MARPOL Annex VI Reg 12: ozone-depleting substances

Background: MARPOL Annex VI 1997 + 2008 amendments

The original 1997 text of MARPOL Annex VI, adopted at the International Conference of the Parties to MARPOL convened in London in September 1997 and entering into force on 19 May 2005 following the ratification threshold under Article 16 of the parent treaty, included Regulation 12 as the air-pollution chapter’s ozone-depleting-substances provision. The 1997 Reg 12 was a relatively short article that prohibited deliberate emissions of ODS during the maintenance, servicing or decommissioning of shipboard systems and prohibited new installations of equipment containing controlled substances as defined under the Montreal Protocol. The 1997 text did not specify the date from which new installations were prohibited; that date was implicitly the entry into force of Annex VI (i.e. 19 May 2005), but the absence of an explicit date created uncertainty about the status of equipment installed between 1997 (adoption) and 2005 (entry into force).

By the mid-2000s, the air-pollution chapter of Annex VI was being fully rewritten in light of the experience of the first generation of Sulphur Emission Control Areas, the introduction of the Tier I, II and III NOx regime under the rewritten Regulation 13, the introduction of the energy-efficiency framework that became EEDI, and the global phasedown of HCFCs under the Copenhagen and Beijing amendments to the Montreal Protocol. In that context, Regulation 12 also needed substantial strengthening: the new-installation date had to be made explicit, the HCFC phase-out had to be aligned with the Montreal Protocol calendar, the on-board documentation regime had to be formalised, and the IAPP supplement had to be extended to cover ODS-containing equipment.

The 2008 amendments to Annex VI were adopted by Resolution MEPC.176(58) on 10 October 2008, with entry into force on 1 July 2010. The 2008 amendments completely rewrote Regulation 12, splitting it into the following operational paragraphs:

• Reg 12.1 prohibits deliberate emissions of ODS during maintenance, servicing or decommissioning. Minimal releases that are unavoidable during recharge or repair must be captured to the extent practicable.
• Reg 12.3 prohibits new installations of equipment containing ODS on ships built on or after 19 May 2005. The exception is HCFCs, for which new installations were permitted until 1 January 2020.
• Reg 12.6 introduces the ODS Record Book as the on-board log of all ODS recharges, transfers, off-loadings and emissions.
• Reg 12.7 requires the ship to carry a list of ODS-containing equipment on board.
• Reg 12.8 requires the ODS list to be annexed to the IAPP (International Air Pollution Prevention) supplement.

The 2008 amendments also introduced the requirement that the ODS Record Book be presented during PSC inspection and be cross-checked against the IAPP supplement for consistency. The ODS Record Book is now a standard PSC inspection target, with a dedicated deficiency code (typically 14601) under the Tokyo MoU and Paris MoU reporting schemes.

A further refinement was introduced by amendments addressing the HCFC phase-out trajectory, aligning the 1 January 2020 new-installation cut-off with the Article 2 (developed-country) HCFC consumption phase-out under the Montreal Protocol Copenhagen and Beijing amendments. The 2020 cut-off applies to new installations on board ships of any age, not just to newbuildings; an existing ship cannot install a new HCFC-charged chiller after 1 January 2020 even if its older HCFC chillers continue to operate under grandfathered status.

Reg 12.1 prohibition on deliberate ODS emissions

Reg 12.1 is the operational core of Regulation 12: it prohibits deliberate emissions of ODS during the maintenance, servicing or decommissioning of shipboard systems. The prohibition applies to all ODS as defined under the Montreal Protocol, including CFCs, HCFCs, halons, methyl bromide, carbon tetrachloride, methyl chloroform, and bromochloromethane.

A “deliberate emission” is one in which the operator vents the substance to atmosphere by intent or by negligence. The classic example is the purge-and-vent practice that was common in pre-2005 ship refrigeration: the chief refrigeration engineer would purge the system to atmosphere to bring it down to ambient pressure, replace a component, and then refill from a recovery cylinder, with the purge gas (typically R-22 in a halon-replacement chiller) lost to atmosphere. Reg 12.1 prohibits this practice and requires the purge gas to be recovered into a class-approved recovery cylinder using a recovery unit (a small compressor-vacuum-pump combination that draws the refrigerant from the system into the cylinder).

Minimal releases that are unavoidable during recharge or repair must be captured to the extent practicable. The phrase “to the extent practicable” recognises that some loss is inevitable: when a service hose is disconnected from a charging port, a small quantity of refrigerant trapped in the hose can’t be recovered; when a leak develops in a tube bundle, the leak rate is determined by the pressure differential and the leak geometry, not by the operator’s intent. The Reg 12.1 obligation in such cases is to minimise the loss by using good practice (e.g. minimising hose length, using self-sealing quick-connects, isolating the leaking section as quickly as possible).

The Reg 12.1 prohibition is a continuing obligation: it applies to all ships at all times, including ships built before 19 May 2005 that continue to operate ODS-charged equipment under grandfathered status. A pre-2005 ship with R-22 chillers can’t vent R-22 to atmosphere during a service even though the chillers themselves aren’t affected by Reg 12.3.

Reg 12.3 ban on new ODS installations from 19 May 2005

Reg 12.3 prohibits new installations of equipment containing ODS on ships built on or after 19 May 2005, the entry into force date of Annex VI. The “ship built on or after” trigger is determined by the keel-laid date under the SOLAS and Annex VI conventional definitions: a ship whose keel is laid on or after 19 May 2005 is subject to the ban from delivery onwards.

The “new installation” trigger is broader than the ship-build trigger. A new installation is one in which a piece of equipment containing ODS is first put into service on the ship: this includes the original installation at the shipyard, but also any subsequent retrofit that introduces an ODS-containing piece of equipment. A 2010-built ship that retrofits a CFC-charged chiller in 2018 has made a “new installation” for Reg 12.3 purposes and is non-compliant.

The 19 May 2005 cut-off applies to CFCs (R-11, R-12, R-13, R-114), halons (1211, 1301, 2402) and the other “primary” ODS controlled by the Montreal Protocol. HCFCs (R-22, R-141b) are subject to a separate cut-off of 1 January 2020 under Reg 12.3 read with the 2008 amendments and later refinements. HFCs (R-134a, R-410A, R-404A, R-407C) are not ODS and are not subject to Reg 12.3; they are covered by the Kigali Amendment to the Montreal Protocol (2016, in force 1 January 2019) and by the EU F-Gas Regulation and the US EPA SNAP regional regimes as greenhouse-gas phasedown measures.

The practical consequence of Reg 12.3 is that all newbuildings since 2005 have been delivered with HFC-based or HFO-based refrigeration and air-conditioning, and with CO2-based or water-mist fire-fighting in lieu of halon. The transition was completed across the world fleet between 2005 and approximately 2010, with the last legacy CFC chillers retired by 2008-2010 and the last halon fire-suppression systems retired by 2010-2012.

HCFC ban on new installations from 1 January 2020

The HCFC component of Reg 12.3 establishes a separate cut-off of 1 January 2020 for new installations of HCFC-containing equipment. The 1 January 2020 cut-off was introduced by the 2008 amendments under MEPC.176(58) and aligned with the Article 2 (developed-country) HCFC consumption phase-out under the Copenhagen and Beijing amendments to the Montreal Protocol. That alignment is exact: the 2007 Montreal Adjustment to the Copenhagen Amendment accelerated the developed-country HCFC phase-out to 100% by 2020 (with a 0.5% service-stock allowance through 2030), and Reg 12.3 adopted the same 1 January 2020 cut-off for new shipboard installations.

Between 19 May 2005 and 31 December 2019, new installations of HCFC-containing equipment were permitted under Reg 12.3, on the grounds that HCFCs (R-22 in particular) had a relatively low ODP (approximately 0.055 for R-22) and were widely available as a low-cost transitional refrigerant. During this 14-year window, many newbuildings were delivered with R-22 chillers, R-22 reefer-container plant, and R-22 air-conditioning. The 1 January 2020 cut-off closes the window for new installations: from that date, no new R-22, R-141b or other HCFC-charged equipment can be installed on any ship of any age.

The 2020 cut-off applies to new installations on board ships of any age, not just to newbuildings. An existing 2015-built ship can’t install a new R-22 chiller after 1 January 2020 even though its existing 2015-vintage R-22 chillers continue to operate under grandfathered status. This means the operator must select an HFC, HFO, CO2 or ammonia chiller for any post-2020 retrofit, which typically incurs a capital premium of 30-50% over an equivalent legacy R-22 chiller of comparable capacity.

The 2020 cut-off does not require the immediate retirement of existing HCFC-charged equipment. Existing R-22 chillers may continue to operate under grandfathered status, with their charges replenished from recycled or reclaimed R-22 stocks. Many flag administrations have set their own end-of-life dates for HCFC-charged equipment (the EU under the F-Gas Regulation prohibited HCFC service from 1 January 2015 for EU-flagged ships), so operators of HCFC-charged ships must cross-check the flag-state regime.

Substance classification: ODS types, status, and metrics

The substances controlled under Reg 12 span a wide range of ozone-depleting potentials and greenhouse-warming potentials. The table below summarises the principal shipboard substances, their Montreal Protocol annex, their regulatory status under Reg 12, and the key physical metrics.

