Engine-Room Fuel Oil Jacketed Piping, Remote Quick-Closing Valves & Purifier Fire Safety Guide

Engine-room fuel oil fire prevention: what SOLAS requires and what to check

1. Jacketed High-Pressure Fuel Lines, Leak Alarms & 220 °C Hot Surfaces

Most serious machinery-space fires do not start in a tank. They start when fuel, lubricating or hydraulic oil escapes from a pressurised joint or a cracked high-pressure pipe and lands on a hot exhaust surface. SOLAS regulation II-2/4.2.2.5.2 requires external high-pressure fuel delivery lines between the high-pressure fuel pumps and the fuel injectors to be protected by a jacketed piping system able to contain fuel from a high-pressure line failure. The jacketed pipe is an outer pipe around the high-pressure pipe, forming a permanent assembly, with a means of collecting leakage and an alarm in case of a fuel line failure.

Treat the leak collector and its alarm sensor as safety equipment in the planned maintenance system. After any injector or fuel pump overhaul, renew the jacket seals as the engine maker's instructions require, make sure the leak drain still runs to the collector rather than an open container, and prove the alarm works before the engine is left running. A blocked drain or a bypassed leak alarm removes the protection the regulation exists to give, and port State inspectors and surveyors look for exactly this kind of defect.

SOLAS II-2/4.2.2.5.3 requires oil fuel lines not to be placed immediately above or near high-temperature units such as boilers, steam pipes, exhaust manifolds and silencers, and, as far as practicable, to be kept away from hot surfaces and ignition sources and screened or otherwise protected against oil spray, with as few joints as possible. Regulation II-2/4.2.2.6.1 requires surfaces above 220 °C that could be hit after a fuel system failure to be properly insulated, and II-2/4.2.2.6.2 requires precautions so that oil escaping under pressure from any pump, filter or heater cannot reach heated surfaces. Regulations II-2/4.2.3 and II-2/4.2.4 apply much of the same discipline to lubricating oil and other flammable oils. IMO MSC.1/Circ.1321 gives guidance on preventing engine-room fires.

• Test the main and auxiliary engine high-pressure fuel leak alarms at the interval and by the method in the engine maker's manual and the SMS, and record each test.
• After injector, high-pressure pump or fuel rail work, check the jacket seals and confirm the leak drains run to the collector before starting.
• On engine-room rounds, look for missing or damaged lagging and hot spots around exhaust manifolds, indicator cocks, turbocharger gas inlets and boiler uptakes.
• Renew insulation that has soaked up fuel or lube oil instead of wiping the outside while oil stays trapped underneath.
• Check that spray protection is fitted on fuel, lube and hydraulic oil joints, filters and heaters near hot surfaces or machinery air intakes.

2. Remote Quick-Closing Valves, Sounding Pipes & Emergency Generator Fuel

If an engine-room fire grows beyond first-aid fire-fighting, the ship has to cut off oil that would otherwise keep flowing from tanks into the space. Under SOLAS II-2/4.2.2.3.4, every oil fuel pipe which, if damaged, would let oil escape from a storage, settling or daily service tank of 500 litres or more situated above the double bottom must have a cock or valve directly on the tank that can be closed from a safe position outside the space concerned. Under II-2/4.2.3.2, the same applies to lubricating oil tanks, except tanks under 500 litres, storage tanks whose valves are closed in normal operation, and cases where an unintended closure of the valve would endanger the safe operation of the main propulsion and essential auxiliary machinery.

Two failures turn quick-closing valves into serious inspection findings. The first is defeating the valve on board: wedges, wire or bolts under a spring-loaded valve after a nuisance trip, or a pneumatic or hydraulic trip reservoir allowed to run down. The second concerns the emergency generator: SOLAS II-2/4.2.2.3.4 requires the remote control for the emergency generator fuel tank valve to be in a separate location from the controls for the other tanks in machinery spaces, so that shutting off fuel during an engine-room fire does not also stop the emergency generator.

