As the UK MAIB describes in its latest Safety Digest, a potential fire hazards from flexible hose installations identified following a fire on board the cargo ship.
The incident
On 19 September 2021, a fire broke out in the auxiliary engine room on board the Finland registered roll-on/roll-off cargo ship Finnmaster while departing Hull, England. The fire was contained and subsequently extinguished without injury to the crew, but the equipment in the auxiliary engine room suffered serious damage.
Finnmaster’s auxiliary engine room was equipped with two main alternators. These were driven by marine gas oil (MGO) fuelled engines and named as auxiliary engine 1 (AE) and auxiliary engine 2 (AE). Each auxiliary engine comprised 12 cylinders in a v-shaped configuration and was rated at 1100 kilowatts. A fuel supply pump supplied the MGO to both auxiliary engines. The fuel supply pipe was then routed to an inboard and outboard set of cartridge filters and a high-pressure fuel injection pump, which were mounted on either side of each engine.
The MAIB investigation identified that the fire started below the outboard turbocharger of AE2 when a small-bore flexible fuel hose failed. Exhaust gas had leaked from the outlet of the turbocharger and caused the fuel hose to overheat and fail allowing MGO to spray onto a high temperature surface, where it ignited and a significant fire developed.
Findings
In this case, the flexible hose assemblies were not needed to accommodate relative movement between fixed piping and machinery parts over their entire length between the cartridge filters and the instrument panel. Furthermore, the routing of the hoses under the turbochargers covered by the insulation pads exposed them to the risk of contact with high temperatures and also made them difficult to inspect.
Safety Lessons
- The risks associated with a modification on safety critical equipment should be considered before and during the work being completed. In this case, the positioning of the fuel pressure gauges and pressure switches required the pressure signal to be transferred from one side of the engine to the other. The relocation of the pressure switch closer to the cartridge filters would have removed the need for a long hose. If this was not possible, a rigid metal pipe secured with clamps and routed at an appropriate distance from the engine’s exhaust might have been a safer option.
- Flexible hoses are recognised as having a higher risk of failure than a properly fitted metal pipe. An isolation valve fitted at the point of supply allows a flexible hose to be safely isolated in the event of leakage.
- Flag state administrations, ship operators, classification societies, marine surveyors and port state control officers are advised of the risks posed by flexible hose assemblies used in systems that carry flammable liquids if they are not installed and maintained in accordance with IMO MSC.1/Circ.1321.
