media that are flammable or moderately toxic, with a PV product of greater than or equal to C MPa·m3, should be classified as Class III pressure vessels. A) 0.1 B) 0.05 C) 0.5 D) 0.457. Horizontal tank for liquid chloromethane, with a maximum operating pressure of 1.1 MPa, an operating temperature of 10°C, a total volume of 0.5 m3, and the medium in question being highly hazardous. Its category is C. A) Class I B) Class II C) Class III 8. For an ammonia storage vessel with a design pressure of 2.2 MPa, a design temperature of 50°C, toxicity level III (moderate hazard), and a volume of 7 m3, its pressure vessel category is C. A) Class I B) Class II C) Class III 9. The shell side design pressure is 1.8 MPa, the design temperature is 50°C, and the medium is propane; the tube side design pressure is 0.4 MPa, the design temperature is 35°C, and the medium is water. Therefore, its pressure vessel category is B. A) Class I B) Class II C) Class III 10. For a storage tank with a design pressure of 0.2 MPa, a design temperature of 30°C, a volume of 1 m3, and a medium of nitrogen, as well as a maximum operating pressure of 0.08 MPa, the category of this vessel is . A) Category I B) Category II C) Outside category 11. Containers B, which contain media that are extremely and highly hazardous in terms of toxicity, and containers A, which also contain media that are extremely and highly hazardous and for which the P.V. value is 0.2 MPa·m3 or greater, are classified as Category III pressure vessels. A) Low pressure, B) Medium pressure, C) Reaction. 12. Multi-chamber pressure vessels (such as heat exchangers, jacketed vessels, etc.) are classified according to the pressure chamber with the highest pressure, and their design and manufacturing requirements follow those specified in C. A) Lower category B) Higher category C) Separate category for each pressure chamber. 13. The Pressure Vessel Regulations stipulate that the phosphorus content (as determined by melting analysis) in steel specifically used for pressure vessels should not exceed C, and the sulfur content should not exceed A. A) 0.020%, B) 0.025%, C) 0.030%, D) 0.032%. 14. The Code specifies that for carbon steel and low-alloy steel used in the main pressure-bearing elements of welded structural pressure vessels, the carbon content shall not exceed A. 14A) 0.25% B) 0.28% C) 0.3% 15. Carbon steel and low-alloy steel sheets used in the manufacture of pressure vessels containing liquefied petroleum gas with a hydrogen sulfide content greater than D mg/L shall be subjected to ultrasonic testing on a sheet-by-sheet basis. A) 25 B) 200 C) 80 D) 10016. Carbon steel and low-alloy steel sheets used for manufacturing pressure vessels with a maximum operating pressure of C MPa or more shall be subjected to ultrasonic testing on a sheet-by-sheet basis. A) 2.5 B) 1.0 C) 10 D) 6.417. When copper and copper alloys are used for pressure-bearing components in pressure vessels, it is generally advisable to choose B. A) Hot-rolled state B) Annealed state C) Work-hardened state D) Pressed state E) Forged state 18. Titanium materials used for manufacturing pressure vessel shells should be used in state B. A) Normalizing B) Annealing C) Quenching and tempering 19. Steel plates used for manufacturing Class III pressure vessels must undergo A. A) Re-inspection B) Normalizing treatment C) 100% radiographic inspection. 20. The Pressure Vessel Code stipulates that steel plates used for manufacturing category III pressure vessels must undergo re-inspection, and the contents of such re-inspection must include at least A. A) The mechanical properties and cold bending properties of each batch of material, as well as the chemical composition for each furnace batch. B) The mechanical properties and cold bending properties of each batch of material. C) The mechanical properties and impact test results of each batch of material, along with their chemical composition. 21. The qualification seal of the pressure vessel design firm must be affixed to the general layout diagram in option B. A) Basic diagram of the pressure vessel designed by this unit B) Blueprint of the pressure vessel designed by this unit C) Blueprint of the pressure vessel designed by another unit. 22. For category III medium-pressure reaction vessels and storage vessels, high-pressure vessels, and mobile pressure vessels, the person who signs on the overall design diagram shall be C. A) Design, proofreading, review B) Design, verification, review (finalization) C) Design, proofreading, review (finalization), person in charge of pressure vessel design technology. 23. The design pressure of fixed pressure vessels used to store liquefied gases without insulation facilities should be no less than C. A) Operating pressure of the gas B) Operating pressure at the highest temperature in summer C) Saturated vapor pressure at 50°C (for critical temperatures ≥50°C) or gas pressure at 50°C under maximum filling conditions (for critical temperatures <50°C). 24. The level of the saturated vapor pressure of liquefied petroleum gas in a closed container depends on B. A) The amount of liquefied petroleum gas B) The temperature level C) The composition of the liquefied petroleum gas components D) The amount of residue 25. The design pressure for fixed liquefied petroleum gas storage tanks should be determined based on the actual saturated vapor pressure of the components in the liquefied petroleum gas at a temperature of no lower than B °C. A) 40 B) 50 C) 20 D) 0. 26. When designing storage containers, if the metal temperature of the shell is affected by the ambient air temperature, the minimum design temperature shall be taken as the lowest value among the average minimum temperatures recorded over the years. A) Month B) Year C) Day D) 100 days 27. For fixed pressure vessels used to store liquefied gas, the designed storage capacity should be calculated using the formula: W=φVρt, where φ is the filling coefficient, and generally φ is taken as C. A) φ=0.7 B) φ=0.8 C) φ=0.928. In storage containers for liquefied petroleum gas, the first flange sealing surface connected by flanges should use C. A) Flat welding flange with neck, metal gasket, and high-strength bolts combination B) High-neck butt welding flange, metal gasket, and high-strength bolts combination C) High-neck butt welding flange, metal wound gasket (with outer ring), and high-strength bolts combination 29. The option in which asbestos rubber sheets cannot be used as flange gaskets for pressure vessels is D. A) Liquefied petroleum gas storage tank B) Liquid ammonia storage tank HG20583 Article 3.2.1.5 C) Liquid chlorine storage tank D) Vacuum vessel (rubber gaskets or wound gaskets should be used) 30. For austenitic stainless steel cylinders that are subject to intergranular corrosion, heat treatment D should be carried out after hot working. A) Annealing B) Normalizing plus tempering C) Stabilization D) Solution treatment E) Solution treatment plus stabilization 1631. The longitudinal seams between adjacent tube sections, as well as the welds used to join the end caps, should be offset from the longitudinal seams of the adjacent tube sections. The length of the outer arc between the centers of these welds should generally be greater than B times the thickness of the cylinder wall, and it should not be less than 100 mm. A) 2 times B) 3 times C) 5 times D) 8 times 32. For pressure vessels with a design pressure of B MPa or more, or those made of D low-alloy steel, a product welding test plate shall be prepared for each Type A joint of such vessels. A) 5 B) 10 C) 100 D) Cr-Mo E) 16MnR. Reactors and storage vessels for flammable materials in Category II pressure vessels must undergo C. A) 100% radiography and 100% ultrasonic testing B) 100% radiography and 20% ultrasonic testing C) 100% radiography or 100% ultrasonic testing 34. For which of the following devices is it not necessary to perform full radiographic or ultrasonic testing on the joints? D. A) Class III pressure vessels B) Pressure vessels with a design pressure greater than 5.0 MPa C) Those that are subjected to pneumatic testing D) Shell-and-tube waste heat boilers with a design pressure less than 0.6 MPa (100% NDE is required for those with a pressure of 0.6 MPa or higher). 