Before hot work is carried out on or near a tank, pipeline, or void that has previously contained flammable cargo or fuel, what must be confirmed by testing?

A. Gas-freeing is only required for tanks that last held crude oil, not other fuels or chemicals

B. A gas-free certificate from a previous, unrelated job is acceptable if issued within the last month

C. The space/system has been proven "gas-free" by atmosphere testing for flammable vapour (and oxygen/toxic gas as relevant), carried out by a competent person, with results recorded on the permit before work begins

D. Visual inspection alone is sufficient if the tank "looks" clean

A. Any task lasting longer than 30 minutes

B. Only welding using electric arc equipment

C. Any work involving an open flame, welding, burning, grinding, or any process that produces sufficient heat or sparks to act as a source of ignition for flammable materials, gases, or vapours

D. Only work carried out inside a cargo tank

A. A clear radius of at least 10 metres (or as defined by the risk assessment for the specific task and materials), with all combustibles removed or adequately shielded

B. No clearance is needed if a fire extinguisher is present

C. Clearance is only relevant for work carried out in an engine room

D. 1 metre is always sufficient regardless of the work type