Trans RINA, Vol 161, Part A4, Intl J Maritime Eng, Oct-Dec 2019
it says: put some cargo in a can, bang it on the ground for a minute and see if the contents start to flow.
The movements of the ship can be softened by adjusting speed and heading. The stability and consequently the ship reaction to an external force can be adjusted by changing the ballast condition of the ship.
Liquefaction and dynamic separation are two sicknesses with one cure. The effective moisture content of the cargo to be loaded should be below the TML. Captain and crew must maximize their effort to verify this. Very often being attentive during loading in addition to a simple test in case of doubt can avoid serious and potentially life threatening danger.”
Due diligence” – two small words –should, of course, never be neglected.
Figure 7. A « negative » can test with moisture at the surface (Spencer & Tilsley, 2011)
If the result of the “can test” shows a high moisture content, loading should be stopped, a Letter of Protest issued, P&I club advised and a more thorough lab test requested.
The process of liquefaction and dynamic separation can be prevented by ensuring that the bauxite has a limited content of fines and moisture content, as both particle size distribution and moisture content are the main parameters for the occurrence of this phenomenon (Russell, 2017).
The effects of dynamic separation cannot be ignored in the field, especially because the physical characteristics of bauxite ore have lately been changing for the worse. For technical reasons, the end receivers of the bauxite ore require to receive a product that consists of smaller lumps. This has resulted in some mines sieving the ore to remove the >100 mm fraction, an operation which can involve washing the ore with high power water jets through a rotary sieve to produce both bauxite fines and coarser material. Inevitably the moisture content of the cargo is increased (Miller, Crouch, & Bell, 2015).
The crew should keep a close watch for the presence of cargo splatter marks on the bulkheads, shell plating and hatch coamings as these can only arise because of transient liquefaction of the cargo as it is being dropped onto the developing cargo stow in the holds. The presence of such marks indicates that portions of the cargo loaded have a moisture content in excess of TML. In addition, the crew should check for accumulation or pooling of water around the periphery of the stow as this may indicate that the cargo is saturated.
At sea, if one feels that the rolling movement of the ship is not regular but “wobbling”, this should be considered as the first indication that there is something wrong with the cargo (Russell, 2017; IMO, 2017).
5. 1.
2. 3.
REFERENCES
AMIDON, G., MEYER , P. & MUDIE, D., (2017) Particle, powder and compact characterization. In: Developing Solid Oral Dosage Forms. s.l.:Elsevier, pp. 271-293.
ANON., (2013) Physical properties of rice. In: Rice Quality. s.l.:s.n., pp. 26-60.
AUSTRALIAN GOVERNEMENT, (2018) Dangerous Cargoes and goods.
[Online]
Available at:
https://www.amsa.gov.au/vessels- operators/cargoes-and-dangerous- goods/dynamic-separation-cargoes (Accessed 27th April 2019)
4. 5.
AUSTRALIAN MARITIME SAFETY AUTHORITY, (2017). Dynamic Separation of Cargoes, Braddon ACT 2612 Australia: AMSA.
BAHAMAS MARITIME AUTHORITIES, (2015) “M.V Bulk Jupiter”, IMO Number 9339947, Official Number 8001956, Report of the marine safety investigation into the loss of a bulk carrier in the South China Sea on January 2nd 2015, Bahamas: Bahamas Maritime Authorities.
6. 7.
BIMCO, (2012) Special Circular N° 4: Solid Bulk Cargoes that Can Liquefy Clause for Charter Parties, Bagsvaerd - Danmark: BIMCO.
BUREAU VERITAS, (2018) Transportable Moisture Limit - Reducing the risk of cargo instability.
[Online] Available 8. at:
https://www.bureauveritas.com/services+sheet/c ommodities/transportable-moisture-limit (Accessed 25th April 2019)
CHAKRABORTY, S., (2017) Ship Stability – What Makes a Ship Unstable?. [Online]
Available 9. at:
https://www.marineinsight.com/naval- architecture/ship-stability-makes-ship-unstable/ (Accessed 25th April 2019)
CLARCK, I., (2008). Stability, Trim and Strength for Merchant Ships and Fishing Vessels. s.l.:The Nautical institute..
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©2019: The Royal Institution of Naval Architects
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