Basic structural requirements for pressure vessels

Take a look at the regulations in GB150! !

This question is too broad and general

There is also a general statement, which is that it must meet the usage requirements.

GB150-1998 \"Steel Pressure Vessels\" and the \"Regulations on Safety Supervision of Pressure Vessels\" both contain relevant provisions; please refer to the corresponding standards for more details.

The question posed by the original poster is too broad; below are some answers provided by the Standards Approval Committee, which can offer some insight: Answers to Questions Regarding Pressure Vessel Standards (First Batch) 1. Question raised: Our company has a product whose jacket is designed to be made of Q235-A material, but now Q235-B is being used as a substitute. Should the jacket test pieces for this product undergo impact tests according to the Q235-B standards? Answer: According to clause 10.5.6.5 of GB150, for shells made of Q235-B steel plates, there is no need to conduct impact tests on sample plates, let alone when Q235-A is used as a substitute. II. Question raised: In GB150, the wall thickness specified for steel pipes in GB8163 can only be 10 or less; is it also permissible to use a value greater than 10? For GB9948 and GB6749 steel pipes, the maximum diameter is 273, and the number of available specifications is limited, which restricts selection options. Could GB5310 be used instead? However, GB150 does not recommend the use of GB5310. Experts, please provide an explanation. Answer: Due to the relatively low technical requirements of GB8163, a limit of wall thickness of 10 mm or less is set; thicknesses greater than 10 mm are not allowed. Paragraph 1.1 of GB6749 states that \"upon the request of the buyer and through agreement between the supplier and buyer, steel pipes other than those specified in Table 1 may be supplied.\" Paragraph 3.1.1 of GB9948-88 states that \"the outer diameter and wall thickness of the pipe shell shall comply with the provisions on outer diameter and wall thickness in GB8163\", and these are not subject to the limit of a maximum diameter of φ273mm. ——The above questions were answered by Professor Qin Xiaozhong from China General Machinery Engineering Corporation. III. Question raised: When implementing the standard JB4708-2000 on \"Welding Procedure Qualification for Steel Pressure Vessels,\" we encountered the issue of whether the procedure qualification for base metal of the same grade II-1 (16MnR-16MnR) is applicable to base metal of grade I-1 (Q235-Q235). In accordance with the provision in 5.3.2.2 of the standard, which states \"...however, the evaluation of base materials of the same steel grade with category number II (or group numbers VI-1, VI-2) applies to welded joints formed from such base materials of that category number (or group number) and base materials of category number I\", since the weldability of steel with group number I-1 is better than that of steel with group number II-1, can it be inferred that the evaluation of base materials of category number II-1 applies to welded joints formed from base materials of the same steel grade but with category number I-1? Answer: It cannot be understood in this way; the evaluation for base material of the same grade as in II-1 is not applicable to welded joints made from base material of the same grade as in I-1. IV. Questions raised: In clause 5.3.4.1 of JB4708-2000 \"Welding Procedure Qualification for Steel Pressure Vessels\", it is stated that \"... the original provisions shall still apply if the test piece undergoes post-weld heat treatment at a temperature higher than the upper transformation temperature, or if the austenitic base material is subjected to solution treatment after welding.\" ”Does this clause refer specifically to situations where welded parts are required to undergo impact testing? When the welded joint does not require impact testing, is it necessary to follow the restrictions applicable to a maximum thickness of 1.1T for the welded joint? ” Answer: 5.3.4.1 specifies the minimum value under such conditions, while the maximum value remains unchanged as specified in Table 8. V. Question raised: In JB4708-2000, can clause 1 of Table 7 regarding root welding with TIG welding be interpreted as follows: When SMAW, SAW, GTAW, or GMAW are used for root welding, and only one welding method is employed in the process evaluation, the thickness of the base material of the test piece should be no less than 13 mm. Can the 10mm GTAW full-thickness butt weld procedure qualification be applied to 16mm flat plate butt welds with 5mm of GTAW root welding, 5mm of GMAW fill welding, and 6mm of SAW cap welding? (Assuming all other factors have been evaluated) For the qualification of the 10mm GTAW full-thickness butt welding process when used for GTAW root welding, what are the requirements regarding the thickness of the base material? Answer: The 10mm GTAW full-thickness butt weld procedure qualification, when used for GTAW root welding, is suitable for weldments with a