Operational Guide · Registers & Logbooks

# Ammonia Engines: Safety and Reliability of the First Units in Service

After years of bench testing only, two-stroke dual-fuel ammonia engines enter real commercial service in 2026: fuel toxicity calls for a safety approach different from the one already familiar for methanol.

ammonia dual-fuel two-stroke engines fuel safety

## Operational Explanation

Following delivery of the first two-stroke dual-fuel ammonia engines by leading manufacturers between late 2025 and early 2026, 2026 marks the entry into real commercial service of the first units: three ammonia-fuelled Capesize bulk carriers intended for iron ore and coking coal transport, in addition to the world's first ocean-going vessel with dual-fuel ammonia propulsion (a gas carrier), already delivered.

Unlike methanol, whose main criticality is its low flash point and near-invisible flame, ammonia poses a primary risk of toxicity: dedicated engines integrate specific containment systems, leak detection sensors, dedicated ventilation, double-walled piping, a release mitigation system with a knockout drum and water scrubbing, as well as fuel valve trains with double block and bleed isolation and nitrogen purging systems. Crew training on these specific systems, distinct from that already acquired for other alternative fuels, is an operational prerequisite, not an option.

MSC 111 update (May 2026): the interim regulatory framework for ammonia as fuel has taken a formal step forward with the approval of dedicated Interim Guidelines and specific interim guidelines for the training of seafarers serving on ships using ammonia as fuel (similar to those already approved for methanol). The final amendments to SOLAS and the IGF Code remain expected to enter into force from 1 July 2028.

## Regulatory Reference

IGF Code (International Code of Safety for Ships using Gases or other Low-flashpoint Fuels), made mandatory by SOLAS Chapter II-1 Part G, provides the general regulatory framework. At MSC 111 (May 2026) the Interim Guidelines for use of ammonia cargo as fuel on gas carriers were approved, focused on the safety of areas outside the cargo zone, together with dedicated interim guidelines for crew training on ammonia-fuelled ships; the final amendments to SOLAS and the IGF Code are expected to enter into force from 1 July 2028, subject to adoption at MSC 112 (December 2026). Until then, the first units in service operate under engine manufacturer type approval, the interim guidelines, and the rules of the applicable Classification Society.

## Scope of Application

Ships with two-stroke dual-fuel ammonia engines in commercial service from 2026, including Capesize bulk carriers and gas carriers; applicable by future extension to other fleet segments as the technology matures.

## Procedure / How to Complete It

1. Train the crew specifically on ammonia containment, leak detection and release mitigation systems, distinct from those of other already familiar alternative fuels.
2. Periodically verify the integrity of double-walled piping and dedicated ventilation systems in ammonia engine spaces.
3. Regularly test the release mitigation system (knockout drum, water scrubbing) according to manufacturer procedures.
4. Maintain specific response protocols for toxic ammonia exposure, distinct from general fire protocols, including dedicated personal protective equipment.
5. Monitor the engine's digital connectivity data (where available) for remote support and operational optimization offered by the manufacturer.
6. Align crew training programmes with the Interim Guidelines for training of seafarers on ammonia-fuelled ships approved at MSC 111 (May 2026).

## Practical Example

Example: the crew of an ammonia-fuelled Capesize bulk carrier follows a dedicated training programme on leak detection systems and the release mitigation system before entering commercial service, distinct from the training already received for other alternative fuels present in the fleet.

## Real Cases

The more than 150,000 hours of design and validation work and over 800 tests declared by one of the leading ammonia engine manufacturers reflect the industry's caution in introducing into real commercial service a fuel with a risk profile (toxicity) substantially different from that of alternative fuels already in use, motivating an investment in redundant safety (double block/bleed, double wall, dedicated mitigation systems) greater than what is typically required for methanol.

## Common Mistakes Mistake Library

Mistake | Consequence | How to avoid it
--- | --- | ---
Crew training on alternative fuels treated generically, without distinguishing specific protocols for ammonia toxicity from the mere flammability of other fuels | Inadequate response in the event of a release or exposure, given the different risk profile | Always train the crew with specific and distinct protocols for every alternative fuel present on board, particularly for ammonia toxicity
Verification of double-walled piping integrity and dedicated ventilation systems postponed or treated as a generic routine check | Risk of an uncontained release in the event of undetected deterioration | Include verification of these specific systems in a dedicated maintenance programme, distinct from general engine maintenance

## PSC Observations

PSC verification of safety systems specific to ammonia engines is still under procedural development, given the novelty of the technology in commercial service; growing attention to crew training protocols and documentation of release mitigation systems is to be expected.

## Operational Tips

- Don't treat ammonia training as an extension of training already acquired for methanol: the primary risk profile (toxicity vs. flammability) is substantially different.
- Periodically verify, with a dedicated programme, the integrity of specific containment and mitigation systems, not only during general engine maintenance.
- Make use of the engine's digital connectivity, where available, for manufacturer remote support at a stage when fleet operational experience is still limited.

## Checklist

- Crew specifically trained on ammonia containment, leak detection and release mitigation systems
- Integrity of double-walled piping and dedicated ventilation systems periodically verified
- Release mitigation system (knockout drum, water scrubbing) tested according to manufacturer procedures
- Toxic exposure response protocols distinct from general fire protocols, with dedicated PPE available
- Engine digital connectivity (where available) monitored for manufacturer remote support
- Training programmes aligned with the MSC 111 (May 2026) Interim Guidelines for seafarers on ammonia-fuelled ships

## FAQ

Why do ammonia engines require a different safety approach from methanol engines?
Because ammonia's primary risk is toxicity in the event of a release, while methanol mainly poses a flammability risk with a nearly invisible flame: safety protocols, training and PPE must be specific to each risk profile.
What specific safety systems do ammonia engines integrate?
Containment systems, leak detection sensors, dedicated ventilation, double-walled piping, a release mitigation system with a knockout drum and water scrubbing, and fuel valve trains with double block/bleed isolation and nitrogen purging.
When did the first ships with ammonia engines enter service?
In 2026, with the entry into service of ammonia-fuelled Capesize bulk carriers and the delivery of the world's first ocean-going vessel with dual-fuel ammonia propulsion.
Where does the IMO regulatory framework for ammonia as fuel currently stand?
At MSC 111 (May 2026) the Interim Guidelines for use of ammonia cargo as fuel on gas carriers and interim guidelines for seafarer training were approved; the final amendments to SOLAS and the IGF Code are expected to enter into force from 1 July 2028.
🎬 Additional photos, videos and interactive diagrams for this topic will be available in a future version of the platform.

## Related Topics

Methanol Engines: Reliability and Spare Parts Management Fire Safety of Onboard Battery Rooms (BESS)

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