98020 Out of the Skeleton Cupboard – Gas Leak

Out of the Skeleton Cupboard – Gas Leak
Report No. 98020.

This happened when I was Master on an elderly but normally well kept VLCC and illustrates a chain of circumstances which might have caused an explosion had it not been for the doggedness and refusal to give up on the part of the Chief Officer.

It started when the Chief Officer reported a smell of gas in the lower deck alleyway. This was the deck beneath the lowest accommodation deck but joined to it by a staircase and shut off with a watertight steel door. It also opened out onto the main deck at each closed by watertight doors. Despite all the safety meetings and discussion on the ship, the crew sometimes would jam the door on the stairwell open when there was a lot of coming and going. The alleyway housed such spaces as the Cargo Control Hydraulic Room, Emergency HQ and its storerooms, a little used IG control station, the foam room and several other lockers.

We tried to find the source of the gas but were unable to. It was getting near dinner time and the Chief Engineer Officer and myself finally decided that the outside alleyway doors must have been recently opened and the gas entered that way from the deck. To his eternal credit, the Chief Officer was not satisfied with this explanation and carried on investigating after the Chief and I had gone up. This is what he found:-

1. In the little used IG control station a small diameter pipeline leading from the IG line to a pressure meter had been cropped off and a stop valve put on the end. This valve was found open so the line was open ended. The control station was largely unused because there was another set of controls in the Engine Room.
    
2. The Second Engineer Officer had emptied the water out of the IG seal tank without informing anybody. We had discussed this at our most recent safety meeting - there was a job which needed to be done on it but no date had been fixed. The 2EO, having some time to spare, had decided to do the job that afternoon.
    
3. The non return valve situated abaft the deck seal tank was passing.

This combination of faults led to gas coming straight back from the cargo tanks into the alleyway. The problem was compounded by myself and the CEO giving up too early and the 2EO emptying the tank without telling anybody.