api plan 21
,

API PLAN 21

  • Fluid is taken from the pump discharge (high-pressure zone), forming a self-flushing closed-loop circulation (no external flush medium required).
  • A flow control orifice (or restriction device) is installed to stabilize the flush flow and prevent over- or under-flow.
  • A cooler (shell-and-tube, plate-type, or coil-type, etc.) is provided to reduce the temperature of the flush fluid before returning it to the seal chamber.
  • Optional instrumentation such as temperature indicators, pressure gauges, vent, and drain connections can be included for operation monitoring and maintenance.
  • Can be used in combination with a throat bushing to improve circulation efficiency and enhance seal chamber conditions.
  • Piping layout can be designed in accordance with API 682 / API 610 standard interface configurations, and supports skid-mounted integrated design.
Categories: ,

API Plan 21 with Cooling Recirculation (API Plan 21) is a mechanical seal flush and cooling arrangement. It utilizes process fluid from the pump discharge (high-pressure zone) for self-recirculation. The fluid is extracted, passes through a flow control orifice, then enters a cooler where its temperature is reduced before being returned to the seal chamber. This provides continuous cooling, lubrication, and flushing to the seal faces.

The system does not require an external flush fluid. It increases the temperature margin within the seal chamber, reduces the risk of vaporization/flash, helps minimize coking, and improves overall seal stability. It is widely used in centrifugal pumps and other rotating equipment under medium- to high-temperature service conditions.

Related products