_{API 682 Plan 62 Seal Support System Introduction}

1. _{Definition & Working Principle}

_{API 682 Plan 62 is an atmosphere-side quench support system for single mechanical seals.}

_{It introduces low-pressure external fluid (steam / nitrogen / clean water) to the outboard (atmosphere side) of the mechanical seal, forming a barrier to control temperature and prevent scaling, coking and crystallization.}

2. _{System Components}

_{Quench Inlet (Q): Connection for external low-pressure fluid supply.}

_{Bushing / Throttle Bushing: Mandatory part; retains quench fluid, limits leakage and protects the bearing housing.}

_{Drain Port (D): Discharges excess quench fluid and impurities.}

_{Valves & Check Valve: Stabilize pressure and prevent backflow.}

3. _{Working Process}

_{Low-pressure quench fluid enters the outboard seal chamber from the quench inlet.}

_{The fluid forms an isolation barrier between the seal face and ambient atmosphere.}

_{It cools / warms the seal and washes away solids, coke and crystals.}

_{Excess fluid and contaminants are drained through the discharge port.}

4. _{Common Quench Media & Functions}

_{Low-pressure Steam (Most Used): For high-temperature hydrocarbon services (residue oil, bitumen); prevent coking and sticking.}

_{Nitrogen: For cryogenic services (liquefied hydrocarbon); prevent icing and oxidation, isolate air.}

_{Clean Water: For medium-temperature easy-to-crystallize media (brine, lye); cooling + prevent salt precipitation.}

5. _{Typical Applications}

_{High-temperature hydrocarbon pumps: crude oil, residual oil, thermal oil.}

_{Easy crystallization / salting media: caustic soda, brine, urea.}

_{Cryogenic pumps: LNG, liquid ammonia.}

_{Corrosive media: isolate air to reduce corrosion.}

6. _{Advantages & Disadvantages}

_Advantages

_{Simple structure, low cost and easy maintenance.}

_{Effectively prevent coking, crystallization and icing; greatly extend seal service life.}

_{No contamination to process fluid.}

_{Disadvantages}

_{Only applicable to single mechanical seal; cannot stop process media leakage to atmosphere fundamentally.}

_{Continuous external fluid supply required, with ongoing operating cost.}

_{Throttle bushing is mandatory; otherwise quench fluid will leak and lose efficacy.}

7. _{Key Operation Notes}

_{Keep quench pressure stable at suitable range.}

_{Throttle bushing installation is required; small clearance design avoids fluid entering bearing housing.}

_{Keep drain line unobstructed to avoid liquid accumulation and backflow.}

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