35. According to the “Pressure Vessel Regulations,” for pressure vessel joints with wall thicknesses greater than 38 mm (where the minimum specified tensile strength of the material is less than 540 MPa), the requirement for non-destructive testing is C. A) 100% radiographic or ultrasonic inspection. B) 100% inspection must be carried out using both radiographic and ultrasonic methods simultaneously. C) 100% inspection using one method, with an additional 20% non-destructive inspection using another method. 36. If the head is joined together (excluding joined heads that are first formed and then welded together), its weld joint factor is C. A) 0.85 B) 0.9 C) 137. For radiographic inspection of butt welds in pressure vessels, a grade of II is considered acceptable; if ultrasonic inspection is used, what equivalent grade should be chosen? A) Grade I B) Grade II C) Grade III 38. During the hydrostatic test, the circumferential membrane stress of the pressure vessel shell shall meet the requirements of A. A) ≤90%φ·σS B) ≤80%φ·σSC) ≤75%φ·σS39. The airtightness test of pressure vessels shall be carried out after the hydraulic test is successful, and the pressure for the airtightness test is C. A) 1.05 times the design pressure B) 1.15 times the design pressure C) The design pressure. 40. The correct relationship among the maximum operating pressure Pw of a pressure vessel, its design pressure P, and the opening pressure Pz of the safety valve is: C. A) Pw＜P＜Pz B）Pw≤P＜Pz C） Pw＜Pz≤P D） Pw≤Pz≤P41.GB150-1998 is applicable to designs with a design pressure not exceeding B. A) 25 MPa B) 35 MPa C) 50 MPa. 42. GB150 is not applicable to which of the following containers? B. A) Vessel with a design pressure of 35 MPa B) Vessel with a vacuum level of 0.01 MPa C) Vessel with an inner diameter of 200 mm 43. GB150-1998 does not apply to which of the following vessels: A, C, D. A) Nuclear pressure vessel B) Liquefied petroleum gas cylinder C) Horizontal vessel D) Ultra-high pressure vessel 44. GB150 does not apply to vessels with an inner diameter of less than C mm. A) 300 B) 100 C) 150 D) 20045. The metal temperature refers to the compressed component C. A) Maximum temperature on the outer surface B) Maximum temperature on the inner surface C) Average temperature along the thickness of the cross-section. 46. The pressure test temperature for pressure vessels refers to B. A) Ambient temperature B) Temperature of the test medium C) Metal temperature of the container shell. 47. Among the following thicknesses, the minimum thickness that meets the requirements for strength and service life is C. A) Nominal thickness B) Calculated thickness C) Design thickness. According to GB150, the effective thickness refers to A. A) Nominal thickness minus thickness allowance B) Sum of calculated thickness and corrosion margin 18 C) Design thickness plus negative deviation value of steel thickness 49. Among the following thicknesses, the minimum thickness that meets the requirements for strength (stiffness, stability) and service life is A. A) Design thickness B) Minimum thickness C) Calculated thickness D) Nominal thickness. 50. According to GB150-1998, the effective thickness refers to B. A) Calculate the sum of the thickness and the corrosion margin. B) Nominal thickness minus the thickness allowance. C) Design thickness plus the negative deviation of the steel thickness. 51. When determining the design pressure of a pressure vessel subjected to external pressures, A, which may occur under normal operating conditions, should be taken into account. A) Maximum internal and external pressure difference B) Maximum external pressure C) Maximum internal pressure D) Maximum internal and external pressure combined. 52. The thickness addition C refers to C. A) Negative deviation of steel thickness B) Sum of the negative deviation of steel thickness and corrosion margin plus the thinning amount for container fabrication C) Sum of the negative deviation of steel thickness and corrosion margin D) Containers heated directly by flame 53. The welding joint coefficient φ for pressure vessels should be selected based on A. A) Weld pattern and non-destructive testing requirements B) Weld categories and types C) Groove pattern and welding process 54. For steel pressure vessels with fully penetrated butt joints equivalent to double-sided welding, when partial non-destructive testing is used, the weld joint factor shall be C. A) 1.0 B) 0.9 C) 0.85 D) 0.85. For a single-sided welded butt joint (with gussets in close contact with the base metal along the entire length of the weld root), when local non-destructive testing is performed, its weld joint coefficient is D. A) 1.0 B) 0.9 C) 0.85 D) 0.856. According to GB150-1998, the hydrostatic test pressure Pt for pressure vessels should be B. A) The larger of 1.15P/t and P+0.1; B) The larger of 1.25P/t and P+0.1; C) 1.25P. 57. In the calculations under GB150-1998, where the test pressure PT = 1.25P/t, if the materials used for various components of the container (cylinders, heads, nozzles, flanges, and fasteners) are different, then the value C is taken from the material/t ratios of those components. A) Average value B) Maximum value C) Minimum value 58. The hydrostatic test pressure for pressure vessels is B, while it is A for vacuum vessels; the stress in the cylinder during hydrostatic testing must not exceed D. A) 1.25P, B) 1.25P/tC) 0.8φσs D) 0.9φσs59. The hydrostatic test pressure PT for external-pressure vessels and vacuum vessels is B. A) PT = 0.2 Mpa B) PT = 1.25P C) PT = 1.05P (where P is the design pressure). 60. During the hydraulic test, the membrane stress бT of the cylinder shall not exceed A, which is the yield limit of the material at the test temperature. A) 90% B) 80% C) 85% 61. When austenitic steel is used at temperatures above 525°C, the carbon content in the steel should be no less than C. A) 0.4% B) 0.03% C) 0.04% 62. When the operating temperature of austenitic stainless steel is greater than or equal to A, the impact test can be omitted. A) -196℃ B) -100℃ C) -200℃ 63. When using Q235-B steel plates to manufacture pressure vessels, the design pressure P is less than or equal to B MPa ； The operating temperature for the steel plate is E ； When used for the housing, the steel plate thickness shall not exceed F mm. A) 10 MPa B) 1.6 MPa C) 2.5 MPa D) 0～200℃ E) 0～350℃ F) 20 mm G) 30 mm 64. Type B, which is used for shell thicknesses >30 mm, should be used in the normalized state. A) 15MnVR (16mm) B) 20R and 16MnR. For pressure-bearing components such as flanged tube sheets and flat covers, steel plates of 20R and 16MnR with a thickness greater than C should be used in the normalized state. A) 30mm B) 40mm C) 50mm 66. Carbon steel and low-alloy steel plates used for shell thicknesses > D mm shall be subjected to tensile and Charpy impact tests one by one. 20A) 28 B) 40 C) 50 D) 60. 67. For the steel plates used in shells, those that require low-temperature impact testing are B and C. A) 20R with a service temperature below 0°C and a thickness of 20 mm. B) 20RC with a service temperature below –10°C and a thickness of 20 mm. C) 16MnR with a service temperature below –10°C and a thickness of 30 mm. D) 0Cr18NiTi68 with a service temperature below 0°C and a thickness of 20 mm. For 20R and 16MnR with a shell thickness greater than A, ultrasonic testing must be performed on each piece, and the quality grade must be at least grade III. A) 30mm B) 50mm C) 60mm. 69. The main bolts of the equipment are made of 35CrMoA material; in what heat treatment state should they be used? B. A) Normalizing B) Quenching and tempering C) Stabilization treatment. 70. The commonly used container heads include oval, disc-shaped, hemispherical, conical, and flat-cover types; in terms of stress distribution, the order from best to worst is B. A) Elliptical, hemispherical, disc-shaped, conical, flat-top ； B) Spherical, oval, disc-shaped, conical, flat lid ； C) Spherical, disc-shaped, oval, conical, flat lid 71. When K≤1, the effective thickness of the oval head shall be not less than C times the inner diameter of the head. A) 0.15% B) 0.2% C) 0.3% (where K is the shape coefficient for the elliptical head). 