Physical and Other Hazards: Engulfment, Falls, Electricity, Machinery, Heat, Noise, Drowning
This domain tests the non-atmospheric hazards that the risk assessment must capture, and the controls that follow from them.
Engulfment
Free-flowing solids such as grain, sand, cement, sugar and fly ash, and liquids such as slurry and sewage. A bridge can form with a void beneath; a person walking on the surface breaks the crust and is buried in seconds. Silo walls can collapse, and slurry can be released suddenly. Controls: never enter onto stored material; use long-handled tools, vibrators or remote equipment from outside; where entry is unavoidable, use a full-body harness with lifeline, a permit, a standby person and a rescue plan.
Falls and access
Openings, ladders, slippery steps and vertical drops. Controls include secured ladders, guard rails, harness and anchor point, adequate lighting, non-slip surfaces and a planned escape route.
Electricity
Portable tools, lighting, pumps and welding sets. Use extra-low-voltage lighting, RCD protection, explosion-proof equipment where a flammable atmosphere is possible, protected cables, and lockout of supplies.
Moving machinery
Agitators, augers, mixers, pumps, conveyors and valves. Isolate and lock out, apply mechanical restraint, verify zero energy and keep the key with the entrant.
Heat
Hot work, steam, hot residues and hot surfaces; heat stress inside an enclosed space; burns. An increase in body temperature is itself a specified risk. Cool the space, ventilate, provide PPE and rotate workers.
Noise
Reflected sound is amplified in a confined space, causing hearing damage and impairing communication. Assess noise, provide hearing protection and agree alternative signals.
Drowning and flooding
Sewers, tanks and pits can flood from upstream discharge, tide or sudden ingress. Isolate inflows, monitor levels and weather, and keep an escape route.
Other hazards
Vermin, sharps, dust, poor visibility, radiation from non-destructive testing, and fire.
Worked example
A worker enters a grain silo to break a bridge of compacted grain. The bridge collapses and he is engulfed. Reasoning: the surface looked solid and the void beneath was invisible. The correct control is to break the bridge from outside with a pole or vibrator; if entry is unavoidable, a harness, lifeline, permit and standby person able to winch him out are required. Walking on stored grain is never acceptable.
Traps that cost marks
- Isolating electricity but not gravity or stored pressure.
- Using a ladder as the only means of escape.
- Assuming noise is not a hazard because the space is small.
- Overlooking heat stress and body temperature as a specified risk.