SOLAS Chapter II-2: Fire Protection, Detection, Extinction

Background

Scope and structure of Chapter II-2

Chapter II-2 sits alongside Chapter II-1 as the second of the two construction-and-equipment chapters of SOLAS. Where II-1 covers the structural envelope and the machinery and electrical installations needed to keep the ship operational, II-2 covers the layered fire-safety architecture that prevents a fire from starting, contains it if one does start, and gets the people on board to safety if it cannot be controlled.

The chapter is built on a goal-based pattern that anticipated by more than a decade the formal Goal-Based Standards introduced in II-1 Part A-1. Each Regulation begins with a high-level objective, narrows to functional requirements, and then sets out either prescriptive provisions or, under Part F, alternative design pathways.

The interaction with the rest of SOLAS is dense:

• Chapter II-1 provides the structural envelope (watertight bulkheads, hull plating, decks) within which fire protection is realised.
• Chapter III provides the survival craft and embarkation arrangements that depend on the means of escape under Chapter II-2 Part D.
• Chapter V provides the bridge from which fire detection alarms are received and from which firefighting operations are coordinated.
• Chapter VI and Chapter VII (carriage of dangerous goods) bring cargo-specific fire risks into the design of cargo space fire protection.
• The ISM Code (Chapter IX) operationalises the fire-safety procedures within the Safety Management System.

The subsidiary mandatory codes

Chapter II-2 does not stand alone. Two codes are made mandatory by direct reference in the chapter and must be read alongside it.

The FSS Code (International Code for Fire Safety Systems, adopted by IMO Resolution MSC.98(73) at the 73rd session of the Maritime Safety Committee in December 2000, as amended by subsequent MSC resolutions) prescribes the engineering standards for every category of installed fire safety equipment: fixed fire detection and alarm systems, fixed gas-extinguishing systems, fixed pressure water-spraying systems, fixed water-based local application fire-fighting systems, automatic sprinkler systems, fixed deck foam systems, inert gas systems, fixed fire-fighting systems in machinery spaces, firefighter outfits, and breathing apparatus. Without the FSS Code, the prescriptive requirements in SOLAS II-2 would be incomplete.

The FTP Code 2010 (International Code for Application of Fire Test Procedures, adopted by IMO Resolution MSC.307(88) at the 88th session of MSC in December 2010, entering force 1 July 2012) replaced the 1998 FTP Code and prescribes the fire test procedures for structural materials, surface linings, primary deck coverings, floor coverings, textiles, furnishings and components installed on ships. Each Annex of the FTP Code covers a different material category. The distinction matters for builders and class surveyors: a material approved under the 1998 FTP Code is not automatically approved under FTP Code 2010 for new-build applications, though flag states have issued transitional arrangements.

Fire safety objectives and functional requirements

The chapter is anchored on three fire safety objectives stated in Regulation 2:

• Prevent the occurrence of fire and explosion.
• Reduce the risk to life caused by fire.
• Reduce the risk of damage caused by fire to the ship, cargo and environment.

These are translated into seven functional requirements:

1. Control of sources of ignition.
2. Control of fire growth potential.
3. Containment of fire to the space of origin.
4. Control of smoke spread.
5. Provision of readily accessible means of escape.
6. Provision of adequate fire-fighting capability.
7. Minimisation of the probability of explosion.

The seven Parts of the chapter (A through G) implement these requirements. The mapping is not exact (some Parts contribute to multiple functional requirements), but the underlying principle is that every prescriptive requirement is justified by reference to one or more of the seven, providing the trace from objective to design feature that the alternative-design pathway in Part F can be tested against.

The Reg II-2/1 general fire safety calculator walks through the high-level applicability and objective mapping for a given ship type.

Major amendment history and incident drivers

Chapter II-2 has been rewritten substantially three times since 1974, each rewrite driven by a major casualty cluster.

Scandinavian Star, 1990 (158 dead in a passenger ferry fire in the Skagerrak) drove the 1992 amendments tightening fire detection in passenger spaces and improving structural fire protection of accommodation. The 1992 amendments introduced sprinkler protection of cabin areas on existing passenger ships and substantially tightened the FTP Code material approval pathway.

Achille Lauro, 1994 (passenger ship lost to fire off Somalia) reinforced the case for quick-response fire detection in machinery spaces and accelerated the move to fixed water mist as an alternative to CO2 in passenger ship machinery spaces. The Achille Lauro investigation also drove the development of the FSS Code toward mandatory adoption.

The 2002 rewrite (adopted by Resolution MSC.99(73) at the 73rd session of MSC in December 2000, entering force 1 July 2002) restructured the chapter into the current goal-based form with the seven functional requirements model, integrated with the FSS Code (Resolution MSC.98(73)) and FTP Code which became mandatory through SOLAS reference. The 2002 rewrite was the largest single revision since 1974, reorganising every Part of the chapter and introducing the alternative-design pathway in Part F.

Ro-ro passenger fire incidents (Norman Atlantic 2014, Sorrento 2015, Modern Express 2016) drove amendments to detection in vehicle decks, fixed extinguishing in vehicle decks, and operational restrictions on cargo securing patterns.

Container ship fire incidents (Maersk Honam 2018, X-Press Pearl 2021, Yantian Express 2019, MOL Charisma 2018) drove amendments that strengthen detection and access for cargo hold firefighting on container ships and tighten pre-stowage segregation of dangerous goods.

Vehicle carrier fires (Felicity Ace 2022, Fremantle Highway 2023, both involving electric vehicle fire growth) drove IMO MSC 109 (December 2023) amendments to vehicle deck detection and fixed extinguishing, with particular attention to lithium-ion battery thermal runaway scenarios. The amendments from MSC 109 extend SOLAS II-2 Regulation 20 requirements for detection and water-based extinguishing on vehicle spaces.

The amendment cycle oscillates between general structural updates (1990s, 2002) and post-incident additions (1992 post-Scandinavian Star, 2002 post-Achille Lauro, 2014 post-Norman Atlantic, 2023-2024 post-Felicity Ace and Fremantle Highway), maintaining a state of continuous regulatory pressure on fire safety design and operations.

