201815 Improvised pressure test causes injury

Two engine room crew were about to undertake a pressure test of an auxiliary engine air cooler. To this end, the sea water outlet pipe of the cooler was sealed using a large wooden plug and a piece of cloth acting as an improvised gasket. The air cooler was partially filled with water and then air pressure of about 4 bar was applied to the cooler from the sea water inlet side. Suddenly, the wooden plug shot out like a bullet with tremendous force and speed. After bouncing off a casing the plug hit one crew member on his helmet, then ricocheted and hit the other crew on his forehead. While the first crew was unhurt, the second was injured, suffering swelling of the forehead with severe pain. Fortunately, the injury was not serious.

Lessons learned
- Wooden plugs or other improvised methods that do not ensure positive and secure closing should never be used for pressure testing.
- Other than on pressure vessels like boiler shells or compressed air bottles, pressure tests should be carried out by hydrostatic means, by filling the appliance with water and creating a head of pressure appropriate for the required test.