Mechanical seal fires are a frequent risk scenario in refineries and petrochemical plants. High-pressure hydrocarbon creates a jet fire — a 5-10 m tall fire column. API 2218 (Fireproofing Practices in Petroleum and Petrochemical Processing Plants) defines structural protection, pump secondary containment and deluge spray water design.
Seal Failure Modes
- Primary seal wear: dry running, abrasive fluid
- Secondary seal failure: flammable liquid escapes
- Pump cavitation: excess vibration, shaft misalignment
- Ignition: hot surface (>350 C autoignition), spark
Typical API 610 pump seal life is 3-5 years.
Firesafe Secondary Seal
- Dual mechanical seal: two primaries + barrier fluid
- API Plan 52/53: external flush + barrier fluid circulation
- API Plan 66: secondary containment + drain
- Magnetic drive pump: no seal — no leak
Deluge Spray Water
API 2218 deluge over pumps:
- Design density: 10.2 L/min/m2 (0.25 gpm/ft2)
- Area: pump + motor + isolation valve
- Nozzle: medium-velocity spray, 60 deg cone
- Activation: flame detector (UV/IR), gas detector or manual
- Water reserve: 30 min (AHJ) or 2 hours (FM Global)
Structural Fireproofing
- Structural steel: PFP (passive fire protection) - intumescent coating, 2-hour rating
- Cable tray: ablative coating or mineral wool
- Pipe support: fireproof concrete coating up to 9 m height
- ESD valve: closes on heat or smoke in 30 s
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Sources & Further Reading
API 2218, API 610, API 682, NFPA 15, NFPA 30, FM Global DS 7-88. API 2218 Petroleum Fireproofing.