Transportable Moisture Limit (TML) for Coal    


Sampling Associates International, LLC

Editor’s note: This article was written to provide information to coal exporters regarding shippers’ responsibilities and compliance with the new IMSBC Code regulations for Transportable Moisture Limit (TML) effective January 1, 2019. The article was reviewed for technical correctness by the Hazardous Materials Division of the United States Coast Guard, which is the “Competent Authority” for the United States and is responsible for interpreting and enforcing the IMSBC Code, including provisions related to the TML. This article first appeared in IHS Markit’s Coal & Energy Price Report and ran as a two-part series.

Paul Reagan is president of Sampling Associates International, LLC and can be contacted via phone at 757.876.5217 or email at

The International Maritime Organization (IMO) publishes the International Maritime Solid Bulk Cargoes (IMSBC) Code which specifies the requirements for carriage of solid bulk cargoes other than grain on vessels to which the International Convention for the Safety of Life at Sea (SOLAS) is applicable.  This article will address the rules and regulations governing the Transportable Moisture Limit (TML) for coal that became mandatory as of January 1, 2019.

Testing for the TML is driven by the safety requirements for identifying and preventing the conditions that might cause a solid bulk cargo to undergo liquefaction in the hold of a ship and create dangerous conditions due to loss of stability of the vessel.

Liquefaction of a solid bulk cargo can occur for a number of reasons – but in the case of coal it is primarily related to the interaction between the particle size of the cargo and its moisture content.

The IMSBC Code states “Cargoes that may liquefy means cargoes which contain a certain proportion of fine particles and a certain amount of moisture.  They may liquefy if shipped with a moisture content in excess of their TML.”

It is important to note that the recent IMO decision to develop a specific test method for determining the TML of coal cargoes was intended to provide clarity on determining whether or not a given coal is both Group B and Group A.  It has long been known that certain coals have the potential to liquefy, as seen by the Group B (and A) classification since the first edition of the IMSBC Code.  The decision by the IMO to update many requirements for cargoes that can liquefy was driven by a concern for safety for all bulk carriers after some serious accidents involving other bulk cargos – most notably, nickel concentrates and iron ore fines.  The truth is that there have been no known coal shipments from the United States that have liquefied in transit.

While the risk of liquefaction of most US coals is remote, it does not relieve US coal shippers of their responsibilities as outlined in the IMSBC Code.  Recent developments in the Code for coal place certain responsibilities on the shipper with respect to declarations to the master of the vessel regarding the cargo to be loaded – as well as certain testing and supporting documentation for those declarations.

02. June 2019 by Terry Headley
Categories: transmission | Comments Off on Transportable Moisture Limit (TML) for Coal