base metal thickness of up to 20mm. VI. Questions raised: In Table 1 of JB/T4709-82, for the material 0Cr17Ni12Mo2, the recommended wire grades for submerged arc welding and TIG welding are H00Cr19Ni12Mo2; for the material 0Cr18Ni12Mo2Ti, the recommended grade is H0Cr20Ni14Mo3 ； In Table 1 of JB/T4709-2000, for the same welding method, the recommended welding wire for material 0Cr17Ni12Mo2 is H0Cr19Ni12Mo2, while for material 0Cr18Ni12Mo2Ti, the recommended welding wire is H00Cr19Ni12Mo2. What is the reason for this change? Is it necessary to adjust the welding procedure qualification and production process as well? Answer: JB/T4709-2000 goes further than JB/T4709-1992, with more rational selection of welding materials. Table 1 provides a recommended list; decisions should be made based on specific circumstances. When changing the wire grade, a new process evaluation must be conducted. ——The above questions were answered by Senior Engineer Ge Zhaowen from Hefei General Machinery Research Institute. Answers to Questions on Pressure Vessel Standards (Second Batch) I. Question raised: Article 34 of the “Regulations on Pressure Vessels” (1999 edition), point 2: “The design pressure of fixed liquefied petroleum gas storage tanks shall be no less than that of liquefied petroleum gas at 50°C…” Here, it refers to the “design pressure”. Article 27 of the Code (Version 90) specifies the maximum operating pressure. Although its essential content remains unchanged, there is still a difference between the \"design pressure\" and the \"maximum operating pressure\"; for tanks equipped with safety valves, the design pressure should be at least 1.05 to 1.1 times the operating pressure. In fact, as can be seen from the text, the design pressure for LPG storage tanks specified in the Code (version 99) is slightly lower than that required by the Code (version 90). Specifically, for domestically produced liquefied petroleum gas, which is mostly a mixture of propane and butane, its saturated vapor pressure at 50°C is “greater than that of isobutane at 50°C and less than or equal to that of propane at 50°C”. Therefore, the design takes into account the saturated vapor pressure of propane at 50°C, which is 17.44 kg/cm2 (absolute pressure); this corresponds to 1.6 MPa (gauge pressure) according to the Gas Design Manual. According to the Code for Pressure Vessels (version 99), the design pressure for storage tanks can be set at 1.61 MPa. Per Appendix B B6 of GB150-1998, for storage tanks equipped with safety valves, the design pressure P ≥ (1.1~1.05)P; accordingly, the operating pressure Pw is ≤ 1.45~1.53 MPa ； According to the Code of Practice (version 90), when the operating pressure is 1.61 MPa, the corresponding design pressure is ≥1.69–1.77 MPa. To date, the design pressure for liquefied petroleum gas storage tanks in our hospital has been set at 1.77 MPa, in accordance with the requirements of the Code of Pressure Vessels (version 90). Can the design pressure for LPG storage tanks be set at not less than the saturated vapor pressure of propane at 30°C, which is 1.61 MPa, in accordance with the provisions of the Code of Pressure Vessels (99th edition)? (For large liquefied petroleum gas spherical tanks, these two design pressures do have an impact on their wall thickness and cost; the wall thickness can vary by 3 to 6 mm. Especially for large tanks with a capacity of over 2000 m3, it is not desirable for the shell plates to be too thick.) ). I hope to receive a prompt reply confirming this. Thank you! Answer: For fixed liquefied petroleum gas storage tanks equipped with safety valves, the relative relationship among the maximum operating pressure, the opening pressure of the safety valve, and the design pressure of the vessel must be taken into account (Articles 146 of the Pressure Vessel Regulations and Article 6.2 of GB150). Clause 34.2 of the Pressure Vessel Regulations cannot be interpreted as allowing the maximum operating pressure to be determined by reversing the design pressure. Therefore, the design pressure for liquefied petroleum gas storage tanks cannot be set at the saturated vapor pressure of propane at 50°C, which is 1.61 MPa; rather, it should be some value greater than (i.e., \"not less than\") 1.61 MPa. 1.61 MPa should be considered as the design pressure, which is equal to or close to the maximum operating pressure in the absence of a safety valve. If a safety valve is installed, 1.61 MPa can only serve as the maximum operating pressure; the design pressure should be higher than 1.61 MPa, as well as higher than the opening pressure of the safety valve. II. Question raised: Pressure vessels are subject to supervision only when they meet all three conditions specified in the Vessel Regulations; however, how should the several types of pressure vessels listed separately in Article 2, Paragraph 2 be understood? For example, in the case of spiral plate heat exchangers, is it sufficient that the design pressure be >0.1 MPa, with no further considerations needed regarding the type of fluid or temperature? Answer: Spiral plate heat exchangers also need to meet three conditions; their external dimensions are calculated based on volume and diameter, without deducting the internal structural components. III. Question: Recently, when planning the layout for a 70m tall tower in our factory, we found that due to the width of the steel plates, it was impossible to avoid placing some manholes above the ring welds; these manholes had to be installed on those welds. We plan to conduct 100% flaw detection on the welds in an area covering 1.5 times the diameter of the manholes around them. Is this acceptable? We do not find any provisions in the \"Regulations on Safety Inspection of Pressure Vessels\" or GB150 that prohibit making holes in welds. May we make holes in welds when it is unavoidable? Are there any other technical measures required after making the openings? Answer: Regarding the situation described in the letter, your handling approach is acceptable; indeed, the regulations and standards do not stipulate that holes cannot be made in welds. For 100% non-destructive testing near the openings, attention should be paid to the required qualification level. Additionally, if there are reinforcement rings, the welds must also be smoothed out. ——The above questions were answered by Section Chief Gao Jixuan from the Boiler and Pressure Vessel Safety Supervision Bureau. Answers to Questions on Pressure Vessel Standards (Third Batch) 1. Question: The deaerator shell is made of stainless steel composite steel plates, and the user requires pickling and passivation treatment. Should this be done on the entire inner surface or only on the welded areas? Answer: If the laminated material has already been pickled and passivated, then only the welded joints need to be pickled and passivated, using the brushing method if necessary ； Of course, it is also possible to acid-wash and passivate the entire inner surface. II. Question raised: Once the outsourced heat treatment test plates and containers return to the company, must their heat treatment reports be approved by the person responsible for heat treatment? (The heat treatment process is developed by our company.) Answer: 1. This issue falls under quality control and is not a question that should be answered according to standards ； 2. The heat-treated test plates shall be heat-treated in the same furnace as the container, and not separately; automatic recording of the heat treatment process shall be available, and such records shall comply with the specified heat treatment procedures. The mechanical properties of the test plates (samples) must be satisfactory. III. Question raised: As specified in Table 10-3 of GB150-1998, the weld bead height should be 0~15% of δ1 and ≤4 mm. How should this be understood? If the plate thickness is 12 mm and δ1 = 4 mm, can it be assumed that e1 = 0.6 mm, and must e1 be ≤ 0.6 mm? If so, it is difficult to maintain this value in actual production; polishing is often required, which results in a significant increase in workload. Answer: This is an error in the standard formulation; it has now been corrected to a remaining height of 0–15% δ. If it is less than 1.5 mm, it shall be considered as 1.5 mm. ——The above questions were answered by Director Li Jingchen of Hefei General Machinery Research Institute. Answers to Questions Related to Pressure Vessel Standards (Fourth Batch) I. Question raised: We are unsure about the following issues when applying the GB150-1998 standard; we would like to seek guidance! The standards specify that the operating temperatures for Q235-A, B, and C are 0~350°C and 0~400°C respectively. Can this material be used at -19~0°C? The various containers used in our refrigeration industry are often employed in temperatures below 0°C – can they still be used? How should we define the operating temperature then? I hope you can find time to respond despite your busy schedule. Answer: In accordance with clauses 4.1.7 and 4.2.3 of standard GB150-1998, when Q235-A, B, and C materials are used for the pressure-bearing components of pressure vessels, they cannot be used at temperatures ranging from -19°C to 0°C (use is allowed at 0°C). Other materials that meet the relevant standards should be selected to manufacture pressure vessels under such conditions. II. Questions raised: Material selection for the design of the new carbon coke tower. The design pressure is 0.35 Mpa, and the design temperatures are 425/475°C; the medium involved is reduced residue oil, which is subject to high-temperature sulfur corrosion. Based on the operating conditions of the four existing carbon coke towers in our plant (put into use in 1989), as well as the recommendations in the Petrochemical Corporation’s “Manual on Corrosion and Protection of Equipment in Petrochemical Plants,” it is specified that 20G material should be used for such equipment, as its high-temperature mechanical properties are superior to those of 20R. However, GB150 (version 1998) excludes 20G from being used in pressure vessels. Given engineering experience, can 20G material