ODP values normalised to R-11. GWP100 from IPCC AR6 (2021) Working Group I, Annex III (2021 values supersede AR5 for compliance purposes; check the governing flag-state regulation for the specific assessment cycle cited). HFCs in Annex F are not ODS and are not subject to Reg 12.3 or the Reg 12.6 Record Book; they fall under the Kigali phasedown and regional F-Gas/SNAP regimes.

Linkage to Montreal Protocol 1987 + amendments

Reg 12 implements at the ship level the Montreal Protocol on Substances that Deplete the Ozone Layer, adopted in Montreal on 16 September 1987 and in force from 1 January 1989. The Montreal Protocol is the principal global instrument governing the production and consumption of ODS; Reg 12 is the IMO ship-side counterpart that governs the use of ODS in shipboard systems. The two instruments are designed to operate together: the Montreal Protocol regulates the upstream supply (production and import), while Reg 12 regulates the downstream demand (use on board ships).

The principal amendments to the Montreal Protocol that bear on Reg 12 are:

• London Amendment 1990: extended the Protocol to carbon tetrachloride and methyl chloroform, accelerated the CFC phase-out from a 50% reduction by 2000 to a complete phase-out by 2000, and extended controls to halons.
• Copenhagen Amendment 1992: extended the Protocol to HCFCs with a phase-out trajectory to 2030 (developed countries) and 2040 (developing countries), and to methyl bromide and HBFCs (hydrobromofluorocarbons).
• Montreal Amendment 1997: introduced production and consumption controls for HCFCs (the Copenhagen Amendment had introduced consumption controls only).
• Beijing Amendment 1999: introduced production controls for HCFCs and added bromochloromethane to the Protocol.
• Kigali Amendment 2016 (in force 1 January 2019): extended the Protocol to hydrofluorocarbons (HFCs) with a phasedown trajectory based on CO2-equivalent consumption.

Reg 12.3 incorporates the Montreal Protocol controlled-substance lists by reference: a substance is “controlled” under Reg 12 if it is listed in Annex A, Annex B, Annex C or Annex E of the Montreal Protocol (CFCs, halons, other CFCs and carbon tetrachloride, HCFCs and methyl bromide respectively). The Kigali Amendment added Annex F (HFCs), but Reg 12.3 does not incorporate Annex F by reference; HFCs are not “ODS” and are not subject to the Reg 12.3 new-installation ban. The Kigali HFC phasedown is implemented separately at the IMO through the MEPC 81 data collection amendment (see below).

Kigali Amendment 2016 (in force 2019) HFC phasedown

The Kigali Amendment to the Montreal Protocol was adopted in Kigali, Rwanda, on 15 October 2016 and entered into force on 1 January 2019. The Kigali Amendment extends the Montreal Protocol approach (production and consumption controls, with separate trajectories for developed and developing countries) from chlorinated ODS to hydrofluorocarbons (HFCs). HFCs are not ozone-depleting (they contain no chlorine or bromine) but are high-GWP greenhouse gases: R-134a has a GWP100 of approximately 1,430, R-410A approximately 2,090, R-404A approximately 3,920 and R-407C approximately 1,770.

The Kigali phasedown trajectory for Article 2 (developed) countries is a stepwise reduction from a 2011-2013 baseline to a 15% residual by 2036. The trajectory for Article 5 (developing) countries is a delayed and more gradual reduction from a 2020-2022 baseline (Group 1) or 2024-2026 baseline (Group 2) to a 15% or 20% residual by 2045-2047. The shipping industry, as a global activity not assigned to a single party, is governed in practice by the flag-state party trajectory, plus regional regimes such as the EU F-Gas Regulation and the US EPA SNAP that have implemented Kigali at the regional level.

The Kigali Amendment does not ban HFCs in absolute terms; it only caps their consumption at the phasedown level. New installations of HFC-charged equipment remain permitted under Reg 12, but the regional regimes are the binding constraint for most operators: the EU F-Gas Regulation (EU 2024/573) prohibits new HFC equipment with GWP above 750 from 2025 (small refrigeration and air-conditioning) and above 150 from 2027 (commercial refrigeration), and the US EPA SNAP delists high-GWP HFCs sector by sector under Section 612.

The IMO is implementing Kigali at the shipping level through MEPC 81 (March 2024) which adopted amendments requiring ships to report HFC charge mass and GWP-weighted equivalent emissions as part of the IMO DCS submission from 2026 onwards. The HFC DCS amendment is a monitoring-only measure; it does not impose a phasedown, but it provides the data baseline against which any future IMO HFC phasedown could be calibrated.

Reg 12.6 ODS Record Book requirement

Reg 12.6 introduces the ODS Record Book as the on-board log of all ODS-related operations. The ODS Record Book is a bound or electronic register that records, for each ODS-containing system, all of the following events in chronological order:

• Recharge of the system with refrigerant or extinguishant (mass in kilograms, type, source, date, signature)
• Transfer of refrigerant between the system and a recovery cylinder, or between cylinders (mass, direction, date, signature)
• Off-loading of refrigerant from the ship to a shore facility for reclamation, recycling or disposal (mass, recipient, date, signature)
• Topping-up to compensate for leakage (mass, date, signature)
• Decommissioning of an ODS-containing system, including the recovery of the working charge (mass recovered, mass deemed unrecoverable, date, signature)
• Bunkering of ODS or ODS-containing equipment (e.g. taking on a new R-22 cylinder for service stock)

The ODS Record Book entries must be made at the time of the event, not retrospectively, and must be signed by the chief engineer or by the engineer responsible for the operation. The Record Book is retained on board for at least 5 years after the date of the last entry (the IAPP renewal-survey horizon).

The ODS Record Book is the primary PSC inspection target for Reg 12 compliance. A PSC officer arriving on board will typically:

1. Inspect the IAPP supplement (Form A or B) to identify the ODS-containing equipment listed under Reg 12.8.
2. Inspect the ODS Record Book to verify that all recharges, transfers and off-loadings of the listed substances are logged.
3. Cross-check the most recent recharge against the manufacturer’s rated charge for the equipment, looking for discrepancies that suggest unrecorded leakage or unrecorded service.
4. Inspect the on-board service stock (R-22 cylinders for grandfathered HCFC equipment, halon cylinders for grandfathered halon systems) and verify that the cylinder serial numbers and charge masses match the Record Book entries.
5. Inspect the recovery cylinder for evidence of recent recovery operations, with the cylinder fill date and mass cross-checked against the Record Book.

A discrepancy at any of these junctions is a Reg 12 deficiency, recorded under PSC code 14601 (or local equivalent).

Reg 12.7 ODS list onboard

Reg 12.7 requires every ship to carry on board a list of equipment containing ODS. The list is a discrete document (typically a single page or a few pages) that identifies each piece of ODS-containing equipment by:

• Equipment description (e.g. “main air-conditioning chiller, port side, frame 78”)
• Manufacturer and model
• Serial number
• Refrigerant or extinguishant type (e.g. R-22, R-12, Halon 1301)
• Rated charge mass in kilograms
• Year of installation
• Location on the ship (compartment, deck, frame)

The Reg 12.7 list is the inventory baseline against which the Reg 12.6 Record Book is logged: every recharge, transfer or off-loading entered in the Record Book must reference an item on the Reg 12.7 list. A piece of ODS-containing equipment that is not on the Reg 12.7 list is a Reg 12 deficiency, even if its operations are correctly logged in the Record Book.

The Reg 12.7 list must be kept up to date: any new ODS-containing equipment installed under grandfathered status (e.g. a replacement R-22 chiller installed before 1 January 2020), and any decommissioned equipment removed from service, must be added to or removed from the list with a dated entry. The list is typically held by the chief engineer alongside the IAPP certificate and the ODS Record Book.

Reg 12.8 IAPP supplement ODS listing

Reg 12.8 requires the Reg 12.7 ODS list to be annexed to the IAPP supplement. The International Air Pollution Prevention (IAPP) certificate is the parent certificate issued under Reg 6 of Annex VI; it is supplemented by either Form A (for ships not required to have an EIAPP certificate, i.e. ships without diesel engines above 130 kW) or Form B (for ships with diesel engines above 130 kW). The IAPP supplement is the detailed schedule of the ship’s air-pollution-relevant equipment and the regulatory framework against which each item is compliant.

The IAPP supplement Section 2.1 lists, for each ODS-containing piece of equipment:

• Equipment description
• Refrigerant or extinguishant type
• Rated charge mass
• Date of installation (to determine the Reg 12.3 grandfathering status)

The Reg 12.8 listing is the regulatory anchor for the Reg 12.7 list and the Reg 12.6 Record Book: a piece of equipment on the Reg 12.8 IAPP supplement must also be on the Reg 12.7 list (with the same description and charge mass), and its operations must be logged in the Reg 12.6 Record Book. A discrepancy between the IAPP supplement and the Reg 12.7 list, or between the Reg 12.7 list and the Reg 12.6 Record Book, is a chain-of-custody break and a Reg 12 deficiency.

