IHM Maintenance in Morocco.

Inventory of Hazardous Materials (IHM) maintenance

IHM maintenance keeps a ship’s Inventory of Hazardous Materials accurate throughout its operating life. The IHM identifies the location and approximate quantity of materials such as asbestos, polychlorinated biphenyls (PCBs), ozone-depleting substances, heavy metals and anti-fouling compounds in the ship’s structure and equipment. Part I is not a one-time newbuilding or first-certification exercise: every new pump, gasket, cable, coating, insulation panel or electronic unit taken on board can change it.

A well-maintained IHM avoids problems at port state control, renewal surveys and sale, and protects crew and contractors from unknowingly disturbing hazardous materials.

Regulatory requirements and standards

The Hong Kong International Convention for the Safe and Environmentally Sound Recycling of Ships entered into force on 26 June 2025. It applies to ships of 500 GT and above engaged in international voyages. New ships need an approved IHM Part I from delivery; existing ships must have Part I in place, verified and certified with an International Certificate on Inventory of Hazardous Materials (ICIHM) no later than 26 June 2030. Part I must be kept up to date. Class societies generally issue the ICIHM on behalf of flag.

The EU Ship Recycling Regulation (EU) No 1257/2013 requires EU-flagged ships to carry an IHM with an Inventory Certificate, and since 31 December 2020 non-EU-flagged ships of 500 GT and above calling at EU ports or anchorages must carry an IHM Part I with a Statement of Compliance. Ships holding EU documentation typically need the HKC certificate as well, although class guidance indicates the IHM itself does not need re-approval.

The technical basis is the 2023 Guidelines for the Development of the Inventory of Hazardous Materials, resolution MEPC.379(80), which added cybutryne to the materials to be listed, with a threshold of 1,000 mg/kg in dry paint. The guidelines also set out the Material Declaration (MD) and Supplier’s Declaration of Conformity (SDoC) formats that suppliers provide for products delivered to the ship.

Survey and maintenance intervals

What the service includes

• Review of the approved IHM, its revision history, the ship’s maintenance procedure and the IHM designated person arrangements
• Collection and screening of MDs and SDoCs from suppliers for items delivered since the last update
• Mapping of additions, removals and replacements to location, quantity and item in Part I
• Update of Part I tables, location diagrams and revision log, with new version issued to the ship
• Onboard visual and sampling checks where evidence cannot be obtained, under a documented sampling plan
• Gap review of older IHMs against MEPC.379(80), including cybutryne in anti-fouling systems
• Survey support package for renewal, additional survey or conversion to the HKC certificate

Materials and equipment typically involved

The guidelines divide materials into those prohibited or restricted on ships, such as asbestos, ODS, PCBs, PFOS, and organotin and cybutryne anti-fouling systems, and those to be listed if present above threshold, including cadmium, hexavalent chromium, lead, mercury, certain brominated flame retardants and radioactive substances. On board they turn up in gaskets and packing, insulation and fire protection, cables, paint systems, batteries, switches and gauges, refrigeration and fire-extinguishing systems, and electronic spares. Replacement of refrigeration plant and halon or CO2 systems should always be reflected, so coordinate with HVAC and refrigeration services and fire suppression systems work.

Common defects and PSC deficiencies

• IHM not updated since initial certification, with no revision log or designated person
• Missing MDs and SDoCs for spares and equipment installed after delivery
• Statement of Compliance or certificate expired, or ship particulars out of date after a change of name or flag
• Asbestos-containing gaskets or insulation delivered as spares from certain markets and installed without detection
• Older IHMs prepared before MEPC.379(80) not checked for cybutryne
• Inventory stored ashore only and not available to crew or inspectors on board

Certificates and documents you receive

The service delivers an updated IHM Part I with revised tables, location diagrams and revision history, an evidence register of MDs and SDoCs, sampling reports and laboratory results where applicable, and a summary of changes since the previous version. For survey, the package supports the class or recognised organisation in endorsing or renewing the ICIHM, Inventory Certificate or Statement of Compliance. Certification itself is issued by the authorised survey body, not by the maintenance provider.

How to prepare the vessel

• Nominate the IHM designated person ashore and a contact on board
• Export purchase orders and delivery records since the last IHM revision
• Gather dry-dock specifications, modification and retrofit records
• Provide the current IHM, certificate, drawings and previous survey report
• For sampling, arrange access, isolations and permits, and brief crew that samples may involve hazardous materials

Information needed for a quotation

• Vessel name, IMO number, flag, class, GT and ship type
• Which regime applies: HKC, EU SRR or both
• Current IHM version, preparation date and guideline basis
• Certificate or Statement of Compliance expiry and target survey date
• Approximate number of purchase orders or items since the last update
• Whether onboard visits or sampling are needed, with port and ETA/ETD
• Known retrofits such as scrubbers, BWTS, refrigeration or fire-fighting changes

vslSafety coordinates a suitable hazardous materials expert or IHM maintenance provider for desk work and, where needed, a local team at the vessel’s port.

Frequently asked questions

Does the Hong Kong Convention apply if our flag has not ratified it?

Class guidance indicates that internationally trading ships of 500 GT and above should obtain HKC documentation even when the flag is not a party, because ships may be inspected in ports of states that are parties, and parties apply the convention so that non-party ships receive no more favourable treatment. Check with your flag and class which organisation will issue the certificate and on what basis.

How often must the IHM be updated?

Part I must be updated whenever items containing listed hazardous materials are added, removed or replaced. Most operators screen purchases continuously and consolidate changes into periodic revisions. The certificate is renewed at intervals not exceeding five years, and the surveyor will check that the maintenance procedure has been followed.

What is the difference between an MD and an SDoC?

A Material Declaration states whether a product contains any of the listed materials above threshold values and in what quantity. The Supplier’s Declaration of Conformity is the supplier’s statement that the MD is correct and backed by its own management system. Both formats are given in MEPC.379(80), and both are required as evidence for each relevant product delivered to the ship.

Can our EU Statement of Compliance be used for the Hong Kong Convention?

The IHM prepared for the EU SRR is generally usable, as both regimes follow the IMO IHM guidelines, but the ship still needs the HKC certificate. Class societies have indicated that the IHM does not need re-approval, though it must be up to date, and older inventories should be checked for cybutryne.

Who can take samples on board?

Sampling should be carried out by a qualified hazardous materials expert following a sampling plan, using PPE and methods that avoid releasing fibres or contaminants, with samples analysed by an accredited laboratory. Findings may also inform wider marine surveys and consultancy work, for example before a sale or conversion.