72. For the larger end of a conical shell, a flangeless structure can be used, with the semi-apex angle of the conical shell being A. A) α≤30° B) α≤45° C) α≤60° 73. For the large end of a conical shell, when the semi-vertex angle α≤, a foldless structure can be used. A) 30o B) 45o C) 60o D) 90o 74. For the small end of a conical shell, when the semi-apex angle α ≤ , a flangeless structure can be used. A) 30o B) 45o C) 60o D) 90o 75. When an oval or oblong hole is made in the housing, the ratio of the long diameter to the short diameter of the hole should not be greater than B. A) 1.5 B) 2.0 C) 2.576. According to the standard GB150-1998 for \"Steel Pressure Vessels\", when the inner diameter Di of the cylinder is greater than 1500 mm, the maximum diameter d of any opening must be less than or equal to B·Di, and also less than or equal to D mm. A) 1/2 B) 1/3 C) 500 D) 1000 E) 52077. The maximum opening diameter for a cylinder with an inner diameter Di≤1500mm should be C. A) The maximum diameter of the opening d ≤ 1/4Di, and d ≤ 320 mm ； B) The maximum diameter of the opening d ≤ 1/3Di, and d ≤ 420 mm ； C) The maximum diameter of the opening d ≤ 1/2Di, and d ≤ 520 mm ； D) The maximum diameter of the opening d ≤ 1/5Di, and d ≤ 220 mm. 78. According to GB150-1998 \"Steel Pressure Vessels\", the maximum diameter d of the openings in convex heads or spherical shells shall be less than or equal to CDi. A) 1/3 B) 1/4 C) 1/297. Option C is incorrect; it does not fall under one of the four conditions under which an opening in a shell does not require additional reinforcement: A) The design pressure is less than or equal to 2.5 MPa; B) The distance between the centers of two adjacent openings is less than twice the sum of their diameters; C) The nominal outer diameter of the fitting is less than or equal to 57 mm (the standard value is 89 mm); D) The minimum wall thickness of the fitting meets the requirements specified in Table 8-1 of GB150. When using reinforcement rings for reinforcement, the correct regulations to be followed are A. A) The minimum standard tensile strength value of the steel, σb, is ≤ 540 MPa. B) The thickness of the reinforcement ring is less than or equal to 2δn (the standard value is 1.5δ). C) The nominal thickness of the shell, δn, is ≤ 28 mm (the standard value is 38 mm). 81. The pressure vessel for which reinforcement rings cannot be used for hole reinforcement is C. A) The medium is highly and extremely hazardous. B) Pd ≥ 10 MPa. C) The shell wall thickness is greater than 38 mm. D) t > 35°C. 82. When using reinforcement rings for reinforcement, the thickness of these rings should be A. A) ≤1.5δn B) >1.5δn C) >δn83. The method used for reinforcement of openings in \"Steel Pressure Vessels\" GB150-1998 is A. A) Equal area method B) Limit analysis method C) Equal area method and limit analysis method. 84. Necked flanges should be manufactured using method A or C. A) Sheet metal B) Hot-rolled C) Forged parts 85. The shoulder height B of grooved, ribbed, and flat-sealed flanges is within the thickness of flange D. A) Included B) Not included (see GB150 Figure 9-1) C) Nominal D) Effective 86. During operation, if the flange is subjected to both internal and external pressures, it should be designed according to condition C. (See GB150, clause 9.6) A) Internal pressure B) External pressure C) Both pressures. 87. The hardness of the bolts used to fasten flanges should be A; the hardness of the nuts should be 30HB. A) Slightly higher than B) Slightly lower than C) Equal to 88. Chapter 10 of GB150-1998 deals with the manufacturing, inspection, and acceptance of pressure vessels of types A, B, and C for use at design temperatures above –20°C. A) Multi-layer wrapping type B) Heat-shrink fitting C) Single-layer welding D) Multi-layer wound plate type E) Flat steel strip type pressure vessel. 89. The welding joints of the main pressure-bearing parts of pressure vessels are classified into C. A) Two categories: A and B B) Three categories: A, B, and C C) Four categories: A, B, C, and D. 90. All butt welds among the various types of convex end caps belong to category A. A) Weld joint of type A B) Weld joint of type B C) Weld joint of type D 91. According to GB150-1998, the joint where the tube sheet is connected to the cylinder in a non-butted manner should be of type B. A) Welded joint of type B B) Welded joint of type C C) Welded joint of type D 92. According to GB150-1998, the welded joints for connections between nozzles and long-neck butt flanges should be of type A. A) Weld joint of type B B) Weld joint of type C C) Weld joint of type D 93. When joining two plates of different thicknesses, the thickness needs to be reduced in case C. A) The thickness of the thin plates is not more than 10 mm, and the difference in thickness between the two plates is more than 1 mm. B) The thickness of the thin plates is greater than 10 mm, and the difference in thickness between the two plates is more than 2 mm. C) The thickness of the thin plates is not more than 10 mm, but the difference in thickness between the two plates is more than 3 mm. 94. The butt weld that requires post-weld heat treatment is B. A) 16MnR with a thickness of 28 mm; B) 15MnVR with a thickness of 30 mm; C) 20R with a thickness of 36 mm (preheating was not applied to any of these welds prior to welding). 95. For steel containers made of 15MnVR with a thickness of 30 mm, the inspection requirements specified for welding joints of types A and B in the technical specifications are incorrect – option B is the wrong one. A) 100% ultrasonic inspection, 20% radiographic re-inspection; B) 20% radiographic testing; C) 100% ultrasonic inspection. 96. For pressure vessel shells and pressure-bearing components made of steel with a thickness δS > A mm, materials such as 12CrMo, 15CrMoR, 15CrMo, as well as other Cr-Mo low-alloy steels of any thickness ； For their Class A and Class B welded joints, 100% radiographic testing or ultrasonic testing shall be carried out. A) 16 B) 25 C) 30. In accordance with GB150-1998, surface magnetic particle or penetrant testing is required, and the acceptance criteria shall comply with item A of JB/T4730-2005. A) Grade I B) Grade II C) Grade III 98. When conducting hydraulic testing on carbon steel and 16MnR vessels, the liquid temperature must not be lower than B °C. A) 0 B) 5 C) 10 D) 25. 99. 20g of steel plate can be used as a substitute for B-grade steel plate. A) 20R B) Q235-C C) 16MnR. Low-temperature vessels refer to B. A) Containers with a metal temperature of -20°C or lower B) Containers designed for a temperature of -20°C or lower C) Containers operating at a temperature of -20°C or lower. 101. For the welded joints of category A and B in low-temperature containers, in addition to the requirement for 100% radiographic or ultrasonic non-destructive testing as specified, partial non-destructive testing is permitted; the inspection length must be at least C times the length of each welded joint, and in any case not less than 250 mm. A) 20% B) 40% C) 50% 102. Scope of application for \"Shell and Tube Heat Exchangers\" GB151-1999: Nominal diameter DN≤ B ； Nominal pressure PN ≤ C ； The product of the nominal diameter and nominal pressure ≤ E. A) 2000mm B) 2600mm C) 35MPa D) 10MPa E) 1.75×104 F) 1.45×104. The nominal diameter of heat exchangers applicable to GB151-1999 is B. A) DN≤2000mm B) DN≤2600mm C) DN≤3000mm. According to GB151-1999, the reference value for calculating the heat exchange tubes in determining the heat exchange area is A. A) Outer diameter B) Mean diameter C) Inner diameter. 