Corrective / preventative actions
A small gas tanker was on a loaded coastal voyage. Prior to arrival at the discharge port, the chief engineer and a company superintendent who was on board to carry out an inspection of the vessel, planned to test the operation of QCVs in the fuel oil (FO) and diesel oil (DO) tanks. At about 11:30, both the chief engineer and superintendent positioned themselves near the FO service tank and ordered the tripping of the tank’s QCV from the remote emergency control station.
After confirming proper closing, the QCV was manually opened and reset. It was then decided to break for lunch. At about 12:40 hrs, when one hour’s notice of arrival had been given by the bridge, the Chief Engineer returned to the engine room. At the time, the vessel was proceeding along the traffic separation scheme in the outer approaches to the destination port. At 12:55 hrs, No. 1 generator engine suddenly stopped, causing a blackout and loss of propulsion and steering. The Master broadcast a safety message on VHF and arranged to display Not Under Control (NUC) signals. Immediately, No. 2 generator engine was started manually and was taken on load, but after about 15 minutes, this generator also stopped. On investigating the problem, the chief engineer found the QCV of the DO service tank was in the closed position.
He quickly opened and reset the valve in the correct position, but the common outlet line that supplied the fuel pumps of both generators had entrained air and had to be purged with diesel oil. After about 20 minutes, both the generators and main engine were restarted, the vessel proceeded slowly to the anchorage and await an escort tug.
Root cause / contributory factors
1. During the testing of the FO tank QCV, the DO tank valve was also inadvertently activated without the testing team noticing, resulting in the interruption of fuel supply to the generator engine;
2. There was no risk assessment / briefing / tool box meeting prior to the test;
3. The Master was not informed about the planned QCV test;
Corrective / preventative actions
1. Safety alert sent out to all vessels, giving specific instructions with reference to the testing of fuel oil and diesel oil QCVs with instructions to ships’ staff to discuss this incident at the next on board safety meeting;
2. Safety Management System (SMS) amended to prohibit the testing of QCVs when vessels are underway;
3. Technical superintendents to prepare and circulate a QCV testing schedule to the fleet;
4. Signs to be placed on both FO and DO service tanks and in vicinity of activation point outside the engine room, warning crew of the risk of blackout if QCVs are shut;
5. Chief Engineer’s standing orders and handover notes to include specific instructions on QCVs and danger of their unintended operation when crew is engaged in tasks near activation points.
Source: Mars/Nautical Institute
