Inadequate maintenance caused partial release of bulk carbon dioxide

Mars Report 2013

The Nautical Institute has issued Mars Report No11-2013 reagrding Inadequate maintenance caused partial release of bulk carbon dioxide as follows:

A vessel was preparing to sail from port after completing discharge when multiple alarms sounded. It was observed that the automatic emergency stop system for the engine room supply fans had already tripped the blowers and the fixed CO₂ gas release alarm had been activated. The generator engines automatically shut down, resulting in a total blackout of the vessel. The crew evacuated the machinery space and mustered, after which the C/E, 1/E and electrician went to the CO₂ room to investigate.

From the condensation and frosting on them, it was evident that eleven cylinders making up one of the several banks of gas for the protection of the E/R had discharged into the main distribution manifold. Fortunately, the main directional dump valve for the E/R remained shut, averting the flooding of the protected machinery spaces and the risk of asphyxiating many of the crew. Later, the residual manifold pressure of about 10 bar was carefully vented via a hose to the atmosphere outside the CO₂ room.

A joint investigation conducted by Port State Control Officer (PSCO) and Classification Society surveyor found that:

1 The set screw designed to regulate the check stem valve operation was not torqued to the required setting, causing it to lift at a much lower pressure than designed;

2 A revised maintenance instruction issued by the makers two years before the incident, containing the procedure and the special tool required for adjusting the torque on each cylinder’s set screw had not been made available to the vessel or to the service contractor which had recently completed the annual servicing of the system. It was later found that the service contractor was not licensed by the maker;

3 The ambient temperature inside the CO₂ room had reached 50C, causing abnormally high pressure to build in the cylinders, eventually resulting in the check stem valve lifting.

Corrective/preventative actions

1 All vessels had their systems checked by authorised service contractors and a number of deficiencies were noted and rectified;

2 The incident was shared with the makers of the fixed fire extinguishing systems fitted on company-managed vessels, their authorised representatives / servicing agents and it was ensured that correct and appropriate maintenance information, instructions and equipment were provided to all vessels.

Source: The Nautical Institute