What are the detailed differences between US standards and Chinese standards?

As the name implies, US standards refer to the standards of the United States； National standards are China’s own standards. If one asks for detailed differences, different standards are simply not comparable to each other. Only standards of the same type can be used to compare the detailed differences between them; this requires referring to specific American and national standards. This is my personal understanding for reference only! All criticism and suggestions are welcome.

China’s standards are generally open in nature; that is, each standard, such as GB 150, 151, and JB 4732, addresses specific technical issues. To handle the entire process of pressure vessel manufacturing, a corresponding set of supplementary standards is required, such as those related to materials, manufacturing, and inspection. The ASME codes are generally comprehensive in nature; to date, they comprise twelve volumes covering rules for the construction of pressure vessels, materials, welding evaluation, non-destructive testing, and more, addressing essentially all aspects related to the construction of pressure vessels. China’s standards GB 150 and JB 4732 are generally based on ASME VIII-1 and VIII-2, but JB 4732 is explicitly designated as an \"analytical design standard,\" which differs from ASME VIII-2, which merely adopts certain concepts of analytical design as another set of regulations for pressure vessel construction. Furthermore, the selection of the safety factor for the allowable stress also varies.

The pressure levels are not exactly the same. For flanges: the national standard typically uses B-series pipes, while the American standard often uses A-series pipes.

China’s standards are generally open in nature; that is, each standard, such as GB 150, 151, and JB 4732, addresses specific technical issues. To handle the entire process of pressure vessel manufacturing, a corresponding set of supplementary standards is required, such as those related to materials, manufacturing, and inspection. The ASME codes are generally comprehensive in nature; to date, they comprise twelve volumes covering rules for the construction of pressure vessels, materials, welding evaluation, non-destructive testing, and more, addressing essentially all aspects related to the construction of pressure vessels. China’s standards GB 150 and JB 4732 are generally based on ASME VIII-1 and VIII-2, but JB 4732 is explicitly designated as an \"analytical design standard,\" which differs from ASME VIII-2, which merely adopts certain concepts of analytical design as another set of regulations for pressure vessel construction. In addition, the selection of safety factors for the allowable stress also varies. Moreover, American standards contain many detailed provisions; most national standards are based on Russian or European standards, but nowadays there are also many standards that have been revised with reference to American standards. The national standards for various containers are now becoming increasingly similar to the American ASME standards

The biggest difference between ASME and GB150 is that ASME includes requirements regarding quality control systems, whereas GB150 has only minimal requirements in this regard. The nature is completely different. GB150 is a purely product standard, whereas ASME is a comprehensive set of regulations that covers product design, manufacturing, inspection, testing, as well as quality control.

The American standard is a comprehensive standard that covers design, manufacturing, and more; it’s quite complicated, and it can be tricky to understand at first； The national standard is quite simple, but it’s easy to read.

What others have said is already very good; I will briefly share my insights regarding the differences in the reinforcement methods for these two standards in my design (specifically regarding the heads of plate-fin heat exchangers and their reinforcement). The diameter of such heads generally does not exceed the limit of 1500 specified in Appendix 1-7 of ASME and in GB150. According to GB150, when Di is less than or equal to 1500, the diameter of the openings must not be more than 0.5 times Di – that’s one of the requirements. Equal-area reinforcement is usually adopted. When the opening ratio is greater than 0.5 but less than 0.8, we follow the standards set by the Ministry of Chemical Industry; when it exceeds 0.8, stress analysis is necessary. In ASME, when the opening ratio is less than or equal to 0.5, the same approach as GB150 is used, that is, equal-area reinforcement. When the ratio exceeds 0.5, we refer to Appendix 1-7 for calculations – since the openings in heat exchangers are usually greater than 0.5, often even greater than 0.8. In practice, when the ratio exceeds 0.5, using Appendix 1-7 is sufficient; however, to be thorough, we sometimes also employ stress analysis methods. These are my insights based on the design of specific products for our company. This post was last edited by HMQ184 on 2009-2-26 at 10:41

Different safety factors are used; the American standard is more conservative

National standards are stricter than American standards in some aspects

1 Correspondence between major pressure vessel standards In China, the classification of pressure vessel standards is relatively detailed; standards are formulated separately based on the type of pressure vessel and the material used for its construction, such as steel pressure vessels, aluminum pressure vessels, horizontal vessels, tower-type vessels, spherical storage tanks, etc. The ASME codes do not establish separate standards for different types of vessels; instead, different load codes are referenced in the design process. For example, when the design pressure is less than 20 MPa, ASME Code Volume VIII, Part 1 is used; when the design pressure is less than 70 MPa, ASME Code Volume VIII, Part 2 is applied; and when the design pressure is greater than 70 MPa, ASME Code Volume VIII, Part 3 is utilized. 2 Design philosophy and safety factor The basic design principle for pressure vessels is that the membrane stress or the maximum direct stress must not exceed the allowable stress. The theory underlying stress calculation is the maximum stress theory. This design concept is applied in the pressure vessel standards of various countries. The allowable stress specified in these standards includes a safety factor; it is lower than the values obtained through performance testing due to the following reasons: (1) the complexity of the stress assessment methods ； (2) A certain degree of stress concentration and its types ； (3) Certain degree of material inhomogeneity ； (4) Geometric factors ； (5) Defects present in the welded joint. The safety factors specified in various national standards vary, based primarily on experience, experimental evidence, and theoretical assessments, while also being consistent with the specified material standards, calculation methods, manufacturing requirements, and inspection requirements. 3 Weld joint coefficient: In ASME codes, the weld joint coefficient depends only on the type of weld joint and the level of non-destructive testing required, and is unrelated to the level of non-destructive testing for any other joints. In other words, different weld joints on the same vessel can have different weld joint coefficients. Weld joint coefficients are specified for all four categories of weld joints (A, B, C, and D), and it is also permissible to use reduced weld joint coefficients in exchange for waiving the requirements for non-destructive testing. In China’s CB 150 standard, the welding joint coefficient specifically refers to types A and B of welding joints; it is not allowed to reduce this coefficient in order to waive the requirements for non-destructive testing. After product manufacturing is complete, radiographic or ultrasonic testing must be carried out on joints of types A and B.

The national standard is the classification method of the European system, while the American standard is the classification method of the American system

:Lol, the relationship between Chinese standards and American standards: what’s the same was copied; what’s different or extra was copied incorrectly; and what’s missing was omitted during copying

Generally speaking, American standards are stricter than Chinese standards, with higher grades, indicating greater manufacturing and processing capabilities.

In many aspects, they are generally similar, but when it comes to the type of tubes used, there are ones in imperial units and ones in metric units； The safety factors people use also vary ； And their chapter divisions are also different ； It’s best to look at it with the Chinese version of the US standard to understand. A long time ago, what was used in China was copied from abroad~