Gard reports lessons learned when the engine room water mist system of an ultra large container ship failed to operate.
The incident
An ultra large container ship was on a voyage from Singapore to Hong Kong. At 2154 hrs the low fuel pressure warning alarm sounded and eighteen seconds later the fire alarm for the engine room activated.
The Chief Engineer then entered the engine room to investigate and noticed flames coming from Auxiliary Engine #1 (A/E1). The quick closing valves were immediately activated. The engine room water mist system had failed to operate.
Crewmembers tried to investigate the failure of the water mist system but were unsuccessful. Inspite of that, the engine crew managed to extinguish the fire using dry powder extinguishers.
After an inspection of the engine room, it was decided to restore the main power. A/E3 was started at 2230 hrs and within one minute, heavy smoke was again seen coming from the engine room.
The Chief Engineer noticed that the fire in A/E1 had reignited. He tried to extinguish it using a portable extinguisher but was unable to control it. The water mist system had again failed to operate. The engine crew was mustered and the decision was made to release the fixed CO2 system.
The Chief Engineer released the fixed CO2 remotely from the fire station at 2243 hrs. To make sure that CO2 had released, the Chief Engineer and the 2nd Engineer went to the CO2 room to check. In the CO2 room, they found that several CO2 cylinders and manifold heads remained frost free and warm indicating that some of the cylinders had not been discharged. There was also a bottle leakage alarm that they failed to notice.
Meanwhile the temperature in the engine room continued to rise. At 2300 hrs the 2nd Engineer donned breathing apparatus and entered the CO2 room to release the cylinders manually. Approximately half an hour later the temperature in engine room was seen to be reducing and the fire was later confirmed to be extinguished. The vessel then had to be towed to the nearest safe port for repairs.
Probable cause
Aa Gard informs, main findings of the investigation were:
Cause of fire and reignition:
- The first fire was caused by fuel spilling onto unprotected hot surfaces from a fractured fuel pressure sensing line on the main inlet fuel supply line serving A/E2. This pipe that had been fabricated onboard and was of inferior specification. This pipe was also not properly supported from the original design and was exposed to excessive vibration leading to fatigue cracks. The maker had issued service letters notifying owners of the risk of fatigue cracks and oil spill from this pipe.
- On the cause of reignition, the report said it was either caused by the reinstatement of the fuel supply or energizing of the main switchboard once the A/E3 was started.
Failure of the water mist system:
- For auto activation, the system required detection by two flame detectors. In this case only one flame detector activated probably because the other was covered by fuel mist.
- Another important finding was that the system did not activate since the crew did not notice the operation mode was set to ‘manual’ on the local control stand. This was done during previous maintenance work on the engine. The crew were not aware of how to override or rectify this.
Failure of fixed CO2 system:
- Out of the allocated 397 cylinders, only 170 cylinders had been fully discharged.
- The fixed CO2 system was inspected and serviced by a classification society approved third party service provider one year before the incident.
- During servicing, they changed all the flexible hoses for the pilot actuators and the discharge lines.
- The new flexible hoses had a different connection profile than the hoses installed originally , as shown in the image.
- A system pressure test was performed during the investigation, and it was noted that the new flexible hoses did not form a sufficiently robust or effective seal on the pilot air-line. Leaks were detected in all connections.
Excellent information and useful
The problem maybe caused by the installation of flame detectors, normally in order to keep the full coverage of all protected area for the Gen. Engine top with T/C, the flame detectors shall be installed inclined. If the flame detectors are installed pendent, considering the installation height from flame detectors to Gen. Engine top and the coverage angle, the whole protected area can’t be covered because of the required length of protected area.
As to the operation mode in “Manual”, it will not affect the manual operation or emergency operation, the ship’s crew can operate the system manually when AUTO release is failed.