105. According to the GB151 standard, when the heat exchange tube is of U-shaped type, its nominal length refers to A. A) Straight pipe section B) Welded section C) Full pipe section 106. In GB151-1999, when cold-drawn carbon steel or low-alloy steel pipes are used as heat exchange tubes, the precision levels for such tubes are Grade I and Grade II; therefore, it is C. A) Design the heat exchanger as a Grade I or Grade II heat exchanger. B) There is no specific method for indicating this. C) Mark it as Grade I tube bank or Grade II tube bank. 107. When the design temperature is below 20°C, use the allowable stress at A °C. A) 20 B) 0 C) 40 D) 100. According to GB151, copper and copper alloys used in the manufacture of heat exchangers should be used in state B. A) Quenching B) Annealing C) Tempering D) Solution treatment 109. The grade of steel forgings used to manufacture tube sheets, flat covers, and flanges shall not be lower than Grade B as specified in JB4726 and JB4728. A) Ⅰ B) Ⅱ C) Ⅲ 100. The grade of the tube sheet forgings used in manufacturing heat exchangers must not be lower than grade A as specified in JB4762 and JB4728. A) Ⅱ B) Ⅲ C) Ⅳ111. When the tube sheet thickness is greater than B, forgings are preferred. A) 50 mm B) 60 mm C) 65 mm112. When the design temperature of the heat exchanger is ≥300°C, the pipe flange should be of type A. A) Butt weld flange B) Welding neck flat flange C) Plate type flat weld flange 113. For the nozzles of steel shell and tube heat exchangers, when the design temperature is 300°C or higher, flange type B must be used. A) Loose type B) Integral type C) Arbitrary type 114. The bending radius of the bent section of the U-tube should be no less than the outer diameter of the heat exchange tube in A. A) 2 times B) 3 times C) 2.5 times. Standard GB151 specifies that the effective thickness of the tube sheet refers to the thickness of the tube sheet at the bottom of the partition groove on the tube side, minus thickness C. A) The portion of the tube side corrosion margin that exceeds the depth of the tube side partition groove. B) The greater of the shell side corrosion margin and the depth of the structural grooves on the shell side of the tube sheet. C) The thickness of both A and B. 116. When the tube sheet and the heat exchange tubes are connected by welding, the minimum thickness of the tube sheet must meet the requirements of structural design and manufacturing, and must be ≥ B. A) 10mm B) 12mm C) 15mm (see GB151 5.6.2.2) 117. According to GB151, when mechanical cleaning is required between the tubes of a heat exchanger, a C arrangement should be used, and the clear distance between adjacent tubes (S-d) should not be less than 6mm. A) Equilateral triangle B) Angled equilateral triangle C) Square D) Angled square 118. A heat exchanger lacks baffle plates and support plates; its tube sheet spacing is L, then the equivalent length Lcr for pressure-induced buckling of the heat exchange tubes is B. (See GB151 Figure 32) A) L B) L/2 C) L/3 D) L/4 119. When strong expansion jointing is used between the heat exchange tubes and the tube sheet in a steel shell-and-tube heat exchanger, the applicable range is B. A) Design pressure ≤ 2.5 MPa, design temperature ≤ 350°C B) Design pressure ≤ 4.0 MPa, design temperature ≤ 300°C C) Design pressure ≤ 1.6 MPa, design temperature ≤ 400°C 120. When the fluid in the shell side of horizontal heat exchangers, condensers, and reboilers is a mixture of gas and liquid or contains solid particles, the baffles should be arranged in pattern A. A) Vertical left-right direction B) Horizontal up-down direction C) Direction at a certain angle 121. The minimum spacing between baffle plates is generally not less than D of the inner diameter of the cylinder, and not less than 50 mm. A) 1/2 B) 1/3 C) 1/4 D) 1/5122. When joining heat exchange tubes, for the butting welds of the same tube, there shall be no more than A such welds on a straight section of tube. A) 1 B) 2 C) 3 D) 4123. When joining heat exchange tubes, for the butt welds of the same tube, the number of U-shaped joints shall not exceed B. (See GB151 6.3.3) A) 1 B) 2 C) 3 D) 4 124. When joining heat exchange tubes, the shortest tube length should not be less than B mm. A) 100 B) 200 C) 300 D) 400125. When joining heat exchange tubes, each tube after being joined should undergo a hydraulic test, with the test pressure being C times the design pressure. A) 1.25 times B) 1.5 times C) 2 times 126. The butt joints of the spliced tube sheets shall be subject to non-destructive testing, with inspection ratios and acceptance levels of A and B. A) 100% X-ray inspection, Grade II; B) 100% ultrasonic inspection, Grade I qualified (see GB151 6.4.1). 127. The sequence of tests for pressure testing of fixed-tube-sheet heat exchangers is B. A) Manage the tube side first, then the shell side; B) Manage the shell side first, then the tube side. 128. For the saddles, lugs, legs, or skirts of low-temperature pressure vessels, it is advisable to use gaskets or connecting plates, trying to avoid welding them to the vessel shell. The material for these gaskets or connecting plates should be determined according to option A. A) The same low-temperature material as the housing B) Q235-B C) 16MnR129. The wall temperature of the heat exchange tube should be chosen as D. A) Average temperature of the fluid inside the pipe B) Average temperature of the fluid outside the pipe C) Average temperature of the fluids on both the inside and outside sides D) Average temperature of the metal along the heat exchange pipe 130. Pressure vessels and their components should be designed with fatigue in mind when subjected to force A. A) Alternating stress B) External load C) **Load 131. The necessary condition for creep to occur is A. A) High temperature B) Low temperature C) Normal temperature 132. Edge stress has: properties A and B. A) Local B) Self-limiting C) Expanding D) Infinite E) Dispersed F) Increasing 133. The theoretical basis for the basic formula used in the calculation of the strength of pressure vessels under internal pressure according to the GB150 standard is A. A) First strength theory B) Third strength theory C) Fourth strength theory 134. To improve the load-bearing capacity of a cylinder under external pressure, the more reasonable approach is C. A) Increase the wall thickness B) Use a material with higher strength C) Install reinforcing rings. 135. E and F are two basic parameters that reflect the sealing performance of gaskets. A) Gasket width B) Gasket material C) Gasket thickness D) Seal surface type E) Pre-compression seal specific pressure y F) Gasket coefficient m136. Stress corrosion cracking is A. A) Brittle fracture of metal under the combined action of sustained tensile stress and specific corrosive agents. B) Brittle fracture of metal under the combined action of sustained bending stress and specific corrosive agents. C) Brittle fracture of metal under the combined action of impact load and specific corrosive agents. 137. When welding dissimilar steels of different strength grades, such as low-carbon steel, low-alloy steel, and high-strength steel, it is generally required that the strength of the weld joint should be at least equal to the lower limit of the tensile strength specified for the base material of the side with lower strength; whereas the plasticity and toughness of the joint should be on par with those of the base material from the side with higher strength but poorer plasticity and toughness. A) Not less than B) Not more than 138. Welding of low-temperature pressure vessels uses B welding rods. A) Acidic welding electrodes B) Low-hydrogen alkaline welding electrodes 139. In the calculation of the tube sheet for fixed-tube-sheet heat exchangers, if none of values A, B, or C obtained by considering various operating conditions with temperature differences meets the strength requirements, it is necessary to install expansion joints. A) Axial stress in the shell, бC B) Axial stress in the heat exchange tubes, бtC C) Pulling force at the connection between the heat exchange tubes and the tube sheet, q D) Radial stress in the tube sheet, бr140. Pressure vessels without feature A ； Pressure vessels with a minimum standard tensile strength of > 540 MPa ； All weld joints of pressure vessels subjected to Test C must undergo 100% radiographic or 100% ultrasonic testing. A) Inspection hole, B) Manhole C) Pneumatic pressure D) Hydraulic pressure. 