Adopted in June 2025, IMO Resolution MSC.581(110) introduces strengthened requirements for enclosed space entry, expanding safety and procedural obligations for shipowners, operators, and shore staff.
Overview
In June 2025, the International Maritime Organization adopted Resolution MSC.581(110), updating the regulatory framework governing enclosed space entry under SOLAS Regulation III/19. The new standards build on Resolution A.1050(27) and address persistent onboard incidents linked to oxygen deficiency and toxic gas exposure.
The revision introduces broader testing parameters, documentation standards, and joint-assessment protocols, requiring all vessels to maintain an Enclosed Space Register, ensure real-time gas monitoring, and formalise risk briefings between ship and shore personnel. The aim is to create a safer, more accountable working environment, where every crew member is equipped, informed, and authorised to prevent unsafe entry.
Key Requirements
1. Gas Detection
New Requirement: Personal detectors must measure O₂, CO, H₂S, LEL, and CO₂.
Action Required Onboard: Replace or upgrade to approved 5-gas detectors. Update calibration records and inventories.
2. Enclosed Space Register
New Requirement: Each vessel must record all enclosed, connected, and adjacent spaces with hazard classification.
Action Required Onboard: Create and maintain a detailed Enclosed Space Register listing space IDs, hazards, and inspection frequencies.
3. Connected and Adjacent Spaces
New Requirement: CO₂ concentration must be ≤ 0.5% (5,000 ppm) before entry.
Action Required Onboard: Integrate CO₂ limits into entry permits and verify readings before and during entry.
4. Safe/Unsafe Signage
New Requirement: Entry only permitted at CO₂ ≤ 5,000 ppm.
Action Required Onboard: Display updated green/red access tags at all entry points after testing.
5. Shore Personnel
New Requirement: Joint risk assessment and briefing mandatory for all contractor or shore entries.
Action Required Onboard: Implement a contractor interface procedure covering RA, communications plan, and permit sign-off.
6. Enclosed Space Emergency Response (ESE-ERP)
New Requirement: Written ERP must address Testing, Protection, and Recovery.
Action Required Onboard: Maintain a signed Enclosed Space Emergency Response Plan, conduct regular drills, and file onboard.
7. EEBD Usage
New Requirement: Emergency Escape Breathing Devices are for escape only.
Action Required Onboard: Remove any reference allowing EEBD use for entry or rescue.
8. Personal Gas Detectors
New Requirement: Each entrant must carry a calibrated personal 5-gas unit.
Action Required Onboard: Add to PPE checklists; verify calibration and bump test records.
9. Crew Empowerment
New Requirement: All crew must be authorised to stop unsafe entry.
Action Required Onboard: Include a Stop Work Authority clause in safety management procedures and briefings.
Operational Implications
For operators, compliance involves more than equipment changes. MSC.581(110) requires integrated documentation systems, verifiable gas readings, and consistent crew training. Many shipowners are now adopting digital registers and formalised pre-entry briefings to ensure audit readiness and cross-team accountability.
The regulation also emphasises culture - empowering personnel to intervene and prevent unsafe practices rather than rely solely on procedural compliance.
MS&C’s Perspective
MS&C supports shipowners and managers in achieving full compliance with MSC.581(110) through:
Early adoption of MSC.581(110) standards ensures safer entry practices, reduces audit risk, and strengthens operational resilience in one of the industry’s most critical safety domains. Our technical and compliance team ensures readiness for PSC inspections and promotes safer, verifiable enclosed space operations across Asia-Pacific fleets.
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