During the production and fabrication of butt welded flanges, certain technical parameters and requirements shall be adopted for production and use, so as to ensure that they can be used and promoted according to certain methods and principles, and certain process methods and principles shall be adopted for production and welding, so as to strictly ensure good quality in use.
1、 The outer slope of neck of butt welding flange shall not be greater than 7o. The technical parameters of butt welding flange shall be strictly controlled during production and welding to ensure that it can fully play its role and value in production and use.
2、 Butt welding flanges are generally made of forgings or forging process. When steel plate or section steel is used for manufacturing, the following requirements must be met:
1. Butt welding flange It shall be subject to ultrasonic flaw detection without delamination defect;
2. It shall be cut into strips along the rolling direction of the steel, bent and butt welded into a ring, and the surface of the steel shall form a cylindrical surface of the ring. Steel plates shall not be directly machined into strips
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 inspection shall be conducted, and the radiographic inspection shall meet the level II requirements of JB4730, and the ultrasonic inspection shall meet the level I requirements of JB4730.
3、 The level and technical requirements of butt welding 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 forgings.
3. If one of the following conditions is met, the requirements of III and forgings shall be met:
(1) Forgings for flanges with nominal pressure PN ≥ 10.0MPa;
(2) Cr Mo steel forgings with nominal pressure PN>4.0MPa;
(3) Ferritic steel forgings with nominal pressure PN>1.6MPa and working temperature ≤ - 20 ℃.
