Experimental investigation on service safety and reliability of full-scale HMPE fiber slings for offshore lifting operations

Abstract

In recent years, high modulus polyethylene (HMPE) fiber slings have been increasingly used in marine transportation and installation projects due to their numerous advantages including lighter than steel ropes, easily handling operation, and no fish hooks et al. Due to the complex behavior of fiber ropes, an effective bedding-in method is necessary to proposed to stabilize the sling length and ensure the safety and reliability of offshore lifting operations. This study proposes a detailed procedures and techniques for evaluating the creep behaviors and load elongation properties of full-scale slings with a normal breaking strength of 10,000 kN. The experimental results reveal that the HMPE exhibits the viscoelastic-viscoplastic behavior and load history effect. Based on the experimental results, the crucial mechanical parameters such as Young's modulus and static stiffness of the HMPE sling are established. A bedding-in procedure of HMPE slings is proposed to remove the structural elongation and to ensure the stability of the length of the sling. The present results have been applied and verified on the evaluation of the slings in Sewol Salvage Engineering. The results can serve as a reference for the application of HMPE slings in offshore lifting operations.