Ultimate capacity of pad eyes used for lifting operations: experimental and numerical simulations

Load capacities of pad eyes used in offshore lifting operations are generally determined based on the guidelines given in lifting standards. In 2012, NORSOK issued a new standard, R-002 ‘Lifting equipment’, to ensure that adequate safety requirements are complied with in connection with lifting operations on the Norwegian continental shelf. To ensure the accuracy of the followed design procedure, this paper presents a comparison of theoretical load capacities of 3.25-ton pad eyes with experimentally and numerically predicted load capacities. Several laboratory tests have been performed to conduct experimental analyses of the load capacities of pad eyes. These tests have included different pinhole sizes in the pad eyes, different strain directions of pad eye pinholes and different loads to which the pad eyes were subjected. Finite element (FE) simulation was performed for two different cases: with base plate and without base plates. The obtained numerical results show that the addition of the plate to the pad eyes increased the capacity of the pad eyes. It also shows that load capacity of the pad eyes gradually decreased with the increase in pinhole size. This shows the importance of following the standard’s requirements. The comparison of results shows that some of the load capacities provided by the FE analysis closer to the experimental and the theoretical results, while a few others were quite far from them. These differences have been comprehensively discussed in the latter part of the paper.