Two Typical Cases Analysis of Casing Connection Pullout

Research on a round thread casing connection pullout case and a buttress thread casing connection pullout accident was carried out combining relative theorys with tests. Macroscopic analysis and dimension measurement and material’s physical and chemical properties were checked for casings and couplings. Thread inspection and full-scale tests were done for casing simples that are same lot with pullout casing. Comprehensive analysis was carried out on these results. Two cases history showed that casing connection dropout may take place if make-up location cann’t reach standard location or make-up torque is too little even if the quality of casing and coupling are in accordance with corresponding standards.