Fig:Cargo liquefaction case at sea
- ensure that detailed stability calculations are carried out before departure from the load port for every cargo loaded. The calculations will then serve as baseline data in the event of a liquefaction incident.
- The master must immediately notify owners. owners should seek the advice of an expert in these circumstances. The likely effect of ballasting the vessel to correct a vessel’s list needs to be calculated and carefully considered before any such operation takes place. Incorrect ballasting may exacerbate the situation causing a further reduction in stability. Even where ballasting has taken place and is successful in returning a vessel upright the cargo onboard is still in a dangerous state.
- The vessel may need to seek the nearest port of refuge.
The problems associated with cargo liquefying whilst onboard vessels are nothing new. However, there have been a number of very serious incidents over recent years where vessels have experienced liquefaction leading to loss of stability and capsize. Cargoes such as iron ore fines, nickel ore, millscale, fluorspar, iron ore concentrates and others have all given rise to liquefaction associated problems in recent years.
The definitions, tests and precautions in the International Maritime Solid Bulk Cargoes (IMSBC) Code for cargoes that may liquefy are widely associated with metal ore concentrates, for which their application is relatively straightforward. However, any cargo containing fine material and moisture has the potential to liquefy and the properties of such cargoes should be queried with the shipper. Intense pressure from shippers, mis-description of cargoes, inadequate testing methods and lack of crew awareness over the potential for liquefaction of some cargoes have all contributed to recent incidents. The purpose of this briefing is to inform and advise Members of the problems associated with liquefaction in general.
In respect of cargoes with particular hazards, such as liquefaction, SOLAS is explicit in requiring the shipper to provide the master, or his representative, with the appropriate cargo information sufficiently in advance of loading to enable the necessary precautions for safe carriage to be put into effect. The format of such information is also supplied in IMO MSC/Circ.663. Additionally there are specific provisions for additional information to be supplied for cargoes which may liquefy in the form of a certificate of moisture content and transportable moisture limit (TML). As such shippers are obliged to provide appropriate cargo information to the master before loading commences.
Liquefaction and the IMSBC Code
The main reference for any ship operator or master when considering whether or not a cargo is likely to liquefy is the IMSBC Code. The dangers associated with commonly shipped cargoes are listed within the Code – Group A cargoes are those that are likely to liquefy. Any cargo listed as Group A should be carried strictly in accordance with the provisions of the IMSBC Code. However, the Code itself warns in Section 1.2.1 that the schedules for individual cargoes are not exhaustive. It may be that some cargoes which can liquefy are not included in the Code e.g. iron ore fines. Ship operators and master’s should not automatically assume there is no risk of liquefaction simply because a cargo does not appear in the IMSBC Code as a ‘Group A’ cargo. Any bulk cargo containing the correct proportion of fine particles and sufficient moisture may liquefy. It is essential that masters and ship operators are familiar with the IMSBC Code.
Section 4 of the IMSBC Code requires the shipper of the cargo to provide the master with appropriate cargo information sufficiently in advance of loading to enable the precautions which may be necessary for the safe carriage of the cargo to be put into effect. The minimum information to be provided is listed in Section 4.2.2.
This information includes both the TML of the cargo and its moisture content at shipment.
The vessel should receive this documentation well in advance of loading and masters should resist pressure from shipper or terminal representatives to begin loading in advance of receipt of the certificate. It is better to delay loading whilst awaiting the certificate than to have to discharge unsuitable cargo loaded in advance of receipt of the certificate. Such discharge may be highly problematic due to the lack of suitable equipment, berths or due to local customs or other regulations. Terminals and shippers may simply be unwilling to accept the discharged cargo.
The shipper’s cargo declaration should be accompanied by a signed certificate stating the cargo’s TML and moisture content. In addition Section 4.3.2 of the Code states that ‘the certificate of TML shall contain, or be accompanied by, the result of the test for determining the TML’, which we understand to mean that the FMP must also be included with the documentation. This should allow the master to calculate the TML to ascertain that it is stated correctly on the declaration and also provides useful evidence in the event of a dispute.
Unfortunately there have been many instances where the information provided by the shipper has stated that the cargo has been within the TML but which cargo has later proven to be liable to liquefy. This can come about through poor testing procedures (despite detailed advice as to the conduct of tests contained within the IMSBC Code), changes in circumstance since testing was carried out e.g. heavy rain, or through lack of understanding by shippers’ representatives of the potential dangers posed to the vessel by spurious figures.
As such, even where the certificate states that cargoes are safe to load, masters and their officers must always be vigilant in monitoring the condition of the cargo as it comes onboard. Different stockpiles of cargo can have different characteristics so vigilance throughout the duration of loading operations is necessary. In the event of a dispute arising over the properties of the cargo intended for loading we would recommend that Members consider the employment of an independent surveyor/expert to assist the master. In such circumstances Members should contact the Association for advice.
- Cargo Liquefying Whilst at Sea
- Sampling and Testing of Bulk Cargo
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