Which document confirms safety for entry after tank cleaning due to hazardous atmospheres?

• A. MARPOL logbook
• B. Cargo manifest
• C. Gas-free certificate
• D. Vessel flag certificate

Answer: (C)

Ensuring safe entry after tank cleaning starts by confirming the space isn’t hazardous. The gas-free certificate is the document that proves this. It is issued after a qualified person has tested the tank’s atmosphere with proper gas detectors and verified the readings meet safe limits (oxygen level suitable for life support and hydrocarbon and toxic gas concentrations below danger thresholds). The certificate records the tank tested, the date and time of testing, the results, and the sign-off by the tester, indicating entry or work inside the tank can proceed without risk of asphyxiation or explosion.

Other documents serve different purposes: the MARPOL logbook tracks pollution prevention and incidents, the cargo manifest lists what is on board, and the vessel flag certificate confirms the ship’s registration and compliance with flag state requirements. They do not certify atmospheric safety for entry after tank cleaning.