Technical Requirements for the Manufacture of Weld Neck Flanges

　　1. The grade of weld neck flanges 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. Weld neck flanges except as follows, 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 weld neck 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. ANSI B16.5 SS304 Class 300 Weld Neck Flange are usually made by forging or forging-rolling process. When making steel plate or section steel, the following requirements must be met: 1. Weld neck flanges 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 Weld neck flanges with necks; 3. The Weld neck flanges seams of rings should be fully penetrated; 4. TheWeld neck flanges seams of rings should be heat treated after welding, and 100% radiographic or ultrasonic flaws should be detected, 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 Weld neck flanges shall not exceed 7O. The technical parameters of Weld neck flanges should be strictly controlled in production and welding to ensure that it can play a full role and value in production and use.