141. Root cleaning by back-gouging of Cr-Mo steel welds should be subject to A or B type flaw detection inspections. A) Magnetic particle testing B) Penetrant testing C) Ultrasonic testing D) Radiographic testing 142. In the design of horizontal containers, A≤Rm/2, A<0.2L, and the maximum value of A shall not exceed 0.25L; here, L refers to B. A) Total length of the horizontal vessel B) Distance between the tangents of the two ends C) Straight-line length of the cylinder. 143. When designing a horizontal vessel, it is necessary to carry out calculations for the wall thickness as well as the reaction forces at the supports, the axial stress in the cylinder, the tangential shear stress in the cylinder, and to perform calculations and checks related to D. A) Wind load B) **Load C) Local peak stress in the cylinder D) Circumferential stress of the cylinder 144. The minimum wall thickness of the tower cylinder made of carbon steel or low-alloy steel, without taking corrosion allowance into account, is 2Di/1000, and it must be no less than B ； The specified minimum wall thickness for towers made of stainless steel is not less than A. A) 2mm B) 3mm C) 4mm145. The thickness of the base ring plate of a tower, whether it has ribbed plates or not, must not be less than B mm. A) 12 B) 14 C) 16. A butt weld with TIG welding for root pass and single-sided welding for double-sided formation can be used as A. A) Double-sided welded, fully penetrated butt welds; B) Single-sided welded joints with gussets that are in close contact with the base metal along the entire length of the weld root. III. Judgment: 1. The standard “Steel Pressure Vessels” GB150-1998 applies to vessels with a working pressure not exceeding 35 MPa. ( × )2. GB150-1998 \"Steel Pressure Vessels\" is not applicable to vacuum vessels. ( × )3. GB150 is not applicable to vessels with a vacuum degree lower than 0.02 MPa. ( √ )4. The scope of application of the GB150-1998 standard includes: ……the welds connecting non-compressed components to the container; it does not cover components other than these welds, such as supports, lugs, skirts, and reinforcement rings. ( √ )5. The calculated pressure refers to the pressure used to determine the thickness of a component at the corresponding design temperature, including the hydrostatic pressure of the liquid column. ( √ )6. When the hydrostatic pressure exerted by the liquid column on the component is less than 10% of the design pressure, it can be ignored. ( × )7. The design temperature refers to the temperature of the medium inside the vessel under normal operating conditions. ( × )8. Test temperature refers to the temperature of the test liquid during the pressure test. ( √ )9. The calculated thickness refers to the thickness obtained by applying the relevant formulas; where necessary, the thickness required due to other loads should also be taken into account. ( √ )10. GB150-1998 specifies that the design thickness refers to the sum of the calculated thickness and the corrosion allowance, while the effective thickness refers to the nominal thickness minus the thickness increment. ( √ )11. GB150-1998 specifies that the nominal thickness refers to the design thickness plus the negative deviation of the steel thickness, rounded up to the standard specification of the steel. ( √ )12. For the container shell, under any circumstances, its nominal thickness shall not be less than the sum of the minimum thickness and the corrosion allowance. ( √ ? )13. Under any circumstances, the metal temperature of pressure vessel components must not exceed the allowable operating temperature of the steel. ( √ )14. The loads that should be considered in the design of pressure vessels include: internal pressure, external pressure or maximum pressure difference; hydrostatic pressure of liquids; the weight of the vessel itself; wind loads and **loads; as well as the gravitational loads from auxiliary equipment and structures such as platforms, escalators, and pipelines. ( × ) 15. The design pressure of a vacuum vessel is equal to the actual operating vacuum pressure. ( × )16. In the calculation of the thickness of compressed components, the additional thickness amount takes into account only the negative deviation in the steel thickness and the corrosion allowance, but not the thickness reduction due to processing. ( √ )17. For pressure vessels made of carbon steel or low-alloy steel, with a medium of compressed air, water vapor, or water, the corrosion margin must be no less than 2 mm. ( × )18. For bolts made of the same material, the safety factor is independent of the bolt diameter. ( √ )19. When the design temperature is below 20°C, the allowable stress of the material shall be taken as that at 20°C. ( √ )20. The welding joint factor Ф should be determined based on the type of welding joints in the pressure-bearing parts of the container and the proportion of length subject to non-destructive testing. ( √ )21. For butt weld joints with root welding by TIG welding and single-sided welding for double-sided formation, after 100% non-destructive testing, the weld joint coefficient is taken as φ=1.00. ( √ )22. When determining the test pressure for a pressure vessel, if the materials used for various pressure-bearing components of the vessel (such as cylinders, heads, flanges, etc.) are different, the maximum value among the material/t ratios of these components should be taken. ( × )23. Pressure tests on externally pressurized vessels and vacuum vessels are conducted using internal pressure, with the test pressure PT=0.2 MPa, regardless of the magnitude of the designed external pressure. ( × )24. The hydraulic test pressure for vacuum containers is 0.2 MPa. ( × )25. During hydraulic and pneumatic testing, the membrane stress σt of the cylinder shall not exceed 90% of the material’s yield strength at the design temperature. ( × )26. When austenitic steel is used at temperatures above 525°C, its carbon content should be ≥0.04%. ( √ )27. When carbon steel and carbon-manganese steel are used for extended periods at temperatures above 425°C, the tendency of the carbide phases in the steel to graphitize must be taken into consideration. ( √ )28. When the steel is used at a temperature of -20°C, the Charpy low-temperature impact test shall be conducted in accordance with the provisions of Appendix C. ( × )29. 16MnR steel plates with a thickness greater than 30 mm shall be subject to ultrasonic testing on a piece-by-piece basis, and their quality grade shall meet the requirements of Grade IV as specified in ZBJ74003-88. ( × )30. The quality grade of the inner cylinder steel plates for multi-layer wrapped pressure vessels shall be no lower than Grade II as specified in JB/T4730.3-2005. ( √ )31. Pressure vessels made of high-alloy steel plates with a thickness >4mm shall be specified in the drawings as steel plates for pressure vessels. ( × )32. When the nominal thickness of carbon steel and low-alloy steel forgings is greater than or equal to 300 mm, the forging grade shall not be lower than Grade III as specified in JB4726. ( × )33. The welding joint coefficient φ for the inner cylinder of a multi-layer wrapped cylinder is 1.0. ( √ ? )34. The applicable range of the strength calculation formula for the wall thickness of an internal-pressure cylinder in the standard \"Steel Pressure Vessels\" GB150-1998 is: P≤0.6tφtφ]. ( × )35. The calculation formula δ=PcDi/2tφ-Pc from GB150-1998 for internal pressure cylinders is applicable to the design of steel pressure vessels with a design pressure not exceeding 35 MPa. ( √ ? )36. The reinforcement ring of a pressure vessel, due to its reinforcing function, must encircle the entire circumference without any interruptions, and continuous welding should be used. ( × )37. Components inside pressure vessels, such as trays, can also be used as reinforcing rings if they are designed to serve a reinforcing purpose. ( √ )38. For elliptical end caps with K≤1, the effective thickness shall be not less than 0.15% of