Alloy flange with alloy steel stud shall adopt high quality steel. The material mark after all should add letters A, such as 5CrMoA、25CrMoVA according to different structure, the bolt can be divided into hexagon head bolts and stud (also known as the stud) two kinds, the stud is divided into two kinds of harness and the harness.
Alloy flange with hexagonal head bolt: often used with flat welding flange and non-metallic gaskets with milder conditions for operation. Commonly used material is BL3 or hexagonal head bolt is Q235B; Stud: often used with butt welding flange at the operating condition is harsh working conditions, among them, because there is no cross section shape on the harness type stud, so its bearing capacity is strong.
Alloy flange with rather than type harness stud is relatively weak bearing capacity. Nut materials often according to and cooperate with bolt material, these combinations have provisions in the general standard. Under normal circumstances, the nut material should be slightly below the bolt, and ensure the nut hardness is lower than bolt hardness HB30 around.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)