Fire due to seawater entering the ventilation system reveals NSIA investigation

Fire damage to starboard battery room. Photo credit: Kripos
Fire damage to starboard battery room. Photo credit: Kripos

The Norwegian Safety Investigation Authority (NSIA) has published its report on the fire on board ‘MS Brim’ in the outer Oslofjord on 11 March 2021.

Immediately before the fire broke out, the battery system was disconnected as a result of a ground fault, which was indicated on the panel on the bridge. Ground faults had been a recurring problem since the vessel was new. The crew therefore perceived the alarm as ‘one of many’, and did not consider it to be serious. They had no possibility of identifying the point of origin of the ground fault alarm or ascertaining how serious it was.

The fire alarm panel indicated fire both in the engine room and in the battery room on the starboard side. This was probably because smoke had spread quickly through the fire division between the battery room and the engine room, as observed by the skipper via the surveillance camera in the engine room. It was also verified by the engineer when he arrived in the engine room. The battery room had fire insulation and was separated from adjacent rooms by fire walls designed to prevent the passage of smoke and flames for one hour. The incident showed that the fire division did not prevent the passage of smoke, which was one reason why the crew did not understand where the fire originated.

Furthermore, there was no camera surveillance of the battery room. The presence of a camera might have helped the crew to dispel the incorrect perception that it was the engine room that was on fire. The DNV’s updated classification rules from 2021 recommend camera surveillance of battery rooms to improve the crew’s situational awareness, in addition to gas monitoring for early detection of gases before they develop into smoke. These are deemed to be important aids to rapid detection of smoke development.

The skipper decided to initiate emergency shutdown of the starboard main engine and emergency generator. This led to much reduced redundancy for manoeuvring, instruments and propulsion.

Because of the incorrect perception of fire in the engine room, the Novec fire suppression agent was first released to the engine room after approximately five minutes. When that failed to reduce the development of smoke, the crew understood that the fire was in the battery room. Hence, it approximately seven minutes before Novec was released to the battery room. Too much time passed from the fire alarm went off until Novec was released for the fire suppression agent to have any significant effect on the battery fire.

Probable cause

The fire on board most likely arose as a result of seawater entering the ventilation system and coming into contact with the high-voltage components of the battery system, causing shortcircuiting, electric arcs and fire. The investigation has also shown that the low IP rating enabled seawater and sea air to enter battery modules.

Late release of the fire suppression agent meant that it had little suppressive effect and did not prevent the fire from developing, but had a cooling effect for a short period. The NSIA investigation has shown that a clear extinguishing strategy that would limit the scope of damage in the event of lithium-ion battery fires is lacking.

The investigation has also identified several areas where the risks associated with the use of lithium-ion batteries were not sufficiently identified or addressed in the design. At present, DNV’s classification rules for battery safety do not sufficiently address the risks associated with the use of lithium-ion batteries on board vessels.

Safety recommendations

– NSIA recommends that the Norwegian Maritime Authority issue requirements for appropriate test methods that reflect the risks associated with the design of different battery types to be chosen for conducting propagation tests.
– NSIA recommends that the Norwegian Maritime Authority ensure that battery safety regulations be developed so that ventilation arrangements do not contribute to batteries and high-voltage components being exposed to humid sea air or seawater.
– NSIA recommends that the Norwegian Maritime Authority introduce additional measures to verify that installations are smokeproof and ensure fire integrity.
– NSIA recommends that the Norwegian Maritime Authority issue requirements for risk assessments relating to the use of lithium-ion batteries, and that they should contain all relevant risks identified by different disciplines, the sum of which represents the vessel’s fire risk.
– NSIA recommends that the Norwegian Maritime Authority, as the administrative authority, cooperate with the Directorate for Civil Protection on stipulating a requirement that all Norwegian vessels, regardless of classification, must be built to a defined standard that ensures battery safety.
– NSIA recommends that the Norwegian Maritime Authority introduce compensatory measures to address the safety of passengers and crew in the event of a lithium-ion battery fire.
– NSIA recommends that the Directorate for Civil Protection strengthen the knowledge and expertise of the parties involved in the first-line response to accidents involving a fire on board a vessel carrying lithium-ion batteries.

Download the full report: NSIA Brim Report 2022

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