Tankerman · Gauging — Closed
Closed gauging of a cargo tank is required when:
- AHandling toxic or volatile cargoes to prevent vapor release and exposure✓ Correct
- BAny time the weather is calm
- CThe tank is empty
- DOnly during ballast operations
Explanation
Closed gauging uses a sealed device (e.g., a closed UTI tape through a vapor lock) so the tank is never opened to atmosphere, preventing toxic/flammable vapor release and crew exposure during gauging.
Authority: ISGOTT (gauging); 46 CFR Subchapter D
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