still be chosen for this equipment? Answer: The claim that the high-temperature mechanical properties of 20G are higher than those of 20R is incorrect. According to GB150 (version 98), it is not allowed to use 20g; this standard no longer provides an allowable stress value for this material. III. Question raised: The shell material is designated as Q235-B, C; should impact test specimens be taken from the product test plates for impact testing? Answer: According to standard 10.5.6.5, when the shell material is Q235-B or C, it is not necessary to take impact specimens from the product’s welding test plates for impact testing. The reason is that the base material undergoes impact test inspections upon leaving the factory, and it has been proven that after being used to manufacture the housing, its impact performance meets the standard requirements; therefore, no such requirements are imposed regarding the sampling for impact tests. IV. Questions raised: We are technical staff from the Design and Development Department of Puer Filters (Beijing) Manufacturing Factory. GB150-98 \"Steel Pressure Vessels\" adds provisions regarding the use of austenitic stainless steel welded pipes in pressure vessels or as heat exchange pipes, along with corresponding manufacturing technology requirements and usage regulations. There are several issues related to GB150-98 \"Steel Pressure Vessels\" that we would like to consult you on: 1. In Appendix A, item A4.2.1C), it states that \"pipes shall be inspected one by one using eddy current or radiographic testing (for large-diameter pipes), with the testing methods and acceptance criteria specified in JB4730.\" How is the scope of large-diameter pipes defined? Can other standards such as GB7735 be used for eddy current testing? 2. According to GB150-98, as well as the enterprise standards of Guangdong Shunde Huafeng Stainless Steel Welded Pipe Factory, and the American standards A249 and A312, stainless steel welded pipes are required to be in a heat-treated state at the time of delivery. Is it necessary for stainless steel welded pipes used in pressure vessel shells or heat exchange tubes to be supplied in a heat-treated state? Can welded pipes manufactured from hot-rolled steel plates in accordance with A4.2.1 a) of GB150-98 be used for pressure vessel shells? 3. Does a welded pipe manufacturer that produces pressure vessel shells (filters) require a special certification for a pressure vessel manufacturing license? 4. Do austenitic stainless steel welded pipes that have passed eddy current testing and hydrostatic testing still require radiographic testing when used to manufacture pressure vessel shells (since eddy current testing is a surface inspection method)? 5. Can eddy current testing detect defects such as weld undercutting? (Because undercuts are not allowed in the welds of stainless steel pressure vessels)？ 6. Do manufacturers of austenitic stainless steel welded pipes need to produce welding test plates for these pipes? 7. Can the filters produced by Puer Filter (Beijing) Manufacturing Factory be designed as fluid pipelines rather than being considered as pressure vessels? Answer: 1. For large-diameter pipes inspected by eddy current testing, the range should be determined based on the actual conditions of the manufacturer, and this should be specified in the company’s standards; the acceptance criteria for eddy current testing shall comply with the provisions of JB4730. 2. The delivery condition of stainless steel welded pipes shall be the heat-treated condition. 3. Welded pipe manufacturers that produce pressure vessel shells should be approved as an exception. 4. The inspection requirements for austenitic stainless steel pipes that have passed eddy current testing and hydrostatic testing and are to be used in pressure vessel shells shall be determined according to the design conditions as specified in the codes. 5. It is possible to specifically request welding test plates from stainless steel welded pipe manufacturers. 6. The filters produced by your factory should be designed as pressure vessels or not, depending on the actual circumstances. Answers to Questions Related to Pressure Vessel Standards (Fifth Batch) I. Question raised: For a Class 1 vessel with an inner diameter of 500 mm, a wall thickness of 6 mm, and made of material Q235B, the design team indicated on the drawings that root welding using TIG welding for the last ring weld could exempt it from non-destructive testing. This does not conform to the requirements of GB150 (since this circumferential weld can be subject to non-destructive testing and is not classified as one that cannot be tested). How should the supervision authority handle this? Looking forward to your prompt reply. Thank you! Answer: Clause 10.8.2.3 of GB150-98 specifies that when radiographic or ultrasonic testing is not possible, for the final circumferential seal weld with a diameter of no more than 800 mm, it is permissible to omit testing if single-sided welding without a backing plate is used; however, root welding