In its recent Safety Digest, UK MAIB a fire incident which took place onboard a vehicle ferry after engine maintenance.
The incident
A vehicle ferry was outbound returning to its operating area after a routine reft. Tere were no passengers or vehicles on board. Once the pilot had disembarked and the vessel was in open water, the bridge team gradually increased the engine speed while the engineers monitored the engine room. A small amount of vapour was noted coming from the aft main engine lagging, close to the turbo blower. Work had been completed on the cooling system in this area, the lagging smelt damp and it initially appeared to be water vapour being produced.
Shortly after, the fire alarm activated in the aft engine room and small fames were seen coming of the lagging. This was extinguished using an aqueous fre-fghting foam (AFFF) extinguisher, and the bridge team were asked for approval to stop the main engine.
After clearing up, and in consultation with the senior chief engineer, it was decided to restart the engine and monitor the situation carefully. The fire reignited after a few minutes’ running and was once again extinguished. Again, the engine was stopped, and this time the lagging was removed; the engine restarted with no further issues. The lagging pad was subsequently replaced.
The company investigation later identifed that during maintenance work on the main engine cooling system a pipe had been removed to allow a leak to be repaired by replacing a seal. This was not a planned task, and no risk assessment or method statement had been produced. When the pipe was removed, around 5 litres of water had drained from the top of the crank case breather box, and some oil residue inadvertently washed into the lagging.
Main engine runs conducted alongside after the repair had not produced sufficient heat to ignite the oils. However, when the main engine was run under load at sea, the increased temperature produced was enough to cause a fire.
Lessons learned
- Whenever maintenance work is carried out around or near potential sources of heat, a risk assessment must be conducted to ensure unexpected results are considered. The working and adjacent areas should be protected from contamination – even if you expect only water to be present. If water can wash oils into places that can then become hot when machinery is running, a source of ignition can be created. In this case the crew were alert and the fre was small. This may not always be the case.
- Even after AFFF is used, sufcient heat will cause fammable material to reignite once it gets hot enough. The crew involved in this incident were monitoring the site carefully and quickly extinguished the second fire. However, the only real solution would have been to remove the fammable material from the source of heat, which was subsequently done by removing and replacing the lagging.
