Updraft
Log inSign up

BL (blind)

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 solid plate that closes off the end of a pipe. Used as a temporary cover during pressure testing, and to cap a line left for a future branch. Available in every nominal pressure from 5K to 63K.

Blind flange dimensions

Blind flange dimensionsDCghtf
Nominal pressure
Show calculated mass
Nominal pressureNominal diameter
[A]		Joint dimensionsRaised facet
[mm]
D
[mm]		C
[mm]		h
[mm]		QuantityThread designationg
[mm]		f
[mm]

Notes

  • References
    • JIS B 2220:2012 steel pipe flanges (Table 14, Table 15, Table 17, Table 18, Table 19, Table 20, Table 21, 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.
  • Because there is no bore, there is no inside diameter, hub diameter, overall length or fillet radius. It is set by the joint dimensions and the flange thickness t alone.
  • The gasket seat is a raised face (RF) at 20K and above, and a full face (FF) at 5K, 10K and 16K. A full face has no g or f (Table 8).
  • The calculated mass is for reference. It assumes a steel density of 7.85 g/cm3.
Steel pipe flanges — BL (blind) | Updraft - Mechanical Engineering Calculators