LIQUEFACTION 1 Carrying solid bulk cargoes involves serious risks, which must be managed carefully to safeguard the crew and the ship. These risks include reduced ship stability, and even capsizing, due to cargo liquefaction. Liquefaction is now seen as a major hazard for bulk carriers. The topic is receiving increasing attention from all industry stakeholders and from the media, because apart from the too high cost of lives, the loss of a ship and its cargoes is very expensive and raises the amount of the insurance policy. The main legislation governing safe carriage of solid bulk cargoes is the International Maritime Solid Bulk Cargoes (IMS- BC) Code, which became mandatory on January 1, 2011 SNF has specially designed FLODRI IOS polymers to capture the water within the ore particles, preventing the rise of pore water pressure, which can lead to liquefaction. The chemical or metallurgical properties of the ores are not changed, only the physical state is changed. 2 LIQUEFACTION is a phenomenon wherein a mass of soil loses a large percentage of its shear resistance, when subjected to transient or periodic loading, and flows in a manner resembling a liquid. Since the holds of bulk carriers are not designed to carry liquid, the following points merit scrutiny: - The loading conditions: an accident on one vessel is often followed by a new accident, or near-accident, on other vessels that have loaded a similar cargo at terminals in the same area and under the same weather conditions. - The difficulty to comprehend or to carry out the sampling procedures at loading ports when the ores nature changes (size distribution, clay gangue) - The effectiveness of the test methods used to determine the Transport Moisture Limit of solid bulk cargoes as dictated by the IMSBC CODE - The accidents happen very fast: the liquefaction of the cargo affects the stability of the vessel, resulting in the vessel capsizing very quickly, sometimes within a few minutes. There is no time for remedial measures or for safe evacuation of the ship. Such accidents are often associated with tragic losses of crew members. GLOSSARY IMO: International Maritime Organization is a specialized agency of the United Nations that is responsible for measures to improve the safety and security of international shipping and to prevent marine pollution from ships. IMSBC Code: Code issued by the IMO to facilitate the safe stowage and shipment of solid bulk cargoes. Concerning safety, solid bulk cargoes are divided into three groups, A B and C. - Group A: consists of cargoes which may liquefy if shipped at moisture content above their transportable moisture limit - Group B: consists of cargoes which possess a chemical hazard which could give rise to a dangerous situation on a ship. - Group C: consists of cargoes which are neither liable to liquefy (Group A) nor to possess chemical hazards (Group B) FMP: Flow Moisture Point measure the water content, expressed as a percentage, at which a sample of cargo will begin to lose shear strength. To meet required moisture levels for loading and maritime insurance criteria, the ores must be tested through several analytical trials issued by the IMO, and presented in the 2012 IMSBC Code. TML: Transport Moisture Limit, maximum moisture content of a cargo that is considered safe for transportation in ships. It is calculated as 90 per cent of the Flow Moisture Point (FMP). DWT: Deadweight tonnage - Max mass a vessel can carry without risks (cargo + crew + fuel + ballast). Bulk Carrier Subclass DWT (tonnes) General Bulker < 10 000 Handysize 10 000 – 40 000 Handymax / Supramax 40 000 – 60 000 Capesize > 100 000 3 danger of cargo liquefaction © Courtesy of the Hong kong Government Flying Service 4 LIQUEFACTION ACCIDENTS Date of Vessel name DWT ‘000 T Lives lost Lost of Vessel Cargo type Route Ship type accident 16/12/1988 Mega Taurus 30 20 Yes Nickel Ore Philippines - Japan Handysize 24/08/1991 Melete 72 25 Yes Iron Ore Australia - England handymax 26/08/1998 Sea prospect 21 10 Yes Nickel Ore Indonesia - Japan Handysize 20/05/2005 Hui Long 15 0 Yes Fluorspar Indonesia - China Handysize 27/09/2007 Heng Tai 16 2 Yes Iron Ore India - Bangladesh Handysize 27/11/2007 Mezzenine 19 26 Yes Iron Ore Indonesia - China Handysize 17/07/2009 Asia Forest 14 0 Yes Iron Ore India - China Handysize 30/08/2009 Hodasco 15 6 0 Yes Iron Ore India - China General Bulker 09/09/2009 Black Rose 38 1 Yes Iron Ore India - China Handymax 27/10/2010 Jian Fu Star 45 13 Yes Nickel Ore Indonesia - China Handymax 10/11/2010 Nasco Diamond 57 22 Yes Nickel Ore Indonesia - China Handymax 03/12/2010 Hong Wei 50 10 Yes Nickel Ore Indonesia - China Handymax 21/11/2011 Bright Ruby 26 6 Yes Iron Ore Malaysia - China Handymax 