Failure Analysis on Fracture of a S135 Drill Pipe

The fracture of drill pipe is mainly controlled by the material of drill pipe and environment of operation, which maybe induces huge loss of economy and society. A fractured 3 1/2″ S135 drill pipe was analyzed through physical and chemical properties, Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) method. Additionally, a series research about sulfur resistance of S135 was also estimated by sulfide stress cracking test and hydrogen-induced cracking test. The results showed that the failure of the drill pipe was belong to sulfide stress corrosion cracking. High H2S content condition and the material with high strength leaded to the final rupture of the drill pipe. The application of drill pipe with high strength was also proposed on the basis of above results and discussion.