Since the inception of modern Arctic operations, classification society ABS has researched the effects of ice on extreme low tem- perature transiting structures. The not-for-profit organisation devel- oped the first set of polar classifica- tion rules, classing the SS Manhattan, the world’s first com- mercial ice breaking tanker, which transited the North West Passage in 1969. ABS was the primary class society for Arctic drilling programs in the 1980s, classing such units as the Arctic drilling rig MOLIQ- PAK, built to ABS class in 1984 for exploration in the Beaufort Sea and refitted under ABS class for service in Russia’s Sakhalin I Field in 1999, and the KULLUK, built to ABS class in 1983 in Japan. In 2006, ABS expanded on ice class rule requirements for hull and machinery, publishing the Guide for Vessels Operating in Low Temperature Environments (LTE Guide) to cover winterisation for vessels. Class rules and guides con- tinue to evolve to help industry move into high-risk environments that pose challenges that must be resolved before wide-scale opera- tions can begin. The latest LTE Guide is dated February 2014. Today, ABS is collaborating with several industry partners in exten- sive R&D activities that target Arctic operations. An example is the Risk-Based Winterisation proj- ect, which is a methodology for using risk assessment as the basis for design choices or for evaluating design options. Another example is the Sustainable Technology for Polar Ships and Structures (STePS2) project, which includes laboratory experiments and numerical experiments being con- ducted to develop new design tools for assessing future Polar Class units. Additional projects have resulted in high-speed ice/struc- ture and ice/ice interaction simu- lation through the use of graphical processor units for the discrete ele- ment method (DEM) as well as GPU-based event mechanics (GEM). Project Roundup Arctic research supported by ABS is under way at Memorial University of Newfoundland (MUN) in St. John’s, where ABS established its Harsh Environment Technology Center (HETC) in partnership with MUN in 2009. Researchers at HETC are evaluating ways ships and offshore structures can be designed and operated safely and effectively in Arctic environments. Research is focusing on gathering data related to technical chal- lenges such as ice-hull interaction and ice loads as well as the effect of beyond frigid temperatures on equipment and equipment winteri- sation. Joint industry efforts are targeting several of these key tech- nical areas. Ice-Hull Interaction ABS is contributing to Joint Industry Projects (JIPs) in which ARCTIC ICE Since 2010, the ABS Harsh Environment Technology Center (HETC) has partnered with academia and industry to address the question, “What can be done about the ice headed the way of an Arctic vessel or asset?” BY HAN YU, JOHN DOLNY AND DAN OLDFORD Solving the Ice Equation Icebergs are a challenge in ice-infested offshore areas such as Atlantic Canada Class’ Arctic Reconnaissance – The National Research Council (NRC) of Canada provides innovation and research support with the goal of improving efficiency, safety and security in the Arctic and works to fur- ther sustainable resource development, marine safety tech- nologies and advancements in cold region infrastructure and transportation – a model scale DP drillship (shown) undergoes station-keeping tests in the NRC’s ice tank (photo: NRC) 38 SCANDINAVIAN OIL-GAS MAGAZINE NO. 11/12 2014
Transcript
Since the inception of modernArctic operations, classificationsociety ABS has researched theeffects of ice on extreme low tem-perature transiting structures. Thenot-for-profit organisation devel-oped the first set of polar classifica-tion rules, classing the SSManhattan, the world’s first com-mercial ice breaking tanker, whichtransited the North West Passage in
1969. ABS was the primary classsociety for Arctic drilling programsin the 1980s, classing such unitsas the Arctic drilling rig MOLIQ-PAK, built to ABS class in 1984 forexploration in the Beaufort Seaand refitted under ABS class forservice in Russia’s Sakhalin I Fieldin 1999, and the KULLUK, built toABS class in 1983 in Japan.
In 2006, ABS expanded on ice classrule requirements for hull andmachinery, publishing the Guidefor Vessels Operating in LowTemperature Environments (LTEGuide) to cover winterisation forvessels. Class rules and guides con-tinue to evolve to help industrymove into high-risk environmentsthat pose challenges that must beresolved before wide-scale opera-tions can begin. The latest LTEGuide is dated February 2014.