25/12/2011 Vinalines Queen 56 22 Yes Nickel Ore Indonesia - China Handymax 22/01/2012 Sun Spirits 11 0 Yes Iron Ore Philippines - China Handysize 16/02/2013 Harita Bauxite 50 15 Yes Nickel Ore Indonesia - China Handymax 14/08/2013 Trans Summer 57 0 Yes Nickel Ore Indonesia - China Handymax 12/10/2013 Bingo 9 0 yes Iron Ore India - China General Bulker 04/04/2014 Grand Fortune 22 13 Yes Iron Ore North Korea - China Handysize 02/01/2015 Bulk Jupiter 47 18 Yes Bauxite Malaysia - China Handymax 13/10/2017 Emerald Star 57 11 Yes Nickel Ore Indonesia - China Handymax The accidents listed resulted in the loss of 214 lives and 21 vessels. The list doesn’t include incidents where vessels have safely reached port. 5 List Of Accidents LIQUEFACTION ACCIDENTS (1988 – 2017) BY CARGOES AND SHIPPING COUNTRIES Bauxite 5% North Korea 5% Australia Fluorspar 5% 5% Malaysia 9% Iron Ore 47% Philippines 9% Nickel Ore Indonesia 43% 48% India 24% Cargoes Shipping Countries Nickel Ores and Iron Ores are the main ores involved in the liquefaction accidents. The main contributing factors are: The cargoes in question are either unprocessed ores or concentrates, which have common characteristics: the fines and the clay contents. The moisture is difficult to control. Thereby, the traditional «can-test» can give misleading results, that is why IMO has issued the IMSBC Code. Tropical climate of the regions where the respective bulk carriers load. The locations of the ports where cargoes are loaded are often remote and underequipped to perform an efficient Sampling Method and TML measurement. Southeast Asian countries were involved in most liquefaction accidents, and casualties, due to: The exportation of Nickel ores, with high clay content. The expanding Chinese markets mainly due to the increasing demand for these minerals from China, Japan and South Korea which have amplified Southeast Asian maritime traffic: iron ore fines, mainly exported from India, and nickel ore, mainly exported from Indonesia, the Philippines and New Caledonia. 6 LIQUEFACTION ACCIDENTS (1988 – 2017) BY SHIP CLASS AND LOSS TONNAGE General Bulker 9% General Bulker 2% Handysize 24%25% Handysize Handymax 43% 48% Handymax 74% LIQUEFACTION ACCIDENTS (1988 – 2017) BY CARGOES AND SHIPPING COUNTRIES Ship Class Loss Tonnage The Handy subclass bulk carriers (Handysize and Handymax) are frequently used in this area. The total loss tonnage is over 700 000 tonnes. CUMULATIVE LIQUEFACTION ACCIDENTS (1988 – 2017) 25 21 20 20 19 18 accidents 15 15 14 12 Cumulative 10 9 6 5 4 4 3 2 1 #2011: Mandatory Implementation ofCode IMSBC 0 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 The suspected liquefaction incidents on bulk carriers continued to occur at a rate of nearly two per year even after the mandatory implementation of the IMSBC Code (red line). So mandatory TML didn’t stop ships from sinking. The effectiveness of the test methods used to determine the TML of solid bulk cargoes have come under question just like the follow-up of the rules dictated by the IMSBC code (FMP measurement procedures). The FMP nume- rical value can vary widely even for cargoes with the same description. It is not possible to predict the FMP of a given cargo from its description, particle size distribution or chemical composition. The FMP therefore needs to be determined by laboratory testing separately for each cargo provided by each ship- per. In cargoes loaded with a moisture content above the FMP, liquefaction may occur unpredictably at any time during the voyage. 7 LIQUEFACTION Principle Interstitial air Shaken COMPACTION LIQUEFACTION Cargoes that are at risk of liquefaction are those containing at least some fine particles and some moisture, although they are not visibly wet in appearance. The most widely known cargoes are mineral concentrates (Nickel and Iron), but also coal, pyrites, mill scale, sinter/pellet feed, etc. Even if they look dry in appearance at the time of loading, these cargoes contain moisture in between the particles. During loading, the cargoes are usually in their solid state. During ocean transport, the heave and pitch as well as the other 4 motions of the ship agitate cargoes resulting in their compaction. This leads to the removal of interstitial air and a reduction of the spaces between particles. If compaction is such that there is more water inside the cargo than there are spaces between the particles, the water pressure inside the cargo can rise sharply and press the particles apart. This suddenly reduces the friction between particles. The effect of this process is a transition from a solid state to a viscous fluid state in which all or part of the cargo can flatten out to the removed of interstitial air and form a fluid surface.