A starting air compressor bursted during running test, throwing pieces of steel all over the engine room. The compressor itself was beyond repairs. Two persons were injured, one of them seriously.
Subsequent investigation showed that some tubes on the high pressure side Air Cooler had fractured. This increased the pressure in the water chamber which cools the high and low pressure cylinders. The coolers and the cooling water chamber were interconnected. The working pressure of the starting air system was 30 bar whilst the working pressure was about 4 bar for the water chamber.
The water chamber was protected against over pressure by a bursting disk which can sustain a pressure of 6 bar. The bursting disk had, however, been replaced by a metal sheet, which would burst at a higher pressure than 6 bar.
This caused collapse of the compressor casing, in way of the cooling water chamber around the high pressure cylinder.
This incident highlights the following:
- Always use manufaturer’s approved spare parts.
- It is always a good practice to be cautious during such test and stay away or be shielded from the potentially dangerous pressurised system.
Source: DNV
Officer of the Watch 
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