the inner diameter of the end cap, which is required to ensure that no local elastic instability occurs under internal pressure. ( √ )39. For elliptical end caps, when Di/2hi=2, the shape factor K is taken as 1. ( √ )40. The connections between the seamless spherical heads and conical heads and the cylinder shall all adopt a fully penetrative weld structure. ( √ )41. For conical shells, a flangeless structure can be used when the half-apex angle α of the cone is ≤ 45°. ( × )42. Under any circumstances, the thickness of the reinforcement section shall not be less than the thickness of the conical shell to which it is connected. ( √ )43. In the standard \"Steel Pressure Vessels\" GB150-1998, the stress analysis method is used for reinforcement through openings. ( × )44. GB150-1998 stipulates that for convex heads or spherical shells, the maximum diameter of openings d ≤ 0.5Di. ( √ )45. All openings on pressure vessels must be reinforced; otherwise, it will affect their safe use. ( × )46. Maximum opening diameter without additional reinforcement: when the nominal thickness of the shell is less than or equal to 12 mm, the nominal diameter of the nozzle is less than or equal to 50 mm. ( × )47. The following requirements shall be followed when using reinforcement rings for reinforcement: the minimum standard tensile strength of the steel shall be ≤ 540 MPa; the thickness of the reinforcement ring shall be ≤ 1.5δn; and the nominal thickness of the shell shall be ≤ 38 mm. ( √ )48. In the calculation of the reinforcement area for openings in elliptical and disc-shaped heads, δ = PcK1Di/(2tφ–0.5Pc); where for elliptical heads, K1 = 1 or 0.9]. ( × )49. For all openings on oval end caps, the same calculation method should be used for performing the opening reinforcement calculations. ( × )50. The reinforcement area required for a pressure vessel subjected to external pressure due to openings is larger than that required for a pressure vessel subjected to internal pressure due to openings. ( × )51. In flange calculations, the shoulder heights of tenons, male/female surfaces, and planar sealing surfaces are not included in the effective thickness of the flange. ( √ )52. The welding joints formed by the butt joint of the flat cover, tube sheet, and cylinder body belong to Class B welding joints. ( √ )53. For the shape deviations of the inner surfaces of elliptical, disc-shaped, spherical, and flanged conical heads, the maximum gap shall not exceed 1.25% of the designed inner diameter Di of the head, and the vertical fold depth in the straight-edge sections shall not be greater than 1.5 mm. ( × )54. The length of the outer arc between the centerlines of Class A welded joints of adjacent cylinders, or the length of the outer arc between the centerline of a Class A welded joint on a head and the centerline of a Class A welded joint on an adjacent cylinder, shall be greater than 3 times the nominal thickness and not less than 100 mm. ( × )55. After the adjacent cylinders are assembled, the distance between Class A welded joints, or the distance from the endpoints of Class A welded joints on the end caps to the Class A welded joints on the adjacent cylinders, shall be greater than 3 times the nominal thickness δn and not less than 100 mm. ( √ )56. In pressure vessel manufacturing, heat treatment is divided into two categories: post-welding heat treatment and heat treatment to improve mechanical properties. ( √ )57. Pressure vessels subject to stress corrosion ； Pressure vessels containing media with an extreme or high toxicity level must undergo post-weld heat treatment. ( √ )58. Pressure vessels that require post-weld heat treatment: Class III pressure vessels ； Design pressure ≥ 5 MPa ； The second category of pressure vessels includes reaction pressure vessels and storage pressure vessels for flammable media. ( × )59. Cr-Mo steel pressure vessels ； The specification states that for containers holding extremely or highly hazardous toxic media, a welding test plate must be prepared for each unit of product manufactured. ( √ ) GB150 10.5.1.160. For pressure vessels that require heat treatment to meet the mechanical property requirements of the material, a heat treatment test plate made from the base material shall be prepared for each vessel. ( √ ) GB150 10.5.461. The length of the area to be inspected by local flaw detection shall be not less than 20% of the length of each weld, and not less than 250 mm ； Local flaw detection must include every intersecting weld joint. ( √ ) 62. At the weld intersections of pressure vessels subjected to local non-destructive testing ； Butt joints covered by reinforcement rings, shims, etc ； Butt joints of fittings with a nominal diameter of ≥250 mm shall be subjected to 50% radiographic or ultrasonic testing. ( × )63. During pressure testing, the range of the pressure gauge should be no less than 1.5 times and no more than 3 times the test pressure. ( √ )64. After the pressure test, compressed air at 0.4–0.5 Mpa should be introduced into the reinforcement ring of the container’s openings to check the quality of the weld joints. ( √ )65. For carbon steel, 16MnR, 15MnNbR, and normalized 15MnVR steel pressure vessels, the temperature of the liquid used for hydrostatic testing must not be lower than 5°C. ( × )66. The safety measures for pressure testing must be approved by the reviewer and signatory in the drawings. ( × )67. For the steel used in the pressure-bearing components of pressure vessels, substitution is permissible as long as the mechanical properties and chemical composition of the materials are identical. ( × )68. The allowable stress for welded austenitic stainless steel pipes is 0.9 times the allowable stress of the corresponding steel grade. ( × )69. The opening pressure of the safety valve should be higher than the operating pressure of the pressure vessel, but lower than the design pressure. ( √ )70. Pressure vessels manufactured from carbon steel and low-alloy steel at temperatures below -20°C are considered low-temperature pressure vessels, and shall be designed, manufactured, inspected, and accepted in accordance with the relevant standards and regulations for low-temperature vessels. ( × ) 71. The steel used for pressure components in cryogenic vessels must be killed steel. ( √ )72. The impact test temperature for steels used in low-temperature vessels shall be lower than or equal to the lowest design temperature of the vessel shell or its pressure-bearing components. ( √ )73. The nameplate of a cryogenic vessel cannot be riveted directly to the shell. ( √ )74. When connecting plug-in nozzles to pressure vessels subjected to fatigue loads, cryogenic pressure vessels, or vessel shells made of steel with a standard room-temperature tensile strength σb > 540 MPa, the corners of the inner diameter of the nozzles should be rounded. ( √ )75. Carbon boiling steel plates and Q235-A steel plates shall not be used in the manufacture of pressure vessels governed by GB150 or relevant codes. ( √ )76. Carbon steel Q235-A plates can be used to manufacture containers with a design pressure of P≥1.6 Mpa. The operating temperature for these plates is 0–350°C. When used for vessel shells, the thickness of the plates should not exceed 20 mm; they are suitable for pressure containers that hold media with a high or extremely high level of toxicity. ( × )77. For GB151-1999 steel shell-and-tube heat exchangers, the applicable parameter is a nominal diameter DN ≤ 2000 mm ； The nominal pressure PN ≤ 35 MPa, and the product of the nominal diameter (mm) and nominal pressure (MPa) shall not exceed 1044]. ( × )78. According to GB151-1999, the method for calculating the heat exchange area is as follows: using the diameter of the heat exchange tube as a basis, subtracting the length of the tube that extends into the tube sheet, and then rounding the result to obtain the heat exchange area. ( × )79. According to GB151-1999, when the heat exchange tubes are U-tubes, the straight section length of these U-tubes constitutes their nominal length. ( √ )80. Corrosion allowance should be considered on