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API Plan 13

Recirculation from the seal chamber through a flow control orifice to pump suction.

API Plan 13


Plan 13 operation is by recirculation of fluids from the seal chamber to the pump’s suction.

Application Notes

  • Standard flush plan selection for most vertical turbine pumps.
  • Flow control orifice can be omitted depending on the required flush flow rate.
  • Helps to reduce the stuffing box or seal chamber pressure.
  • Can also be used for high head horizontal pumps where Plan 11 cannot be used (i.e. low pressure differential between seal chamber and pump discharge).
  • Vents air or vapors from the seal chamber in vertical pumps.
  • Applicable for all general duties with sufficient pressure differential.
  • Provides cooling for the seal.
  • Polymerizing fluids can cause clogging of the orifice and piping.
  • Should not be used with fluids which are at risk of freezing, thickening, or solidifying in external piping.


  • Provides venting for air and vapors within vertical pumps
  • Useful as a general duties seal plan
  • Provides efficient seal cooling


  • Using polymerizing fluids with this seal plan will lead to clogging of the orifice and pumps
  • Not suitable for use with fluids that might freeze or thicken within external piping

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