Part A: General

Application and the seven-part structure

Part A defines the application of Chapter II-2 to passenger ships, cargo ships of 500 GT and above, and tankers. Different parts of the chapter apply with different thresholds and modifications:

• Passenger ships of any size (more than 12 passengers carried) are covered by all of Chapter II-2 with the most demanding requirements applied progressively as ship size increases: additional MVZ subdivision for ships over 60 m length, sprinkler systems for accommodation, SRtP from 120 m length.
• Cargo ships of 500 GT and above on international voyages are covered by Chapter II-2 with most provisions applying. Smaller cargo ships are partially exempt.
• Tankers (oil tankers, chemical tankers, gas carriers) carry additional fire safety provisions reflecting the cargo fire risk: deck foam systems on oil tankers, gas-tight bulkheads on chemical tankers, water-spray on gas carriers, all under specific Regulations and the IBC and IGC Codes.
• Ro-ro passenger ships carry additional vehicle deck provisions including specialised detection and extinguishing systems.
• High-speed craft and unconventional ships are covered by alternative codes (HSC Code) under Chapter X.

The Reg II-2/1 calculator returns the applicable subset for a given ship type, length and gross tonnage.

Definitions: A, B and C class divisions

The definitions in Part A establish the vocabulary that recurs throughout the prescriptive provisions. The division classification system is the architectural backbone of structural fire protection.

The temperature criterion for A-class divisions requires that the average unexposed-side temperature does not rise more than 140 degrees Celsius above initial and that the maximum temperature at any single point does not exceed 180 degrees Celsius above initial.

Further definitions address the spatial zones:

• Main vertical zone (MVZ): a zone bounded by A-class divisions, dividing the hull and superstructure into compartments whose maximum length on any deck is 48 metres (with an absolute area limit of 1,600 square metres on any deck within the zone). The MVZ is the principal architectural fire control element on passenger ships.
• Main horizontal zone: a horizontal subdivision used in addition to MVZ on large passenger ships, bounded by A-class decks.
• Special category space: an enclosed space above or below the bulkhead deck intended for the carriage of motor vehicles with fuel in their tanks for self-propulsion.
• Vehicle space: an enclosed space intended for the carriage of vehicles other than passenger cars, trains or merchandise.
• Ro-ro space: a space intended for the carriage of motor vehicles or cargo on wheels (trailers, road tankers, containers on chassis) by drive-on drive-off operation.
• Accommodation space: spaces used for public spaces, corridors, lavatories, cabins, offices, hospitals, cinemas, games rooms, hairdressing salons, pantries containing no cooking appliances and similar.
• Service space: spaces used for galleys, pantries containing cooking appliances, lockers and storerooms, workshops other than those forming part of the machinery space.
• Machinery space (category A): a space and trunks containing main propulsion machinery, generating machinery, oil-fired boilers and oil-fired auxiliaries, oil-fuel pumps and similar.

The containment of fire calculator returns the required division class for a bulkhead or deck given the spaces on either side and the ship type.

Part B: Prevention of fire and explosion

Part B implements the first of the seven functional requirements: control of sources of ignition.

Probability of ignition (Regulation 4)

Regulation 4 requires the design to limit ignition sources within machinery and accommodation spaces. Practical implementation includes:

• Fuel oil and lubricating oil systems must be arranged so that any oil spillage from a leak cannot reach a hot surface (such as exhaust manifolds, turbocharger casings or boiler furnaces). High-pressure fuel injection lines on diesel engines must be jacketed (double-walled with leakage detection) so that any leak is contained and signalled rather than spraying onto a hot surface.
• Hot surfaces above 220 degrees Celsius must be insulated where reachable by flammable liquid spray. The insulation must itself be non-flammable, oil-impermeable (or sealed against oil ingress), and durable in the engine room environment.
• Electrical installations in hazardous areas (defined zones around fuel and cargo systems) must be of certified explosion-protected type. The hazardous-area zoning is per the IEC 60079 series with specific marine adaptations in IEC 60092-502 (Tankers).
• Open flames and smoking are prohibited in fuel transfer and tank-cleaning areas; smoking is restricted to designated areas elsewhere on board with non-combustible ash trays and dedicated smoking-room ventilation.
• Hot work (welding, cutting, grinding) requires a documented permit-to-work, with the surrounding area cleared of combustibles, fire watch posted, atmospheric testing for flammable gas, and the permit valid only for a defined time. The Hot Work Permit system is one of the most-cited operational requirements in PSC inspections.
• Galleys and laundries require fat-fryer suppression systems, automatic stove cut-out on detection of high temperature, and lint trap maintenance schedules.
• Engine room cleanliness: oil drips must be promptly cleaned; rags and oily waste stored in metal-lidded containers and removed for shore disposal; the engine room must be free of accumulated combustible material that could support fire growth.

Inert gas systems (Regulation 4.5 and MSC.365(93)): Oil tankers of 20,000 DWT and above must be fitted with an inert gas system under the original SOLAS II-2 Regulation 4.5 requirements. IMO Resolution MSC.365(93), adopted at the 93rd session of MSC and entering force 1 January 2016, extended this requirement to oil tankers of 8,000 DWT and above constructed on or after that date. The inert gas system maintains the cargo tank ullage atmosphere below the lower flammable limit (typically below 8 percent oxygen), preventing the conditions needed for explosion.

The probability of ignition calculator returns the regulatory requirements applicable to a given space and machinery type.

Fire growth potential (Regulation 5)

Regulation 5 controls the rate at which a fire that has started can grow, by limiting the use of combustible materials in accommodation and service spaces:

• Bulkheads and ceilings in accommodation spaces are typically of non-combustible construction. Where combustible bulkheads are accepted (in defined low-risk locations), they must satisfy flame-spread tests and surface-burning characteristics under FTP Code 2010 Annex 1 Part 5.
• Surface linings, ceilings and floor coverings must satisfy specific FTP Code 2010 tests:
  • Part 5: Test for surface flammability of bulkhead, ceiling and deck finish materials (lateral spread, heat release rate, smoke production, flaming dripping).
  • Part 7: Test for vertically supported textiles and films.
  • Part 8: Test for upholstered furniture.
  • Part 9: Test for bedding components.
• Furniture in passenger ship cabins and crew accommodation must meet ignitability and heat-release tests under the FTP Code 2010, with ignition sources of cigarette and small flame.

The intent is to limit the fire growth rate so that detection and suppression have time to act before the fire becomes unmanageable. The post-Scandinavian Star tightening was particularly aimed at this requirement; the Scandinavian Star fire grew rapidly through corridor wall linings that failed to meet the (then new) FTP Code criteria.