both sides of the tube sheet. ( √ )81. No corrosion margin is considered for the heat exchange tubes. ( √ )82. When grooves are made in the tube sheet and head plates, the metal that protrudes above the bottom surface of the partition groove can be used as a corrosion margin; however, when this corrosion margin is greater than the depth of the groove, the difference between the two values should also be added. ( √ )83. For heat exchangers in which the design pressure of the tube side is greater than that of the shell side, the drawing shall specify detailed requirements regarding the testing methods and test pressures for the joints connecting the heat exchange tubes to the tube sheet. ( √ )84. The heat exchanger cylinder can be manufactured from welded pipes of carbon steel or low-alloy steel. ( × )85. GB151-1999 stipulates that when the tube sheet itself has a shoulder for mating with the cylinder, forgings should be used. ( √ )86. When the design temperature of the heat exchanger tube sheet flanges is 250°C or higher, butt-welded flanges shall be used. ( × )87. In heat exchanger design, the thickness of the shell is calculated using the relevant formulas in GB151-1999, so there is no need to consider other factors. ( × )88. When the tube sheet and heat exchange tubes are connected by welding, the minimum thickness of the tube sheet must meet the requirements of structural design and manufacturing, and this minimum thickness shall be ≥ 12 mm. ( √ )89. When it is not possible to ensure that the shell-side pressure and the tube-side pressure act simultaneously under all conditions, the pressure difference between these two pressures can still be used for the design of the tube sheet. ( × )90. The method specified in GB151-1999 can be used to calculate cases where the area around the tube sheet without tubes is wide (k>1.0), or for fixed tube sheets that are weld-connected to flanges. ( × )91. When designing the tube sheet, if either the shell side pressure or the tube side pressure is negative, it is necessary to consider dangerous combinations of pressure differences. ( √ )92. When connecting the heat exchange tubes to the tube sheet, welding is used instead of expansion joining. ( × )93. When using strength expansion joining, the hardness of the heat exchange tube material generally must be lower than that of the tube sheet material. ( √ )94. A shock plate should be installed when the medium is corrosive or abrasive gases, vapors, or gas-liquid mixtures. ( √ )95. When the medium is volatile, flammable, explosive, toxic, or valuable, a stuffing box type heat exchanger is suitable. ( × )96. According to GB151-1999, the heat exchange tubes in heat exchangers are not allowed to be joined together. ( × )97. When conducting hydraulic tests on each heat exchange tube after assembly, the test pressure shall be 1.25 times the design pressure. ( × )98. 100% radiographic or ultrasonic testing shall be conducted on the butt joints of spliced plates. According to JB/T4730, it shall meet the standard with a radiographic inspection result of grade III or above, or an ultrasonic inspection result of grade II or above. ( × )99. Except for stainless steel, the welded tube sheet should undergo stress-relief heat treatment. ( √ )100. Welded flanged tube boxes made of carbon steel or low-alloy steel, or tube boxes with radial openings exceeding 1/2 of the inner diameter of the cylinder, shall undergo post-weld heat treatment. ( × )101. For tube boxes made of carbon steel or low-alloy steel with partition plates, the flange sealing surfaces can be machined after welding the partition plates and flanges. ( × )102. Class A weld joints of low-temperature heat exchangers shall adopt double-sided welding or fully penetrated butt joints equivalent to double-sided welding. ( √ )103. When the U-shaped heat exchange tubes in low-temperature heat exchangers are cold-formed with a bending radius less than 10 times the outer diameter of the tubes, stress-relief heat treatment must be carried out after cold forming. ( √ )35104. When the base materials on either side of a welded joint in a low-temperature heat exchanger have different requirements regarding impact testing, the impact testing temperature for the metal of the welded joint should be lower than or equal to the lower of the temperatures required for the two base materials. (×)105. When calculating the wall temperature of a heat exchanger, the symbol K represents the overall heat transfer coefficient calculated based on the external surface area of the heat exchange tubes, with the unit being W/(m2·℃). ( √ )106. The provisions of the \"Regulations on Safety Technical Inspection of Pressure Vessels\" do not apply to pressure vessels operating under vacuum. ( √ )107. The Code is applicable to designs with a design pressure of 0.1 MPa or greater ； The inner diameter (for non-circular cross-sections, this refers to the largest dimension of the cross-section) is greater than or equal to 0.15 m, and the volume is greater than or equal to 0.25 m³ ； The medium is a gas, a liquefied gas, or a liquid with a maximum operating temperature equal to or higher than its standard boiling point. ( × )108. Vacuum vessels are external-pressure vessels; therefore, they are subject to the \"Regulations on Safety Inspection of Pressure Vessels.\" ( × )109. Vessels with a maximum operating pressure below 0.1 MPa and a design pressure above 0.1 MPa are required to comply with the \"Regulations on Safety Inspection of Pressure Vessels.\" ( × )110. Low-pressure vessels whose toxicity level corresponds to extremely hazardous or highly hazardous media, and whose pV value is 0.2 MPa·m3 or greater, are classified as third-class pressure vessels. ( √ )111. Medium-pressure vessels with an extreme or high degree of toxicity should be classified as category III pressure vessels. ( √ )112. A storage vessel with a medium of air, a design pressure of 2.0 MPa, and a volume of 50 m3 should be classified as a Class III pressure vessel. ( × )113. Low-pressure vessels that are extremely and highly hazardous in terms of toxicity, and for which pV≥0.2 MPa·m3, are classified as Category III vessels. ( √ )114. A cryogenic liquid carbon dioxide storage tank with a volume of 8 m3 is classified as a Class III pressure vessel. ( × )115. Multi-chamber pressure vessels shall have their category determined based on the highest-pressure chamber, and shall be managed for use in accordance with that category. ( √ )116. Multi-chamber pressure vessels should be designed and manufactured in accordance with the requirements of the highest-pressure chamber among them. (×)117. The phosphorus content in steel materials specifically used for pressure vessels should not exceed 0.030%, and the sulfur content should not exceed 0.020%. ( × )118. For carbon steel and low-alloy steel used in welding structural pressure vessels as the main pressure-bearing elements, their carbon content shall not exceed 0.25%. ( √ )119. For pressure vessels made of carbon steel and low-alloy steel with a maximum operating pressure of ≥10 MPa, the steel plates must be subjected to ultrasonic testing one by one. ( √ )120. Steel plates used for pressure vessels whose contained media are extremely or highly toxic should be subjected to ultrasonic testing on a sheet-by-sheet basis. ( √ )121. Titanium materials used for manufacturing pressure vessel shells should be used in the annealed state. ( √ )122. On the general design drawing of high-pressure vessels, only the signatures of the design, verification, and approval (finalization) personnel are required. ( × )123. For pressure vessels containing mixed liquefied petroleum gas without insulation at normal temperatures, 50°C shall be used as the design temperature. ( √ )124. For pressure vessels that cannot have inspection holes installed for special reasons, 100% radiographic or ultrasonic non-destructive testing shall be carried out on each longitudinal and circumferential weld joint, and the calculated thickness shall be indicated on the design drawings. ( √ )125. Before welding pressure vessel products, a