The IAPP supplement is updated at each annual, intermediate or renewal IAPP survey (typically every 12 months for annual, every 30 months for intermediate, every 60 months for renewal). Between surveys, the chief engineer is responsible for keeping the Reg 12.7 list synchronised with the actual ship state.

CFC substances: R-11, R-12, R-13, R-114

The chlorofluorocarbons (CFCs) are the original Annex A Group I controlled substances under the Montreal Protocol. The four principal shipboard CFCs are:

• R-11 (CCl3F, trichlorofluoromethane): a low-pressure refrigerant historically used in centrifugal chillers for accommodation air-conditioning. ODP approximately 1.0 (the reference value); GWP100 approximately 4,750.
• R-12 (CCl2F2, dichlorodifluoromethane): a medium-pressure refrigerant historically used in reciprocating chillers, reefer-container plant and provision-room refrigeration. ODP approximately 1.0; GWP100 approximately 10,900.
• R-13 (CClF3, chlorotrifluoromethane): a low-temperature refrigerant historically used in cascade systems for blast freezing and very-low-temperature cargo. ODP approximately 1.0; GWP100 approximately 14,400.
• R-114 (C2Cl2F4, dichlorotetrafluoroethane): a low-pressure refrigerant historically used in centrifugal chillers and in heat-pump applications. ODP approximately 1.0 (variant-dependent); GWP100 approximately 9,180.

CFCs were phased out of new production under the Montreal Protocol from 1995 (developed countries) and 2010 (developing countries), and phased out of new installations on ships under Reg 12.3 from 19 May 2005. Existing CFC installations may continue to operate under grandfathered status, but service stock is exhausted in most jurisdictions and the practical service horizon for CFC-charged equipment expired around 2010-2012.

A small number of legacy ships still carry CFC-charged equipment, principally R-12 in older reefer-container plant. Service of such equipment is now done by drop-in replacement with HFC blends (e.g. R-401A, R-409A) or by complete retrofit to an HFC- or HFO-charged system.

HCFC substances: R-22, R-141b

The hydrochlorofluorocarbons (HCFCs) are the Annex C Group I controlled substances under the Montreal Protocol. The two principal shipboard HCFCs are:

• R-22 (CHClF2, chlorodifluoromethane): the workhorse refrigerant of the 1990s and 2000s, used in reciprocating chillers for accommodation air-conditioning, in reefer-container plant, in provision-room refrigeration, and in cargo-hold air-conditioning for refrigerated cargo. ODP approximately 0.055; GWP100 approximately 1,810.
• R-141b (CH3CCl2F, 1,1-dichloro-1-fluoroethane): a foam-blowing agent historically used in polyurethane and polyisocyanurate insulation foams for refrigerated cargo holds and reefer containers. ODP approximately 0.11; GWP100 approximately 725.

HCFCs were phased into new production under the Montreal Protocol Copenhagen and Beijing amendments with a developed-country phase-out by 2030 and a developing-country phase-out by 2040. New installations of HCFC-charged equipment on ships were prohibited from 1 January 2020 under Reg 12.3 read with the 2008 amendments. Existing HCFC installations may continue to operate under grandfathered status with service stock from recycled or reclaimed R-22.

The R-22 service stock is being progressively depleted as the 2030 production phase-out approaches; many flag administrations and class societies are advising operators of HCFC-charged ships to plan for retrofit to HFC, HFO or natural refrigerant by 2028-2030 to avoid a service-stock crunch. A typical HCFC-to-HFO retrofit for a ship’s main air-conditioning chiller costs USD 50,000-200,000 depending on system size, with the upper end applying to large LNG carriers and cruise ships with multiple chiller plants.

Halon substances: 1211, 1301, 2402

The halons are the Annex A Group II controlled substances under the Montreal Protocol. The three principal shipboard halons are:

• Halon 1211 (CBrClF2, bromochlorodifluoromethane): a streaming agent used in portable fire extinguishers. ODP approximately 3.0; GWP100 approximately 1,890.
• Halon 1301 (CBrF3, bromotrifluoromethane): a total-flooding agent used in fixed fire-extinguishing systems for engine rooms, machinery spaces, paint stores and electrical compartments. ODP approximately 10.0 (the highest of any controlled substance); GWP100 approximately 7,140.
• Halon 2402 (C2Br2F4, dibromotetrafluoroethane): a streaming agent used in portable extinguishers and in some fixed systems, principally on Russian and Soviet-era ships. ODP approximately 6.0; GWP100 approximately 1,640.

Halons were the dominant fixed-fire-extinguishing agent on ships from the 1970s through the 1990s, valued for their high extinguishing efficiency, low concentration requirement (5-7% v/v for Halon 1301 vs 30-40% for CO2), rapid extinguishment, and non-conductivity (suitable for electrical compartments). The principal historical application was the engine-room total-flooding system under SOLAS Reg II-2/10.

Halons were phased out of new production under the Montreal Protocol from 1994 (developed countries), and new installations of halon-containing fire systems on ships were prohibited from 19 May 2005 under Reg 12.3. Existing halon systems may continue to operate under grandfathered status with service stock from the international halon bank (a UNEP-coordinated reserve of recycled halon for essential uses, principally aviation and military). The shipping industry is not on the essential-uses list, so service stock for shipboard halon systems is sourced from commercial halon banks at progressively rising prices (USD 50-150 per kilogram in the late 2020s).

The replacement agents for shipboard total-flooding fire suppression are CO2 (the legacy alternative, requiring high concentration and posing asphyxiation risk to crew), water mist (high-pressure or low-pressure systems for engine rooms and accommodation), inert gas (IG-541, IG-55) mixtures (typically nitrogen, argon and CO2), and HFC-227ea or HFC-23 (clean agents, but high-GWP and now subject to Kigali phasedown).

Methyl bromide and quarantine/preshipment exception

Methyl bromide (CH3Br) is the Annex E controlled substance under the Montreal Protocol. It is a fumigant historically used for agricultural cargo fumigation (grain, timber, fresh produce), structural fumigation of ship cargo holds, and soil fumigation in shore facilities. ODP approximately 0.6; GWP100 approximately 5.

Methyl bromide was phased out of most new uses globally from 2005 under the Copenhagen Amendment to the Montreal Protocol, with a single major exception: quarantine and preshipment (QPS) uses, defined as treatments to prevent the introduction or spread of regulated pests across borders. QPS uses include the fumigation of imported timber and grain to comply with the importing country’s phytosanitary requirements, and the fumigation of containerised cargo at the port of loading or discharge to comply with quarantine regulations.

Reg 12 covers methyl bromide through the same general prohibition as for other ODS: new installations of methyl-bromide-containing equipment on ships are prohibited from 19 May 2005 under Reg 12.3, and deliberate emissions during maintenance are prohibited under Reg 12.1. The QPS exception in the Montreal Protocol is mirrored in Reg 12 by the implicit recognition that fumigation operations complying with the importing country’s phytosanitary regulations are not “deliberate emissions” within the meaning of Reg 12.1; they are regulated separately under the IMSBC Code (Section 9 on cargo fumigation) and under SOLAS Reg VI/4.

A modern ship carrying grain or timber that is fumigated in transit with methyl bromide must record the fumigation in the cargo log; the fumigation is not a Reg 12 deficiency provided it is conducted under QPS and provided the fumigant is vented through a controlled venting line (typically a stack vent at the top of the cargo hold, with the vent gas not collected for recovery because methyl bromide breaks down rapidly in the atmosphere).

HFCs: R-134a, R-410A, R-404A, R-407C (not ODS but GHG)

The hydrofluorocarbons (HFCs) are not ozone-depleting substances and are not subject to Reg 12.3. They are, however, high-GWP greenhouse gases and are subject to phasedown under the Kigali Amendment to the Montreal Protocol and to phase-out under regional regimes (EU F-Gas, US SNAP). The four principal shipboard HFCs are:

• R-134a (CH2FCF3, 1,1,1,2-tetrafluoroethane): the dominant CFC and HCFC replacement refrigerant of the 2000s and 2010s, used in centrifugal and reciprocating chillers, in reefer-container plant, in provision-room refrigeration, and in mobile air-conditioning. GWP100 approximately 1,430; ODP zero.
• R-410A (50/50 R-32/R-125 blend, difluoromethane and pentafluoroethane): a high-pressure refrigerant used in residential and small commercial air-conditioning, also used in some shipboard accommodation air-conditioning. GWP100 approximately 2,090; ODP zero.
• R-404A (44/52/4 R-125/R-143a/R-134a blend): a low-temperature refrigerant used in reefer-container plant and in cascade systems for blast freezing. GWP100 approximately 3,920 (the highest of the common shipboard HFCs); ODP zero.
• R-407C (23/25/52 R-32/R-125/R-134a blend): an R-22 retrofit refrigerant for reciprocating chillers, used in many post-2000 shipboard air-conditioning systems. GWP100 approximately 1,770; ODP zero.

HFCs are not on the Reg 12.7 ODS list and are not entered in the Reg 12.6 ODS Record Book. They are listed in the IAPP supplement Section 2.1 as informational entries by many class societies as a matter of good practice, and are entered in the MEPC 81 HFC DCS (data collection system) from 2026 as the data baseline for any future IMO HFC phasedown.