The fire growth potential calculator returns the test compliance requirements for a given material in a given application.

Smoke generation potential (Regulation 6)

Regulation 6 controls smoke generation from materials in accommodation and service spaces, with quantitative tests under the FTP Code 2010 returning a maximum optical density and toxicity index:

• FTP Code 2010 Part 2: Test for smoke and toxicity, specifying maximum smoke density (specific optical density) and toxicity (concentration of toxic gases) at specified time intervals during burn.
• The smoke density test produces a Ds(max) value (maximum specific optical density) which must not exceed prescribed limits for the material’s intended application.
• The toxicity test produces concentrations of HCl, HBr, HF, HCN, NO/NO2, SO2 and CO during burn; the concentrations must not exceed prescribed levels.

Smoke from burning interior finishes is the largest single cause of death in modern passenger ship fires. The Scandinavian Star fatalities were almost entirely smoke-related; survivors reported visibility falling to below one metre within minutes of the fire alarm. Smoke density limits in Regulation 6 directly target this risk.

Probability of explosion

Specific provisions on explosion prevention apply to:

• Tankers carrying flammable cargo: inert gas systems mandatory on oil tankers as described above. The IGC Code (gas carriers) and IBC Code (chemical tankers) carry equivalent requirements for those vessel types.
• Cargo of dangerous goods under Class 1 explosives and certain Class 4 and Class 5 entries: specific stowage and segregation rules to prevent explosion sources.
• Battery rooms containing lead-acid or lithium-ion batteries: ventilation to prevent hydrogen accumulation, gas detection, fire suppression appropriate to battery chemistry.
• Paint stores and lamp rooms: ventilation, certified electrical equipment, and segregation from accommodation.

Part C: Suppression of fire

Part C is the longest part of the chapter and covers everything from the detection of an incipient fire through to its extinguishment.

Detection and alarm (Regulation 7)

Every passenger ship must have a fixed fire detection and alarm system covering all machinery spaces, control stations, accommodation and service spaces. Cargo ships must have detection in all machinery spaces of category A (those above a power threshold) and certain other spaces.

The detector technology choice depends on the space type:

• Smoke detectors for accommodation, corridors, stairways and most service spaces (smoke is the earliest warning indicator for fires fuelled by interior finishes, electrical insulation, or paper).
  • Optical (photoelectric) smoke detectors detect light-scattering by smoke particles; sensitive to smouldering fires.
  • Ionisation smoke detectors detect changes in air ionisation due to smoke; sensitive to flaming fires.
  • Combined optical/heat detectors offer broader coverage in mixed-fuel environments.
• Heat detectors in galleys, drying rooms, and other spaces where smoke is normally present from cooking or process operations.
  • Fixed-temperature detectors trigger at a set point (typically 57 degrees Celsius for accommodation, higher for galleys).
  • Rate-of-rise detectors trigger when temperature rises above a defined rate, useful for fast-developing fires.
• Flame detectors in machinery spaces with high fuel inventory where smoke detection is unreliable in the convective air patterns. UV (ultraviolet) and IR (infrared) flame detectors look for flame-specific spectral signatures.
• Gas detectors in cargo holds carrying dangerous goods, in IGF-Code fuel preparation rooms, and in pump rooms on tankers. Detector calibration is gas-specific (methane for LNG, hydrogen for fuel cell installations, etc.).

Modern fire detection systems are addressable: each detector reports its identity to the central panel, allowing pinpoint identification of the alarm source rather than just the zone. Voice alarm systems on passenger ships supplement bell-style alarms with pre-recorded voice messages in multiple languages directing passengers to muster stations.

The fire alarm panel on the bridge must indicate the zone of detection and provide audible and visible alarm. Cargo ship requirements are reduced relative to passenger ships but no longer optional: the 2002 rewrite removed the previous “either fire patrol or fixed detection” alternative, requiring fixed detection in all spaces previously covered by fire patrol alone.

The Reg II-2/7 detection calculator returns the detector technology and zone count required for a given ship and space.

Control of smoke spread (Regulation 8)

Smoke control includes:

• Mechanical ventilation must be capable of being shut down from outside the space being ventilated. The shutdown control must be at the bridge or at an accessible permanent location near the protected space.
• Fire dampers in ventilation ducts that pass through A-class divisions, with remote closure from the bridge. The dampers must close automatically on operation of the fire detection system or of a temperature-sensitive fusible link.
• Pressurisation of escape stairways in passenger ships to keep smoke out of escape routes. The pressurisation system (powered by emergency-supply fans) holds the stair at a positive pressure relative to adjoining corridors so that smoke cannot ingress.
• Smoke extraction from atriums and large public spaces using sized exhaust fans, calibrated to maintain a smoke layer above the head height of evacuating passengers.

The interaction with the ship’s general ventilation requires careful design: HVAC systems are often integrated with fire control, with dampers, fans and ductwork reconfigured automatically on fire alarm to support smoke control rather than continuing normal HVAC operation.

Containment of fire (Regulation 9)

This is the structural fire protection regulation. The hull and superstructure are divided into main vertical zones by A-60 divisions, with stricter requirements between specific space types per the fire integrity tables in the regulation.

The fire integrity tables are read row-by-column, with the row being the space on one side and the column being the space on the other side; the cell entry is the required division class. Sample entries (passenger ship table):

(Simplified excerpt; the actual tables in Regulation 9 are more extensive and include sub-classes.)

Key entries worth noting:

• Between an accommodation space and a category A machinery space: A-60 in both directions.
• Between two adjacent accommodation spaces: B-15 may suffice (lower risk).
• Between a control station and any other space: A-60 (the control station is the master’s tactical position and must remain habitable through fire emergency).
• Between a paint store and any space: A-60 (paint store is high fire-load).
• Between a galley and any space: A-60 on the cooking-equipment side.

The MVZ structure overlays this: regardless of the fire integrity table requirement, every MVZ boundary is at least A-60 (and typically A-60 with structural insulation continuous through the boundary).

The containment of fire calculator implements the fire integrity tables for both passenger and cargo ships.

Fire fighting (Regulation 10)

Regulation 10 sets the requirements for water supply, fire pumps, fire mains, hydrants, hoses, nozzles and fixed extinguishing systems. This is one of the most prescriptive regulations in SOLAS and the operational backbone of the suppression layer.

