air vent head – Officer of the Watch

Incident Information on Thermal Oil Heater Fire in the Funnel

May 30, 2013 by Officer of the Watch Leave a Comment

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.

Damaged Air Vent Head

March 1, 2013 by Officer of the Watch 1 Comment

A vessel was undergoing a periodical survey by a DNV class surveyor. A total of 19 air vent heads (mostly from ballast tanks) were found to be defective and the surveyor requested the master to repair this before leaving port. This example is taken from a DNV case but defective vent heads (sometimes also called air pipe closing devices) are frequently found in ship surveys, so this example is by no means unique.