The Kigali phasedown trajectory and the regional F-Gas/SNAP regimes are progressively pushing the shipping industry away from high-GWP HFCs toward low-GWP HFOs (R-1234yf, R-1234ze) and natural refrigerants (CO2, ammonia, hydrocarbons). The transition is mature for newbuildings (most 2025+ newbuildings are delivered with HFO or natural refrigerant chillers) and is in progress for existing ships at major retrofit windows.

ODS detection methods: electronic, bubble, UV dye, ultrasonic

Reg 12.1’s requirement to capture deliberate emissions to the extent practicable depends on detecting leaks early so that they can be repaired before significant ODS is lost. The four principal leak-detection methods used on ships are:

• Electronic leak detector: a handheld device that detects refrigerant by either heated-diode, infrared or corona-discharge sensing. Sensitivity is typically 5-15 grams per year for halogenated refrigerants. The detector is moved slowly along the suspect joint or component; an audible or visual alarm indicates a leak. This is the primary method for routine surveys.
• Bubble test: a soap solution (or proprietary leak-detection foam) is applied to the suspect joint and the formation of bubbles indicates a leak. Sensitivity is approximately 10-30 grams per year. The bubble test is used for confirmation and for locating a leak that the electronic detector has detected at the room level but not at the component level.
• Ultraviolet (UV) dye: a fluorescent dye is added to the refrigerant charge at approximately 5-10 ml per kilogram of refrigerant. Leaking refrigerant deposits dye at the leak site, which fluoresces under a UV lamp (365 nm). Sensitivity is approximately 5-10 grams per year for chronic leaks. The UV method is used for chronic slow-leak diagnosis where the electronic detector and bubble test can’t pinpoint the source.
• Ultrasonic: a microphone-and-amplifier device detects the high-frequency sound generated by the turbulent flow of escaping refrigerant. Sensitivity is approximately 30-100 grams per year (less sensitive than the other methods), but the technique works regardless of the refrigerant type and is therefore useful for natural-refrigerant systems (CO2, ammonia, hydrocarbons) where electronic refrigerant-specific detectors are not applicable.

A best-practice survey regime combines the electronic detector (for the routine baseline scan), the bubble test (for confirmation), the UV dye (for chronic leaks), and the ultrasonic (for natural-refrigerant systems and for very-high-pressure leaks). The detection-method selection should be recorded in the ODS Record Book alongside the leak-discovery date and the corrective action taken.

ODS recovery and class-approved cylinders

Reg 12.1’s requirement to capture refrigerant during recharge or repair is met operationally by transferring the refrigerant from the system to a recovery cylinder before opening the system. The recovery operation uses a recovery unit (a small compressor-condenser-evaporator combination that draws the refrigerant from the system into the cylinder) connected via service hoses to the system’s service ports.

The recovery cylinder must be:

• Class-approved: certified by a recognised classification society (DNV, LR, ABS, BV, NK, RINA, KR, CCS, RS, IRS) under the relevant pressure-vessel rules. Generic “DOT 4BA-300” or “TPED” cylinders are typically acceptable.
• Refrigerant-specific: a cylinder used for one refrigerant must not be used for another without purging and cleaning to a documented procedure. Cross-contamination between refrigerants is a common cause of poor service-stock quality.
• Within fill-mass limits: the cylinder may be filled to no more than approximately 80% of its rated capacity at 70 degrees F (21 degrees C), to provide headspace for thermal expansion. Overfilled cylinders are a serious safety hazard (risk of hydrostatic rupture).
• Marked and labelled: the cylinder must carry a permanent stamp identifying the rated capacity, working pressure, manufacturer, serial number and last hydrostatic test date, and a removable label identifying the current contents (refrigerant type, mass, source).

The recovery operation is logged in the ODS Record Book with the cylinder serial number, the mass recovered, the source equipment, and the date. The recovered refrigerant may be re-used in the same or a similar system on board (after filtering and dehydration), off-loaded to a shore reclamation facility, or off-loaded to a destruction facility. The receiving facility issues a manifest that is filed alongside the ODS Record Book entry.

Venting refrigerant to atmosphere as part of a recovery operation is a direct breach of Reg 12.1 and is a common deficiency at pre-2005 vessels operated by inexperienced crew. PSC officers will sometimes inspect the recovery unit for evidence of recent use (warm or with condensation) as a cross-check that recoveries are being performed when service operations are recorded.

Relationship to SOLAS II-2/10.4 fire-fighting (Halon legacy)

SOLAS Regulation II-2/10.4 governs fixed fire-extinguishing systems for engine rooms, machinery spaces and other category-A machinery spaces. The 1974 SOLAS text permitted halon as the principal total-flooding agent; the 1992 amendments and later revisions progressively restricted halon and required alternative agents for new installations.

The interaction between SOLAS II-2/10.4 and MARPOL Annex VI Reg 12 is as follows:

• Pre-2005 ships with halon total-flooding systems: the system continues to operate under SOLAS grandfathering and under Reg 12.3 grandfathering. The halon charge is logged in the Reg 12.6 ODS Record Book and listed in the Reg 12.7 list and the Reg 12.8 IAPP supplement. Routine maintenance (pressure testing, weight check) is conducted without venting; any service requiring discharge is followed by recovery into a class-approved halon cylinder.
• Post-2005 ships: new installations of halon systems are prohibited under Reg 12.3 (Annex A Group II). The fixed-fire system uses CO2, water mist, inert gas or a clean agent (HFC-227ea, HFC-23, or HFO-1233zd). These agents are not subject to Reg 12 (HFCs and HFOs are not ODS), but the HFC clean agents are subject to the Kigali phasedown and the regional F-Gas/SNAP regimes; HFC-23, with a GWP100 of approximately 12,400, is being progressively phased out in favour of HFO-1233zd (GWP100 approximately 7).
• Shore service: the halon recovery, recycling and destruction infrastructure is now concentrated in a small number of UNEP-coordinated halon banks, principally in Europe, North America and East Asia. Shipowners with halon systems must plan service-stock procurement well in advance of any maintenance window.

The decision tree for a pre-2005 ship with a halon engine-room system is now typically: maintain in service until the next major refit, then retrofit to inert gas or water mist at an estimated cost of USD 200,000-1,000,000 depending on the engine-room volume and the system architecture. A retrofit is usually combined with the 5-yearly SOLAS renewal survey to minimise off-hire.

Alternative refrigerants: HFOs (R-1234yf, R-1234ze)

The hydrofluoroolefins (HFOs) are a class of refrigerants developed in the 2010s as low-GWP replacements for HFCs. HFOs are unsaturated (containing a carbon-carbon double bond) which makes them atmospherically reactive and gives them very short tropospheric lifetimes (days to weeks vs decades for HFCs) and very low GWPs. The two principal shipboard HFOs are:

• R-1234yf (CH2=CFCF3, 2,3,3,3-tetrafluoropropene): a direct replacement for R-134a in mobile and stationary air-conditioning. GWP100 approximately 4 (a 350-fold reduction from R-134a); ODP zero. Mildly flammable (A2L classification).
• R-1234ze(E) (trans-CHF=CHCF3, trans-1,3,3,3-tetrafluoropropene): a replacement for R-134a in centrifugal chillers and in heat-pump applications. GWP100 approximately 6; ODP zero. Mildly flammable (A2L classification, but with a higher LFL than R-1234yf).

HFO chillers are now standard equipment for newbuildings delivered from approximately 2020 onwards. The capital cost premium over an equivalent R-134a chiller is approximately 30-50% at the chiller skid level, due to the higher cost of HFO refrigerant (USD 80-120 per kilogram vs USD 30-50 per kilogram for R-134a) and to the additional A2L safety features (refrigerant leak detection, ventilated machinery space, restricted hot-surface temperatures). The total-installed cost premium at the ship level is somewhat lower (5-15%) because the refrigerant cost is a small fraction of the total chiller cost.

The operational economics favour HFOs over HFCs once the Kigali phasedown and the EU F-Gas Regulation restrictions bite: new HFC-charged equipment with GWP above 750 can’t be installed in the EU from 2025, which effectively forces all new air-conditioning chillers in EU shipyards to be HFO. The US EPA SNAP delistings drive a similar transition for US-flagged ships and US-built newbuildings.

Alternative refrigerants: CO2 (R-744) marine refrigeration

CO2 (R-744) is a natural refrigerant with zero ODP and GWP100 of 1 (the reference). CO2 has been used as a refrigerant since the late 19th century but fell out of favour in the 1930s with the advent of CFCs; it has returned to favour in the 2010s and 2020s as a low-GWP replacement for HFCs in commercial refrigeration and increasingly in marine refrigeration.

CO2 systems operate at very high pressure: the critical point is at 31.1 degrees C and 73.8 bar, so most marine refrigeration applications operate transcritically with the discharge pressure typically 80-120 bar. The high-pressure operation requires stainless-steel pipework, brazed-plate or shell-and-tube heat exchangers rated for 130 bar or higher, and specialist compressors (semi-hermetic reciprocating or scroll). The high-pressure operation also imposes enhanced safety requirements (pressure-relief devices, leak detection, controlled access).