Fire pumps and water supply

Every ship must have main fire pumps with total capacity not less than the value given by the Regulation 10 formula. The correct form per the SOLAS consolidated text is:

where $L$ is the length of the ship in metres, $B$ is the breadth in metres, and $D$ is the depth to the bulkhead deck in metres. Each main pump must deliver at least two-thirds of this calculated capacity. The minimum regardless of ship size is 25 m3/h. For a Panamax bulk carrier (L = 225 m, B = 32.2 m, D = 19.3 m): $Q = (0.15 \times \sqrt{225 \times 51.5} + 2.4)^2 = (0.15 \times 107.7 + 2.4)^2 \approx 345$ m3/h; each of the two required main pumps must deliver at least 230 m3/h.

The minimum number of jets simultaneously available from the fire main depends on ship size: 4 jets on cargo ships of 1,000 GT and above, with the corresponding minimum water flow per jet specified in Regulation 10.

In addition, every ship must have an emergency fire pump located outside the main machinery space, with its own power source (typically a dedicated emergency diesel) and its own fuel and starting arrangements, capable of supplying the two highest-positioned hydrants on the ship at the required pressure.

Fire main piping is typically of seamless steel with welded connections, sized to deliver the required flow with adequate residual pressure at the most remote hydrant. The piping passes through fire-rated bulkheads with appropriate penetration sleeves and includes isolation valves at strategic points so that damaged sections can be isolated.

The emergency fire pump calculator sizes the emergency pump for a given ship. The fire pump capacity calculator returns the total required capacity.

Hydrants, hoses and nozzles

Every fire main hydrant must be of approved type with quick-coupling outlets compatible with the ship’s hose. Hydrants are spaced so that any deck position can be reached by two jets from independent hydrants (redundancy if one hose is damaged or removed for service).

Hoses are typically 18 metres long, with woven jacket, lined for chemical resistance, certified for working pressure of approximately 10 bar. Nozzle types include:

• Combination nozzles providing both straight stream and fog patterns, adjustable by twist of the nozzle barrel.
• Spray nozzles for water mist and water spray applications.
• Foam-makers for combined water/foam application from a single nozzle.

Hose stowage is at racks adjacent to the hydrant, with hose immediately deployable.

Fixed gas-extinguishing systems

CO2 systems are still the most common fixed gas system for machinery space and cargo space protection. The minimum quantity is set as a percentage of the gross volume of the largest protected space:

• 35 percent of the gross volume of the largest machinery space, or the combined machinery and boiler space when ventilation can be shut off from both (with the proviso that the minimum quantity shall not be less than that required for the larger space alone at 40 percent where the conditions for the combined-space reduction are not met).
• 40 percent of the gross volume of the largest machinery space where the conditions for the 35 percent reduction do not apply.
• 30 percent of the gross volume of the largest cargo space, where general cargo is carried.

The CO2 must be discharged in:

• Two minutes or less for machinery spaces (rapid discharge to overcome ventilation and achieve smothering concentration).
• Ten minutes or less for cargo spaces (slow discharge to avoid pressurisation damage to the hold).

Operational requirements include:

• Pre-discharge alarm with audible and visible warning, sustained for a defined period before discharge initiates, allowing personnel to evacuate.
• Manual override capable of postponing discharge if it is verified that the alarm is false.
• Lock-out of the discharge mechanism during maintenance.

The discharge of CO2 raises the pressure in the protected space. The CO2 storage room itself, when alarms warn of leakage from cylinders, must be designed for the resulting pressure. The CO2 room pressure calculator returns the design pressure for a given cylinder bank and room volume.

CO2 systems have known operational limitations: they are toxic at the smothering concentration (lethal in less than five minutes at the typical 40 percent concentration), they discharge cold gas that can damage cold-sensitive equipment, and they are essentially single-shot (recharging requires shore-side service). The CO2 system volume adequacy check calculator verifies quantity against space volume.

Fixed water mist and foam

Fixed water mist systems have largely replaced CO2 in new-build passenger ship machinery spaces because of the safety advantage: water mist is non-asphyxiating in the protected space, which matters because passenger ship engine rooms are often manned during normal operation. Water mist is a complex regulatory area because the FSS Code recognises various mist technologies (high pressure, low pressure, single-fluid, twin-fluid) with different type-approval test pathways. Each technology must be approved against fire test scenarios specific to the protected space (engine room, accommodation corridor, ro-ro deck, etc.).

Foam systems protect tanker cargo decks (Class B fires from leaking cargo) and helicopter facilities. Foam concentrate must be of an approved type under the FSS Code:

• AFFF (Aqueous Film-Forming Foam): synthetic foam producing a film of water and surfactant on hydrocarbon fuel surfaces; effective against gasoline, diesel, jet fuel.
• Alcohol-Resistant AFFF (AR-AFFF): AFFF formulated to resist the polar-solvent effect of alcohol cargoes.
• Protein foam: natural-protein-based foam with good heat resistance, widely used for marine deck fires.
• Fluorine-free foams: alternatives driven by environmental concerns over fluorinated foams (PFAS); the IMO has been examining these for marine applications, and the FSS Code allows their use where type-approval equivalence is demonstrated.

Foam application rate (litres per minute per square metre of fire surface) and foam expansion ratio (volume of foam per volume of solution) are specified by the FSS Code for each application class. The foam concentrate for tanker deck calculator returns required quantities for a given deck area.

Firefighter outfit

Each ship must carry firefighter outfits sized to the crew. The outfit includes:

• Fire-resistant suit with helmet, boots, gloves and reflective material, certified for short-duration exposure to radiated heat at 1000 degrees Celsius.
• Helmet with integrated face shield.
• Boots with steel toe and chemical-resistant soles.
• Gloves of chemical-resistant material with gauntlet length.
• Axe for forced entry.
• Lifeline and harness of fire-resistant material.
• Self-Contained Breathing Apparatus (SCBA) of approved type with a duration of at least 30 minutes. Spare cylinders or recharging facility must allow continuous use over an extended firefighting operation.

The minimum number of complete outfits: 2 on cargo ships of 500 GT and above; 3 (or one per 80 metres of total length) on passenger ships; additional sets for tankers and ships carrying dangerous goods. The Reg II-2/10 fire-fighting calculator returns the equipment requirements for a given ship type.

