Regulations for thick-walled steel pipes in engineering: corresponding regulations and various regulations for the actual selection and use of thick-walled pipe fittings. When thick-walled steel pipes and thick-walled pipe fittings are selected or used, they must first follow the relevant regulations and various regulations in the specifications, especially for pipelines that transport extremely or highly hazardous fluid media, flammable media, and high-pressure gases. Under this premise, the type of pipe fittings is mainly determined based on the purpose and conditions of use (pressure, temperature, fluid medium).
Problems in the selection standards for thick-walled steel pipes:
1. Formulated from the standard system. For the selection in the project, there are standards for pipes, but there are no corresponding standards for forgings or castings. The reality is that the standards for pipe fittings and forgings borrow the standards for forgings of pressure vessels, without considering the differences between the two, such as welding, film inspection, and other regulations.
2. The standards for pipe fittings vary greatly, and the content lacks consistency and systematicity, resulting in contradictions in the connection, and causing inconvenience in use.
3. There is no type test standard for pipe fittings. Only GB12459 and GB13401 standards specify the pressure calculation for the burst test of steel butt-welded seamless pipe fittings and steel plate butt-welded pipe fittings. There are no other types of test standards or implementation standards to ensure the manufacturing of pipe fittings. Thick-walled seamless pipe weight formula: [(outer diameter-wall thickness)*wall thickness]*0.02466=kg/meter (weight per meter).
Determination of the strength grade of thick-walled steel pipes:
1) Pipe fittings that express their grade or specify pressure-temperature ratings in nominal pressure should use the pressure-temperature rating specified in the standard as their use basis, such as GB/T17185;
2) For pipe fittings that only specify the nominal thickness of the straight pipe connected to them in the standard, their applicable pressure-temperature ratings should be determined according to the benchmark pipe grade specified in the standard, such as GB14383~GB14626.
3) For 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 benchmark should be determined by pressure design or analytical analysis by relevant regulations. In addition, the strength grade of the pipe fittings should not be lower than the pressure under the severe working conditions that the entire pipeline system may encounter during operation.
Post time: Jul-22-2024