The flat welded flange with neck, like the flat welded flange of the plate type, also extends the steel pipe, pipe fittings, etc. into the flange and connects with the equipment or pipeline through the fillet weld.
The sealing surface forms are: protruding surface (RF), concave surface (FM), convex surface (M), tenon surface (T), groove surface (G), full plane (FF), ring connection surface (RJ)...
