Problems in the regulations and selection standards for thick-walled steel pipes in engineering projects

First, the regulations for thick-walled steel pipes in engineering projects:
The corresponding regulations and various regulations for the actual selection and use of thick-walled steel pipe fittings. When thick-walled steel pipe fittings are actually selected or used, they must first follow the relevant regulations and regulations, especially for steel pipes that transport extremely or highly hazardous fluid media, flammable media, and high-pressure gases. Under this premise, the type of steel pipe fittings is mainly determined based on the purpose and use conditions (pressure, temperature, fluid medium). The following mainly lists the relevant regulations/specifications for reference only.
1. Special Equipment Supervision Law;
2. Special Equipment Inspection Regulations;
3. Pressure Pipeline Management and Supervision Regulations;
4. Special Equipment Supervision and Inspection Regulations;
5. Special Equipment Design/Manufacturing/Installation Supervision and Management Regulations (Draft);
6. Pressure Pipeline Technical Supervision Regulations (Draft);
7. Industrial Metal Pipeline Technical Specifications (Draft).

Second, the problems in the selection standards for thick-walled steel pipes:
1. Formulated from the standard system. There are standards for pipes in the project, but there are no corresponding standards for forgings or castings. The reality is that the standards for steel pipe forgings borrow the standards for pressure vessels, without considering the differences between the two, such as welding, film inspection, and other regulations.
2. The standards for steel pipe fittings vary greatly, and the content lacks consistency and systematicity, resulting in contradictions in the connection, causing inconvenience in use.
3. There is no type test standard for steel pipe fittings. Only GB12459 and GB13401 standards specify the pressure calculation for the burst test of steel butt-welded seamless steel pipe fittings and steel plate butt-welded steel pipe fittings. There are no other types of test standards or implementation standards to ensure the manufacture of steel pipe fittings.
Thick-walled seamless pipe weight formula: [(outer diameter-wall thickness)*wall thickness]*0.02466=kg/meter (weight per meter).

Third, determination of the strength grade of thick-walled steel pipes:
1) Steel pipe fittings that use nominal pressure to indicate their grade or specify a pressure-temperature rating should use the pressure-temperature rating specified in the standard as their use basis, such as GB/T17185;
2) For steel pipe fittings that only specify the nominal thickness of the straight pipe connected to them in the standard, their applicable pressure-temperature rating should be determined according to the benchmark steel pipe grade specified in the standard, such as GB14383~GB14626.
3) For steel pipe fittings that only specify the external dimensions in the standard, such as GB12459 and GB13401, their pressure-bearing strength should be determined through verification tests.
4) For others, the use basis should be determined by pressure design or analytical analysis in accordance with relevant regulations. In addition, the strength grade of steel pipe fittings should not be lower than the pressure under the severe working conditions that the entire steel pipe system may encounter during operation.