Hyphae

Coke Oven Gas Explosion

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Hazard · draft · confidence 0.88

Generated from the Hyphae knowledge graph. Drafted by claude-sonnet-4-6

Fire and explosion hazard arising from leaks of coke oven gas (COG), a hydrogen-rich fuel gas (~50–55 vol% H₂) produced and distributed throughout integrated steel plants. COG is highly flammable over a wide concentration range in air, and any ignition source can trigger a deflagration or detonation.

Exposure routes

  • Inhalation of CO-containing COG (acute CO poisoning)
  • Blast and thermal injury from ignition of accumulated gas
  • Oxygen displacement in enclosed spaces (asphyxiation)

Mechanism

COG leaking from oven seals, collecting main joints, byproduct plant piping, or fuel distribution pipework mixes with air to form flammable mixtures. Hydrogen’s lower explosive limit (LEL) is ~4 vol% and upper explosive limit (UEL) is ~75 vol%, giving an exceptionally wide flammability range. Ignition by sparks, open flames, or hot surfaces causes rapid combustion; in confined spaces this produces pressure waves capable of structural damage. Asphyxiation occurs in poorly ventilated areas where COG displaces oxygen below 16 vol%.

Mitigations

  • Positive back-pressure maintained inside ovens to prevent air ingress
  • Fixed COG/CO/H₂ gas detectors throughout the battery and byproduct plant
  • Personal gas detectors required in areas with COG pipework
  • Regular inspection and maintenance of oven seals, doors, and pipework
  • Permit-to-work system for entry into confined spaces and gas-exposed areas
  • Water seals (hydraulic mains) to prevent air backflow into COG systems

Severity

High. COG explosions in coke plants have caused multiple fatalities and major plant damage. CO toxicity at 200 ppm (0.02 vol%) causes headache; 1200 ppm causes immediate physiological danger; >10,000 ppm is immediately dangerous to life and health (IDLH).

Warning signs

  • Elevated CO or H₂ readings on fixed or personal monitors
  • Smell of COG (has a characteristic coal-gas odor from residual sulfur and aromatic compounds)
  • Visible flame at oven door gaps or lid areas

Connections

Incoming

  • Has hazard ← Cokemaking — COG is ~50% H2; distributed throughout the steel plant as fuel. Fixed and personal CO/H2 monitors required; positive back pressure maintained in ovens.
  • Has hazard ← Coke Oven Gas — COG is ~50-55 vol% hydrogen; extremely flammable over wide range (LEL ~4 vol% H2 in air). CO component (~5-7 vol%) creates acute toxicity hazard.

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