Marine CO2 applications include:

• Reefer-container plant for refrigerated containers carried below deck or on open deck on container ships and reefer ships. CO2 reefer containers are now offered by all major manufacturers (Carrier, Daikin, Star Cool) and are increasingly the standard for new builds.
• Provision-room refrigeration on cruise ships, ferries and merchant vessels. CO2 provisions plants are common on European-built newbuildings.
• Cargo-hold refrigeration on reefer ships carrying chilled or frozen cargo. CO2 is competitive with ammonia for medium-temperature applications and is preferred for cargo proximity because it is non-toxic.

CO2 systems have a capital premium of 30-50% over an equivalent R-134a system, due to the high-pressure pipework and components. The premium is justified by regulatory certainty (CO2 is not subject to any phasedown), by operating-cost savings (CO2 has lower compressor power consumption at low ambient than HFCs), and by carbon-benefit credit under the Kigali baseline.

Alternative refrigerants: ammonia (R-717) for refrigerated cargo

Ammonia (NH3, R-717) is a natural refrigerant with zero ODP and GWP100 of 0 (or near-zero, with some indirect effects via tropospheric chemistry). Ammonia has been the dominant industrial refrigerant for over a century, particularly in fishing and refrigerated cargo on ships where its excellent thermodynamic efficiency and low cost outweigh its toxicity and flammability.

Ammonia systems operate at moderate pressure (typically 8-15 bar) using reciprocating compressors or screw compressors, shell-and-tube or plate heat exchangers (typically of carbon steel rather than stainless steel because ammonia is incompatible with copper alloys), and flooded or direct-expansion evaporators. The principal safety hazards are toxicity (lethal at approximately 5,000 ppm with prolonged exposure, with strong olfactory warning at 5-50 ppm) and flammability (B2L classification, with a relatively narrow flammable range of 16-25% v/v in air).

Marine ammonia applications include:

• Fishing-vessel cargo holds for seawater chilling (RSW) and for direct refrigerated-storage of catch. Ammonia is the dominant refrigerant in Norwegian, Icelandic, Russian and Japanese fishing fleets.
• Reefer-ship cargo holds carrying frozen fish, meat or fruit. Ammonia is the historical standard for European-flagged reefer ships.
• LNG-carrier cold-box refrigeration for re-liquefying boil-off gas on Q-Max and Q-Flex carriers (cascaded with a propane outer cycle).
• Refrigerated-container plant in some designs, although CO2 is now more common for new container designs.

Ammonia systems on ships must comply with the IGC Code (International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk) and the IGF Code for safe handling, including gas-tight machinery rooms, fixed gas detection, emergency ventilation, and personal protective equipment (full-face respirators, chemical-resistant suits) for service personnel. The ammonia charge is not an ODS and is not subject to Reg 12, but the safety regime is more demanding than for HFC or HFO.

Alternative refrigerants: hydrocarbons (R-290, R-600a)

Hydrocarbons are natural refrigerants with zero ODP and GWP100 of 3-5. The two principal shipboard hydrocarbons are:

• R-290 (propane, C3H8): a medium-pressure refrigerant used in small commercial refrigeration, in some heat-pump applications, and in selected reefer-container designs. GWP100 approximately 3; ODP zero. Highly flammable (A3 classification).
• R-600a (isobutane, C4H10): a low-pressure refrigerant used in domestic refrigeration and in some small commercial applications. GWP100 approximately 3; ODP zero. Highly flammable (A3 classification).

Hydrocarbon refrigerants offer excellent thermodynamic efficiency (often better than HFCs and HFOs at the same operating conditions) and very low refrigerant cost (USD 5-15 per kilogram for technical-grade R-290 vs USD 80-120 for R-1234yf). The principal operational constraint is flammability: A3 refrigerants must be charged in small quantities (typically less than 150 grams for an air-conditioning unit, less than 2 kilograms for a commercial refrigeration unit), in hermetic or semi-hermetic systems, with leak detection and ignition-source elimination in the immediate vicinity.

Marine hydrocarbon applications are currently limited to:

• Provision-room refrigeration on small vessels (yachts, fishing vessels, tugs) where the charge size is below the IGF flammability threshold.
• Heat-pump applications for accommodation heating on Norwegian-built ferries where the heat-pump charge is integrated into a sealed package.
• Domestic appliances (galley refrigerators, ice-makers, drinks coolers) where R-600a is now standard for newbuilds.

Hydrocarbons are not on the Reg 12.7 ODS list and are not subject to Reg 12, but they are subject to the SOLAS II-2 flammability provisions and to flag-state safety regulations. The hydrocarbon charge is recorded in the ship’s safety documentation rather than in the ODS Record Book.

EU F-Gas Regulation 517/2014 + 2024 revision

The EU F-Gas Regulation (EC) 517/2014, which entered into force on 1 January 2015, implements the EU regional regime for fluorinated greenhouse gases including HFCs, PFCs and SF6. The Regulation imposes:

• A phasedown of HFC consumption in the EU from a 2009-2012 baseline to a 21% residual by 2030, ahead of the Kigali Amendment trajectory.
• Equipment-specific bans on placing on the market new equipment with high-GWP refrigerants: e.g. new domestic refrigerators with HFCs above GWP 150 banned from 1 January 2015; new commercial refrigeration above GWP 2,500 banned from 1 January 2020; new mobile air-conditioning above GWP 150 banned from 2017.
• Service bans on the use of HFCs above GWP 2,500 to service existing equipment from 1 January 2020 (with exceptions for reclaimed and recycled refrigerant).
• Mandatory leak checks for stationary refrigeration, air-conditioning and heat pumps, with frequency depending on the CO2-equivalent charge (annual for charges above 5 tonnes CO2-eq, semi-annual for charges above 50, quarterly for charges above 500).
• Mandatory recovery of HFCs at end of equipment life, with specified efficiencies.
• Certification of personnel and companies handling HFCs.

The 2024 revision (EU 2024/573) entered into force on 11 March 2024 and tightens the phasedown trajectory, accelerates the equipment-specific bans (e.g. new commercial refrigeration above GWP 150 banned from 2027 instead of the original 2020 schedule), introduces HFO controls for the first time (since some HFOs degrade in the atmosphere to trifluoroacetic acid, a persistent pollutant), and aligns the EU regime with the Kigali Amendment Article 5 trajectory for trade with developing countries.

The F-Gas Regulation applies to EU-flagged vessels and to shipboard equipment installed in EU shipyards for any flag. EU-flagged ship operators must conduct annual leak checks under the F-Gas regime, retain records for 5 years, and use F-Gas-certified personnel for all service operations. The records dovetail with the Reg 12.6 ODS Record Book for those substances on both lists (currently only the few residual HCFC charges; HFCs are F-Gas-only and not on the ODS list).

US SNAP and the AIM Act

The US Significant New Alternatives Policy (SNAP) under Clean Air Act Section 612 (added by the 1990 amendments) is the EPA’s programme for evaluating and listing acceptable substitutes for ODS. SNAP is a technology-forcing regime: substitutes are listed as acceptable, acceptable with use conditions, acceptable with narrowed use limits, unacceptable, or pending review for each end-use sector (refrigeration, air-conditioning, fire suppression, foam-blowing, solvents, etc.).

SNAP listings are sector-specific and substance-specific. The principal SNAP listings relevant to ships are:

• Refrigeration and air-conditioning: most HFCs (R-134a, R-410A, R-404A) were listed as acceptable in the 1990s and 2000s, but several have since been delisted (i.e. moved from acceptable to unacceptable) for specific end-uses under the 2015 SNAP Rule 20 and 2016 SNAP Rule 21. R-134a was delisted for new mobile air-conditioning from model year 2021 onwards.
• Fire suppression: halons remain unacceptable for new total-flooding systems; HFC-227ea is acceptable for total flooding; HFC-23 is acceptable but progressively narrowing under the 2024 SNAP review.
• Foam-blowing: most HCFCs delisted from 2010-2015; HFC-245fa delisted for new appliance foam from 2021.

The AIM Act (American Innovation and Manufacturing Act 2020) authorises EPA to phase down HFC production and consumption in the US along a Kigali-aligned trajectory: 85% reduction from baseline by 2036. The AIM Act SNAP rules issued from 2021 onwards implement the AIM phasedown sector by sector, with 2025 final rules restricting new HFC equipment in commercial refrigeration, residential air-conditioning and heat pumps.

US-flagged ships are subject to AIM Act and SNAP rules for new installations and for service of existing installations using virgin HFCs (reclaimed and recycled HFCs typically remain available). US shipyards delivering newbuildings under the Jones Act must source HFC-charged equipment that complies with the relevant SNAP delistings.

Hong Kong Convention and the Inventory of Hazardous Materials

The Hong Kong International Convention for the Safe and Environmentally Sound Recycling of Ships, adopted in 2009 and in force from 26 June 2025, requires ships of 500 GT or above on international voyages to carry an Inventory of Hazardous Materials (IHM). The IHM is a three-part document: Part I covers hazardous materials present in the ship’s structure and equipment (ODS among them), Part II covers operationally generated wastes, and Part III covers stores.