welding procedure qualification shall be conducted for T-joints that require full penetration. ( √ )126. Post-weld heat treatment should be carried out after all welding work is completed and the inspections are successful, prior to the pressure test. ( √ )127. For pressure vessels made of austenitic stainless steel whose coefficient φ for containers and welded joints is taken as 1, the depth of undercut on the weld surface shall not exceed 0.5 mm. ( × )128. The purpose of welding test plates and specimens for pressure vessel products is to evaluate the mechanical properties and bending strength of the welded joints as well as other pressure-bearing components in these products. ( √ )129. The proportion of non-destructive testing for the butt joints of pressure vessels in the \"Regulations on Safety Inspection of Pressure Vessels\" is three types: 20%, 50%, and 100%. ( × )130. For reaction pressure vessels and storage pressure vessels containing flammable media that fall under Category 2 pressure vessels, only partial non-destructive testing is required. ( × )131. Welded joints of pressure vessels with a design pressure greater than 5.0 MPa must undergo 100% non-destructive testing. ( √ )132. For a low-pressure shell-and-tube waste heat boiler with a design pressure of 0.6 MPa, the technical specifications shall require 20% radiographic or ultrasonic testing to be carried out on the butt joints. ( × )133. Aluminum pressure vessels with a design pressure of 1.0 MPa, that are non-flammable and have a moderate level of toxicity, shall undergo 100% radiographic inspection. ( √ )134. For pressure vessels made of carbon steel with a wall thickness greater than 30 mm, if radiographic testing is used for their butt joints, local ultrasonic testing shall be performed on each welded joint. (× )37135. When performing local non-destructive testing on pressure vessels, local non-destructive testing should also be carried out at the intersections of welded joints. ( × )136. For pressure vessels that undergo local non-destructive testing, the manufacturer may not be held responsible for the quality of the weld joints in the areas that were not tested. ( × )137. When checking the pressure for the pressure resistance test, the wall thickness used should take into account the additional wall thickness; for hydraulic tests, the pressure applied must also include the static pressure of the liquid column. ( × )138. The airtightness test should be carried out after the hydraulic test is successful. ( √ )139. Pressure vessels with a medium toxicity level that is extremely high, hazardous, or for which minor leaks are not permitted due to design constraints must undergo a gas-tightness test. ( × )140. When repairing or modifying pressure vessels by welding, patching or replacement is generally required. ( √ )141. The safety accessories of pressure vessels, including safety valves, rupture disc devices, emergency shut-off devices, pressure gauges, level gauges, temperature measuring instruments, and safety interlock devices for quick-opening pressure vessels, must comply with the provisions of the Pressure Vessel Regulations; in addition, they must also meet the requirements of the relevant standard applicable to each of them. ( √ )142. The opening pressure of the safety valve shall not exceed the design pressure of the pressure vessel ； The calibrated burst pressure of the rupture disc shall also not exceed the design pressure of the pressure vessel. ( √ ) HG20580 Page22143.GB150 adopts a conventional design approach overall, but the stress classification design method is also applied in certain specific areas. ( √ )144. High-pressure vessels must be thick-walled vessels. 0/Di≤1.5 indicates a thin-walled container. ( × ? )145. When selecting the material and type of gasket, factors such as the corrosiveness of the medium to be sealed, the pressure and temperature of that medium, and the stability of the operation should be taken into consideration. ( √ )146. Containers with a working pressure of 10 MPa ≤ P < 100 MPa are considered high-pressure containers. ( × )147. The high-pressure Kazari sealing structure recommended by GB150 is of the self-tightening or semi-self-tightening type. ( ? )148. The main factors affecting the strength of the tube sheet: the elastic supporting force exerted by the tube bundle on the tube sheet ； The weakening of the tube sheet strength due to tube holes ； Support forms around the tube sheet ； The effect of temperature difference. ( × )149. In fixed-tube-sheet heat exchangers, expansion joints should be considered if the temperature difference between the tube wall and the shell wall is greater than 50°C. ( × )38150. When the skirt of an upright container and the shell are connected by butt welding, it is not necessary to check the tensile stress in the weld joint. ( × )151. Materials such as austenitic steel, copper, and aluminum cannot be inspected using the magnetic particle testing method. ( √ )152. Metal temperature refers to the average temperature of the pressurized components of a vessel along its cross-sectional thickness, rather than the highest temperature on the inner and outer surfaces. ( √ )153. When a oblong hole is made in the shell, and when the length axis/short axis ratio is ≤ 2 with the short axis parallel to the cylinder axis, the reinforcement for the hole is calculated based on the short axis of the oblong hole. ( √ )154. When determining the positions of the supports for a horizontally mounted container supported at two points, the distance A from the center line of the support to the tangent line of the head shall be ≤ 0.2L, where L is the length of the straight section of the cylinder. ( × )155. When a horizontal container is supported by double saddle supports, the structural design of the two saddle supports must be exactly the same. ( × )156. In horizontal containers, the position A of the saddle should not be greater than 0.2L; when necessary, A shall not exceed 0.25L at most. ( √ )157. When selecting an ear-type support design, only the total mass of the equipment and the eccentric loads need to be considered. ( × )158. For steels with good plasticity, there are often an upper yield point and a lower yield point on their tensile stress-strain curves; generally, the lower yield point is taken as the yield limit. ( √ )159. The degree of stress concentration at the hole edge is independent of the size and shape of the hole. ( × )160. The primary stressed components refer to those in a pressure vessel that are primarily subjected to overall primary membrane stress. ( × )161. The main measures currently used to prevent intergranular corrosion in stainless steel are: the use of solution treatment ； Reduce the carbon content in steel or add elements that stabilize carbides. ( √ )162. In the tensile testing of steel, the test results are the same whether δ5 or δ10 specimens are used. ( × )163. To avoid excessive bolt force, the width of the gasket should be kept as narrow as possible, provided that the gasket is not crushed. ( × )164. The design pressure of the liquefied petroleum gas storage tank is 1.77 MPa; therefore, a safety valve with a nominal pressure of 1.6 MPa should be used. ( × )165. Equipment and components made of austenitic stainless steel shall not be subjected to stabilization or solution treatment in stages. ( ×? )166. The purpose of welding procedure qualification is to verify the correctness of the welding procedure devised by the welding contractor. ( √ )167. The butt weld joints of austenitic stainless steel can be inspected using X-ray testing and ultrasonic testing, while the surface of these weld joints is usually inspected by magnetic particle testing. ( × )168. When connecting plug-in nozzles to pressure vessels subjected to fatigue loads, cryogenic pressure vessels, or vessel shells made of steel with a standard room-temperature tensile strength σb > 540 MPa, the corners of the inner diameter of the nozzles should be rounded. ( √ )169. The degree of stress concentration at the hole edge is related to both the size and shape of the hole. ( √ )__