Attention required when loading a clay cargo following liquefaction incident

Image courtesy of West P&I Club
Image courtesy of West P&I Club

The West P&I Club has recently encountered a cargo liquefaction case involving a cargo of ball clay that was loaded in Lumut, Malaysia for discharge in Chittagong, Bangladesh. A similar case was reported in 2013. Therefore the Club issues this warning and urges operators to pay special attention when loading a clay cargo.

According to the cub, laboratory testing of samples of the cargo drawn from the vessel showed a Flow Moisture Point (FMP) of 29.7% and Transportable Moisture Limit (TML) of 26.7%, when determined on the flow table, and an FMP of 32.1% and TML of 28.9% when determined by the penetration test. The lowest moisture content of the cargo onboard was notably higher than either TML, at 36.4%.

The International Maritime Solid Bulk Cargoes (IMSBC) Code contains a schedule for Clay, describing it as a light to dark grey product which is usually moist but not wet to the touch comprising of 10% soft lumps and 90% soft grains. The entry states that the cargo shall be kept as dry as practicable, that it shall not be handled during precipitation and that the moisture content of the cargo shall be kept as low as practicable to prevent the material from becoming glutinous and difficult to handle.

Although the schedule for Clay classifies it as Group C (ie a material which has no chemical hazards and is not liable to liquefy), this is a generic entry which does not necessarily apply to all clays. For example, the IMSBC Code contains a schedule for Ilmenite Clay which is classified as Group A (ie a material which may liquefy). In November 2000 a vessel carrying Ilmenite Clay was almost lost off the coast of Finland following the liquefaction of such a cargo.

It should also be noted that the Code of Safe Practice for Solid Bulk Cargoes (the predecessor to the IMSBC Code) once contained an entry for Kaolinite Clay which referred to this cargo as having a Transportable Moisture Limit (TML), thus indicating that it could liquefy. The latter observation is particularly important given that Ball Clay is a type of Kaolinite Clay.

Vessels due to load Ball Clay in Malaysia are strongly advised to notify the Managers beforehand so that a local surveyor can be appointed to identify the location of the cargo, check the shipper’s cargo documentation and carry out “can” tests on representative samples of the cargo before and during loading.

As with any other dry bulk cargo, loading should not commence until the shippers have provided a cargo declaration as required by the IMSBC Code. Irrespective of the cargo group declared by the shipper, Ball Clay from Malaysia should be regarded as being a Group A cargo and the shipper should be asked to provide test certificates showing that the moisture content of the material is less than the TML.

If the shippers fail to produce the cargo information required by the IMSBC Code, or do not provide test certificates, or if there are any doubts regarding the validity or accuracy of such certificates, or if a “can” test results in the appearance of free moisture or fluid conditions, loading should be halted or postponed as appropriate. In such an event the Managers should be notified immediately as it may be necessary to draw and send cargo samples to an independent laboratory to verify the TML and moisture content. Additional advice from an expert may also be required.

It should also be remembered that while a sample which remains dry following a “can” test indicates that the moisture content is less than the FMP, the moisture content may still exceed the TML. Determining the latter is only possible in a laboratory.

Click to read the flyer: West-Club-Cargo-Liquefaction-Incident-Ball-Clay-from-Malaysia-2013_08

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