Existing firefighting methods and safety rules not ready for growing interest in methanol conversion projects, warns new study
Methanol as a low-carbon fuel is an attractive choice for vessel owners and operators as they look to transition to net zero. Orders for methanol-fuelled newbuilds have increased 9% in the last 12 months, 2% more than those for LNG-fuelled ships. There has also been a surge of interest in converting existing ships to use the fuel, with Maersk, Seaspan and COSCO, amongst others, all recently announcing significant methanol dual-fuel retrofit projects.
Without doubt, shipping will need to draw on these retrofits if it is to have any hope of reaching IMO’s interim emissions targets – it is a powerful measure that can be implemented relatively quickly. However, as the number of owners and operators looking to convert their vessels to methanol dual-fuel operation continues to grow, so does the risk of future catastrophe.
That is the stark warning from global survival technology solutions provider Survitec, which is calling on the industry for immediate action to prevent dangerous gaps in fire safety. The alert follows the conclusion of a new safety study carried out by the company that reveals existing firefighting methods used to extinguish machinery space spray and pool fires on conventionally fuelled vessels are inadequate when dealing with methanol-based fires.
For the study, extensive comparative fire tests were carried out on dual-fuel marine engines using diesel oil (DO) and methanol.
Another approach needed
“Our findings indicate that if existing vessels are retrofitted to run on methanol, they will also need a complete overhaul and redesign of their fixed firefighting arrangements. The challenge now is to communicate that to shipowners, operators and class societies,” Michal Sadzynski, product manager for Water Mist Systems at Survitec, tells The Naval Architect.
Sadzynski explains that Survitec’s tests confirm that traditional water mist fire suppression mechanisms do not perform as expected on methanol pool fires and methanol spray fires. “Another approach is needed,” he says.
Methanol is a methyl alcohol (CH3OH) that burns in a completely different way than hydrocarbon fuels and has a much lower flashpoint of 12°C. However, while there are established fire safety regulations and testing standards for diesel fuels, clear test protocols for alcohol-based fuels such as methanol and ethanol have yet to be developed.
“We believe this is a high-risk situation that needs immediate action,” says Sadzynski. “Methanol fires are far more aggressive than fires involving traditional hydrocarbon fuels. Methanol fires have different physicochemical properties and so they cannot be extinguished as easily or with the same approach.”
The Survitec tests found that while local application firefighting (LAFF) water mist systems are highly effective in absorbing heat and displacing oxygen on diesel fires, they do not produce the same results on methanol fires.
“For a diesel fire, water mist has two mechanisms at play,” notes Sadzynski. “First, very small droplets of water falling on the flame take energy out of it, and secondly the barrier created around the flame by the water mist makes it hard for oxygen to get to the flame, causing suffocation of the fire. For a diesel fire, it’s the perfect system – that’s why it’s so popular.
“Methanol is a totally different story. Because methanol is an alcohol it can mix with water so having small droplets of water falling on the fire is ineffective. The second mechanism, suffocation, is also redundant as methanol has its own oxygen, so is still able burn.”
Survitec’s solution was to completely rethink nozzle placement, spacing and other factors to make water mist suppression effective on methanol.
“We can now assure that this system will work when used for methanol fires, which is critical when considering local application firefighting systems,” says Sadzynski.
He points out that the LAFF system is the only firefighting system on the vessel that releases automatically if a fire starts and so is key to the prevention of serious injury to crew or significant damage to equipment. “What’s important for you as the operator or owner of the vessel is to extinguish the fire as soon as possible. If not, it will spread. If it spreads, it will prove very costly,” Sadzynski says.
He adds: “After the local application system, there is the total flooding system. For methanol, we believe the best solution would be a gas-based system. But it’s not automatic and relies on human reaction. With a gas-based system, questions around whether or not all of the fire dampeners and doors are closed and if all the crew are evacuated from the space can delay the release. Also, the decision to deploy a system that costs a lot of money has to be made. It takes time, and in that time the fire is still on the engine and it’s still burning equipment that you will need to repair or replace.”
Tackling pool fires
For bilge areas, statutory rules formulated in IMO’s interim guidelines for ships using methyl or ethyl alcohol as fuel, MSC.1/Circ.1621, establish a requirement for an approved alcohol-resistant foam system for ships running on methanol. For the first time, a fixed, low expansion foam system is mandatory under the rules when it comes to protecting machinery space bilges.
Maciej Niescioruk, product manager, Foam Systems, Survitec, says: “Our tests demonstrate that standard discharge devices do not properly extinguish methanol pool fires in the confined bilge space. It is crucial to deliver properly expanded foam on the methanol pool fire and this is not an easy task within such a narrow space where throw length is limited.”
According to Niescioruk, MSC.1/Circ.1621 provides the industry with a starting guideline but it is very general and therefore open to interpretation. “For example,” he says, “for the total flooding system it says that it needs to be checked and verified that it works but if there is a lack of information on how to design a particular system, please refer back to existing rules, et cetera. This can lead class societies to approve a system not by actually fire testing them, but through pure legislative action.
“Moreover, methanol compliance for local application firefighting systems is not yet covered.”
Some newbuilds may require retrofits
Niescioruk tells TNA that it is difficult to say how many of the methanol-ready ships already in operation and newbuilds ordered have firefighting systems on board that are capable of firefighting a methanol fire, but that it is very likely that a number will need some modification to render them safe if the current arrangement of equipment is based on the rules that exist for diesel engines.
On the back of the new safety study, Survitec is encouraging all stakeholders to come together to address methanol’s unique fire risks and create clear standards, new testing protocols and updated safety rules for methanol.
“What is important for Survitec now is to raise awareness of the issue,” says Sadzynski. “For example, we recently had one customer approach us for a retrofit project who didn’t appreciate the difference between methanol and diesel fires until we presented our results.”
“We hope that the findings in this study and continued research will give a better understanding of methanol as an alternative ship fuel and safer conversions to methanol in the future,” concludes Niescioruk.