Structural integrity (Regulation 11)

This regulation requires that the load-carrying structure of the ship be protected from fire so that a fire-induced collapse does not occur during the time required for evacuation and firefighting. Steel structure loses load-carrying capacity at temperatures above approximately 500 degrees Celsius; the regulation requires steel members in load paths that experience fire to be protected to A-60 standard or to be of a non-combustible heat-resistant alternative material.

For passenger ships, the structural integrity requirement extends to the SRtP scenarios under Part G: the ship must be capable of structurally surviving a defined fire scenario (one MVZ on fire) and returning to port under its own propulsion.

Ventilation systems

While ventilation is not a separate Regulation, it is referenced extensively in Regulation 9 (containment) and Regulation 8 (smoke control). Specific requirements include:

• Galley exhaust ducts must be of steel, with grease-trap arrangements at termination, accessible for cleaning, and provided with fire-rated dampers at penetrations.
• Cargo hold ventilation systems on ships carrying dangerous goods must be sized for sufficient air change rate to prevent flammable atmosphere accumulation.
• Accommodation HVAC must be capable of being shut down zone-by-zone on fire alarm, with re-circulation paths blocked by fire dampers.

Part D: Means of escape

Part D implements functional requirement 5: provision of readily accessible means of escape.

The provisions cover:

• Two means of escape from every accommodation space (passenger and crew) and every space normally manned, with the routes leading to embarkation deck or to a safe area. The two routes must be widely separated so that a single fire scenario cannot block both.
• Stair widths sized to the population that may use them: typically 900 mm minimum, wider for high-occupancy stairs (passenger ship main stairs may be 1,500 mm or more). Stair calculations use evacuation flow models to determine the required width for the design population.
• Dead-end corridor restrictions: typically maximum 7 metres dead-end in accommodation. Beyond 7 metres, an alternative escape must be provided.
• Travel distance limit: maximum total travel distance from any point to the nearest stair entry, typically 25 metres in accommodation.
• Emergency lighting along escape routes powered from the emergency source under Chapter II-1 Part D, capable of operating for the full emergency period (18 or 36 hours depending on ship type).
• Low-location lighting (LLL) markers along escape routes, photoluminescent or electrically powered, visible when smoke fills the upper part of a corridor. LLL is mandatory on passenger ships.
• Emergency Escape Breathing Devices (EEBDs) located along escape routes from accommodation in sufficient quantity to support evacuation through smoke-filled corridors. Minimum count: one per 25 metres of corridor, with additional units at machinery space exits. The EEBD duration calculator checks EEBD adequacy for a given escape route.
• Escape signage with photoluminescent markings indicating direction of escape.
• Locked doors must not block escape: any door on an escape route must be openable from the inside without a key. Self-closing doors must be tested for operation.

The Reg II-2/13 means of escape calculator returns the route count, stair width and EEBD count for a given ship.

Part E: Operational requirements

Part E covers the operational dimension of fire safety: how the ship is run day-to-day.

Operational readiness (Regulation 14)

Fire-fighting equipment must be maintained in working order at all times. The schedule of inspections and tests is set out in the chapter and the FSS Code, and is documented in the fire safety operational booklet required to be carried on board:

• Fire main pressure test: weekly opening of hydrants to verify pressure and flow.
• Fire pump weekly run: to verify start, run and prime.
• CO2 system weekly inspection: cylinder pressure check, control valve operation, alarm test (without discharge).
• Detection system weekly test: detector activation by smoke or heat source as appropriate.
• Fire damper monthly test: closure and reopening verification.
• Hose annual hydrostatic test: at 1.5 times working pressure.
• Foam concentrate quality test: every five years to verify the concentrate has not degraded.

Instructions, training and drills (Regulation 15)

Every member of the crew must receive fire safety training appropriate to their role. Drills must be held with prescribed frequency:

• At least one fire drill every month for cargo ships.
• At least one fire drill every week on passenger ships, with a minimum of one drill within 24 hours of departure if more than 25 percent of the crew has been replaced.

Drills must include a realistic scenario, deployment of firefighter outfits, operation of fire pumps and the fire main, and operation of fixed extinguishing systems (without actual discharge for the gas systems). Required scenario types for training over a year include:

• Engine room fire from oil spillage onto hot surface.
• Accommodation fire (cabin or galley).
• Cargo hold fire.
• Vehicle deck fire (ro-ro vessels).
• Bunker spill ignition during fuel transfer.
• Helicopter fire on helideck (if applicable).

The fire drill frequency calculator returns the required interval and content for a given ship and voyage.

Fire control plan and operational booklet (Regulation 15)

Every ship must carry on board, posted in conspicuous locations, a fire control plan showing:

• Control stations.
• Various fire sections enclosed by A-class and B-class divisions.
• Fire detection and alarm systems with the location of detectors.
• Fixed extinguishing systems with the location of nozzles, manifolds and storage.
• Fire main with hydrants, hoses and isolation valves.
• Means of access to compartments, decks and dampers.
• Ventilation systems with master control locations.

A duplicate fire control plan must be kept ashore in a designated location accessible to shore-side firefighting authorities (typically at the operator’s office; the IMO requires the location to be marked on the plan itself).

The fire safety operational booklet, separate from the plan, contains the operational procedures: how to operate each fire-fighting system, drill procedures, maintenance schedules and emergency response procedures. The booklet is updated whenever the ship’s fire safety equipment is modified.

Operations (Regulation 16)

Specific operational requirements address:

• Hot work permits: documented permit-to-work for any welding, cutting, grinding or other hot work, valid only for a defined location and time, with fire watch posted.
• Smoking restrictions: smoking confined to designated areas with non-combustible ash trays.
• Paint and combustible-stores arrangement: stowage in dedicated lockers, segregated from accommodation, with ventilation.
• Galley fat-fryer protection: automatic fat-fryer suppression with high-temperature cut-out.
• Bunkering procedures: fire-watch posted during bunkering, hot-work prohibition in adjacent areas, smoking ban on the entire ship during bunkering.
• Fire patrol: continuous fire patrol on passenger ships in service (typically a roving fire watchman during the night and during periods of reduced activity).

Port state control fire safety inspections

PSC inspectors target fire safety as one of their primary inspection categories. Common deficiencies include:

• Fire pump fails to start on weekly test.
• Hydrant outlets corroded or damaged.
• Hose hydrostatic test certificates expired.
• Fire dampers seized or non-functional.
• Fire control plan out of date (modifications not reflected).
• Fire detection system zone faulted.
• Fixed CO2 system pressure low.
• Personal protective equipment incomplete or expired.
• Fire drills not conducted or not documented at required frequency.