ODS-charged refrigeration equipment and halon fire-suppression systems appear in IHM Part I as hazardous materials on account of their regulated status under the Montreal Protocol and MARPOL Annex VI Reg 12. The IHM Part I entry for an ODS-charged system records the substance type (e.g. R-22), the approximate quantity in kilograms, and the location (compartment and deck). For ships holding grandfathered HCFC or halon systems, the IHM Part I ODS entry must be consistent with the Reg 12.7 ODS list and the Reg 12.8 IAPP supplement; a discrepancy between the IHM and the IAPP is a documentation deficiency under both instruments.

At end of life, the ship presents its IHM to the ship recycling facility as the handover document for the hazardous-material recovery and disposal obligations. The recycling facility must handle the ODS recovery under the Ship Recycling Plan and under the receiving country’s Montreal Protocol obligations. The Reg 12.1 prohibition on deliberate emissions runs up to and including the recycling event: a ship dismantled at a facility that vents its R-22 charge to atmosphere is in breach of Reg 12.1 unless the flag administration has explicitly delegated the Reg 12.1 obligation to the recycling facility under a formal transfer agreement.

The IHM regime has added a second, independent documentation thread for ODS alongside the existing Reg 12.7 list and Reg 12.8 IAPP supplement. Operators preparing for the Hong Kong Convention compliance window should cross-check their IHM Part I against the IAPP supplement and the Reg 12.7 list and reconcile any discrepancies before the IHM is presented to a flag-state surveyor.

IMO 2024 ODS Phase-Out Review

The IMO conducted a full ODS Phase-Out Review in 2024 as part of the Annex VI air-pollution review under MEPC 81 (March 2024) and MEPC 82 (October 2024). The review covered:

• Effectiveness of Reg 12.3 in eliminating new ODS installations on newbuildings: all post-2005 newbuildings reviewed were CFC-free and all post-2020 newbuildings reviewed were HCFC-free, demonstrating effective implementation.
• Status of grandfathered ODS-charged equipment: the global fleet was estimated to retain approximately 8,000 vessels with at least one HCFC-charged system (mostly R-22 air-conditioning) and approximately 2,500 vessels with halon fire-suppression systems. The grandfathered fleet was projected to decline naturally to fewer than 2,000 HCFC and fewer than 500 halon by 2035 through normal scrapping.
• Service-stock adequacy: R-22 service stock from recycling and reclamation was projected to be adequate for the grandfathered fleet through 2030, with progressive tightening from 2030-2040 as the Montreal Protocol developing-country phase-out completes. Halon service stock was projected to be tight from 2030 onwards.
• HFC monitoring under MEPC 81 amendments: the data collection regime introduced from 2026 was endorsed as the basis for any future HFC phasedown.
• Recommendation on early HCFC retirement: MEPC 82 declined to mandate early HCFC retirement, leaving it to flag-state and operator discretion in light of service-stock economics.

The 2024 review concluded that Reg 12 is effective for new installations and that the natural-scrapping trajectory will eliminate grandfathered ODS by approximately 2040, ahead of the Montreal Protocol developing-country end date. No further IMO ODS phase-out is currently under consideration.

Class society implementation: DNV, LR, ABS, BV, NK, RINA, KR, CCS, RS, IRS

The major IACS classification societies have each issued rules and guidance notes for Reg 12 implementation, covering the IAPP supplement preparation, the ODS Record Book maintenance, the recovery cylinder approval and the survey procedures. The principal class regimes are:

• DNV (Norway/Germany): DNV Rules for Classification of Ships Pt 6 Ch 5 includes the air-pollution survey scheme; DNV Refrigerant Regulations briefing (2024 edition) provides operator guidance on Reg 12 and the F-Gas Regulation. DNV-flagged ships in northern Europe are typically the leaders on HFO and CO2 retrofits.
• Lloyd’s Register (UK): LR Rules for Ships Pt 5 Ch 24 (Refrigeration) and Pt 5 Ch 25 (Fire-Fighting) cover the equipment side; LR Class News briefings provide the operator-facing guidance. LR is particularly active in HFO clean-agent fire-suppression for Asian newbuildings.
• ABS (US): ABS Rules for Building and Classing Marine Vessels Part 4 includes the air-pollution survey; ABS Guide for Air Pollution Prevention covers Reg 12.6 and Reg 12.8 in detail. ABS-flagged ships and US-built newbuildings are subject to additional AIM Act/SNAP compliance.
• Bureau Veritas (France): BV Rules NR 467 cover the air-pollution survey; BV is active in EU shipyard newbuildings on HFO and CO2 implementation under the F-Gas Regulation.
• NK / ClassNK (Japan): NK Rules for the Survey and Construction of Steel Ships Part B include the air-pollution survey; NK is active in Japanese-built newbuildings on HFC-227ea and HFO clean-agent fire-suppression.
• RINA (Italy): RINA Rules for the Classification of Ships Part F Section 8 cover the air-pollution survey.
• KR / Korean Register: KR Rules and Guidance cover the air-pollution survey for Korean-built newbuildings, which constitute a substantial fraction of the global newbuilding output.
• CCS / China Classification Society: CCS Rules for the Construction of Sea-Going Steel Ships cover the air-pollution survey; Chinese newbuildings have been progressively tightening HFO compliance from 2020 onwards.
• RS / Russian Maritime Register: RS Rules cover the air-pollution survey, with particular attention to halon-2402 grandfathered systems on Russian-flag ships.
• IRS / Indian Register of Shipping: IRS Rules cover the air-pollution survey for Indian-flagged newbuildings, which are growing in volume from the 2020s onwards.

The class society performs the annual, intermediate and renewal IAPP surveys at which the Reg 12 documentation is reviewed; for ships classed by an IACS member with delegated authority from the flag state, the class survey is the statutory survey for IAPP purposes. The class society also approves recovery cylinders under its pressure-vessel rules, leak detectors under its instrument rules and service procedures under its operational guidance.

PSC inspection: ODS Record Book vs IAPP supplement

Port state control (PSC) inspection of Reg 12 compliance is conducted under the regional Memoranda of Understanding (Paris MoU, Tokyo MoU, USCG, Caribbean MoU, Mediterranean MoU, Indian Ocean MoU, Black Sea MoU, Riyadh MoU, Vina del Mar Agreement, Abuja MoU). The principal PSC focus areas for Reg 12 are:

• IAPP certificate validity (PSC code 14199): the IAPP certificate must be in date and the supplement must list all ODS-containing equipment. An expired IAPP certificate is a Reg 6 deficiency rather than a Reg 12 deficiency, but it is often the entry point for a Reg 12 inspection.
• ODS Record Book maintenance (PSC code 14601): the Record Book must be on board, current, and consistent with the IAPP supplement. Common deficiencies include missing entries (refrigerant top-up not logged), entries without signatures, entries that reference equipment not on the Reg 12.7 list, and entries that reference dates inconsistent with the chief-engineer log.
• Reg 12.7 list completeness (no specific PSC code, often included under 14601): the list must cover all ODS-containing equipment on board. PSC officers will typically walk the engine room and accommodation cross-checking visible equipment nameplates against the list.
• Recovery cylinder presence (no specific PSC code, judgement-based): the ship must carry at least one class-approved recovery cylinder appropriate to the on-board ODS. Absence of a recovery cylinder, or presence of a non-compliant cylinder, is a Reg 12.1 deficiency in spirit even if no specific code applies.
• Service-stock cylinder labelling (no specific PSC code): R-22 service cylinders for grandfathered HCFC systems must be labelled, secured against rolling, and in date for hydrostatic test.

PSC inspections are typically completed in 2-4 hours for a routine inspection without findings. A finding under code 14601 is graded as operational deficiency (action item, no detention) if the documentation is recoverable, or as detention-grade if the documentation is materially missing or fraudulent. Detention is rare for Reg 12 alone but not unprecedented; the more common pattern is a 14601 finding bundled with other Annex VI deficiencies (BDN issues, NOx Tier mismatch, EIAPP missing) that together cross the detention threshold.

HCFC retrofit cost: USD 50,000-200,000/ship

The decision to retrofit a grandfathered HCFC-charged system to an HFC, HFO or natural-refrigerant alternative is driven by:

• Service-stock economics: R-22 prices have risen from USD 10-20 per kilogram in the early 2010s to USD 40-80 per kilogram in 2025-2026, with further increases projected through 2030. A single recharge of a 200 kg system costs USD 8,000-16,000 just for refrigerant.
• Leak rate: an old chiller may leak 10-20% of its charge per year, so the lifetime refrigerant cost can exceed the retrofit cost over 5-7 years.
• Reliability: aged R-22 systems suffer from compressor wear, control failures and tube-bundle leaks at progressively higher rates from year 15-20 onwards.
• Regulatory exposure: a flag administration or class society may impose an end-of-life date on HCFC-charged equipment, forcing retrofit to a fixed timeline.

