Enclosed-space entry after tank washing: a collapsed crew member and an incomplete permit
MT Gulf Trader is an oil tanker at anchorage. No. 4 port cargo tank has been washed and ventilated for three hours. The entry permit records oxygen 20.9% and LEL 0% from a reading taken at the tank deck hatch, but there is no reading from the tank bottom and no continuous monitor. A fitter enters with a torch to inspect the tank cleaning, wearing overalls and a dust mask but no breathing apparatus. A standby man remains at the hatch but has no rescue harness or communications with the bridge. Ten minutes later the fitter is seen collapsed at the bottom of the tank. The standby man shouts for help and an able seaman runs over with a rope, intending to climb down.
1. What is the immediate danger, and what should the able seaman and standby man do first?
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The immediate danger is that the tank atmosphere at the bottom may be oxygen-deficient or contaminated, even though the deck-level reading was acceptable. The collapsed fitter may have entered a pocket of heavier hydrocarbon vapour or hydrogen sulphide, or disturbed sludge that released gas. The able seaman must not climb down with a rope. Would-be rescuers without breathing apparatus frequently become the next casualties, and the standby man is not equipped or trained for entry rescue.
First, raise the alarm and call the master and rescue team. Stop any ventilation change that could worsen conditions, keep the hatch clear, and prevent anyone from entering without SCBA and a rescue harness. The standby man should stay at the hatch and maintain communication, using the agreed emergency signal. The rescue team should approach with self-contained breathing apparatus, a lifeline and harness, and continuous gas monitoring. If the ship has no trained team immediately available, the master should request shore or port rescue assistance. The priority is to protect the rescuers while reaching the casualty.
2. Identify the failures in the entry permit and gas-testing process.
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The permit was invalid for this entry. Gas testing was done only at the deck hatch, not at the bottom, and there was no continuous monitoring. Oxygen and LEL readings alone are not sufficient for an oil tank that may contain hydrogen sulphide or hydrocarbon pockets; the test should include the specific toxic gas hazards and should be taken at several levels, including the bottom and any remote spaces. The permit also failed to require a rescue harness, lifeline, communications and a trained standby man.
The fitter entered with a dust mask, which gives no protection against oxygen deficiency or toxic gas. A torch is not a substitute for intrinsic safety or for atmosphere control. The standby man had no communications with the bridge and no rescue equipment. These are not minor paperwork issues: they show that the permit was treated as a formality. A valid permit must be issued after isolation, ventilation, testing, marking and briefing, and it must specify the entry conditions and emergency arrangements.
3. What prevention measures should the ship put in place after this incident?
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The ship should review the enclosed-space entry procedure and enforce a stop-work authority for anyone who sees an unsafe entry. Permits should require gas tests at top, middle and bottom, continuous monitoring, and specific checks for hydrogen sulphide and hydrocarbon vapour where relevant. Rescue arrangements should be verified before entry: harness, lifeline, SCBA sets, trained rescue team, communications and a standby man who does not enter. Drills should include a rescue from a tank bottom, not only a discussion at the hatch.
The company should investigate the incident as a near miss or accident, identify why the fitter entered without breathing apparatus, and check whether production pressure influenced the decision. Crew training should cover the limitations of dust masks and the danger of untrained rescue. The permit system should be audited, and the master should ensure that ventilation is continued and monitored until the tank is proved safe. The aim is to make the safe way the practical way, not to add another form after the event.