What are the special requirements for the selection of steel plates for welded flanges?

Note on the production of welded flanges:

1. The steel plate for the welding flange should be ultrasonically inspected without delamination defects to ensure good quality and performance problems. It is produced and inspected according to certain quality requirements to ensure that there is no quality problem in the steel plates produced and used;

2. It should be cut into strips along the rolling direction of the steel, and be welded into a ring shape by bending, and the surface of the steel forms a cylindrical surface. In the production of butt welding flanges, steel plates shall not be directly machined into neck flanges, and they shall be fabricated and processed by a certain process.

Large flanges refer to flanges that exceed the dimensions specified by the relevant department. Generally refers to the flange of the size above DN2000. Such products are all welded products, without threaded, threaded products often used specifications to DN15-DN100. The large size among the pressure standards of 0.25MPa to 1.6Mpa in the flange standard GBT9119-2010 is DN2000. In the 2.5MPa pressure standard, the big one is the DN800.