CO2 system blockages safety bulletin: the impact of a safety finding
In our final Maritime Safety Week blog, Simon Graves and Graham Wilson explain how issuing a safety warning during an investigation can have an immediate effect.
Section through blocked CO2 pilot hose coupling showing incomplete bore through the stem
In September 2021, a fire broke out in the auxiliary engine room on board the Finland registered ro-ro cargo ship Finnmaster while it was leaving the port of Hull in the UK. The MAIB is conducting an investigation into this accident, supported by the Safety Investigation Authority Finland. Our lead inspector for the investigation, Simon Graves, explains a key initial safety finding from the investigation that is already having a major impact on the maritime industry:
The crew activated the onboard fixed fire extinguishing system to attempt to fill the machinery spaces with carbon dioxide (CO2) to put the fire out. The system was designed to empty a total of 42 cylinders into the engine room, each holding 45kg of CO2. In the event, only 21 of the cylinders activated and therefore only half of the required amount of CO2 was injected into the space. Thankfully, the crew were able to extinguish the fire without any injuries but the partial failure of the CO2 system could have had far worse consequences.
In the early stages of the MAIB investigation, it became apparent that the fixed CO2 fire extinguishing system partially failed due to a blockage in some of the flexible hoses, which supply CO2 to the valves on the cylinders to open them when the system is activated. Detailed examination of the flexible hoses fitted to the system identified a manufacturing defect in some of the hose assembly couplings that had prevented the flow of CO2 through the system. The investigation into the source of the hose assemblies, which had been installed earlier in the year, indicated that more than 33,000 hose assemblies originated from the same supply chain and were likely installed on ships around the world, a small percentage of which may have the same manufacturing defect.
In early 2022, we published safety bulletin 1/2022 detailing the identified issue with the CO2 system on Finnmaster and recommending that recipients of the affected hose assemblies check their systems to ensure that they are fully operational should they be required in an emergency. We also requested that information on any findings be fed back to us to establish the extent of the issue.
Since the safety bulletin was issued, the MAIB has received a number of positive reports of findings in fixed fire extinguishing systems affected by the same issue. In one case, five affected hoses were identified on a large drill ship certified to carry 200 people. The failure of the fixed CO2 firefighting installation on board this vessel could have had catastrophic consequences and major loss of life.
We continue to receive responses to the safety bulletin and urge any companies still to respond to our recommendation in the bulletin to confirm that they have taken immediate remedial action to identify and rectify any blocked pilot hose assemblies on affected CO2 fire extinguishing systems.
Graham Wilson, the Principal Inspector for the investigation goes on to note:
The MAIB’s complex technical investigation into this accident is ongoing and will be published in due course. However, issuing urgent safety bulletins such as this to inform the industry of significant safety issues as soon as they are identified, and to recommend that organisations take timely appropriate action, is a key element of the MAIB’s role. The success of this particular bulletin in identifying and addressing a safety critical issue on other ships highlights the value and importance of these safety warnings. It truly demonstrates the effectiveness of the MAIB in helping to prevent future accidents.
Request for information
If you are a service provider, owner or operator and have details of any blocked pilot system hose assemblies that will further assist this investigation, then please follow the instructions below:
Email maib@dft.gov.uk with the title ‘CO2 Pilot System Hose Assembly Issues’ and include the name of the vessel, the date and place of installation of the affected hose assemblies, and details of the defects identified.
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