Inspection and surface quality of seamless steel pipes for high-pressure chemical fertilizer equipment (GB 6479-2000)
Seamless steel pipes for high-pressure chemical fertilizer equipment (GB 6479-2000) specify the requirements for the inspection and surface quality of steel pipes for high-pressure chemical fertilizer equipment. This standards apply to seamless and cold-finished hot-rolled steel pipes (hereinafter referred to as steel pipes) with an outer diameter not more than 508mm, which are used for conveying media with a pressure at the ambient temperature greater than or equal to 5.0MPa and a medium temperature not greater than 300 ℃. The materials of the steel pipes specified in this standard are carbon structural steels (series 16Mn and 10#), carbon manganese structural steels (series 20Mn, 16MnV and 10#Mo) and low alloyed structural steels (series 20MoV and 15Mo3).
Inspection and surface quality of steel pipes:
1. Visual inspection
When steel pipes of this standard are inspected by visual examination, the appearance quality of the external surface of the steel pipes is the main performance index. The surface of the steel pipes should be free of defects such as cracks, such as cracks and loose burrs, and the surface must meet the requirements for smoothness, distortion and unevenness.
2. Chemical composition inspection
The chemical composition of the material of the steel pipes should meet the requirements of the steel pipes’s specification. The chemical composition of the steel pipes should be inspected by chemical analysis.
3. Water pressure test
The water pressure test of steel pipes shall be carried out in strict accordance with the requirements of the steel pipess drawings and technical documents. The extreme value of the pressure shall not be greater than the pressure specified in the technical documents.
4. Dimensional inspection
The steel pipes should meet the requirements for internal and external diameter, wall thickness, length and curvature, and should meet the requirements for thickness variation of the steel pipes in the same batch. After the steel pipes are straightened, the butt joint of the two steel pipes should be connected and sealed, and the welding at the butt joint should meet the requirements.
5. Surface performance of steel pipes
The surface performance of the steel pipes should meet the requirements of the steel pipess specification. The steel pipes should not have spots and indentations. The surface of the steel pipes must be clean, and the surface of the steel pipes must be free of rust and dirt.
6. Non-destructive testing
Non-destructive testing of steel pipes should be carried out in strict accordance with the requirements of the steel pipess drawings and technical documents. The types of non-destructive testing shall be determined in accordance with the requirements of the technical documents.
In conclusion, the inspection and surface quality of steel pipes for high-pressure chemical fertilizer equipment are established according to GB 6479-2000. It is necessary to strictly control the quality of steel pipes in order to ensure the safety and reliability of the steel pipes. The quality indicators listed above should be inspected one by one in order to guarantee the performance of the steel pipes.
