Frequent failures of thermal oil circulation pump leads to fire says report

The Bahamas Maritime Authority published its report on the ro-ro passenger ferry Pride of Hull, which suffered a fire on 20 October 2020, in the Humber Estuary, UK.

At approximately 20:01 on 20 October 2020, Pride of Hull sailed from the river terminal in Hull, UK, on its scheduled service to Europoort (Rotterdam), Netherlands. The bridge team consisted of the master, chief officer and two ABs. The chief engineer was in the engine control room with the engineer officer of the watch (EOOW).

At 20:35 the vessel’s fire detection system alarm sounded, with the bridge’s fire panel indicating a fire on Deck 1, zone 4: Oil treatment pumps. The AB sent to check the fire panel then relayed this to the engine control room as a fire detected in the “fuel treatment room”. The EOOW went directly to the fuel treatment room to identify the cause of the alarm. 21 seconds later, the fire detection system started to identify further alarms in multiple locations in the engine rooms.

Alerted, the chief engineer left the engine control room and opened the watertight door to the aft engine room which was filling with thick black smoke; at approximately the same time, the vessel’s Hi-Fog fire suppression system activated at the thermal oil circulation pumps. The engineer’s call was activated, the bridge was informed and a “Code Bravo” (restricted incident) was announced on the public address system to direct crew to muster for firefighting and control.

Propulsion was lost at 20:44 but emergency power was maintained and the vessel anchored approximately 10 minutes later.

At 20:47 the first firefighting team entered the aft engine room on breathing apparatus (BA) with two objectives: identify the source of the smoke and restore electrical power. Visibility was severely limited and no fire could be seen, the team proceeded with restoring power. In parallel, further teams were shutting down ventilation, isolating electrics and checking for hot spots.

The smell of burning plastic from the aft engine room and the loss of power lead the engineering team to believe the fire was electrical in nature
BMA said.

Post-fire scene examination identified that thermal oil circulation pump #1 was the seat of the fire.

Probable cause
Examination of the thermal oil circulation pump identified that progressive bearing failures caused extreme frictional heating, generating temperatures in the order of 1,200°C, far in excess of the auto-ignition temperature of the thermal oil used in the system.

Furthermore, assessment of the fire suppression system identified that the system’s effectiveness was compromised by pump output when multiple zones were activated and its dependence on a domestic fresh water pump to maintain supply for longer than two minutes.

Additionally, the system’s pumps were not connected to the emergency switchboard and therefore stopped when the vessel lost electrical power. These limitations were compliant with requirements but were not reflected in emergency response guidance.

Lessons learned
According to BMA, “frequent failure of equipment generally indicates a weakness in the system.”

Detection of causal factors can identify multiple ways to address particular weakness: it is important to assess the impact of an engineering change before execution to ensure the best approach.

What is more, operators and crews should check that the design of their fire suppression systems meet their operational requirements and ensure contingency plans reflect any limitations of the system.

Download the report: BMA Pride of Hull report

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