Mod 5 - Mechanical Seals

Module from the Rotating Equipment Training Curriculum curriculum.

MECHANICAL SEALS — API 682 FLUSH PLANS · Learning Objectives · 1. Select between single, dual unpressurized, and dual pressurized seal arrangements 2. Specify appropriate API 682 flush plan for service conditions 3. Understand seal face materials, operating limits, and failure modes 4. Troubleshoot common seal failures (short life, excessive leakage) · API 682 Flush Plans — Quick Reference

Plan	Description	Seal Arrangement	Application	Fluid Limitation	Key Equipment
Plan 11	Recirculation from pump discharge through orifice to seal	Single	Clean, cool process fluid, low solids	Clean, non-polymerizing, <400°F	Orifice, tubing
Plan 13	Recirculation from seal to pump suction (reverse circulation)	Single	Clean fluids with adequate pressure differential	Low-pressure differential services	Tubing, check valve
Plan 21	External cooler in Plan 11 loop	Single	Hot service >300°F, clean fluids	Clean, no polymerization	Cooler, orifice, tubing
Plan 23	Pumping ring circulation through external cooler (closed loop)	Single	High-temperature service, need to keep seal cool	Clean fluid, <600°F process	Pumping ring, cooler, thermosiphon or forced
Plan 32	External source of clean flush to seal (quench/flush)	Single	Dirty or abrasive process, slurries	Any (clean external source required)	Clean flush supply, flow control
Plan 52	Buffer fluid reservoir, unpressurized (atmospheric tank)	Dual unpressurized	Fugitive emission control, moderately hazardous	Buffer fluid compatible with process	Buffer tank, level indicator, alarm
Plan 53A	Pressurized barrier fluid reservoir (bladder accumulator)	Dual pressurized	Toxic/lethal service, zero-emission requirement	Barrier fluid must be compatible and clean	Bladder accumulator, pressure source, tubing
Plan 53B	Pressurized barrier fluid with pumping ring	Dual pressurized	High-temp toxic service, need barrier circulation	Clean barrier fluid, good heat removal needed	Pumping ring, cooler, reservoir
Plan 53C	Pressurized barrier fluid with external circulation pump	Dual pressurized	Maximum barrier reliability, highest-hazard service	Clean barrier fluid	Circulation pump, cooler, reservoir, instruments
Plan 54	External pressurized barrier fluid system (central system)	Dual pressurized	Multiple seals on common barrier system	Central barrier supply available	Central supply, distribution panel
Source: API 682 5th Ed, FOS Chief Files — SEALS folder, IPE-EP-6-1-1 (Centrifugal Pumps)

Source: Rotating_Equipment_Training_Curriculum_v1.xlsx · Sheet: Mod 5 - Mechanical Seals

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