Near miss: Fire hazard from engine room equipment failure

A member has reported a near miss incident relating to a fire hazard in a separator room. During routine planned maintenance and testing of a main engine lube oil purifier during a port call, smoke was noted emerging from beneath the guard of the purifier pre-heater.

The vessel’s smoke detection system activated, indicating smoke in the separator room. A General Alarm was sounded and a broadcast made to inform the crew that a potential emergency was developing and “In Port” fire procedures were activated.

The heater was immediately isolated both electrically and mechanically. Bridge was informed that although smoke was present there was no fire and the situation was under control. The heater was monitored to ensure that it cooled appropriately and presented no further danger.

Our member noted the following:

• There was some initial confusion at the time of the alarm, for two reasons:

• The vessel was preparing to conduct an “At Sea” emergency drill, which required personnel to muster on board, rather than ashore, and personnel assumed the drill had been brought forward
• Communications were hampered by a fault with the vessel PA system. The Master had to rely on portable UHF communications to clarify the exact situation.

What caused the incident?

• The immediate cause was the overheating of the lube oil pre-heater, which in turn overheated the paint on the heater casing, causing smoke;
• The engineer carrying out the work noted his concerns with the operation of the heater. He shut down the system by activating the heater stop button, and had the intent to report a possible fault;
• Events overtook his intentions: the smoke activated the smoke detection system and raised the General Alarm;
• The root cause was discovered to be a failed switch in the safety cut-off mechanism, which was found to have failed in the “Reset” position; this meant that, even if the heater had tripped, it would have immediately reset itself thereby keeping the heater on.

Positive points noted:

• Concerns were identified and support was sought in a timely way;
• When they heard the alarm, the duty engineer and chief engineer immediately activated both mechanical and electrical isolations, complete killing the system;
• The vessel was brought to Emergency Stations relatively quickly, despite communications problems;
• Investigation correctly identified the failed component and chain of events that led to the hazard;
• The vessel notified shore management in a timely way and provided full supporting information about the incident.
• Negative points noted:
• Emergency communications – vessel management had notified shore management of the recurring defect with the PA system, but repairs had been deferred and then cancelled;
• What happens when a real emergency occurs during a drill or exercise? There was no policy or guidance in place to deal with this possibility.

Particular actions taken:

• Investigation of similar systems to ensure no other latent failures or defects that may result in recurrence;
• Immediately pursue and action any outstanding defects related to communications and/or emergency response systems;
• Implement and publish a procedure for emergencies occurring during drills and exercises.

Members may wish to refer to the following incident:

• Diver helmet hat light [a dive helmet hat light which overheated to the point that the outer casing caught fire]