Offshore module drilling rig has become an important equipment of offshore oil and gas development, especially,the significantly future application in the field of deep water. Due to the long time working and complex workingconditions of in-service derrick of offshore module drilling rig, analysis of its load-carrying capacity assessment is ofgreat significance. Field test shows that in common the derrick of offshore module drilling has an intrinsic defect of stressconcentration in addition to external damages including initial bending and load eccentricity. In this paper, the finite elementmethod is combined with field test method, two assessment methods are put forward, respectively. Stress concentrationdetection on derrick main rod is carried out by using metal magnetic memory detector, and the detection results showthat larger degree of stress concentration phenomenon exists on eleven rods of derrick, and stress concentration degree ofindividual rod is serious. Loading stress test and finite element analysis are carried out on the derrick of offshore moduledrilling rig. According to comprehensive comparison, it is concluded that hoisting capacity for the derrick cannot reach4500 kN. Two kinds of structure reinforcement scheme are proposed, and comparison results show that the reinforcementscheme with four legs can improve the actual load-carrying capacity of the derrick. Reinforced derrick can achieve thenew design value of derrick carrying capacity. In this study, the evaluation method is correct, which can analyze the derrickcarrying capacity of offshore module drilling rig more objective and accurate, and we also provide a new train ofthought and reference for the steel structure carrying capacity assessment.
展开▼
