Engine Room Flooded with CO2 – Unintentional CO2 Release

The tow/tug vessel crew members were carrying out weekly safety checks and the intention was to try out the operation of the emergency fuel shut off valves in the engine room.  The tug boat had a design where the emergency fuel shut off valve and the CO2 release valve were positioned inside the same control box.

The design was such that before flooding CO2 inside the engine room, the fuel shut off valve has to be operated such that the fuel to the engines and generators are shut off.

The Incident:

On a towboat, a crew member intended to test the emergency fuel oil shut-off valves.  He opened the panel door that contained both the emergency fuel oil shut-off and the CO2 release handles.  He activated what he thought was the fuel oil shut-off but instead CO2 was released.  Fortunately, the audible alarm system and release time delay functioned as intended, allowing personnel to safely evacuate the machinery spaces prior to the CO2 discharge.

Lessons learned:

1. Emergency systems should be designed with human factors in mind; they must be logically understood and easily operated during high-stress situations.
2. System training should provide the familiarity needed during an emergency or other situations.
3. Pre-test coordination and review of procedures will minimize accidental and potentially fatal discharges.

Source: MARS

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