Leakage Failure Analysis of 80SS Tubing in Gas Field

During acidizing process in a gas field, leakage of 80SS anti-sulfur tubing occurred.The main reasons for failure of the tubing have been investigated based on analysis techniques of chemical composition analysis,Optical Microscopy (OM), Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) , X-ray Diffraction (XRD) and mechanical test. The results show that composition and mechanical properties of the tubing were all in accordance with the corresponding requirements of API Spec 5CT standards. Furthermore,leakage of tubing from inner wall was caused by combined impacts of acid corrosion, H2S corrosion, low PH value, high temperature and a certain pressure. Meanwhile, Low concentration of corrosion inhibitor was also one of the factors of corrosion perforation.