using gas shielded welding is required. If radiographic or ultrasonic testing is possible, it is not allowed to skip such testing. II. Questions raised: I would like to seek your advice regarding the current issues related to the manufacturing of elliptical heads. Article 5.4 on page 9 of JB/4737—95 stipulates that “when a head is formed by welding two steel plates together or three plates that are symmetrical with respect to each other, the distance between the welds and the center line of the head should be less than 1/4 of the nominal diameter.” However, GB150—1998 does not mention any such requirement on page 118 regarding the manufacturing, inspection, and acceptance of heads. In actual head manufacturing processes, can the requirement stated in Article 5.4 of JB/4737-95, namely that the distance between the welds and the center line of the head should be less than 1/4 of the nominal diameter, be disregarded? Answer: Requirement 5.4 in JB4737-95 is inconsistent with that in GB150-98, and it need not be made mandatory; the newly formulated head standard JB4746 (replacing JB4737-95) also does not include this requirement. III. Questions raised: In the process of implementing GB150-98, for containers such as liquefied petroleum gas storage tanks and liquid ammonia storage tanks that require post-weld heat treatment, when preparing test plates for these products, a single welding test plate is made, and then both this test plate and the container are subjected to heat treatment together in order to evaluate the performance of the welded joints. The supervision and inspection agency stationed at our factory believes that such containers should have two welding test plates made: one for testing the welding process parameters after welding, and the other to be heat-treated along with the container. How exactly should product welding test plates be prepared in this situation? Answer: Regarding the situation described by your factory, in accordance with clauses 10.5.1.5h and 10.5.6.4 of GB150-98, the standard requires only one product welding test plate to be prepared, and it stipulates that this test plate must undergo post-weld heat treatment in the same furnace as the container, in order to verify whether the mechanical properties of the welded joint are satisfactory after heat treatment. IV. Question raised: Recently, when planning the layout for a 70m tall tower in our factory, we found that due to the width of the steel plates, it was impossible to avoid placing some manholes over the ring welds; these manholes had to be installed on top of those welds. We plan to conduct 100% flaw detection on the welds in an area covering 1.5 times the diameter of the manholes around them. Is this acceptable? We do not find any provisions in the \"Regulations on Safety Inspection of Pressure Vessels\" or GB150 that prohibit making holes in welds. May we make holes in welds when it is unavoidable? Are there any other technical measures required after making the openings? Answer: Regarding the situation described in the letter, your handling approach is acceptable; indeed, the regulations and standards do not stipulate that holes cannot be made in welds. For 100% non-destructive testing near the openings, attention should be paid to the required qualification level. Additionally, if there are reinforcement rings, the welds must also be smoothed out. Answers to Questions on Standards Related to Pressure Vessels (Sixth Batch) I. Question raised: We have encountered the following issues while implementing the \"Regulations on Safety Supervision of Pressure Vessels.\" Article 63 of these regulations stipulates that the manufacturers of pressure vessel components (such as end caps and forged parts) shall, in accordance with the contents of the quality certificates for such components, provide quality certificates for those components to both the pressure vessel manufacturer and the user of the pressure vessel. 1. We are a pressure vessel manufacturing plant; the end caps used by us are only formed through outsourcing, being pressed by specialized end cap manufacturers. From raw material procurement, inspection, cutting, flange assembly, to weld radiographic testing, our factory carries out all these tasks in accordance with the relevant provisions of the quality assurance manual. For the external head manufacturing factory, is it sufficient for it to issue only the \"Head Product Qualification Certificate\" and the \"Quality Inspection Report\", with the latter containing only information related to pressing and shaping? Is it necessary to issue a \"Product Quality Certification Letter\", and is it required to issue a \"Supervision and Inspection Certificate\" as well? 2. The pressure vessel forgings currently used in our factory are purchased from external suppliers. If the forging manufacturer is located in another province or city, must the inspection certificate be issued by the inspection authority in the location of the manufacturer? Can we have the \"Inspection Report\" issued by the inspection authority in