Disclaimer: The above image is for representation of the below incident and need not be considered as an actual case image.
Summary
The Maltese registered MV Maribella sailed from Pittsburgh, San Francisco Bay, on 26 July 2015. She was bound for Long Beach, California with 41,171 tonnes of pet coke. On 27 July 2015, at approximately 2013 (LT), a fire alarm indicated a fire in the engine-room. At the time, Maribella was in position 34° 49´ N 122° 58´ W. One generator was running and the vessel’s engine-room was on UMS mode.
The second engineer, who was on duty, entered the engine room and immediately discovered a fire on and around auxiliary engine no. 1. Shortly afterwards, the fixed overhead water mist fire extinguisher was triggered and the emergency generator fired up. All crew members were mustered at the muster station and they promptly shut the ventilation system.
The emergency fire team observed that the fire had been contained in a relatively small area and practically doused in water. Nonetheless, the team used portable CO2 fire extinguishers to ensure that the fire had been completely extinguished . Preliminary assessment of the area indicated damage around auxiliary engine no. 1. Overhead electrical cables and wires leading to the fixed fire and flame detection systems were burnt.
Both systems were rendered inoperative. No pollution, injuries and cargo damage were reported. Other plant equipment and machinery were also checked. Nos. 2 and 3 auxiliary engines were switched on and monitored for performance. By 2320, all shipboard functions were found normal and Maribella resumed her voyage to Long Beach.
Figures 1a to 1d: Stereomicrographs of the bolt plug head/top and point surface
Cause of fire
It was observed that the vent plug (Hexagon Socket Head Bolt) on no. 2 fuel oil injection pump had slackened during operation and marine gas oil feeding the auxiliary engine splattered on the exhaust pipe. The engine had been in operation for only 200 hours since last overhauled on 15 July 2015. At the time of damage survey in Long Beach, the cause of loosening of the vent plug had not been identified. The ship’s managers, however, advised that during the overhaul of the generator’s fuel oil pumps, the crew had replaced the copper washer before tightening the vent plug.
Figures 2a to 2f: Bolt thread at each of the six facets of the plug
Findings
The safety investigation was unable to conclude with absolute certainty the psychological origin of the actions taken when the fuel oil injection pump was boxed up again. However, considering that the technical analysis revealed a brittle metallic washer, it was considered more plausible that there was never the intention to replace the old metallic washer during the assembly of the pump.
Figures 3a and 3b: Micrographs of the metallic washer
Recommendations
- Bring this simplified safety investigation report to the attention of crew members on board Company vessels;
- Issue a Fleet Circular prohibiting the re-use of metallic washers and emphasise the importance of correct tightening procedures on installed equipment and machinery.
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Source: Transport Malta
