BSafe Case Study — A Strong Smell Was Read as Proof, Not a Warning

A Smell Judged Sufficient

The ship had discharged benzene and was proceeding in ballast, cleaning cargo tanks ahead of the next chemical cargo. The final cleaning stage — manual wiping of residual wash water, known as mopping — requires physical tank entry under an enclosed-space entry permit issued by the master, with the hatch cover marked to show a permit was live.

On the morning of the incident, the chief officer sent four deck ratings to bring mopping equipment to the main deck. The permit process had not yet started, and the tank atmosphere had not been tested. The chief officer had noted a strong smell of cargo residue at deck level and, on that basis, judged it unnecessary to test the atmosphere — reasoning it was clearly still unsafe regardless.

Entering Ahead of the Sequence

One of the ordinary seamen went in through an open hatch before the atmosphere had been tested or the tank cleared. He wasn't carrying a portable multi-gas detector. He was wearing a filter-type mask — protection that does nothing in an oxygen-deficient space and nothing against benzene vapour specifically.

The bosun, walking the deck, looked down into the tank and saw him collapsed at the bottom. The alarm went up immediately. The chief officer and second officer donned self-contained breathing apparatus and recovered him, fitted an EEBD, and began CPR on deck with shore medical support. He did not survive.

The autopsy found injuries consistent with a fall onto a hard surface — meaning the atmosphere had incapacitated him before he reached the bottom of the ladder. Benzene was detected in his system.

What the Investigation Found

• The strong smell at deck level was treated as proof the tank was unsafe and therefore not worth testing — the opposite of the intended logic. A permit exists precisely to convert a suspicion into a measured, confirmed result before anyone enters.
• The enclosed-space entry permit had not been initiated before ratings were sent to prepare for the work — the sequence itself started out of order.
• The OS entered on his own initiative, ahead of any authorisation, wearing PPE that gave no meaningful protection against either an oxygen-deficient atmosphere or residual benzene vapour.
• A tank that looks or smells inactive from deck level, with a hatch open or a fan running, is not evidence it's safe — only measured, recorded gas testing under a completed permit process actually confirms that.

Recommended Actions

Directly from what the investigation identified:

1. A strong smell or other sensory cue is a reason to test the atmosphere immediately, not a substitute for testing it — treating ‘it obviously smells unsafe’ as equivalent to a confirmed reading skips the one step that actually protects anyone.
2. The enclosed-space entry permit sequence has to be genuinely completed — gas tested, verified, hatch marked — before any preparatory work that puts crew near an untested space, not just before the point someone physically climbs in.
3. Filter-type masks are not appropriate protection for an unconfirmed atmosphere or a known toxic vapour like benzene — the correct equipment for tank entry until atmosphere is confirmed safe is self-contained breathing apparatus, not a filter mask worn ‘as protection.’
4. Multinational crews benefit from a permit and briefing process that doesn't rely on informal, verbal judgement calls being correctly understood and followed by everyone present — the process itself has to be the safeguard, not one officer's on-the-spot assessment.

Human Element Analysis

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Related Reading

• Cargo Hold & Enclosed Space Fatalities — three real 2025 investigations, the same underlying pattern
• BSafe Case Study 8 — another chemical tanker incident where PPE didn't match the actual hazard