the location of our company? Answer: 1. The relevant items on the “Head Qualification Certificate” are to be filled out jointly by your factory and the unit that manufactures the head. It is up to the user (your company) to decide whether to issue a “supervision and inspection certificate” for the end cap. 2. It is up to the user (your company) to decide whether to have the forgings inspected. However, if your company wishes to obtain an inspection certificate, it can only be issued by the inspection authority located in the place where the forgings are manufactured. II. Question raised: Based on what type of equipment should the urea dust cleaning tower be designed? Answer: After reviewing the equipment structure diagram and relevant data, this urea dust cleaning tower can be designed as a bin-type device. III. Questions raised: A company manufactures containers with a diameter not exceeding 500 mm (seamless tubes are commonly used), a wall thickness of less than 10 mm, a design pressure of 1.0 MPa, a design temperature of below 200°C, and whose medium is steam. The welding of the container’s cylinder and end caps is carried out using the single-sided welding with double-sided formation technique via manual arc welding without gaskets. The following questions are hereby raised: 1. Is single-sided welding with double-sided formation in manual arc welding equivalent to the \"fully penetrated butt joint equivalent to double-sided welding\" as specified in clause 3.7 of GB150-1998? 2. How is the welding joint coefficient determined at this time? If a coiled cylinder is used, how is the welding joint coefficient determined? Answer: 1. It is difficult to achieve a welded joint with single-sided welding and double-sided formation using the manual arc welding method; for the weld between the cylinder and the head, TIG welding can be used for the root pass. 2. In the design calculations, when seamless tubes are used for the cylinder, a welding joint coefficient of 1.0 is applied. If a welded cylinder is used, the welding joint coefficient for longitudinal seams of type A should be adopted; however, other type A and type B joints on the cylinder must meet the same inspection requirements as those for longitudinal seams of type A. IV. Questions raised: Our company is designing a nitrogen storage tank with a design pressure of 10.0 MPa; it belongs to category III high-pressure vessels. For the longitudinal weld joints of the cylinder, double-sided welding is employed, with full radiographic inspection. For the final circumferential weld at the junction between the cylinder and the head, single-sided welding is used (with gaskets in close contact with the base metal along the entire length of the weld root). There are two different opinions regarding how to correctly select the weld coefficient: 1. The weld coefficient for the container should be set at 1.0; this value is then used in the formula for calculating the cylinder wall thickness, and the resulting thickness is indicated on the overall layout diagram. 2. The container weld coefficient is set to 0.9; this value is used in the formula for calculating the thickness of the circular wall, and the resulting wall thickness is indicated on the overall layout diagram. Our understanding is that a weld coefficient of 1.0 should be selected as the weld coefficient for the container. Please advise if our understanding is correct. Answer: The formula for calculating the thickness of a pressure vessel cylinder is derived from the strength of the overall (primary) circumferential membrane stress in the cylinder; therefore, the corresponding weld coefficient should be that of the longitudinal welds in the cylinder. Although there is also a circumferential film stress in the cylindrical fillet, it does not belong to the overall film stress but rather to the local film stress; its allowable stress is different from the allowable stress used in the calculation of cylinder thickness (which is one time higher). Therefore, it should not be confused with the circumferential weld coefficient. However, to ensure the strength and safety of the entire cylinder, it is generally advisable to make the ring seam coefficient consistent with that of the longitudinal seam. If there are genuine manufacturing difficulties, a difference from the longitudinal seam is permitted, in which case the provisions of 10.8.2.3 in GB150-1998 shall be followed. At this time, although the circumferential seam coefficient may differ from the longitudinal seam coefficient, the longitudinal seam coefficient is still used when calculating the cylinder thickness.

1. Meet performance requirements. 2. Be safe, reasonable, economical, and reliable. 3. The appearance shouldn’t be too ugly, haha:lol

General requirements: safety and reliability, as well as cost-effectiveness and practicality. References can be made to GB150-1998 \"Steel Pressure Vessels\", the \"Regulations on Safety Inspection of Pressure Vessels\", and HG 20583-1998 \"Design Specifications for Steel Chemical Process Vessels\", among others.