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DNV Marine Operations Rules for Subsea Lift Operations Simplified Methods for Prediction of Hydrodynamic Forces Tormod Be DNV Marine Operations 29th November 2011 DNV Marine Operations' Rules for Subsea Lift Operations Slide 229. November 2011 Content Brief overview of relevant DNV publications DNV Rules for Marine Operations, 1996, Pt.2 Ch.5Lifting Capacity Checks Simplified Methods for prediction of Hydrodynamic Forces oin Splash Zone, DNV-RP-H103 Ch.4 oin Deepwater, DNV-RP-H103 Ch.5 DNV Marine Operations' Rules for Subsea Lift Operations Slide 329. November 2011 Relevant DNV Publications Lifting- and subsea operations : Specially planned non-routine operationsRoutine operations DNV Standard for Certification No.2.22 Lifting Appliances October2011 DNV Rules for Planning and Execution ofMarine Operations 1996 and DNV-OS-H101 Marine Operations, General - 2011 Specially planned, non-routine operations oflimited durations, at sea. Marine operations are normally related to temporary phases as e.g. load transfer, transportation and installation. DNV-OS-E402 Offshore Standard for Diving Systems October2010 DNV Standard for Certification No. 2.7-3Portable Offshore UnitsMay 2011 DNV Marine Operations' Rules for Subsea Lift Operations Slide 429. November 2011 DNV-RP-C205 Environmental Conditions and Environmental Loads October 2010 DNV-RP-H101 Risk Management in Marine and Subsea Operations, January 2003 DNV-RP-H102 Marine Operations during Removal of Offshore Installations, April 2004 DNV-RP-H103Modelling and Analysis of Marine Operations,April 2011 Relevant DNV Publications - Other DNV Marine Operations' Rules for Subsea Lift Operations Slide 529. November 2011 Relevant DNV Publications - WebSite Most DNV publications can be downloaded for free at: http://www.dnv.com The 1996 DNV Rules for Marine Operations is not in the DNV intranet site.DNV Marine Operations' Rules for Subsea Lift Operations Slide 629. November 2011 Content Brief overview of relevant DNV publications DNV Rules for Marine Operations, 1996, Pt.2 Ch.5Lifting Capacity Checks Simplified Methods for prediction of Hydrodynamic Forces oin Splash Zone, DNV-RP-H103 Ch.4 oin Deepwater, DNV-RP-H103 Ch.5 DNV Marine Operations' Rules for Subsea Lift Operations Slide 729. November 2011 Capacity Checks - DNV 1996 Rules Dynamic loads, lift in air Crane capacity Rigging capacity, (slings, shackles, etc.) Structural steel capacity (lifted object, lifting points, spreader bars, etc.) Part 2 Chapter 5 Dynamic loads for subsea lifts are estimated according to DNV-RP-H103 DNV Marine Operations' Rules for Subsea Lift Operations Slide 829. November 2011 Capacity Checks DAF for Lift in Air Dynamic loads are accounted for by using a Dynamic Amplification Factor (DAF). DAF in air may be caused by e.g. variation in hoisting speeds or motions of crane vessel and lifted object. The given table is applicable for offshore lift in air in minor sea states, typically Hs < 2-2.5m. DAF must be estimated separately for lifts in air at higher seastates and for subsea lifts ! Table 2.1 Pt.2 Ch.5 Sec.2.2.4.4 DNV Marine Operations' Rules for Subsea Lift Operations Slide 929. November 2011 The dynamic hook load, DHL, is given by: DHL = DAF*(W+Wrig) + F(SPL) ref. Pt.2 Ch.5 Sec.2.4.2.1 Capacity Checks - Crane Capacity W is the weight of the structure, including a weight inaccuracyfactor The DHL should be checked against available crane capacity The crane capacity decrease when the lifting radius increase.DNV Marine Operations' Rules for Subsea Lift Operations Slide 1029. November 2011 The maximum dynamic sling load, Fsling, can be calculated by: Fsling = DHLSKLkCoGDW/ sin ref. Pt.2 Ch.5 Sec.2.4.2.3-6 where: Capacity Checks - Sling Loads SKL = Skew load factor extra loading caused by equipment and fabrication tolerances. kCoG= CoG factor inaccuracies in estimated position of centre of gravity. DW = vertical weight distribution e.g.DWA =(8/15)(7/13)in sling A. = sling angle from the horizontal plane. Example : DNV Marine Operations' Rules for Subsea Lift Operations Slide 1129. November 2011 Safe working load, SWL, and MBL, of the shackle are checked by : a) Fsling