Tank gauging and venting complete the picture. SOLAS II-2/4.2.2.3.1 forbids carrying fuel oil, lubricating oil and other flammable oils in forepeak tanks. Under II-2/4.2.2.3.5.1, sounding pipes should not end in machinery spaces; where the Administration accepts that this is impracticable, they may, provided an oil-level gauge is fitted, the pipes end away from ignition hazards or are screened, and each one has a self-closing blanking device with a small-diameter self-closing control cock below it to check that no oil is present before opening. Cylindrical gauge glasses are prohibited (II-2/4.2.2.3.5.2). Under II-2/4.2.2.4, air pipes, overflow pipes and relief valves must discharge where oil or vapour cannot cause a fire or explosion, and never into crew, passenger or machinery spaces; keep any flame screens fitted under the approved arrangement intact.

• Walk every fuel oil tank, and every lubricating oil tank the rule covers, of 500 litres or more above the double bottom and confirm nothing blocks the quick-closing valve.
• Check the quick-closing valve air receiver or hydraulic accumulator outside the machinery space on rounds as the SMS requires, with clear tank labels and reset instructions.
• Operate the quick-closing valves remotely in drills and when surveyors ask, arranging fuel supply to running generators safely beforehand.
• Confirm the emergency generator fuel tank control is at its separate location, clearly marked, and not linked to the engine-room shut-off controls.
• Test every machinery-space sounding pipe's self-closing device and control cock, and check air and overflow pipe heads and any flame screens on deck.

3. 60 °C Flashpoint, the 2026 Supplier Declaration & Heated Tank Alarms

SOLAS II-2/4.2.1 sets the flashpoint limits for oil fuel. Except where the regulation allows otherwise, no oil fuel with a flashpoint below 60 °C may be used (II-2/4.2.1.1). Emergency generators may use fuel with a flashpoint of not less than 43 °C (II-2/4.2.1.2), and fuel between 43 °C and 60 °C may be permitted under the conditions in II-2/4.2.1.3, for example for emergency fire pump engines and auxiliary machines outside category A machinery spaces. Ships using gas or other low-flashpoint fuels follow the IGF Code. In a periodically unattended machinery space, heated daily service or settling tanks need a high-temperature alarm if the fuel's flashpoint can be exceeded (II-2/4.2.5.2).

Since 1 January 2026, SOLAS II-2/4.2.1.6, added by MSC.520(106), requires ships carrying oil fuel to receive before bunkering a declaration, signed and certified by the oil fuel supplier's representative, that the fuel to be supplied meets the flashpoint requirement of II-2/4.2.1, and stating the test method used to determine the flashpoint. The bunker delivery note must show either the flashpoint or a statement that it has been measured at or above 70 °C. Under II-2/1.2.5 this also applies to ships built before 1 July 2012. On the MARPOL side, MEPC.362(79) added the flashpoint to the bunker delivery note in Annex VI Appendix V, in force since 1 May 2024.

MARPOL Annex VI regulations 14.10 to 14.12 (MEPC.324(75)) also require ships of 400 GT and above to have in-use fuel oil sampling points fitted or designated, normally downstream of the service tank: ships built on or after 1 April 2022 from delivery, older ships by the first IAPP renewal survey on or after 1 April 2023, so that a representative sample can be taken; a low-flashpoint fuel service system needs none. Port State officers use these points while the fuel is hot and under pressure, so keep each point labelled, its valve working and the area clean so a sample can be taken safely.

• Before the bunker manifold is opened, obtain and file the supplier representative's signed flashpoint declaration stating the test method (SOLAS II-2/4.2.1.6).
• Check that the bunker delivery note shows the flashpoint, or a statement that it was measured at or above 70 °C.
• Test high-temperature alarms on heated settling and daily service tanks in periodically unattended machinery spaces, and confirm the set point is as the approved arrangement requires.
• During heavy-fuel to distillate changeovers, control fuel heating as the ship's changeover procedure says.
• Check the in-use fuel sampling points for labelling, a working valve and a clean, safe place to take the sample.

