DNV GL: The Primary Factors in Ro/Ro Fires
DNV GL has published a new paper on the risks of fire within vehicle spaces on ro/ro and ro/pax ships. The society studied 18 fires on ro/pax ships, eight fires on cargo ro/ros, and nine fires on pure vehicle carriers over a period from 2005 through 2016 (or 35 fires on 2100 ships); in general they found that the incidence rates are low, but that certain cargoes and vessel designs may have marginally greater risks.
Findings vary between vessel classes: on ro/pax, reefer unit or reefer unit power connections were the primary culprit, the cause of four out of the five worst fires studied. Other causes for minor fires included electrical systems, cargo in trucks and used vehicles being towed or transported. Of the five major ro/pax fires studied, three resulted in a total loss – all on open cargo space ro/ros. The remaining two fires were contained, both on closed ro/ro space vessels. Rapid and effective crew response, including proper use of fixed firefighting deluge systems, was an important factor in containment.
On cargo ro/ro ships, several fires resulted from cargo shifting due to heavy weather, but all but one were well enough contained that the vessel was not permanently removed from service. Fixed CO2 systems played a prominent role in firefighting strategies, allowing crew to flood uninhabited decks with gas to safely suppress fires. "In one incident, the CO2 was successfully applied within 15 minutes. This demonstrates that even CO2 systems can be released in a quick and safe manner if crew are prepared for that task. The damages in this case were rather limited," DNV found.
On pure car and truck carriers, only one vessel was permanently taken out of service following a fire over the survey period. However, three vessels sustained major structural damages from fire and one crew member was killed in a CO2 discharge incident.
Over all vessel classes, 40 percent of the fires reported over the period did not have an identified cause – but of those that did, reefer fires and cargo shifts were leading culprits. There were some unusual standouts as well, including the 2010 fire on the Pearl of Scandinavia due to “un-authorized charging of rebuilt electric car" – a conventional Nissan which had been converted to an electric vehicle by its owner, who allegedly plugged a homemade car charging cord into a 220-volt charging station while the vessel was under way. In a post-accident report, Denmark's Danish Institute of Fire and Security Technology determined that the fire, which burned several trailers and prompted the vessel's evacuation, was due to an "explosion in the battery pack in the rear end of the car."
Proximate causes aside, the four fires resulting in a total loss over the decade studied were all on open ro-ro space vessels – suggesting particular difficulties with the design, the authors found. "The open Ro-Ro spaces represent challenges with regard to fire scenario, as we have here well-ventilated fire under a tight steel deck which reflects heat and accumulates fire gases. There are also notable challenges with regard to escape ways, location of life-saving appliances and air intake to the engine room and emergency generator, which can be contaminated and damaged by smoke and flames emerging from openings provided in the side of the Ro-Ro spaces," the study found.