Indian Iron Ore fines liquefaction resulting to vessels capsize or excessive list
A lot of clubs have issued alert regarding the liquefaction of iron ore cargoes loaded from Indian ports during the monsoon period.
Although the shippers issue all necessary documents regarding TML and moisture content of the cargo, some times it has been noted that these documents do not represent the actual condition of the cargo.
Iron ore fines with moisture content above TML can liquify if vessel experience bad weather, resulting to excessive list or even capsize under heavy weather conditions.
The major factor that increases the moisture content in the cargo above TML is the rain during storage in open space or during transit from the mines to the port in open top train wagons.
Instructions to masters / operators
- Cargoes TML (Transport Moisture Limit) and moisture’s content should be measured by the shipper as close as possible to loading. Sampling and testing should not take place more than 7 days prior to loading. Relevant certificate should be provided to master.
- For cargoes stored in open space. Between measured date of moisture content and loading, no raining should have occurred. If it has, new moisture measurements should be taken.
- Master should be familiar with IMSBC code.
- Crew should monitor for cargo spatter onto bulkheads, slopping plate and side shell during loading. These spatter pattern is presented in the following pictures with read arrows and indicates that the cargos moisture is above the TML. Cargoes with higher moisture content from TML are prone to liquefaction.
- Finally, if the managers or the crew has doubts about the moisture content of the cargo to be loaded, an independent surveyor is to be appointed for sampling and measuring moisture content during loading.
It is also recommended managers to arrange independent surveyors, on a preventive bases, for every vessel loading iron ore in India during the monsoon period.
In situ practical experiment to determine liquefaction
“A ship’s master may carry out a check test for approximately determining the possibility of flow on board ship or at the dockside by the following auxiliary method:
Half fill a cylindrical can or similar container (0.5 to 1 litre capacity) with a sample of the material. Take the can in one hand and bring it down sharply to strike a hard surface such as a solid table from a height of about 0.2 m. Repeat the procedure 25 times at one or two second intervals. Examine the surface for free moisture or fluid conditions. If free moisture or a fluid condition appears, arrangements should be made to have additional laboratory tests conducted on the material before it is accepted for loading.“
IMSBC Code (2009 Edition) Section 8 Page 33