The typical retrofit cost ranges are:

• Small accommodation chiller (50-100 kg charge): USD 50,000-80,000 including new chiller, installation, refrigerant charge, controls integration and commissioning. Suitable for small dry-cargo ships, tugs and fishing vessels.
• Medium accommodation chiller (100-300 kg charge): USD 80,000-150,000 including new chiller, pipework modifications, controls integration and commissioning. Suitable for mid-size container ships, tankers and bulk carriers.
• Large multi-chiller plant (300-1,000 kg total charge): USD 150,000-200,000 per chiller, with ship totals reaching USD 600,000-1,500,000 for a multi-chiller plant. Suitable for cruise ships, large container ships and LNG carriers.
• Reefer-container plant (per container): USD 5,000-15,000 per reefer container for a CO2 retrofit, with the capital cost typically rolled into the container leasing rate. Most operators retire and replace rather than retrofit.

The retrofit window is typically aligned with the 5-yearly SOLAS renewal survey to minimise off-hire. A planned retrofit during a 14-day renewal-survey docking adds USD 50,000-200,000 to the retrofit cost in off-hire opportunity cost if the retrofit extends the docking duration; this is usually avoided by pre-staging the new chiller and pipework spool pieces.

HFO/CO2 chiller capital premium

The capital cost premium of HFO and CO2 chillers over equivalent HFC chillers is approximately 30-50% at the equipment level. The premium drivers are:

• Refrigerant cost: HFO at USD 80-120 per kilogram vs HFC at USD 30-50 per kilogram; CO2 at USD 1-3 per kilogram. Refrigerant cost is a small fraction of the chiller cost (typically 2-5%), so this driver is modest.
• Heat exchanger cost: HFO chillers use brazed-plate or shell-and-tube heat exchangers similar to HFC chillers, with comparable costs. CO2 chillers require stainless-steel heat exchangers rated for 130 bar or higher, which can add 20-30% to the heat-exchanger cost.
• Compressor cost: HFO compressors are essentially direct replacements for HFC compressors with minor modifications (different oil, different bearings). CO2 compressors are specialist transcritical units with higher pressure ratings and higher rotational speeds, adding 30-50% to the compressor cost.
• Controls and safety cost: HFO chillers require A2L safety features (refrigerant leak detection, ventilation controls, hot-surface limits) that add 5-10% to the controls cost. CO2 chillers require high-pressure safety features (relief valves, gas-cooler pressure controls, oil-management systems) that add 10-15%.
• Pipework cost: HFO chillers use copper or copper-alloy pipework similar to HFC chillers. CO2 chillers require stainless-steel pipework throughout, adding 30-50% to the pipework cost.

The total chiller-skid-level premium is approximately 30-50% for HFO over HFC and 40-60% for CO2 over HFC. The total-installed cost premium at the ship level is somewhat lower (10-20% for HFO, 20-30% for CO2) because the refrigerant and heat-exchanger costs are a fraction of the total installed cost (which includes pipework runs, controls integration, electrical supply, and commissioning).

The premium is typically recovered over 5-10 years through avoided HFC service costs (in regions with F-Gas/SNAP enforcement), avoided HFC phase-out retrofit costs (in regions where high-GWP HFCs are progressively delisted), and operating-cost savings from higher seasonal efficiency in cooler ambient (CO2) or from lower refrigerant top-up rates (HFO and CO2 typically have lower lifetime leak rates due to better gasket and seal compatibility).

MEPC 81 (2024) HFC DCS amendment from 2026

MEPC 81 (March 2024) adopted amendments to the Annex VI Regulation 22A data collection system (DCS) for fuel-oil consumption, extending the DCS to include HFC consumption from calendar year 2026 onwards. The amendments were adopted by Resolution MEPC.385(81) and are scheduled to enter into force on 1 March 2026 under the tacit acceptance procedure of MARPOL Article 16.

The HFC DCS amendment requires every ship of 5,000 GT or above (the same threshold as the fuel DCS) to report annually:

• HFC charge mass for each piece of equipment containing HFC, in kilograms by substance type
• HFC top-up mass during the calendar year, in kilograms by substance type (for each piece of equipment)
• GWP100-weighted equivalent CO2 emissions from HFC top-ups, in metric tonnes CO2-equivalent
• Equipment inventory as of 31 December of the reporting year

The data is submitted to the IMO through the flag administration in the same submission cycle as the fuel DCS data (by 31 March of the following year). The data is aggregated by the IMO Secretariat and published in the IMO GHG Study updates and in dedicated HFC Status Reports.

The HFC DCS is a monitoring-only measure; it does not impose a phasedown or any direct limitation. It establishes the data baseline against which any future IMO HFC phasedown could be calibrated, and it provides operators and regulators with visibility on the shipping-industry HFC inventory and emissions. The dataset will be progressively extended through 2026-2030 with further granularity (e.g. service stock vs equipment charge, leak rate vs top-up rate) as MEPC reviews the regime.

The HFC DCS does not modify the Reg 12 ODS Record Book regime; the two regimes operate in parallel, with the ODS Record Book covering the regulated ODS (CFCs, HCFCs, halons, methyl bromide) and the HFC DCS covering the Kigali-controlled HFCs. Operators must maintain both books for the relevant substances.

Prohibition timeline and the quantities behind it

Regulation 12 is a set of discrete prohibitions and documentation duties, not a continuous limit function. The two date thresholds and the substance metrics that drive them are the load-bearing numbers an engineer needs.

The new-installation ban on CFCs and halons takes the form:

That 19 May 2005 cut-off is the entry into force date of Annex VI under Article 16 read with the 1997 adoption text. Ratification by 15 states representing 50% of world tonnage was reached on 18 May 2004, which triggered the 12-month entry into force. The HCFC ban runs to a later date:

The 1 January 2020 cut-off is calibrated against the Article 2 developed-country consumption phase-out of HCFCs under the Copenhagen Amendment (1992) as accelerated by the 2007 Montreal Adjustment: a 100% phase-out of HCFC consumption by 2020 for developed countries, with a 0.5% service-stock allowance through 2030. An existing ship can’t install a new HCFC-charged chiller after that date even where its older HCFC chillers keep running.

The ozone-depletion potentials that put each substance class on or off the prohibition list span more than two orders of magnitude:

The CFC ODP near 1.0 reflects the stratospheric chlorine release per kilogram, normalised to R-11. R-22’s ODP of 0.055 reflects its shorter atmospheric lifetime (12 years against 45 years for R-12) and lower chlorine fraction. Halon-1301’s ODP of 10 reflects the bromine catalytic efficiency, roughly 50 times that of chlorine in stratospheric ozone destruction, scaled by the bromine fraction. The greenhouse-gas contrast that drives the Kigali transition is just as wide:

R-134a’s GWP of about 1,430 over 100 years reflects its infrared absorption in the 8-12 micron atmospheric window weighted by a 14-year residence. R-1234yf’s GWP near 4 reflects an atmospheric lifetime of approximately 11 days, set by OH radical attack on the unsaturated bond. The shift away from high-GWP HFCs runs along the Kigali trajectory: HFC phasedown under the Kigali Amendment drives new installations toward HFO, CO2, NH3 and hydrocarbon alternatives with GWPs below 10.

CO2-equivalent emissions and the EU F-Gas leak-check trigger

The mass-times-GWP product is the single arithmetic operation an operator runs on every top-up. A refrigerant top-up releases, in CO2-equivalent terms:

This is the Kigali baseline metric that calibrates the global HFC phasedown, the basis for the EU F-Gas leak-check thresholds (5, 50, 500 tonnes CO2-eq), and the basis for the SNAP delisting decisions in the US. The same product sets the annual leak-check obligation:

Stationary equipment with a charge above 5 tonnes CO2-eq draws an annual check; above 50, semi-annual; above 500, quarterly. There is no Reg 12 leak-check frequency mandate, so the F-Gas thresholds are the de facto standard for stationary equipment on EU-flagged ships and a widely adopted industry benchmark elsewhere.

The ODS Record Book under Reg 12.6 is retained for at least 5 years after the last entry. That 5-year horizon is calibrated to the IAPP renewal-survey cycle: every IAPP certificate is renewed at most every 5 years, and the renewal surveyor must review the ODS history since the last renewal. The 5-year retention keeps the record available at the renewal survey.

What the framework assumes

The Reg 12 documentation chain holds only if a set of preconditions is met, and each is a point a PSC officer or class surveyor can probe.

The substance classification must be correctly performed at the equipment-installation stage. Equipment charged with a substance kept off the Reg 12.7 list because the installer judged it non-ODS is a deficiency even where the misclassification is honest.

The ODS Record Book entries must be made at the time of the event by a competent person. Retrospective entries don’t satisfy Reg 12 in spirit even where they are factually correct.

The recovery cylinder must be class-approved, refrigerant-specific, within fill-mass limits, and within hydrostatic-test date.

The leak detection must run at intervals matched to the equipment service history. The EU F-Gas Regulation supplies the de facto standard for stationary equipment above 5 tonnes CO2-eq.

The flag administration must maintain a competent authority for IAPP certification and ODS Record Book audit. Administrations with weak ODS oversight can issue compliant-looking IAPP supplements that mask operational non-compliance.