Today, ABS is collaborating withseveral industry partners in exten-sive R&D activities that targetArctic operations. An example isthe Risk-Based Winterisation proj-ect, which is a methodology forusing risk assessment as the basisfor design choices or for evaluatingdesign options. Another example isthe Sustainable Technology forPolar Ships and Structures(STePS2) project, which includeslaboratory experiments andnumerical experiments being con-ducted to develop new design toolsfor assessing future Polar Classunits. Additional projects haveresulted in high-speed ice/struc-
ture and ice/ice interaction simu-lation through the use of graphicalprocessor units for the discrete ele-ment method (DEM) as well asGPU-based event mechanics(GEM).
Project RoundupArctic research supported by ABS isunder way at Memorial Universityof Newfoundland (MUN) in St.John’s, where ABS established itsHarsh Environment TechnologyCenter (HETC) in partnership withMUN in 2009. Researchers atHETC are evaluating ways shipsand offshore structures can bedesigned and operated safely andeffectively in Arctic environments.Research is focusing on gatheringdata related to technical chal-lenges such as ice-hull interactionand ice loads as well as the effectof beyond frigid temperatures onequipment and equipment winteri-sation. Joint industry efforts aretargeting several of these key tech-nical areas.
Ice-Hull InteractionABS is contributing to JointIndustry Projects (JIPs) in which
A R C T I C I C E
Since 2010, the ABS Harsh Environment Technology Center (HETC) has partnered with academia and industry to address the question, “What can be done about the ice headed theway of an Arctic vessel or asset?”
BY HAN YU, JOHN DOLNY AND DAN OLDFORD
Solving the Ice Equation
Icebergs are a challenge in ice-infested offshore areas such as
Atlantic Canada
Class’ Arctic Reconnaissance –
The National Research Council (NRC) of Canada providesinnovation and research support with the goal of improvingefficiency, safety and security in the Arctic and works to fur-ther sustainable resource development, marine safety tech-nologies and advancements in cold region infrastructureand transportation – a model scale DP drillship (shown)undergoes station-keeping tests in the NRC’s ice tank (photo: NRC)
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full-scale structural arrangementsclose to Polar Class strengtheninglevels are being subjected to icesamples shaped as ice cones andloaded on hydraulic rams to morethan 300 metric tonnes of force.
The results of tests carried out tovalidate numerical simulations ofboth ice and structural deforma-tion are providing valuable insightinto the plastic overload capacityof typical ice-belt structures. Ice-hull interaction experimentsinclude high-energy collisionsusing a novel double pendulumcollision apparatus, capable ofswinging more than nine metrictonnes of ice and steel at a closingspeed greater than 10 metres/sec-ond.
Ice ManagementHETC is managing the first phaseof a JIP aimed at closing knowl-edge gaps that exist in understand-ing ice loads on floating struc-tures.
ABS-hosted workshops in St. John’shave facilitated a comprehensivereview of different structural con-
figurations, interaction scenarios,ice management, station-keepingsystems, numerical models, modeltesting procedures, design codes,full scale data, and operationalexperience. Areas of uncertaintyidentified by workshop participantswill be explored to provide recom-mendations toward a dedicatedfull-scale measurement campaignthat will be coupled with physicalmodel testing and numerical mod-elling efforts targeting prioritisedareas of development.
Event MechanicsA new paradigm for simulationcalled GEM simulates a long andspatially extensive process as aseries of events. Unlike continuummechanics, which focuses on thefine mechanical detail of materialbehaviour, event mechanics allowsmodelling of complex problems asa mesh of events rather than as amesh of elements.
A simulation domain containinghundreds or thousands of discreteand interacting ice floes can bemodelled easily. Each ship/iceimpact is modelled along with
every ice/ice interaction. This sim-ulation approach allows engineersto calculate time histories of vesselresistance, speed, orientation, andposition. The performance of icebreakers in various ice conditionsexecuting different tactical
manoeuvres as they protect an off-shore asset can be assessed.
Work at MUN has demonstratedthe ability to achieve simulationspeeds faster than real time, whichvastly exceeds the speeds achiev-able by standard continuummechanics models. Far from fin-ished, the work will continue toinclude more complex interactionssuch as floe splitting, floe submer-gence, rubble pile-up, and moor-ing systems.