A serious fire safety deficiency results in detention until the deficiency is rectified. Detention is also recorded against the operator’s PSC profile, affecting future inspection priority. The Paris MOU annual report for 2023 listed fire safety as among the top five deficiency categories.

Part F: Alternative design and arrangements

Part F mirrors the Chapter II-1 provision, allowing fire safety designs that depart from prescriptive requirements provided an engineering analysis demonstrates equivalent safety. The procedure requires:

• Identification of the prescriptive provisions from which alternative is sought.
• Definition of the alternative design.
• Engineering analysis (often using computational fluid dynamics for smoke spread, finite element analysis for structural fire protection, evacuation modelling for escape routes).
• Approval by the flag state.

Part F has been extensively used for novel passenger ship architectures where the prescriptive rules give unworkable layouts:

• Cruise ship atriums of 4 to 8 deck heights, with smoke extraction systems sized by CFD analysis to maintain a clear smoke layer above passenger head height for the required evacuation time.
• Large public spaces (theatres, dining rooms, casinos) with subdivision rules waived in favour of compartment-equivalent fire detection and fixed sprinkler protection.
• Balcony cabins with combustible balcony components subjected to specific fire test approval and segregation analysis.
• Open-air decks with combustible furniture approved on the basis of natural ventilation and rapid fire-watch response.

The alternative design framework was reused in Chapter II-1 Part F and Chapter III Part C. It is one of the most consequential regulatory innovations in the modern SOLAS regime. The Reg II-2/17 alternative design calculator provides a reference framework for the equivalence analysis.

Part G: Special requirements

Helicopter facilities (Regulation 18)

Ships fitted with a helideck must have helideck-specific fire-fighting capability:

• Foam supply at the rate set by the helicopter type’s gross weight: typically 6 litres per minute per square metre of helideck for the deck class corresponding to the helicopter.
• Manual application monitors with fixed mounting at the helideck perimeter and capability of throwing foam over the entire deck.
• Deluge system providing simultaneous water spray over the helideck.
• Foam concentrate stowage sized for at least five minutes of full-rate application.
• Helideck construction of materials capable of withstanding the helicopter’s hot exhaust impingement during landing.
• Wind direction and speed indication at the helideck.

The Reg II-2/18 helicopter facilities calculator sizes the foam supply and deluge requirements.

Carriage of dangerous goods (Regulation 19)

Ships carrying IMDG Code dangerous goods in packaged form or in solid form in bulk are subject to additional requirements:

• Water spray and water mist systems for cargo holds carrying Class 1 explosives, Class 2 gases, Class 3 flammable liquids, and Class 4 flammable solids.
• Personnel protection (extra firefighter outfits, decontamination provisions for Class 5 oxidisers and Class 8 corrosives).
• Bilge pumping arrangement to handle leak from cargoes that react with water.
• Hot work prohibition during DG carriage and detailed fire patrol routine.
• Ventilation of cargo spaces with detection of accumulating toxic or flammable vapours.
• Document of Compliance (DoC) issued by the flag state, listing the IMDG classes the ship is approved to carry. PSC inspections frequently verify the DoC against the actual cargo manifest.
• Master’s authority to refuse cargo if the ship is not equipped to handle the consignment.

The Reg II-2/19 dangerous goods carriage calculator returns the equipment requirements for a given DG cargo manifest.

Vehicle, special category and ro-ro spaces (Regulation 20)

Vehicle decks present special fire risk because of the combination of fuel inventory in the cargo, the open-plan layout that supports rapid horizontal fire spread, and the inability to effectively seal the deck for CO2 discharge. The provisions include:

• Fixed fire detection covering the deck.
• Fixed water-based extinguishing system (water-based foam, water mist or sprinkler) sized for the deck area.
• Fire patrol during voyages with vehicle decks loaded.
• Mechanical ventilation of the deck during loading and unloading and at ten air changes per hour during the voyage.
• Restriction on hot work, smoking and the carriage of certain dangerous goods.

Electric vehicle and lithium-ion battery fire risk (2023-2024 amendments)

The casualties aboard Felicity Ace (2022) and Fremantle Highway (2023) intensified IMO action on electric vehicle fire safety. At MSC 109 (December 2023), the IMO adopted amendments to SOLAS II-2 Regulation 20 addressing vehicle spaces on car carriers and ro-ro passenger ships. These amendments (expected to enter force 1 July 2026, subject to the standard tacit acceptance procedure) require:

• Water-based extinguishing capability providing defined application rates over electric vehicle stowage zones.
• Improved fixed fire detection (heat-sensing systems with faster response times for deep vehicle decks).
• Dedicated water supply for flooding-level response to battery fire scenarios.
• Ship-specific fire-fighting plans for electric vehicle cargoes.

The underlying technical challenge with lithium-ion battery thermal runaway is well-documented: the battery generates its own oxidant from electrolyte decomposition, making CO2 or inert-gas smothering ineffective. Cooling with large quantities of water is currently the primary response. A battery cell that has entered thermal runaway can reignite hours or days later as residual cells decompose; flooding capability addresses this by submerging the affected area.

Toxic gas release (hydrofluoric acid, HF, and other combustion products) from burning lithium-ion batteries requires crew using full breathing apparatus rather than standard firefighter outfit during close-approach firefighting.

The Reg II-2/20 vehicle space calculator returns the requirements for a vehicle deck.

Casualty threshold and Safe Return to Port (Regulations 21 and 22)

For passenger ships of length 120 metres or more (or with three or more main vertical zones), constructed after 1 July 2010, Regulations 21 and 22 implement the Safe Return to Port (SRtP) philosophy. Under SRtP:

• The ship must remain capable of returning to port under its own propulsion after defined casualty scenarios, including a fire affecting one main vertical zone or one major fire-fighting space.
• Essential systems (propulsion, steering, navigation, fire safety, communication, ventilation in safe areas) must remain operational after the casualty.
• A safe area must be available for assembly of all persons on board, with adequate ventilation, sanitation and provisioning capacity for the duration of the return-to-port voyage.

The casualty threshold defines the design fire scenario:

• Fire affecting one MVZ on an accommodation deck.
• Fire affecting one major fire-fighting space (engine control room, boiler room).
• Loss of one bow thruster.
• Loss of one main propulsion unit (in twin-screw arrangements).
• Loss of one main switchboard.

