Australian naval architecture consultancy IMC has provided specialist analysis that has assisted in three recent projects involving the safety of shipping of iron ore and coal in bulk.
Iron Ore Fines – Technical Working Group
In 2009 a number of bulk carriers transporting iron ore fines experienced difficulties following cargo shifts. Two of these ships sank, adding to numerous other founderings of ships carrying other bulk mineral cargoes, particularly nickel ore.
In 2010 the IMO Sub-committee on Dangerous Goods, Solid Cargoes and Containers (DSC) released a circular which stated ‘iron ore fines cargoes may liquefy and should be treated as such’. Following this, investigations into transportable moisture limits for iron ore fines cargoes began with the formation of a technical working group (TWG) by the world’s major iron ore companies.
In the first project IMC supported the work of the TWG by carrying out a range of bulk carrier stability, vessel motions, and cargo shifting simulations as part of a project to investigate the adequacy of existing methods for determining transportable moisture limit (TML) for iron ore fines. The work IMC carried out formed part of the ‘Iron Ore Technical Working Group’ submission to the 18th Session of the IMO Sub-committee on DSC.
As a result of the work carried out by the TWG, and assistance from the relevant competent authorities, a new TML test has been incorporated into the International Maritime Solid Bulk Cargoes (IMSBC) Code 2013.
Coal Transportable Moisture Limits
In a project undertaken by the Australian Coal Association Research Program and supported by the University of Newcastle, research was undertaken to develop a test to determine the transportable moisture limit (TML) for Australian coal.
As part of the research, IMC carried out simulations to determine worst case accelerations in the cargo holds of three different ship types when undertaking voyages in a range of worst case seaways.
As a result of the research the modified Proctor-Fagerberg (P-F) test for coal TML has been accepted by the Australian Maritime Safety Authority (AMSA), which has issued an exemption which allows the modified P-F test to be used to determine coal TML.
Work continues to incorporate the modified testing into permanent IMO instruments.
Iron Ore – Materials Hazardous in Bulk
The IMSBC Code specifies a test to determine if bulk cargoes are corrosive and should be classified as hazardous. Material testing has indicated that application of the specified test to iron ore provides highly variable results.
As part of a project to determine if an alternative test could be undertaken, IMC provided detailed analysis and interpretation of the types of steel that is commonly used to construct bulk carriers and comparison of different steel grade with those specified in the IMSBC Code.
As a result of the research undertaken AMSA has issued an exemption that allows the Australian iron ore industry to utilise an alternative test to determine if iron ore and iron ore fines are required to be classified as corrosive solids.
Research continues for the identification of a test protocol for assessing the corrosivity of iron ore and iron ore fines as solid bulk cargoes.