Damaged welded pipes for oil and gas rigs exposed to internal pressure - Failure estimation

Abstract

The paper deals with the integrity assessment of API J55 steel casing pipes for drilling rigs, manufactured by high frequency contact welding procedure. The influence of corrosion defects on the pipeline load carrying capacity is determined through pressure test of a pipe with corrosion damages simulated by machining the circular holes. Finite element analysis of the damaged pipe subjected to internal pressure is used for determining the stress/strain conditions in the damaged area of the pipe. Also, numerical model was used for establishing the load carrying capacity of the pipe with different damage levels (i.e. defect depth and length). Several expressions from the literature are used for estimation of the maximum pressure in the damaged section of the pipe, and the solutions are compared with the predictions of finite element models and experimental results.