The casualty threshold defines the boundary between casualties for which the ship must continue under its own power and casualties for which evacuation to lifeboats is permitted. Casualties below the threshold are managed under SRtP; casualties above the threshold trigger evacuation.

The Reg II-2/21 casualty threshold calculator and the Reg II-2/22 SRtP design criteria calculator walk through the casualty scenarios and the required system survivability. The SOLAS SRtP time calculator returns the required safe-return duration for a given ship’s operational area.

Safety centre (Regulation 23)

A passenger ship covered by the SRtP regime must include a safety centre from which the master can control all safety-critical functions: fire detection, fire-extinguishing systems, ventilation, watertight doors, public address, electrical isolation, navigation, propulsion and communication. The centre is typically integrated with or adjacent to the navigation bridge.

Specific safety centre requirements include:

• Manned during navigation in port approaches and other periods of elevated risk.
• Equipped with all fire safety system control panels.
• Voice communication to all parts of the ship.
• Visual indication of doors, dampers, ventilation and watertight integrity status.
• CCTV displays from key fire-prone spaces.

The Reg II-2/23 safety centre calculator lists the systems required at the centre.

Notable casualties

Scandinavian Star, 1990

The passenger and ro-ro ferry MS Scandinavian Star caught fire on 7 April 1990 in the Skagerrak between Norway and Denmark. 158 of the 482 people on board died, almost all from smoke inhalation. The fire was deliberately set in a corridor and grew rapidly because of inadequately fire-rated wall linings and the absence of automatic fire detection.

The investigation found:

• The corridor wall linings did not meet the FTP criteria (then in draft) for surface flame spread.
• Smoke detection was confined to specific zones and did not cover the corridor where the fire was set.
• Crew response was delayed; passengers in cabins received no early warning.
• Smoke filled accommodation corridors within minutes; visibility fell to less than one metre.
• Many of the dead were found in their cabins or in stairways close to their cabins, suggesting they were overcome before they could reach embarkation deck.

The casualty drove tightening of detection requirements, the smoke generation limits in Regulations 5 and 6, and the FTP Code finalisation. Subsequent passenger-ship cabin fires showed improvement after the 1992 amendments took effect.

Achille Lauro, 1994

The Italian-flagged passenger ship Achille Lauro caught fire and sank off Somalia on 30 November 1994. Two people died. The fire originated in the main engine room (likely an oil leak onto a hot surface) and spread through ventilation pathways to accommodation areas before the crew could control it. The ship was scuttled in deep water after passenger evacuation.

The casualty contributed to:

• Development of fixed water mist as a viable alternative to CO2 in passenger ship machinery spaces (with the safety advantage of being non-asphyxiating).
• Tightening of fuel oil and lube oil arrangements to reduce ignition probability.
• Fire damper specifications for ventilation paths between machinery spaces and accommodation.

Norman Atlantic, 2014

The ro-ro passenger ferry Norman Atlantic caught fire on 28 December 2014 in the Adriatic on a voyage from Patras to Ancona. Approximately 11 people died (multiple uncertainties because of unauthorised passengers). The fire originated on the vehicle deck, possibly in a refrigerated trailer’s diesel generator, and spread before suppression could be brought to bear. The fixed water-spray system on the deck failed to control the fire because of the open-plan layout and the wind that was driving smoke through accommodation.

The casualty drove amendments tightening:

• Vehicle deck detection (faster and more sensitive).
• Fixed extinguishing capability (higher water flow rates, better distribution).
• Ventilation control during fire (closure of vents, smoke extraction).
• Cargo securing patterns (preventing trailer-to-trailer fire spread).

Maersk Honam, 2018

The container ship Maersk Honam caught fire on 6 March 2018 in the Arabian Sea. Five crew died. The fire originated in a cargo hold and spread to multiple holds before suppression could be effective. The post-incident review identified a Class 5.1 oxidising substance (calcium hypochlorite) as a likely contributor to fire growth.

The case drove industry-led pre-stowage segregation guidance for Class 5 oxidisers on container ships and contributed to amendments under development for:

• Container hold detection (faster and more sensitive).
• Access for firefighting (boundary cooling, water lances reaching deep into stowed containers).
• Stowage planning to keep dangerous goods away from accommodation.
• Hold flooding capability for major cargo fires.

X-Press Pearl, 2021

The container ship X-Press Pearl caught fire on 20 May 2021 off Colombo, Sri Lanka, and sank on 2 June. The fire originated in nitric acid leakage from a container, ignited combustibles, and spread through hundreds of containers including pelletised polyethylene. The environmental impact was severe, with thousands of tonnes of plastic pellets washed ashore.

The casualty drove regulatory pressure for:

• Tighter inspection of dangerous goods containers (random verification of declared contents).
• Consideration of extended hold-flooding capability.
• Pre-stowage chemical-compatibility analysis for high-risk goods.

Felicity Ace, 2022

The car carrier Felicity Ace caught fire in mid-Atlantic on 16 February 2022 and sank on 1 March 2022. The cargo included approximately 4,000 vehicles, of which a significant proportion were electric. The fire is widely understood to have been associated with lithium-ion battery thermal runaway in the cargo. No crew died (the crew evacuated). The casualty intensified the IMO debate about vehicle deck fire safety on car carriers, ro-ro and ro-pax vessels, directly feeding into the MSC 109 amendments on Regulation 20.

Fremantle Highway, 2023

The car carrier Fremantle Highway caught fire on 26 July 2023 in the North Sea, between the Netherlands and Germany. One firefighter died. The vessel was carrying approximately 3,800 vehicles, reportedly including some electric cars. The fire started on the car deck and proved very difficult to control, with the vessel ultimately salvaged and towed to port. The incident reinforced the conclusions from Felicity Ace and was directly cited in the MSC 109 deliberations on electric vehicle fire safety amendments.

Container fire industry initiatives

The recurring container ship fires have triggered industry-led initiatives that operate alongside the IMO regulatory cycle:

• CINS (Cargo Incident Notification System): industry database of container incidents (loss, damage, fire, mis-declaration), shared among carriers and used to identify patterns.
• National Cargo Bureau (NCB) and similar inspection services: pre-loading random inspection of containers for compliance with IMDG declarations.
• IUMI (International Union of Marine Insurance) working group on container ship fires, providing actuarial analysis and risk-based recommendations to insurers and to the IMO.
• Cargo declaration verification programmes by major carriers, with random sampling of containers for declared-versus-actual content.
• Stowage planning tools with built-in IMDG segregation and dangerous-goods exclusion zones.

