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Home › Engine Room › Ammonia Engines: Safety and Reliability of the First Units in Service
Operational guide · Safety & equipment

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

For ships using ammonia as fuel, distinguish MSC.1/Circ.1687 from the IGC/MSC.1/Circ.1702 route for gas carriers using cargo as fuel. Consider STCW.7/Circ.27 for training and the ship’s approval conditions.

ammoniadual-fueltwo-stroke enginesfuel safety

Operational Explanation

For ships using ammonia as fuel, distinguish MSC.1/Circ.1687 from the IGC/MSC.1/Circ.1702 route for gas carriers using cargo as fuel. Consider STCW.7/Circ.27 for training and the ship’s approval conditions.

Regulatory Reference

MSC.1/Circ.1687; MSC.1/Circ.1702; STCW.7/Circ.27; applicable SOLAS/IGF or IGC and ship-specific approval.

MSC.1/Circ.1687 excludes ships covered by the IGC Code from its scope. MSC.1/Circ.1702 addresses ammonia cargo used as fuel: the two references are not cumulative obligations for every ship. Identify the ship’s approval route first. IMO MSC.1/Circ.1687, 1.1.

MSC.1/Circ.1702 (7 July 2026) supplements IGC chapter 16 for gas carriers using ammonia cargo as fuel. Its annex, 2.1.1, applies outside the cargo area except where risk assessment or specific provisions require otherwise. The whole-system risk assessment also covers fuel arrangements inside the cargo area (2.5.1). Ship- and equipment-specific familiarization is addressed in 2.4.1. MSC.1/Circ.1702, annex 2.1.1 / 2.4.1 / 2.5.1.

Failure assessment should include leak containment and isolation, detection, ventilation and protection availability, as well as the engine. Maintenance procedures should cover all ammonia installations and personnel should have protection appropriate to the operation’s exposure risk; the emergency plan must also address toxic exposure. IMO MSC.1/Circ.1687, chapters 4, 18 and 20.

To assess reliability, record actual operating hours on ammonia, operating mode, failures, downtime, interventions and component version. Separate trial, delivery and commercial-service evidence: a single demonstration does not quantify fleet reliability. IMO: ISM maintenance and safety management.

STCW.7/Circ.27 (6 July 2026), annex 1–3, provides ammonia-specific training guidance based on Circ.25. It distinguishes familiarization for all seafarers, basic training for designated safety duties and advanced training for masters, engineer officers and personnel immediately responsible for fuel and systems. Applicable mandatory instruments take precedence (1.3); verify training and evidence accepted by the Administration. IMO — STCW.7/Circ.27.

Scope of Application

Technology-based: ships approved to use ammonia as fuel. Ordered, engine delivered, ship delivered and commercial service are distinct statuses requiring primary owner/yard/class evidence.

Procedure / How to Complete It

  1. Identify ship type and ammonia arrangement.
  2. Select 1687 or cargo-as-fuel 1702 within scope.
  3. Apply training guidance 27 and approved competence requirements.
  4. Follow design-specific toxicity, detection, ventilation, PPE, emergency and maintenance controls.
  5. Do not state a mandatory amendment/date until IMO adopts and publishes it.
  6. Remove fleet firsts without a primary source and precise status.

Practical Example

A gas carrier using ammonia cargo as fuel checks 1702 and IGC; another ammonia-fuelled ship uses 1687 and its SOLAS/IGF/alternative approval.

What Typically Goes Wrong

Confusing the three interim instruments, imposing 1 July 2028, or citing first ships/commercial service without owner/yard/class source and status.

Common Mistakes Mistake Library

MistakeConsequenceHow to Avoid It
Confusing the three interim instruments, imposing 1 July 2028, or citing first ships/commercial service without owner/yard/class source and status.Non-compliant decision or treatmentFollow the approved arrangement and applicable sources

What the PSCO Checks

Check the approval route, manuals, training and familiarisation, detection and protection system status, maintenance and defect management. Compare leak and exposure response capability with the ship’s plan and assigned duties.

Operational Tips

Preparation checklist

FAQ

What is the general ammonia guidance?
MSC.1/Circ.1687; cargo as fuel has separate MSC.1/Circ.1702.
Which training guidance?
STCW.7/Circ.27, listed by IMO in July 2026 for ammonia, within the framework of generic guidance STCW.7/Circ.25. Verify flag-accepted competence and training requirements for the duties performed.
Do amendments enter on 1 July 2028?
Do not state that without a mandatory instrument adopted and indexed by IMO.

Related Topics

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

Last substantive revision of this page: 16 September 2026 · page fingerprint 94c2ddb0c51c