Key Lessons from a Real Engine Room Fire
Purpose
This article highlights important lessons learned from a recent engine room fire that required the activation of a fixed CO₂ fire-extinguishing system. The case draws attention to critical maintenance, configuration, and inspection aspects of CO₂ systems that can directly affect their performance during an emergency.
The objective is to raise awareness among shipowners, operators, inspectors, masters, and crew regarding potential failure modes that may not be immediately apparent during routine inspections.
Background
A vessel recently experienced a serious engine room fire involving the No. 2 diesel generator. The fire originated when fuel sprayed from a high-pressure pump onto hot exhaust components, resulting in rapid ignition.
Once the engine room was evacuated and all personnel were accounted for, the shore-based fire response team, together with the vessel’s Master and Chief Engineer, assessed the situation and determined that it was safe to activate the fixed CO₂ fire-extinguishing system. The system was released and successfully extinguished the fire.
During the subsequent investigation, however, a critical deficiency was identified. Of the 118 CO₂ cylinders allocated to the engine room, only 109 discharged. Further examination revealed that several cylinders had safety pins still installed in their actuating heads, preventing valve operation. For the specific type of actuating head fitted, removal of the safety pin was required for automatic discharge.
This finding significantly reduced the total quantity of extinguishing agent released and highlighted a serious vulnerability that could have compromised fire-fighting effectiveness under different conditions.
Types of Actuating Heads
Generally, there are two predominant types of actuating heads, commonly referred to as Type A and Type B, although this may not be consistently used by all manufacturers:
This requirement applies to engine room CO₂ systems. For Type A systems serving cargo holds that are not connected by pilot lines, safety pins may remain installed under normal conditions, as these systems are designed for manual activation, with the pins removed at the time of discharge.
The image below, taken from the incident described in the background section, clearly shows that in this Type A system the valves operated as intended where the safety pins had been removed. Where the safety pin remained installed, the valve did not open and no CO₂ was discharged.
Flexible Pilot Lines
Flexible pilot lines, sometimes referred to as pilot loops, are a critical component of fixed CO₂ fire-extinguishing systems. These lines convey CO₂ pressure to the actuating valves, enabling them to open and release the extinguishing agent. The system manual should specify the requirements for pilot lines, including the minimum bending radius, and pilot lines should be installed in a manner that avoids sharp bends or excessive mechanical stress.
Flexible pilot lines should be inspected in accordance with the applicable inspection and maintenance requirements and kept in good condition. Replacement is required where there is evidence of deterioration or distress that could lead to failure. The hose assembly may require replacement if any of the following conditions are observed:
.1 leaks at fittings or along the flexible hose;
.2 damaged, cut, or abraded outer cover;
.3 kinked, crushed, flattened, or twisted flexible hose;
.4 hardened or excessively stiff flexible hose;
.5 blistered, soft, degraded, or loose outer cover;
.6 cracked, damaged, or severely corroded fittings; or
.7 slippage of fittings on the flexible hose.
The pilot lines shown below are clearly in poor and unsatisfactory condition, exhibiting significant kinking that could impair system operation.
Recommendations
Shipowners, operators, masters, and crew are advised to inspect the fixed CO₂ fire-extinguishing system(s) installed on board in order to identify the type of actuating heads fitted and to verify that safety pins are correctly configured. For systems in an operationally ready condition, safety pins should not be installed on Type A actuating heads and should remain installed on Type B actuating heads, as applicable. Pilot lines should also be inspected to confirm correct installation, routing, and overall condition. All inspections and any corrective actions should be properly recorded in the logbooks and in the records maintained for the testing, inspection, and maintenance of fire-protection systems and appliances.
When inspecting fixed CO₂ fire-extinguishing systems, flag State inspectors who encounter safety pins installed on Type A actuating heads should refer to the onboard manufacturer’s manual and/or system drawings to verify whether the installation is correct before raising a finding. Inspectors should also verify the installation and condition of pilot lines and, where deficiencies are identified, raise appropriate findings.
Whenever fixed CO₂ fire-extinguishing systems are subjected to inspection or maintenance, strict safety precautions must be observed to prevent the risk of accidental discharge and to protect personnel involved in or present during the activities. Measures to prevent inadvertent release, such as locking or removing operating arms from directional valves or closing and locking the system block valve, should be implemented as an initial safety step. All personnel should be informed in advance of the planned activities. Upon completion of inspection or maintenance, the system must be restored to normal operational status in accordance with SOLAS Chapter II-2, Regulation 14, and the restoration recorded in the service chart (Appendix to MSC.1/Circ.1318, Rev.1, as amended) and in the ship’s log.
