Operational Guide · Registers & Logbooks

# Dangerous Solid Bulk Cargoes: the IMSBC Code, Liquefaction and Self-Heating

Nickel ore, bauxite fines and iron ore fines can turn from a solid into sludge during the voyage: liquefaction of Group A bulk cargoes has caused the loss of several ships and is now governed by increasingly detailed cargo schedules.

IMSBC Code liquefaction solid bulk cargo self-heating bulk carrier

## Operational Explanation

The IMSBC Code (International Maritime Solid Bulk Cargoes Code) classifies solid bulk cargoes into three groups: Group A (cargoes that may liquefy if carried at a moisture content above their own Transportable Moisture Limit, TML), Group B (cargoes with chemical hazards, including self-heating, or the emission of toxic or flammable gases) and Group C (cargoes without particular hazards of this kind). Nickel ore, bauxite fines and iron ore fines are among the best-known Group A cargoes, introduced as dedicated schedules after a series of ship losses caused precisely by cargo liquefaction during the voyage.

The 2025 edition of the IMSBC Code, in force from 1 January 2025 (with voluntary application already possible from 2024), includes 12 new cargo schedules and has amended 11 existing ones; further amendments are expected to enter into force from 1 January 2027, with voluntary application possibly available from 1 January 2026.

## Regulatory Reference

SOLAS Chapter VI makes the IMSBC Code mandatory for the carriage of solid bulk cargoes; the 2025 edition (in force from 1 January 2025) introduces 12 new cargo schedules and amends 11 existing ones; further amendments are expected to enter into force from 1 January 2027 (voluntary application from 1 January 2026).

## Scope of Application

Dry cargo ships (bulk carriers and general cargo ships) carrying solid bulk cargoes classified as Group A or B under the IMSBC Code, with the Master responsible for checking the cargo's moisture content against the TML before loading.

## Procedure / How to Complete It

1. Check the IMSBC classification of the cargo (Group A, B or C) and the specific applicable cargo schedule before accepting it for loading.
2. For Group A cargoes, request and examine the moisture content certificate and verify that it is below the Transportable Moisture Limit (TML) declared by the shipper.
3. Apply the 'can test' or other practical checks available on board in the event of doubt about the documentation supplied by the shipper, before authorising loading.
4. For Group B cargoes, check the specific chemical hazards (self-heating, gas emission) and the related precautions set out in the applicable IMSBC schedule.
5. Monitor cargo conditions during the voyage (temperature for cargoes prone to self-heating) as required by the specific schedule.

## Practical Example

Example: before loading a cargo of bauxite fines (Group A), the Master requests the shipper's moisture content certificate, compares it against the declared TML for that specific cargo, and, in the event of doubt, requests independent sampling before authorising loading.

## Real Cases

The Group A schedules for nickel ore, bauxite fines and iron ore fines were introduced in recent years in response to a series of ship losses caused by cargo liquefaction during the voyage: the phenomenon turns the cargo from an apparent solid into a fluid mass that shifts with the ship's roll, compromising stability up to capsizing in some of the most serious cases documented by the industry.

## Common Mistakes Mistake Library

Mistake | Consequence | How to avoid it
--- | --- | ---
Shipper's moisture content certificate accepted without independent verification in the event of doubt | Cargo with moisture above the TML loaded without the risk being detected | Always request independent verification (e.g. a can test) in the event of doubt about the documentation supplied, before authorising loading
Cargo classified as Group C based on generic analogies, without checking the specific IMSBC schedule | Risk of liquefaction or self-heating not recognised and not managed | Always check the specific applicable cargo schedule, rather than relying on the classification of apparently similar cargoes
Cargo temperature not monitored for Group B cargoes prone to self-heating | Failure to detect a developing self-heating condition in time | Apply the temperature monitoring required by the specific IMSBC schedule for the entire voyage
IMSBC documentation (cargo schedule, moisture certificate) not kept on board or not immediately available | PSC deficiency and difficulty verifying compliance during the inspection | Keep the complete documentation on board for every IMSBC cargo carried, easily available for verification

## PSC Observations

PSCOs check the IMSBC classification of the cargo carried, the presence of moisture content documentation for Group A cargoes, and compliance with the specific precautions required by the applicable cargo schedule.

## Operational Tips

- Never rely solely on the shipper's documentation for Group A cargoes: independent verification in the event of doubt is the most effective defence against liquefaction.
- Always check the specific applicable IMSBC cargo schedule, since the required precautions vary significantly from one cargo to another even within the same group.
- Continuously monitor the temperature of Group B cargoes prone to self-heating, rather than limiting checks to occasional inspections.

## Checklist

- IMSBC classification of the cargo (Group A/B/C) checked before loading
- Moisture content certificate checked against the TML for Group A cargoes
- Independent verification carried out in the event of doubt about the shipper's documentation
- Temperature monitoring applied for Group B cargoes prone to self-heating
- Complete IMSBC documentation kept on board and easily available

## FAQ

What is the Transportable Moisture Limit (TML)?
It is the maximum moisture content below which a Group A cargo can be safely carried without risk of liquefaction during the voyage; above this limit the cargo can turn from a solid state into an unstable fluid mass.
Which cargoes belong to Group A of the IMSBC Code?
Cargoes that may liquefy if the moisture content exceeds their own TML; among the best known are nickel ore, bauxite fines and iron ore fines, introduced as dedicated schedules after several ship losses caused by liquefaction.
What is the difference between IMSBC Groups A, B and C?
Group A concerns the risk of liquefaction from excessive moisture; Group B concerns chemical hazards such as self-heating or the emission of toxic/flammable gases; Group C comprises cargoes without these specific hazards.
When do the new amendments to the IMSBC Code enter into force?
The 2025 edition is in force from 1 January 2025 with 12 new cargo schedules; further amendments are expected to enter into force from 1 January 2027, with voluntary application possibly available from 1 January 2026.
🎬 Additional photos, videos and interactive diagrams for this topic will be available in a future version of the platform.

## Related Topics

Draft Survey and Determining Cargo Quantity Cargo Hold Survey for Bulk Carriers (IT)

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