Amendments to the IMSBC Code aiming to improve the safe transport of cargoes that may liquefy have been agreed by the IMO.
The article "Cargo liquefaction - An update", which appears elsewhere in this issue of Gard News, makes reference to works at the IMO during the past year which have culminated in joint industry papers being submitted to the 16th Session of IMO Sub-Committee on Dangerous Goods, Solid Cargoes and Containers (DSC 16). The session included a meeting of a Working Group on Amendments to the IMSBC Code whose report sets out a number of agreed amendments to improve the safe transport of cargoes that may liquefy, including the following:
- Clarification that the "competent authority" shall operate independently from the shipper. Amendments to the IMSBC Code aiming to improve the safe transport of cargoes that may liquefy have been agreed by the IMO.
- A requirement that the moisture content and TML (transport moisture limit) certificates be issued by an entity recognised by the competent authority of the port of loading.
- A requirement that the shipper has in place procedures for sampling, testing and controlling moisture content and for these procedures to be approved by the competent authority of the port of loading.
- A requirement that the shipper facilitates access to stockpiles for the purpose of inspection, sampling and subsequent testing by the ship's nominated representative.
Iron ore fines
More specifically, the DSC 16 Working Group also agreed that an IMO Correspondence Group should develop a new schedule(s) for iron ore fines and to consider test methods. This Group, which is now functioning with input from industry, including the International Group of P&I Clubs (IG) and experts customarily advising the IG Clubs, will report to the next IMO DSC Editorial and Technical Group meeting in March 2012. In the meantime, it was also agreed, albeit with resistance from industry (specifically those representing ship interests), that the existing DSC circular concerning iron ore fines would be revised. This circular (DSC.1.Circ/63, dated 7th October 2011) introduces what can best be described as a temporary definition of iron ore fines: a cargo "mainly constituted by iron bearing minerals with a size up to 6.35 mm". The revised circular also goes on to provide that "if there is a question about the applicability of this circular for a specific particle size distribution of iron ore, advice should be sought from the competent authority of the port of loading" and that "the Master should observe current best practice when handling and carrying this cargo, such as the use of specifically designed filters to protecting the cargo holds bilge covers to stop the ingress of this fine cargo into the bilge".
As mentioned, these revisions met with some resistance from industry, as it was felt somewhat premature to be making revisions to a 2010 circular pending the findings of the Correspondence Group. Several obvious questions also arise. How is the master supposed to make an appropriate assessment of particle size distribution and can the competent authority be relied on to make the correct assessment? What is a specifically designed bilge filter and who should approve it?
It is difficult to answer these questions here, but experts advising Gard and other IG Clubs take the view that bilge covers can not and do not avoid liquefaction and that particle size is not the issue - the issue is whether or not the cargo, or a part of it, may develop a flow state at a certain moisture content. Studies have shown that the potential to liquefy is principally governed by the behaviour of the very fine material in a cargo (1 mm in size and smaller), and not the sizing of the larger material. The presence of particles greater than 6.35 mm in the cargo does not automatically categorise the cargo as Group C. If it contains a proportion of fine particles under 1 mm it may be a Group A cargo, irrespective of particles greater than 6.35 mm being present. If there is any doubt regarding whether a material is Group A or Group C, it should be submitted for testing for flow properties. Ultimately, the revisions to the circular may simply lead to more shippers trying to avoid declaring iron ore fines as Group A cargo and to more owners seeking expert advice on each cargo.
With regard to nickel ore, a draft new schedule proposed by France categorising this cargo as Group A was accepted in principle by the Working Group and will be forwarded to the Editorial and Technical Group for further consideration.
It is also worth mentioning that the Working Group considered the issue of developing alternative requirements on the prevention of accidents through ship design. Further consideration of this and any stability mitigation measures following the occurrence of liquefaction were left for consideration by other IMO Committees. In July 2011 the Italian classification society RINA announced that it had "established rigorous design standards for the modification or newbuilding of dry bulk cargo carriers to enable them to carry fine ores safely at any moisture content.1 It remains to be seen whether the cost of modification of existing ships (estimated at USD 3 million for a Supramax bulker) will be commercially feasible, as the number of modified new builds is unlikely to provide the capacity needed to meet world demand for a long time to come.
The agreed amendments to the IMSBC Code will probably only come into effect in 2013 at the earliest.
1 See www.rina.org/en/news/press/_file/attacksnickel_eng.pdf.
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