Study On Strength Analysis And Failure Mode Of Quick Coupling Connections Of Wellhead Platform Conductors

Conductor is a key component of wellhead platform, which is connected by quick coupling connection in the early years. Quick coupling connection is the main component to connect the conductors and has an important effect to the structure safety. In addition to this, large amounts of these wellhead platforms have entered into the evening of their design life, which requires a comprehensive safety assessment of the existing situation and the extended service life. Therefore, aimed at quick coupling connection, study on strength analysis and failure mode is conducted in this paper.First of all, the finite element model of wellhead platform is generated in ANSYS. Stress analysis of wellhead platform is completed under different environmental load combinations, and emphases studied the strength of wellhead platform under ice load. Safety assessment of wellhead platform under ice load is conducted, as ice load is the control load of platform. The results show that the safety factor is not satisfied with the engineering requirement. Some measures should be taken when the thickness of ice over 25cm. According to the most dangerous condition, the internal forces are extracted and the preparations for local analysis of quick coupling connection are completed.Next, partial analysis of quick coupling is conducted. The finite element model of the quick coupling connection is generated, and the strength analysis of the quick coupling is completed with the internal forces which are extracted in the previous chapter. The difficulties in generating model and analyzing are solved. Reasonable approaches to the interaction simulation between all parts of quick coupling connection are discussed emphatically. The exertion of end internal forces is proposed, which is more convenient to apply forces and moment. Considering the complication in structure of quick coupling connection, the simplified finite element model is proposed.Finally, the failure mode of quick coupling is analyzed emphatically. In order to reveal the possible damage forms further, finite element analysis is conducted with all kinds of forces applied to alone. Based on the these analysis above, the damage model is generated and different damage cases, including crack on circlip, groove undamaged,25% damaged,50% damaged and completely damaged cases, are investigated. At the same time, the effect of damage location of the groove on the quick coupling connection was also analyzed and compared. Research results demonstrate that groove damage has an important effect on the strength on the quick coupling, and the function of groove is mainly provided by its tension side.