This incident is referring to a vessel which had an exhaust gas heated Thermal Oil installation. The thermal oil circulating pump stopped and the stand-by pump did not start. No alarm indicating abnormal condition was given. The thermal oil system temperature and pressure increased until the safety valve directed the oil into the compensating (expansion) tank. The expansion tank overflowed (again no alarm was given) through its air vent head. The air vent head was mounted inside the funnel, close to the exhaust pipes. An explosion was heard from the funnel followed by a fire.
Officer of the Watch 