Iron Ore Fines and Liquefaction: The Risk That Sinks Vessels
Quote from chief_editor on May 31, 2026, 3:00 amWet iron ore fines can liquefy during transit, causing catastrophic vessel instability. The moisture trigger point is not always where shippers test it.
Iron ore fines — the fine-particulate fraction of iron ore processing that passes through a specified mesh size — are classified under the International Maritime Solid Bulk Cargoes (IMSBC) Code as a cargo that may liquefy. Liquefaction occurs when the moisture content of the cargo exceeds its Transportable Moisture Limit (TML): the material loses shear strength, behaves as a liquid rather than a solid, and can shift violently during vessel motion, causing catastrophic stability loss.
A number of major bulk carrier losses in the 2000s and 2010s were attributed to, or suspected to involve, cargo liquefaction of iron ore fines shipped from Indian and Indonesian ports. The bulk carrier Bulk Jupiter sank in January 2015 in the South China Sea with 18 crew members, carrying a cargo of bauxite that is believed to have liquefied. The investigation pointed to cargo moisture content exceeding TML as a probable contributing factor. Earlier incidents involving iron ore fines shipments from Indian ports in 2009 and 2010 also raised liquefaction concerns.
The financial consequence of a liquefaction-related cargo casualty is enormous: vessel loss, cargo loss, crew loss, P&I and hull insurance claims, and potential criminal liability for shippers who certified moisture content below TML when the actual moisture was above it.
The TML Test Is a Laboratory Measurement. The Cargo Is Not a Laboratory.
The Transportable Moisture Limit is determined by laboratory testing of a representative sample using the flow table test or the Proctor/Fagerberg test specified in the IMSBC Code. The TML result establishes the maximum moisture content at which the cargo can be safely loaded.
The gap between the laboratory TML test and the actual cargo condition at loading is where the risk lives. TML testing is conducted on samples taken from the stockpile days or weeks before loading. If rain falls on the stockpile between sampling and loading, the moisture content of the cargo at loading may exceed the TML even though the certificate shows compliant moisture.
Some origins are particularly susceptible. Indian iron ore fines export terminals in Goa and Karnataka have experienced monsoon season periods where stockpile moisture increases rapidly between the TML sampling date and the vessel's loading date. The time pressure of vessel scheduling — vessels chartered for specific laycans, terminals with queues — creates operational pressure to load cargoes that may have exceeded TML rather than delay and incur demurrage.
IMSBC Code requirements include provisions for can test assessment prior to loading — a simplified field test that can be conducted at the terminal immediately before loading to identify obviously wet cargo. Whether this test is consistently applied, and whether its results are acted upon when loading is commercially urgent, is a question of terminal operations and oversight rather than regulatory requirement.
The industry response has included more frequent moisture testing during loading, third-party verification of TML certificates, and enhanced port state control inspections at origins with documented liquefaction history. Some classification societies require additional certification for iron ore fines shipments from specified origins. The regulatory framework continues to develop as incidents recur and the mechanisms are better understood.
The Shipper's Declaration and Its Limitations
Shippers of Group A bulk cargoes — those that may liquefy — are required under IMSBC Code to provide a cargo declaration stating the moisture content and TML, confirming that the cargo moisture is below TML. This declaration is issued by the shipper, who may be the mine, the terminal operator, or the trading company handling the export.
A trading company that purchases iron ore fines FOB and resells CIF becomes the shipper for the leg they arrange. Their cargo declaration relies on the TML certificate and moisture certificate provided by the seller. If those certificates are inaccurate — whether through fraud or through the time gap between sampling and loading — the trading company has made a declaration they cannot independently verify.
The liability for a liquefaction incident where the declared moisture was below TML but actual moisture was above it falls on the party who made the inaccurate declaration. Understanding what verification the trading company actually performed before signing that declaration — and whether they had the operational ability to verify moisture at loading rather than at sampling — is a question with significant legal consequences if the worst happens.
Wet iron ore fines can liquefy during transit, causing catastrophic vessel instability. The moisture trigger point is not always where shippers test it.
Iron ore fines — the fine-particulate fraction of iron ore processing that passes through a specified mesh size — are classified under the International Maritime Solid Bulk Cargoes (IMSBC) Code as a cargo that may liquefy. Liquefaction occurs when the moisture content of the cargo exceeds its Transportable Moisture Limit (TML): the material loses shear strength, behaves as a liquid rather than a solid, and can shift violently during vessel motion, causing catastrophic stability loss.
A number of major bulk carrier losses in the 2000s and 2010s were attributed to, or suspected to involve, cargo liquefaction of iron ore fines shipped from Indian and Indonesian ports. The bulk carrier Bulk Jupiter sank in January 2015 in the South China Sea with 18 crew members, carrying a cargo of bauxite that is believed to have liquefied. The investigation pointed to cargo moisture content exceeding TML as a probable contributing factor. Earlier incidents involving iron ore fines shipments from Indian ports in 2009 and 2010 also raised liquefaction concerns.
The financial consequence of a liquefaction-related cargo casualty is enormous: vessel loss, cargo loss, crew loss, P&I and hull insurance claims, and potential criminal liability for shippers who certified moisture content below TML when the actual moisture was above it.
The TML Test Is a Laboratory Measurement. The Cargo Is Not a Laboratory.
The Transportable Moisture Limit is determined by laboratory testing of a representative sample using the flow table test or the Proctor/Fagerberg test specified in the IMSBC Code. The TML result establishes the maximum moisture content at which the cargo can be safely loaded.
The gap between the laboratory TML test and the actual cargo condition at loading is where the risk lives. TML testing is conducted on samples taken from the stockpile days or weeks before loading. If rain falls on the stockpile between sampling and loading, the moisture content of the cargo at loading may exceed the TML even though the certificate shows compliant moisture.
Some origins are particularly susceptible. Indian iron ore fines export terminals in Goa and Karnataka have experienced monsoon season periods where stockpile moisture increases rapidly between the TML sampling date and the vessel's loading date. The time pressure of vessel scheduling — vessels chartered for specific laycans, terminals with queues — creates operational pressure to load cargoes that may have exceeded TML rather than delay and incur demurrage.
IMSBC Code requirements include provisions for can test assessment prior to loading — a simplified field test that can be conducted at the terminal immediately before loading to identify obviously wet cargo. Whether this test is consistently applied, and whether its results are acted upon when loading is commercially urgent, is a question of terminal operations and oversight rather than regulatory requirement.
The industry response has included more frequent moisture testing during loading, third-party verification of TML certificates, and enhanced port state control inspections at origins with documented liquefaction history. Some classification societies require additional certification for iron ore fines shipments from specified origins. The regulatory framework continues to develop as incidents recur and the mechanisms are better understood.
The Shipper's Declaration and Its Limitations
Shippers of Group A bulk cargoes — those that may liquefy — are required under IMSBC Code to provide a cargo declaration stating the moisture content and TML, confirming that the cargo moisture is below TML. This declaration is issued by the shipper, who may be the mine, the terminal operator, or the trading company handling the export.
A trading company that purchases iron ore fines FOB and resells CIF becomes the shipper for the leg they arrange. Their cargo declaration relies on the TML certificate and moisture certificate provided by the seller. If those certificates are inaccurate — whether through fraud or through the time gap between sampling and loading — the trading company has made a declaration they cannot independently verify.
The liability for a liquefaction incident where the declared moisture was below TML but actual moisture was above it falls on the party who made the inaccurate declaration. Understanding what verification the trading company actually performed before signing that declaration — and whether they had the operational ability to verify moisture at loading rather than at sampling — is a question with significant legal consequences if the worst happens.