Steel pipe flanges
Welded
SOP (slip-on welding, plate flange)Nominal pressure 5K, 10K, 10K thinThe pipe is slipped in and fillet welded. It is a flat plate with no hub and is the cheapest type. It is used for general low-pressure piping.SOH (slip-on welding, hub flange)Nominal pressure 5K, 10K, 10K thin, 16K, 20K, 30KA plate flange with a hub added to lower the stress at the root. Choose it where SOP does not stand the pressure or the repeated loading.SW (socket welding flange)Nominal pressure 5K, 10K, 16K, 20KThe pipe is pushed to the bottom of the socket and welded on the outside only. It is used for small-bore piping, 10A to 80A.WN (welding neck flange)All nominal pressures 5K to 63KIt is butt welded to the pipe. The joint is the strongest of all, and it is used for piping under high pressure, high temperature or repeated loading.
Other than welded
LJ (lapped flange)Nominal pressure 5K, 10K, 16K, 20KIt is not fixed to the pipe but bears on the collar of a stub end. The flange turns freely, so lining up the holes is easy, and it can be a different material from the pipe.TR (threaded flange)Nominal pressure 5K, 10K, 16K, 20KThe pipe is screwed in with a taper pipe thread. It is used on sites where welding is not possible, and on lines where welding is unwanted. Only 10A to 150A are covered.IT (integral flange)Nominal pressure 5K, 10K, 16K, 20K, 30KA flange made in one piece with the body of a valve or a machine. It is not a separate part, so the table is consulted to match the joint dimensions to the mating side.BL (blind flange)All nominal pressures 5K to 63KA plate with no bore that closes the pipe end. It is used to stop a line off for testing, or for a branch to be added later.
Dimensions common to all types
Gasket seat dimensionsTable 13Dimensions for the raised face (RF), the male and female face (MF) and the tongue and groove face (TG). The full face (FF) has no seat dimensions.Flange dimensional deviationsTable 22Tolerances on the outside diameter, the bolt holes, the inside diameter, the thickness and so on. Each dimension applies to a set type and gasket seat.
Notes
- References
- JIS B 2220:2012 steel pipe flanges