API Plan 62

API Plan 62

Quench stream from an external source to the atmospheric side of the seal faces. The quench stream can be low pressure steam, nitrogen or clean water.

A  Valve
B  Check valve
C  Drain

Seal chamber details

1  Quench (Q)
2  Drain (D)
3  Flush (F)
4  Seal chamber

Example seal: EagleBurgmann MBS682 single metal bellows mechanical seal.

P&ID according to API


1  Quench (Q)
2  Drain (D)


  • The quench fluid cools the seal faces from underneath and also reduces coking and oxidation of the media by creating a barrier between the seal faces and the atmosphere.
  • Flushes away built-up material or solids underneath the seal faces.
  • Uses water, steam or nitrogen.
  • Applied with or without quench baffle.


  • Used with steam to avoid coking or crystallization in hot hydrocarbon services.
  • Used with nitrogen to avoid icing in cryogenic services.
  • Used for services that tend to salt out e.g. caustic and salt services.
  • Applied at horizontal as well as vertical pumps.


Remarks, checkpoints

  • It has to be ensured that a close clearance throttle bush is fitted on the atmospheric side of the seal.
  • Quench pressure to be maintained between 0.2 to 0.3 barg (2.9 to 4.3 PSIG).




Pump media characteristics

  • High temperature
  • Leakage may form solids
  • Cryogenic

Location, function

  • Atmospheric side



2CW-CW*, 3CW-FB*, 3CW-BB*, 3CW-FF*

* Remark: The configurations listed for each individual piping plan are to be understood as recommendations including possible utilizations which may also be applied.