This guide explains MSC.1/Circ.1318 fixed CO2 maintenance requirements for fixed carbon dioxide fire-extinguishing systems on board SOLAS vessels. The systems protect machinery spaces, cargo pump-rooms, and other enclosed areas. MSC.1/Circ.1318/Rev.1 is the IMO circular that sets the recommended scope and intervals. It applies under SOLAS Chapter II-2 Regulation 14.

Use this page to align shipboard PMS tasks with class and flag expectations. In addition, the guide helps you prepare for Port State Control inspections. Finally, it shows how to structure maintenance evidence so your records survive scrutiny. You can download the full text of MSC.1/Circ.1318/Rev.1 as a PDF below.

OJ Safety performs MSC.1/Circ.1318-compliant inspections, servicing, and certification of fixed CO₂ systems. We work on board vessels across the Baltic, Nordic, and European regions.

What is MSC.1/Circ.1318/Rev.1?

MSC.1/Circ.1318/Rev.1 is the Revised Guidelines for the Maintenance and Inspections of Fixed Carbon Dioxide Fire-Extinguishing Systems. The IMO Maritime Safety Committee issued it under SOLAS Chapter II-2 Regulation 14. It revises and replaces the original MSC.1/Circ.1318. In practice, it sets the recommended scope and intervals for testing, inspection, and maintenance of fixed CO₂ systems on board ships.

The circular applies to:

• Fixed CO₂ systems protecting machinery spaces (Category A and other)
• CO₂ systems protecting cargo pump-rooms
• CO₂ systems protecting cargo holds (where fitted)
• CO₂ systems protecting paint stores, flammable liquid lockers, and similar enclosed spaces

Typically, the circular sets monthly, annual, 2-yearly, 5-yearly, and 10-yearly actions. Importantly, regulators cite it together with SOLAS II-2/14.2.2. Therefore, maintenance of fixed CO₂ systems becomes a SOLAS requirement. As a result, Port State Control, flag administrations, and IACS classification societies verify compliance during periodic surveys.

MSC.1/Circ.1318 fixed CO2 maintenance — inspection intervals at a glance

The table below summarizes the main intervals:

Note: flag state, class society, or manufacturer requirements may adjust the exact intervals. Always confirm with your class society and equipment maker before scheduling.

What does a monthly check of a fixed CO₂ system include?

Monthly checks are visual. They confirm readiness without discharging or operating the system. Required items include:

• Cylinder bank — no leakage, no corrosion, pressure within manufacturer limits (where gauges exist)
• Manifold and valves — no mechanical damage, correct valve position, locking pins in place
• Release stations and cabinets — doors closed and sealed, visible signage, release handles secured against accidental operation
• Pneumatic and electrical control lines — no visible damage, tight connections
• Alarms panel — power on, no fault indications
• Boundaries of protected space — working doors, dampers, and vent flaps
• Posted instructions and crew familiarization — visible and legible

Document every monthly check in the PMS. In addition, take photographs as evidence.

What is required for the annual MSC.1/Circ.1318 inspection?

The annual inspection is functional. A competent person performs it. Typically, this is an authorised service supplier approved by the flag administration or recognised by a classification society.

The inspection covers:

• Functional test of audible and visual alarms inside the protected space and at the release stations
• Functional test of the time-delay device — verify the actual delay against the design value
• Inspection of boundaries: bulkheads, decks, doors, dampers, and ventilation flaps
• Inspection of bottle stations, manifolds, and external distribution piping
• Inspection of release cabinets and pilot lines
• Check of fire detection and shutdowns linked to CO₂ release
• Inspection of automatic and manual changeover valves
• Verification of cylinder lists, hydrostatic test dates, and maintenance records

When are CO₂ cylinders hydrostatically tested?

Fixed CO₂ cylinders require hydrostatic pressure testing every 10 years. The clock starts from the previous test date or first commissioning. The test follows:

• ISO 6406 for seamless steel gas cylinders, or ISO 18119 (revised standard for periodic inspection)
• Manufacturer’s recommendations
• Flag state and class society requirements

After 20 years of service, additional checks may apply. In some cases, a shorter retest interval kicks in. Cylinders that fail the hydrotest go out of service. The records of hydrotest dates stay on board. Furthermore, each cylinder also carries a stamped retest date.

What evidence do class and PSC expect?

Port State Control and classification surveyors look for an unbroken paper trail. Typically, a class survey or PSC inspection requires:

• Authorised service supplier report, signed and stamped
• Calibrated gauge logs for pressure tests
• Alarm and time-delay test sheets with measured values
• Cylinder list with serial numbers and hydrotest dates
• Photographs of accessible system components
• PMS tickets closed with reference to the service report
• Class endorsement where attendance was required
• Manufacturer’s manual and approved drawings on board

In practice, missing or inconsistent records rank among the most common deficiencies in PSC inspections. Hardware faults follow close behind.

Common deficiencies during PSC and class inspections

Based on practical inspection experience, surveyors most frequently flag the following on fixed CO₂ systems:

• Overdue hydrostatic tests on individual cylinders or the whole bank
• Flexible hoses not renewed at the 10-year limit
• Time-delay alarm out of specification — measured value differs from design
• Boundary penetrations — cable transits, vent flaps that fail to close
• Release station signage missing or unreadable
• Locking pins missing on master valves
• Discrepancy between the cylinder list and the physical installation
• Missing crew training records
• Pilot lines blocked or corroded — revealed during blow-through

OJ Safety inspection reports cover every one of these points. As a result, you can close findings before the next class or PSC attendance.

How MSC.1/Circ.1318/Rev.1 relates to other regulations

MSC.1/Circ.1318/Rev.1 sits in a broader regulatory framework:

• SOLAS II-2/14 — the legal requirement to maintain fire safety systems (parent regulation)
• MSC.1/Circ.1432 — general FFE maintenance and inspection guidelines, broader scope
• MSC.1/Circ.1516 — amendments to MSC.1/Circ.1432
• FSS Code, Chapter 5 — design and performance requirements for fixed gas fire-extinguishing systems
• ISO 6406 / ISO 18119 — periodic inspection of seamless steel cylinders
• Flag state circulars — may impose stricter intervals or witnessing requirements

For an overview of related IMO circulars, see our IMO & SOLAS Regulations section. In addition, for general fire-fighting equipment maintenance, see our Firefighting Equipment Regulations guides.

Download MSC.1/Circ.1318/Rev.1 — full PDF

You can download the full text of MSC.1/Circ.1318/Rev.1 below. Use it to plan maintenance windows. Also, attach it as evidence to PMS tasks. Furthermore, reference it during class surveys and PSC inspections. Finally, brief shipboard officers with it.

How OJ Safety supports MSC.1/Circ.1318 fixed CO2 maintenance

RINA and other major classification societies approve OJ Safety as a Service Supplier under category D — Inspection and maintenance of fire-extinguishing equipment and systems. We deliver:

• Annual and 5-yearly fixed CO₂ system inspections
• Hydrostatic testing of CO₂ cylinders, in cooperation with certified test facilities
• Renewal of flexible hoses, valves, and associated components
• Pilot line and discharge piping blow-through
• Time-delay and alarm calibration
• Documentation packs ready for class and PSC

In practice, we serve vessels across the Baltic, Nordic, and European ports — both alongside and in dry-dock. Contact us for a quotation or to schedule an MSC.1/Circ.1318 fixed CO2 maintenance inspection.