GB flange of another a layer mean for: according to national standards requirements of size, and tolerance range, production of flange, difference Yu not by standard size production of flange tablets also said II standard flange (was called non-standard flange is not right of), usually some no good businesses will reduced flange thickness, and OD two items size to reached save material of purpose, also useful waste steel or scrap steel processing flange, usually this steel is chemical components and mechanical performance not standard of waste, what with black Mills private steel production flange, Obsolete steelmaking technology used in this private steel cannot be guaranteed mechanical properties and weldability, used may not be welded or welded steels itself for cracks, holes and other leaks after, so buy flange as far as possible to adopt the national standard flanges. If funds are limited under Select second flange must be carefully observed and measured the flange dimensions so as not to fall for it.