SOH (slip-on welding, hub flange)

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.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.

A plate flange (SOP) with a hub added to reduce the stress at the root of the weld. Chosen where an SOP is not strong enough for the pressure or the cyclic loading. Available in nominal pressures 5K to 30K.

Slip-on welding flange (hub type) dimensions

Nominal pressure	Nominal diameter [A]	Joint dimensions					Inside diameter		Raised face		t [mm]	Hub diameter		T [mm]	r [mm]	l [mm]
Nominal pressure	Nominal diameter [A]	D [mm]	C [mm]	h [mm]	Quantity	Thread designation	d₀ [mm]	d [mm]	g [mm]	f [mm]	t [mm]	a [mm]	b [mm]	T [mm]	r [mm]	l [mm]

Notes

References
- JIS B 2220:2012 steel pipe flanges (Table 14, Table 15, Table 16, Table 17, Table 18, Table 19, Annex F)
The source has one table per nominal pressure. Here they are combined into a single table, with a rule where the nominal pressure changes. A dash means the dimension is not specified for that pressure. Selecting a single nominal pressure above drops the columns that do not apply, giving the same column layout as the source.
At 5K and 10K only the larger sizes are available (450A and above for 5K, 250A and above for 10K). For smaller sizes use a plate flange (SOP) or a socket welding flange (SW).
At 20K and 30K there are three forms, A, B and C (Table 2). The dimensions are the same for all three; what differs is the detail of the weld and the mass. The stopper l is fitted only to Type C.
The inside diameter d is given only at 20K and 30K. On Type C the pipe butts against the stopper, so the inside diameter is set separately from the spigot bore d₀.
The gasket seat is a raised face (RF) at 20K and 30K, and a full face (FF) at 5K, 10K, 10K thin and 16K. A full face has no g or f (Table 8).
Inside diameter d is adjusted to suit the inside diameter of the pipe it joins.
The calculated mass is for reference. It assumes a steel density of 7.85 g/cm³.