200834 Rupture of economiser with fatalities

Official report: IMO Sub-Committee on Flag State Implementation - 11th Session

An economiser (waste heat boiler) on a passenger ship ruptured during sea trials after a repair period. Two people died from steam burns and three others were injured as a result of the failure.

Result of investigations
The shipboard economisers were not to be pressurised for the sea trials. The necessary steam was to be provided by a temporarily installed oil-fired boiler.
The engineers decided not to drain the water from the economisers. Instead, they intended to vent them by using the hand easing-gear to lift the economiser safety valves from their seats.
They did not realise that the safety valves on the port economiser had corroded in the closed position and that they were not venting the economiser despite the position of the indicators on the hand easing-gear.
When sufficient pressure developed, the port economiser ruptured at a circumferential welded joint.
The safety management system (SMS) did not contain adequate procedures to ensure the maintenance and safe operation of the steam generating plant.

Lessons learnt
The preoccupation of the engineering staff with the shipboard repairs and sea trials might have prevented them from thoroughly considering the consequences of not draining the economisers.
The heavy workload during the trials might also have interfered with the engine room staff's making appropriate engine room rounds to verify that the economiser was actually being vented.
This incident might have been prevented by adequate risk assessment of boiler safety devices, alarms, means of control and indication; also strict adherence to sea trials procedures.