Purging (cargo tank)
Replacing one gas atmosphere in a cargo tank with another (typically replacing flammable hydrocarbon with inert gas before tank entry, or vice versa before loading).
In practice
Atmospheric prep before drydock or annual class survey. Cargo tanks purged with inert gas to <2% HC, then with air to >21% O2. Gas-free certificate issued by an approved chemist before any hot work.
Regulatory detail & full definition
On crude tankers, purging means replacing tank atmosphere with inert gas to < 8% O2 before loading or after discharge. On LNG carriers, purging means replacing inert gas with cargo vapour (gassing-up). Documented in tank atmosphere log; entry to a purged tank requires SCBA and confirmed atmosphere test (O2, LEL, H2S, CO).
Authoritative source: SOLAS Chapter III (Life-saving appliances) ↗
Related
Source: ISGOTT Ch. 11; SOLAS III/19 (enclosed-space drills)
High confidence
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