These initiatives have reduced the frequency of container ship fires but have not eliminated them; the structural risk associated with high-density containerisation of mixed cargo remains.

Documentation

Required documents and plans include:

• Fire control plan posted on board with duplicate held ashore at a designated location.
• Fire safety operational booklet on board with operating procedures.
• Records of fire drills, fire safety training and equipment maintenance under Regulation 14 and the FSS Code.
• The Cargo Ship Safety Construction Certificate or Passenger Ship Safety Certificate (depending on ship type), evidencing compliance with Chapter II-2 alongside Chapter II-1.
• Document of Compliance for the Carriage of Dangerous Goods (under Regulation 19).
• IMDG Code on board with current amendments.
• Hot work permit forms.
• Fire patrol log (passenger ships).

Limitations

The material in this article reflects SOLAS Chapter II-2 as it stood in the consolidated text through the amendments adopted at MSC 109 (December 2023). Several caveats apply:

• Alternative fuel fire safety: IMO is developing interim guidelines for ships using ammonia, hydrogen and methanol as fuel under the IGF Code framework and associated interim guidelines. As of mid-2026, no adopted SOLAS II-2 amendment incorporating fire-safety provisions specifically for these fuels as installed onboard systems has entered force; practitioners must check the current state of the relevant MSC circular or interim guideline. This article does not present any such provisions as adopted SOLAS amendments.
• MSC 109 amendments: the vehicle-space amendments from MSC 109 are subject to the standard tacit-acceptance procedure. Entry-into-force date should be verified against the IMO amendment status page and any relevant flag-state circular before relying on them for a specific design.
• Flag-state interpretation: flag states issue circulars and policy letters that interpret or supplement the prescriptive requirements. A design approved by one flag state under Part F may not be automatically recognised by another.
• Retroactive vs. new-build applicability: many requirements apply only to ships constructed on or after a specific date. This article generally describes requirements as written in the current consolidated text; it does not map every requirement to the construction-date applicability that determines whether a given existing ship must comply.
• Class rules: classification societies issue unified requirements (IACS UR F series) and individual class rules that typically exceed the SOLAS minimum. A ship classed to Lloyd’s, DNV, Bureau Veritas or another IACS member society will have additional fire safety requirements beyond those described here.
• This article is for general reference only. Designs, surveys, compliance assessments and incident investigations must be based on the current SOLAS consolidated text and applicable codes as issued by the IMO and the relevant flag state, not on secondary sources.

Related Calculators

• SOLAS II-2/1, Application fire safety Calculator
• SOLAS II-2/4, Probability of ignition Calculator
• SOLAS II-2/5, Fire growth potential Calculator
• SOLAS II-2/7, Detection and alarm Calculator
• SOLAS II-2/9, Containment Calculator
• SOLAS II-2/10, Fire fighting Calculator
• SOLAS II-2/13, Means of escape Calculator
• SOLAS II-2/17, Alternative designs Calculator
• SOLAS II-2/18, Helicopter facilities Calculator
• SOLAS II-2/19, Carriage of DG Calculator
• SOLAS II-2/20, Vehicle/special category spaces Calculator
• SOLAS II-2/21, Casualty threshold passenger ship Calculator
• SOLAS II-2/22, Design for safe return passenger Calculator
• SOLAS II-2/23, Safety centre passenger Calculator
• CO₂ Room, Over-Pressure Check Calculator
• CO₂ System, Volume Adequacy Check Calculator
• Emergency Fire Pump, SOLAS Requirement Calculator
• Fire Pump Capacity SOLAS Calculator
• SOLAS Fire Drill Frequency Calculator
• SOLAS II-2 Safe Return to Port Time Calculator
• EEBD Duration, SOLAS II-2 Check Calculator
• Foam Concentrate for Tanker Deck Calculator
• Fire Nozzle, Required Discharge Calculator
• Fire Main Diameter (SOLAS II-2) Calculator
• HFC-227ea Quantity (FM-200) Calculator

See also

• SOLAS Convention parent article
• SOLAS Chapter II-1: Construction, Subdivision, Stability, Machinery and Electrical Installations
• SOLAS Chapter III: Life-Saving Appliances and Arrangements
• SOLAS Chapter V: Safety of Navigation
• SOLAS Chapter VI: Carriage of Cargoes and Oil Fuels
• FSS Code: International Code for Fire Safety Systems
• Marine Fire Detection and Fixed Fire Fighting Systems
• IMDG Class 1 Explosives
• IMDG Class 2 Gases
• IMDG Class 3 Flammable Liquids
• IMDG Class 4 Flammable Solids
• IMDG Class 5 Oxidisers and Organic Peroxides
• IMDG Class 8 Corrosive Substances
• IMSBC Code
• LNG as Marine Fuel
• Methanol as Marine Fuel
• Ammonia as Marine Fuel
• Hydrogen as Marine Fuel
• ISM Code
• Battery Hybrid Propulsion
• Container Ship

References

• IMO, International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended, Chapter II-2.
• IMO Resolution MSC.99(73) (December 2000), Adoption of amendments to SOLAS Chapter II-2 (the 2002 restructure), entering force 1 July 2002.
• IMO International Code for Fire Safety Systems (FSS Code), Resolution MSC.98(73), as amended.
• IMO International Code for Application of Fire Test Procedures (FTP Code 2010), Resolution MSC.307(88), entering force 1 July 2012.
• IMO Resolution MSC.365(93), Amendments extending inert gas system requirements to tankers of 8,000 DWT and above, entering force 1 January 2016.
• IMO MSC/Circ.1430 (2012), Revised guidelines for the design and approval of fixed water-based fire-fighting systems for ro-ro spaces.
• IMO MSC.1/Circ.1369 and successor circulars on Safe Return to Port.
• IMO MSC.1/Circ.1471 and successor circulars on guidance for ro-ro passenger ship fire safety.
• IMO MSC 109 (December 2023), Adopted amendments on fire safety requirements for vehicle spaces.
• IUMI Position Paper on Container Ship Fires, multiple editions (2015 onward).
• CINS Cargo Incident Notification System Annual Reports.