Recommend an API 682 seal piping plan โ flush, buffer, barrier or quench โ from the seal arrangement and service conditions
Understand why seals need a flush, the API 682 Arrangements 1/2/3, and the flush, buffer, barrier and quench plans
API 682 organizes seals into three arrangements; the arrangement decides which family of flush plans applies:
Functions are per API 682 Annex G. The recommendation is engineering guidance โ confirm the final plan with your seal vendor.
An API flush plan (API 682, Annex G) is a standardized piping arrangement that conditions the fluid at a mechanical seal โ cooling it, cleaning it, supplying a buffer or barrier fluid, or applying a quench. Each plan has a number (Plan 11, 23, 52, 53A, and so on) so that engineers, vendors, and operators describe the same arrangement consistently on a P&ID.
Plan 11 recirculates fluid from pump discharge through a flow-control orifice into the seal chamber โ the default for clean general service. Plan 23 uses a pumping ring to circulate seal-chamber fluid through a cooler and back, the most efficient cooling plan for hot service such as hot water or boiler feed water. Plan 32 injects a clean flush from an external source into the seal chamber, used for dirty, abrasive, or polymerizing service where the process fluid must be kept away from the faces.
Both are dual-seal plans, but Plan 52 supplies an unpressurized buffer fluid kept below process pressure (Arrangement 2) for containment and leakage monitoring, while Plan 53 (53A/53B/53C) supplies a barrier fluid pressurized above process pressure (Arrangement 3) so that no process fluid escapes to atmosphere. Use Plan 53 for hazardous, toxic, or no-leak-to-atmosphere service; use Plan 52 where a small amount of contained, monitored leakage is acceptable.