A weld neck flange (WN flange) means a flange has a neck for welding with the pipe, it is easily to recognized by their long tapered neck on the flange (The neck is also called hub in the weld neck flange).
The weld neck flange is connected with the pipe or pipe fitting from the neck in butt welding method, that means the neck should be have same material, outer diameter and wall thickness with the pipe. The tapered neck can supply a high strength reinforcement to support flange and steel pipe. It means the weld neck flange is suitable to used in high pressure and extremely temperature situation.
With a neck on one side of the flange, the other side of the flange is sealing face, which are between the two flanges joint. WN flange usually supplied with flat face (FF), raised face(RF) and ring type joint (RTJ). The raised face has a height on the flange rather than the flat face, the RTJ face is used to contain the gasket ring which are specially for high pressure application.
In different standard for weld neck flange, the dimensions of the flange and sealing face have a different technical data, it is necessary to confirm all the details to make sure the flange can match the joint with the pipe and another flange. Hebei haihao group flange factory can design and produce the welding neck flanges as per customer request.