Iron Ore Fines
requires the shipper to retest in these circumstances but often shippers fail to do this), 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.
Sampling and Testing of Cargo
Sampling and testing procedures for bulk cargoes that may liquefy should be carried out to international standards such as the test procedures described in Appendix 2 of the IMSBC Code.
Flow Moisture Point (FMP) and Transportable Moisture Limit (TML) Flow Moisture Point – the maximum water content, expressed as a percentage, at which a sample of cargo will begin to lose shear strength. Cargoes with moisture content beyond FMP may be liable liquefy.
Transportable Moisture Limit - is defined as 90% of the FMP.
From the ship operators and master’s perspective the important figures for the laboratory to determine are the TML of a representative sample of the cargo to be loaded and its actual moisture content. It is a requirement of the International Convention for the Safety of Life at Sea (SOLAS) that the average moisture content of any type of granular cargo in any cargo space must not be higher than the TML. This is an important point; it is of little use to the vessel if an average moisture content of all cargo is provided. This may lead to dry cargo in some holds and cargo liable to liquefy in others which may adversely affect the vessel’s stability.
In order to find the TML the laboratory must first determine the FMP of the sample using one of the prescribed techniques.
Loading a cargo above, at or near its FMP represents an unacceptably high risk for vessels and for this reason a safety margin is allowed – this gives the TML.
After determining the FMP the moisture content of the cargo is obtained by drying samples of the cargo in accordance with Section 4.6.4 of the Code. If the moisture content of the cargo sampled is below the TML then, on the face of it the cargo should be safe to load. However, there is
no way for the vessel’s operators or master to determine whether or not the sampling and testing procedures used by shippers are adequate and/or accurate.
A Flow Table
Can Test In order that the vessel can make its own assessment of the likelihood of the cargo to liquefy the IMSBC Code describes a shipboard method known as the “can test”, IMSBC Code (2009 Edition) Section 8 Page 33. This involves filling a small can with the material and repeatedly banging it on a hard surface (see right). The appearance of the material at the end of the test can be used to form an opinion regarding the suitability of the material for shipment. This test should not be a substitute for proper laboratory testing using an appropriate methodology. However, if can tests carried out on a cargo presented for loading indicate a propensity for liquefaction, this is a major warning sign that the cargo as a whole may be unsafe for carriage. Expert advice should then be sought. Where shippers
North of England P&I Association, The Quayside, Newcastle upon Tyne, NE1 3DU, UK Tel: +44 191 232 5221 Fax: +44 191 261 0540 Email: loss.pr
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