When the steel plate to manufacture flange, must meet the following requirements

　　1 steel plate by ultrasonic flaw detection, without delamination defects;

　　2 steel rolling along the bias cut into strips, by bending welded into a ring, and the ring formed on the surface of steel cylinder. May not take the steel plate directly machined into the neck flange;

　　3 ring butt weld should be taken full penetration weld;

　　4 ring butt weld should stop after welding heat treatment, and 100% radiographic or ultrasonic testing, and radiographic fit II JB4730 request, JB4730 I with ultrasonic inspection request.