Worked example: a grandfathered R-22 chiller event

A 4,500 TEU container ship built in 2003 (pre-2005, grandfathered) runs two R-22 air-conditioning chillers in the accommodation block. Chiller A holds a 200 kg R-22 charge, installed 2003, leaking at approximately 8% per year. Chiller B holds 180 kg, installed 2003, leaking at approximately 6% per year.

The ODS Record Book at the start of 2026 shows the 2025 top-up history: Chiller A received 18 kg R-22 in March 2025 and 14 kg in October 2025; Chiller B received 12 kg in June 2025. Total 2025 R-22 top-up was 44 kg from on-board service stock, which started 2025 at 80 kg and ended at 36 kg. The GWP-equivalent emissions, with R-22 at GWP100 = 1,810, work out to 44 kg x 1,810 / 1,000 = 80 tonnes CO2-eq.

The IAPP supplement Section 2.1 lists both chillers with their refrigerant type (R-22), charge mass (200 kg, 180 kg), and installation year (2003). The Reg 12.7 list reproduces the same data and adds the manufacturer (Carrier 30HXC), serial numbers, and engine-room location (frame 65, port and starboard).

In March 2026, Chiller A leaks rapidly during a routine watch and the watch engineer picks up R-22 in the engine-room atmosphere on the fixed detector. The chief engineer isolates the chiller and connects the recovery unit, then recovers approximately 150 kg of the 200 kg charge into a class-approved recovery cylinder; the remaining 50 kg has already leaked to atmosphere through the failed seal. The leak event is logged in the ODS Record Book with the date (12 March 2026), the equipment (Chiller A, IAPP supplement reference 2.1.1), the recovered mass (150 kg), the unrecovered mass (50 kg), and the corrective action (compressor seal replacement at next docking). An unscheduled top-up entry follows in May 2026 when the seal is replaced and the chiller is recharged with 200 kg of reclaimed R-22 from a shore service supplier, and the IAPP supplement is updated at the next annual survey to reflect the May 2026 service date.

The 50 kg unrecovered release is a Reg 12.1 deviation but not a deliberate emission within the meaning of the prohibition; it’s a mechanical failure that the chief engineer addressed at once. The Tokyo MoU PSC inspection in August 2026 reviews the Record Book entries, finds them complete and consistent with the IAPP supplement, and closes without deficiency. The case shows that a grandfathered HCFC-charged ship operates compliantly under Reg 12 when the documentation regime is kept tight and the recovery gear is in place.

Limitations

Reg 12 has hard edges where its scope ends or where flag-state discretion takes over. These are the cases that produce the most disputed PSC findings.

• Sealed hermetic units: Galley refrigerators, drinks coolers and similar factory-sealed appliances are usually excluded from the Reg 12.7 list under most flag-state implementations, since they’re sealed and hold small quantities (under 1 kg) of refrigerant. The threshold is a flag-state limitation: some flags set 3 kg, some 5 kg.
• Mobile equipment: Reefer containers brought on board with cargo are not the ship operator’s ODS for Reg 12 purposes; they’re the container operator’s ODS, recorded in the container operator’s F-Gas registry. The ship’s Reg 12.7 list covers only ship-installed equipment.
• Drop-in replacement refrigerants: A blend such as R-407C used as a drop-in for R-22 is not an ODS (it holds no chlorine) but is subject to Kigali phasedown as an HFC blend. The Reg 12 documentation moves from the R-22 listing to an HFC listing at changeover, with the changeover logged in the Record Book.
• Decommissioned equipment: An ODS-charged unit removed from service must have its working charge recovered under Reg 12.1; once dismantled and scrapped, the recovery mass is logged in the Record Book and the unit is struck from the Reg 12.7 list.
• Sale of equipment off the ship: An ODS-charged unit sold to a shore facility while still holding its charge requires that facility to be competent to handle ODS under the receiving country’s regulations; the transfer is logged in the Record Book with recipient details.
• End-of-life ship recycling: A ship recycled at an IHM-compliant facility under the Hong Kong Convention (in force 26 June 2025) transfers its remaining ODS-charged equipment to the facility, which handles ODS recovery under the receiving country’s regulations. The Record Book closing entry records the transfer.
• Flag change: A flag change calls for a new IAPP certificate from the receiving flag, with the IAPP supplement re-issued to include the ODS list. The Record Book runs on uninterrupted; some receiving flags require certified translation of the existing Record Book.
• Naval and government-owned vessels: Excluded from MARPOL under Article 3.3; flag-state-specific ODS regimes apply in their place.

ODP and GWP figures are model-derived integrals over assumed atmospheric lifetimes, so the values cited here track the IPCC and WMO assessment in force at the time of writing and shift by a few percent between assessment cycles. Use the value the governing regulation references, not the latest scientific figure, when a compliance determination turns on the number.

Regulatory basis

The instruments behind Reg 12 are the MARPOL chapter itself, the IMO resolutions that built and extended it, and the Montreal Protocol family it implements at sea.

• MARPOL Annex VI Regulation 12: ODS prohibition, ODS Record Book, IAPP supplement listing
• Resolution MEPC.176(58): 2008 amendments establishing the modern Reg 12 regime
• Resolution MEPC.385(81): 2024 amendments adding HFC DCS reporting from 2026
• Montreal Protocol on Substances that Deplete the Ozone Layer (1987): parent global treaty
• London Amendment (1990): extension to carbon tetrachloride and methyl chloroform
• Copenhagen Amendment (1992): extension to HCFCs and methyl bromide
• Beijing Amendment (1999): HCFC production controls
• Kigali Amendment (2016, in force 1 January 2019): HFC phasedown
• Hong Kong Convention (2009, in force 26 June 2025): IHM Part I ODS listing at end of life
• Regulation (EU) 2024/573: EU F-Gas Regulation (superseding 517/2014)
• AIM Act 2020 + EPA SNAP: US HFC and ODS phase-down

Common compliance errors

The recurring Reg 12 mistakes cluster around the boundary between ODS and HFC, around the documentation chain, and around the recovery duty.

• Treating HFCs as ODS: HFCs aren’t ozone-depleting and aren’t subject to Reg 12.3 or the Reg 12.6 Record Book. They fall under Kigali phasedown and F-Gas/SNAP regional rules, recorded separately.
• Treating the 19 May 2005 ban as covering all ODS without exception: HCFCs were exempt until 1 January 2020 under the explicit Reg 12.3 exception.
• Failing to log small top-ups: a 1-2 kg top-up after a minor service is a Reg 12.6 entry and must be logged. There is no de minimis threshold.
• Treating the ODS Record Book as a commercial document: it’s a statutory document, and entries can’t be retroactively altered or deleted. Errors are corrected by a dated correction entry that references the original, not by erasure.
• Confusing the Reg 12.7 list with the Reg 12.8 IAPP supplement: the two are distinct documents that must hold consistent information. The IAPP supplement is updated at IAPP surveys; the Reg 12.7 list is updated continuously.
• Overlooking the F-Gas Regulation for EU-flagged ships: it imposes obligations beyond Reg 12, including mandatory leak checks, certified personnel, and HFC reporting.
• Overlooking the AIM Act/SNAP for US-flagged ships and US-built newbuildings: the AIM Act phasedown imposes substance restrictions beyond Reg 12.
• Failing to recover refrigerant during decommissioning: a unit removed from service still holds its working charge until that charge is recovered. Scrapping a charged unit is a direct Reg 12.1 violation.
• Treating methyl-bromide fumigation as a Reg 12 violation: cargo fumigation under the QPS exception is regulated under SOLAS VI/4 and the IMSBC Code, not Reg 12.
• Overlooking the Hong Kong Convention IHM Part I for ODS: from 26 June 2025, ships of 500 GT or above require an IHM that must list ODS-charged equipment consistently with the Reg 12.7 list.

See also

• MARPOL Annex VI: parent annex (air pollution)
• MARPOL Annex VI Regulation 13: NOx Tier I, II, III: companion air-pollution regulation
• MARPOL Annex VI Regulation 14: sulphur cap: companion air-pollution regulation
• MARPOL Annex VI Regulation 18: Bunker Delivery Note: companion documentation regulation
• MARPOL Convention: top-level treaty
• What is EEDI: energy-efficiency design index
• What is EEXI: energy-efficiency existing-ship index
• What is CII: carbon-intensity indicator
• Hong Kong Convention: ship recycling and IHM (in force 26 June 2025)
• Per-fuel WTW: VLSFO and MGO
• Helsinki Convention 1992: Baltic regional regime
• MARPOL Annex I: oil-pollution regime
• MARPOL Annex I Regulation 15: discharge control: companion oil-discharge regulation
• IMO 2020 sulphur cap: Reg 14 sulphur 0.50% global cap
• Calculator catalogue

Related calculators

• Ozone-Depleting Substances - Phase-Out Check
• MARPOL Annex VI/12 - Ozone-depleting substances
• MARPOL Annex V/10 - Garbage Record Book
• MARPOL Annex II/16 - Cargo Record Book
• MARPOL Annex I/36 - Oil Record Book Part II
• MARPOL Annex I/17 - Oil record book Part I
• MARPOL Annex III - Packaged Harmful Substances
• MARPOL Annex VI/7 - Duration of certificate