The Load Analysis and Betterment of Casing Connections

For a common casing thread, the forces acting on each thread under tensile loads are not uniform, which decreases the load-bearing capacity of the casing connections notably. According to the structure character of casing connections, a mechanical model was developed to analyze the force and deformation on casing threads under tensile load. Then a method was presented for optimizing the load distribution on each casing thread. Moreover, concerning the feasibility of the thread processing, this paper also put forward an approximate method:the pitch of pin keeps unchanged, the pitch of box change slightly according to the calculation result. At last, a finite element model was founded to test the approximate method. The results show the approximate method is effective. Thus it can be taken as references in improving the design of casing thread so as to improve the quality of the connections.