Fire Hazards and Prevention: Flammable Liquids, Gases, Electrical Hazards, Hot Work and Housekeeping
Prevention questions test whether you can spot the ignition source, the fuel and the pathway before a fire starts. The examinable content is the permit system, flammable liquid and gas behaviour, electrical risk and housekeeping discipline.
Flammable liquids and gases
- A flash point at or below 60 °C marks a liquid as flammable for stowage and handling; below 23 °C treat it as a continuous vapour hazard.
- LPG vapour is heavier than air and pools in bilges and chain lockers; methane (LNG) is lighter and rises, but still accumulates in enclosed tops and trunks.
- Bond and earth the hose and manifold before loading distillates - static will ignite vapour at a tank opening.
Electrical hazards
Overloaded circuits, damaged insulation, loose terminals, non-approved portable heaters and improvised wiring are the common causes. Isolate and lock off before work, use earth-leakage protection, and never apply water to live equipment.
Hot work
A permit signed by the master or responsible officer, a gas-free certificate for the space and all adjacent spaces, removal of combustibles within about 11 m, screens and blankets, a charged hose at hand, and a fire watch during the work and for at least one hour after.
Housekeeping
Oily rags in self-closing metal bins (spontaneous heating), clear escape routes, closed fire doors, a ventilated paint locker with no ignition source, gas cylinders secured upright, no smoking.
Worked example
Hot work on a bracket on the engine-room bulkhead, with a bonded store on the far side. Reasoning: steel conducts heat, so the far side must be gas-free, stripped of combustibles and watched, and the fire watch continues for an hour after the last spark. A certificate for the engine room alone is not enough.
Traps
- 'Diesel is safe' - its flash point is around 60 °C, but a spray or a hot surface changes that.
- Certifying the work space but not the space behind the bulkhead.
- Packing up the fire watch the moment the welder stops.