Why must hot work atmosphere testing continue throughout the work, not just before it starts?

A. Testing only needs to be repeated if the worker changes

B. Continuous testing is only a formality with no real safety basis

C. Heat from the work itself can liberate trapped vapour from coatings, sludge, or adjacent structure, or disturb residues, causing the atmosphere to deteriorate after work has begun even though the pre-work test was clear

D. A single pre-work test is always sufficient once gas-free status is confirmed

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