WinterisationThe ABS LTE Guide represents a setof mostly prescriptive requirementsbased on assumptions about vesseloperations. This approach is usedextensively in areas such as theGulf of St. Lawrence or the BalticSea. However, companies requirean approach to safety that canallow for demonstrating compe-tence in dealing with risk withoutfollowing prescribed action.
Through HETC, ABS is developinga risk-based winterisationapproach to vessel design thatdelivers a low level of risk whilepermitting the use of practical
Modelling work taking place in Canada will continue to assess more complex interactionssuch as floe splitting, floe submergence, rubble pile-up, and mooring systems
Understanding the ice load capacity of Arctic ships and offshore structures was one ofthe key aims of the USD 7.2 million STePS2 project at MUN. The STePS2 team hascarried out three ice impact tests by striking a 1-metre diameter ice cone against a spe-cially designed Ice Impact Module developed by Dr Robert Gagnon, a physicist at theNRC of Canada’s Ocean, Coastal and River Engineering facility in St. John’s. When thetests on the Impact Module are complete, the next series of tests will measure iceimpact on steel structural panels with the goal of determining the strength and over-load capacity of ice class structures. (photo: STePS2)
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solutions. This approach is beingapplied collaboratively with adesigner to a new vessel designintended for harsh-environmentoperations, where the operatorshave a long history of safe opera-tions. Areas of noncompliance withthe prescriptive requirements arebeing highlighted and risks evalu-ated based on probability and con-sequences of failure. ABS is usingvaluable feedback from this exer-cise to enhance the LTE Guide,while the client is using the feed-back to make informed decisionsin the detailed design phase.
Arctic OperationsHandbookWork concluded at the end of 2013on a 15-member JIP establishedthe previous year to develop anoperations handbook that address-es safety and sustainability of off-shore operations in the Arctic. TheJIP focused on operational activi-ties associated with transportingand installing fixed, floating, andsubsea units as well as dredging,trenching, pipe laying, and float-ing oil and gas production inArctic and cold-weather conditions.Potential risks that could arise inspecific Arctic conditions wereidentified to improve the under-standing of the operational chal-lenges involved.
Arctic OperationalLimitationsThrough the InternationalAssociation of ClassificationSocieties (IACS), ABS is working atthe forefront of regulatory regimeinitiatives to assist IMO with itsproposed international code ofsafety for ships operating in polarwaters (Polar Code).
As a member of IACS, ABS is help-ing to develop the new PolarOperational LimitationsAssessment Risk Indexing System(POLARIS). POLARIS providesguidelines for prudent operationsin a range of ice environmentsbased on a vessel’s ice class nota-tion and the associated notional
The Authors:Han Yu is ABS Manager of the Harsh Environment Group in the Technology department, where heis responsible for R&D efforts of harsh environment technologies. His latest research areas are full-scale measurements of ships in harsh environments and Arctic technologies. Mr Han has more than30 years’ experience working as a naval architect in the shipbuilding industry and marine researchfield.
John Dolny is senior engineer at the ABS Harsh Environment Technology Center (HETC) in St.John’s, NL, where he is responsible for the maintenance of ABS ice class requirements, guidanceand interpretation to clients, as well as managing or supporting joint scientific and applied researchprojects with industry partners and academia. Mr Dolny also participates as a member and techni-cal advisor of the U.S. delegation to the IMO on initiatives related to the development of a manda-tory Polar Code.
Dan Oldford is part of the research team at the ABS Harsh Environment Technology Center in St.John’s, NL, where he is involved in R&D efforts targeting Arctic issues, including winterisation.Oldford worked as an ABS surveyor in Canada before joining the ABS HETC. He is a graduate ofthe Ocean and Naval Architectural Engineering Program at Memorial University in St. John’s.
capability. Work is on-going to createtools for its applica-tion.
As the offshore indus-try considers the bestmethod to venturesafely into ice-proneareas to develop oiland gas resources,class is working in stepwith academia andindustry to verify thatfrontier vessel designsare constructed to con-tend with this dynamicand challenging environment. n
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