BS ISO 24042:2020 pdf download – Liquid cargo handling equipment — Crude oil offloading system —Tandem mooring winches 5 Design 5.1 General requirements The design of tandem mooring winches shall meet the requirements of ISO 7825 and 5.2 to 5.8. 5.2 Material stresses In accordance with material stresses given in ISO 3730:2012, 4.2 and ISO 7365:2012, 4.1, winch manufacturers shall determine the strength requirements of winch components to enable them to withstand the loads specified in 5.3. 5.3 Basic calculations 5.3.1 The allowable calculated stress of any affected part under the hawser deployment and recovery load shall not be greater than 0,4 times the upper yield strength of the material. 5.3.2 The allowable calculated stress of any affected part under the safe working load shall not be greater than 90 % the upper yield strength of the material. 5.3.3 In dynamical calculations, the required power of actuators on the drive chain shall not be greater than 80 % the rated power of actuators. 5.3.4 The hawser deployment and recovery load of the tandem mooring winch shall be not more than 33 % of the design breaking load of the hawser when it operates under the corresponding nominal speed. 5.3.5 The safe working load shall be not more than 80 % of the design breaking load of the hawser. 5.4 Drum and hawser 5.4.1 Hawser 5.4.1.1 The hawser is generally composed of a main rope, chafe chains, thimbles, shackles, a messenger rope and buoys. The chafe chains, main rope, thimbles and shackles withstand the mooring pull. The messenger ropes and buoys are mainly used to connect the lifting vessel before the mooring operation. 5.4.1.2 If the quick release device is independent, a chafe chain shall be provided at the head and tail of the main rope. The head chafe chain is used to connect the lifting vessel, while the tail chafe chain is used to connect the quick release device. 5.4.1.3 If the quick release device is integrated into a tandem mooring winch, only head chafe chains rather than tail chafe chains can be configured for the connection of the receiving tanker. 5.4.2 Drum diameter 5.4.2.1 For polyester and polyamide (nylon) hawser main ropes, the diameter of the drum shall be not less than six times the design diameter of the main rope. 5.4.2.2 For polypropylene hawser main ropes, the diameter of the drum shall be not less than four times...
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