Mariners Digest
The IGF Code and alternative fuels: where methanol, ammonia and hydrogen stand
The IGF Code has been mandatory under SOLAS since 1 January 2017 for ships using gas or other low-flashpoint fuels, but its detailed rules cover natural gas only. Ships burning methanol, ammonia or hydrogen are approved case by case through the Code’s alternative design route, using IMO’s interim guidelines: methanol since 2020, ammonia since 2024 and hydrogen since MSC 111 in May 2026.
What the IGF Code is and which ships it covers
- Adopted by resolution MSC.391(95) on 11 June 2015, and made mandatory through amendments to SOLAS chapters II-1 and II-2; it took effect on 1 January 2017.
- Applies to ships to which part G of SOLAS chapter II-1 applies, that is ships using gases or other low-flashpoint fuels, other than gas carriers, which are covered by the IGC Code. IMO invites flag States to apply it, as far as practicable, to cargo ships under 500 GT as well.
- Low-flashpoint fuel means a gaseous or liquid fuel with a flashpoint lower than SOLAS regulation II-2/4 otherwise allows (60°C for oil fuel).
- Part A-1 holds the specific requirements for natural gas. IMO says requirements for other low-flashpoint fuels will be added to the Code as they are developed.
- Alternative design (section 2.3): a fuel the Code does not yet address can be used if it meets the Code’s goal and functional requirements with an equivalent level of safety, demonstrated under SOLAS regulation II-1/55 and approved by the Administration.
Sources: IMO, resolution MSC.391(95) (IGF Code text, PDF), IGF Code page and Amendments to IMO instruments (60°C flashpoint); read on 13 November 2026.
IMO interim guidelines for each fuel
| Fuel or system | Circular | Approved by | Issued |
|---|---|---|---|
| Methyl / ethyl alcohol (methanol, ethanol) | MSC.1/Circ.1621 | MSC 102 (Nov 2020) | 7 Dec 2020 |
| Fuel cell power installations | MSC.1/Circ.1647 | MSC 105 (Apr 2022) | 15 Jun 2022 |
| LPG fuels | MSC.1/Circ.1666 | MSC 107 (Jun 2023) | 30 Jun 2023 |
| LPG cargo as fuel (gas carriers, IGC Code) | MSC.1/Circ.1679 | MSC 108 (May 2024) | 1 Jul 2024 |
| Ammonia | MSC.1/Circ.1687 | MSC 109 (Dec 2024) | 26 Feb 2025 |
| Hydrogen | MSC.1/Circ.1701 | MSC 111 (May 2026) | 7 Jul 2026 |
| Ammonia cargo as fuel (gas carriers, IGC Code) | MSC.1/Circ.1702 | MSC 111 (May 2026) | 7 Jul 2026 |
Sources: the circulars themselves (PDF, cover pages), listed on IMO’s Future Fuels and Technology safety guidelines page; read on 13 November 2026.
What “interim” means in practice
- The guidelines are not mandatory; they give Administrations a common basis for approving an alternative design. Most state their aim as at least the same level of safety and reliability as comparable conventional oil-fuelled machinery (the ammonia-cargo guidelines compare with LNG-fuelled machinery).
- IMO calls the ammonia guidelines provisional and high-level, goal-based guidance that does not address every provision in detail and will be revised once experience is available.
- The Maritime Safety Committee keeps each set under review in the light of experience, and most of the circulars invite Member States to report the experience they gain.
- The Sub-Committee on Carriage of Cargoes and Containers (CCC) continues to develop or amend safety rules for LNG, hydrogen, ammonia, methyl/ethyl alcohol, low-flashpoint oil fuels and fuel cells.
Sources: IMO, MSC.1/Circ.1687 paragraphs 2 and 3, MSC.1/Circ.1701 and the MSC 111 meeting summary; read on 13 November 2026.
IGF Code amendments: recent and next
| Date | Change | Resolution |
|---|---|---|
| 1 Jan 2026 | IGF Code amendments in force | MSC.551(108) |
| 1 Jan 2026 | IGF and IGC Codes: high manganese austenitic steel for cryogenic fuel and cargo tanks | MSC.523(106) |
| 1 Jan 2028 | Further IGF Code amendments in force | MSC.567(109) |
| 1 Jul 2028 (planned) | “One ship, one code”: SOLAS II-1 and IGF Code changes for gas carriers using alternative fuels; drafts approved at MSC 111, for adoption at MSC 112 | Not yet adopted |
Sources: IMO, Amendments to IMO instruments: upcoming and recent entry into force dates and the MSC 111 meeting summary; read on 13 November 2026. What changed on 1 January 2026 is listed on our SOLAS amendments 2026 page.
Crew training
- STCW.7/Circ.25 (8 September 2025): generic interim guidelines on training for seafarers on ships using alternative fuels and new technologies.
- STCW.7/Circ.27 (6 July 2026): interim guidelines on training for seafarers on ships using ammonia as fuel.
- MSC 111 also approved interim guidelines on training for seafarers on ships using methyl/ethyl alcohol as fuel.
Sources: the two circulars (PDF) and the MSC 111 meeting summary; read on 13 November 2026. See also our page on the STCW comprehensive review.
Questions
Which fuels does the IGF Code cover?
The detailed requirements in part A-1 of the IGF Code cover natural gas. For any other low-flashpoint fuel, such as methanol, ammonia or hydrogen, the ship must show through the alternative design route that it meets the Code's goals and functional requirements, approved by the flag Administration.
Are the IMO interim guidelines for methanol, ammonia and hydrogen mandatory?
No. They are MSC circulars, not SOLAS amendments. They give Administrations a common basis for approving an alternative design under the IGF Code, and IMO keeps them under review as experience is gained.
Which IMO circular covers methanol as fuel?
MSC.1/Circ.1621, the Interim guidelines for the safety of ships using methyl/ethyl alcohol as fuel, approved by MSC 102 in November 2020 and issued on 7 December 2020.
Which IMO circular covers ammonia as fuel?
MSC.1/Circ.1687, approved by MSC 109 (2 to 6 December 2024) and issued on 26 February 2025. IMO describes it as provisional, high-level goal-based guidance. Gas carriers burning their ammonia cargo have a separate circular, MSC.1/Circ.1702 of 7 July 2026, linked to the IGC Code.
Are there IMO rules for hydrogen-fuelled ships?
MSC 111 (13 to 22 May 2026) approved the Interim guidelines for the safety of ships using hydrogen as fuel, issued as MSC.1/Circ.1701 on 7 July 2026. Ships using fuel cells can also refer to MSC.1/Circ.1647 of 15 June 2022.
Is there training guidance for crews on ammonia or methanol ships?
Yes, as interim guidance: generic guidelines for alternative fuels and new technologies (STCW.7/Circ.25, 8 September 2025), and ammonia-specific guidelines (STCW.7/Circ.27, 6 July 2026). MSC 111 also approved interim training guidelines for methyl/ethyl alcohol.
Mariners Digest is made by CryoSim. It is not affiliated with or endorsed by IMO. This page summarises IMO’s published documents in CryoSim’s own words and is not legal or technical advice; SOLAS, the IGF and IGC Codes, your flag State’s requirements and your class society’s rules always take precedence. Published 2026-11-13, updated 2026-11-13. See also the IMO Net-Zero Framework, FuelEU Maritime, SOLAS amendments in force in 2026 and Mariners Digest.