4. Purifiers, Remote Stops & SOLAS II-2/10.5.6 Local Application Systems

Heated fuel oil purifiers combine hot oil, high-speed bowls, frequent opening for maintenance and pressurised hoses. In a periodically unattended machinery space, SOLAS II-2/4.2.5.1 requires equipment that treats flammable liquids automatically, such as fuel oil purifiers, to have arrangements to prevent overflow spills and, whenever practicable, to be installed in a special space reserved for purifiers and their heaters. Further arrangements (ventilation, doors, drip trays) follow class rules and the approved design. Overhaul bowls, seals and hoses at the purifier maker's intervals with kits suitable for the fuels in use.

SOLAS II-2/5.2.2.3 requires means of stopping forced and induced draught fans, oil fuel transfer pumps, oil fuel unit pumps, lubricating oil service pumps, thermal oil circulating pumps and oil separators (purifiers). Machinery-space power ventilation must be stoppable from two positions, one outside the space (II-2/5.2.2.2), and the controls must be outside the space so a fire there cannot cut them off (II-2/5.2.2.4). Keep each stop labelled with what it serves and be ready to demonstrate it working at surveys and inspections.

SOLAS II-2/10.5.6 applies to passenger ships of 500 GT and above and cargo ships of 2,000 GT and above built on or after 1 July 2002; of ships built earlier, only passenger ships of 2,000 GT and above had to comply, by 1 October 2005 (II-2/1.2.2.4). Machinery spaces of category A above 500 m³ must have, in addition to the main fixed system, an approved fixed water-based or equivalent local application fire-extinguishing system. It protects areas such as the fire hazard portions of internal combustion machinery, boiler fronts, the fire hazard portions of incinerators and purifiers for heated fuel oil, without engine shutdown, evacuation or sealing the space. For ships built before 1 July 2014 the machinery covered is that used for main propulsion and power generation (MSC.338(91)). Periodically unattended spaces need both automatic and manual release; continuously manned spaces need manual release only. Activation must give a visual and distinct audible alarm in the protected space and at continuously manned stations. Maintain the system to the ship's fire maintenance plan under SOLAS II-2/14, using MSC.1/Circ.1432, and never shut a section valve to hide a leaking nozzle.

• Keep the purifier area clean and ventilated, heater flanges tight, and drip trays and floor plates free of sludge and oil.
• Overhaul purifier bowls, seals and flexible hoses at the maker's intervals and check feed connections for leaks once back at working temperature.
• Test the remote stops outside the machinery space for fans, fuel transfer and unit pumps, lube oil service pumps, thermal oil pumps and purifiers, and check each is labelled.
• Confirm local application section valves over purifiers, engines and boilers are open, the system is set for automatic release where the space is periodically unattended, and maintenance is logged.
• Keep spare jacketed high-pressure fuel pipes, spray protection, quick-closing valve seals and purifier seal kits in the technical stores.

Frequently Asked Questions

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Regulatory & Technical Sources

• IMO Resolution MSC.99(73): revised SOLAS chapter II-2, regulations 4 (oil fuel, lubricating oil and other flammable oils), 5.2 (means of control in machinery spaces) and 10.5.6 (fixed local application systems)
• IMO Resolution MSC.338(91): SOLAS II-2/10.5.6.3 amendment (fire hazard portions of internal combustion machinery, ships built on or after 1 July 2014)
• IMO Resolution MSC.520(106): SOLAS II-2/4.2.1.6 to 4.2.1.8 supplier flashpoint declaration and bunker delivery note flashpoint (in force 1 January 2026)
• IMO Resolution MEPC.324(75): MARPOL Annex VI regulation 14 in-use and on-board fuel oil sampling points