What are the technical requirements for stainless steel flanges

　　The grade and technical requirements of stainless steel flange shall meet the corresponding requirements of jb4726-4728.

　　1. Grade I forgings are allowed for carbon steel and austenitic stainless steel forgings with nominal pressure PN of 0.25mp-1.0mpa.

　　2. In addition to the following provisions, forgings with nominal pressure PN of 1.6mpa-6.3mpa shall meet the requirements of grade II or above.

　　3. If one of the following conditions is met, it shall meet the requirements of III and Forgings:

　　(1) Forgings for flanges with nominal pressure PN ≥ 10.0MPa; (2) Chromium molybdenum steel forgings with nominal pressure PN > 4.0Mpa; (3) Ferritic steel forgings with nominal pressure PN > 1.6Mpa and working temperature ≤ - 20 ℃.

　　2、 Stainless steel flanges are generally made of forgings or forging and rolling process. When made of steel plate or section steel, the following requirements must be met:

　　1. The flange shall be subject to ultrasonic flaw detection without delamination defect;

　　2. The steel shall be cut into strips along the rolling direction, bent and butt welded into a ring, and the surface of the steel shall form the cylindrical surface of the ring. It is not allowed to directly machine the steel plate into a neck butt welding flange;

　　3. The butt weld of the ring shall be full penetration weld;

　　4. The butt weld of the ring shall be subject to post weld heat treatment and 100% radiographic or ultrasonic flaw detection. The radiographic flaw detection shall meet the class II requirements of JB4730 and the ultrasonic flaw detection shall meet the class I requirements of JB4730.