Butt welding flange

Technical requirements for high pressure butt welding flange:
1. The grade of butt welded flange and its technical requirements 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. Except for the following provisions, forgings with nominal pressure PN of 1.6 MPa-6.3 MPa shall meet the requirements of grade II or above. 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 (> 10.0 MPa); (2) chromium-molybdenum steel forgings with nominal pressure PN > 4.0 MPa; (3) ferrite steel forgings with nominal pressure PN > 1.6 MPa and working temperature (< -20 degrees Celsius).
2. Butt welding flange is usually made by forging or forging-rolling process. When using steel plate or section steel, the following requirements must be met: 1. butt welding flange should be detected by ultrasonic wave without delamination defect; 2. It should be cut into strips along the rolling direction of steel, welded into rings by bending and butt welding, and the surface of steel should form a cylinder of rings. No steel plate can be directly machined into butt-welded flanges with necks; 3. The butt-welded seams of rings should be fully penetrated; 4. The butt-welded seams of rings should be heat treated after welding, and 100% radiographic or ultrasonic flaws should be made, and the radiographic flaws meet the requirements of JB4730 level II, and the ultrasonic flaws meet the requirements of JB4730 level I.
3. The lateral inclination of the neck of butt-welded flange shall not exceed 7O. The technical parameters of butt welding flange should be strictly controlled in production and welding to ensure that it can play a full role and value in production and use.