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Standard for production and inspection of welding flanges

The product level and technical requirements of the butt welding flange should meet the relevant requirements in JB4726-4728. Carbon steel or austenitic stainless steel forgings with a nominal pressure of 0.25 MP to 1.0 MPa are allowed to be manufactured using Class I forgings. Forgings with a nominal pressure between 1.6 MPa and 6.3 MPa shall meet the requirements for class II or above grade forgings. For the flange forgings with nominal pressure not less than 10.0 MPa, chrome-molybdenum steel forgings with nominal pressure exceeding 4.0 MPa, ferritic steel forgings with nominal pressure exceeding 1.6 MPa and working temperature not exceeding -20 degrees Celsius, such flat welding Flange forgings must meet the requirements of Class III forgings.
Under normal circumstances, butt welding flanges are manufactured using forgings or forging techniques. If steel or steel materials are to be used for manufacturing, they must meet these requirements. Welded flanges must be ultrasonically inspected and tested. There should be no delamination defects. It is to be cut into strips along the rolling direction of the steel, and it is welded into an annular shape by a bending process. At the same time, the surface of the steel must be formed into a cylindrical surface, and it cannot be machined into a belt neck by using a steel plate material. Welded flanges. For the butt weld of the ring, full penetration welds are required. The ring butt welds must be heat treated after welding, and must also be tested for 100% ray or ultrasonic flaw detection. The ray inspection results should be consistent with In the relevant requirements of Class II in JB4730, the results of the ultrasonic inspection of the welding flange must meet the requirements of Class I standards in JB4730.

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