Structural Evaluation of Repair Methods on Dented Tubular Members Used in Jacket Platforms

Today, Iran's oil and gas industry requires maintenance, repair, renovation, and reconstruction methods for the existing platforms. It is essential to discuss the repair of offshore platforms since they mostly have been in service beyond their design lives and subjected to damages mentioned in the following. Furthermore, offshore platforms' increased number and service lives add to the need for the in-situ repair of offshore platforms. The most important reasons for the structural repair of offshore platforms include corrosion, fatigue, the collision of floating objects (e.g., vessels), the fall of heavy objects, and intensive storms. By considering the dent damage of platform members, which typically arise from the fall of heavy objects and the collision of floating objects, the present study investigates the damages resulting from such incidents during the operation of platforms and proposes the required repair methods. The repair methods include grouting, member replacement, mechanical clamps, and doubler plates. Once the experimental model of a dent-damaged member was validated, the repair methods were applied to the models, examining the strength of the members. The results indicated that the member strength reduced by up to nearly 40% at a dent depth as large as 0.3 of the member diameter (d=0.3D). However, the reduced strength could be compensated from 12% to about 125%, by applying the repair methods.