Research on Damage Assessment of Corroded Oil and Gas Pipelines Based on Fracture Mechanics

Generally, oil and gas pipeline is made of carbon steel, alloy steel and other metal materials. The biggest threat to the integrity of the oil and gas pipeline is the presence of corrosion. Corrosion will happened when the metal pipeline is affected by chemical or electrochemical attack, or microbial reaction with its environment. With the increasing of the service time, the corrosion of the oil and gas pipelines has become more and more serious. The wall thickness of the corroded pipeline will be lessened and that may lead the decrease of the strength of the pressurized pipeline. Thus, a leak may be happened at the corrosion area if the actual operation pressure of the pipeline is larger than the maximum safe pressure. So it is significant to study and assess the damage condition of the corroded oil and gas pipelines. Based on the theoretical foundations of fracture mechanics, the mathematical model for the failure pressure of corroded oil and gas pipelines was built in this paper firstly. And then, the corrosion damage level of the pipeline was divided into 3 grades according to the ability of the corroded pipeline. Furthermore, 20 corroded pipes were selected to study the damage assessment. The maximum safety operating pressure and damage level of each corroded pipe were carried out by applying the proposed mathematical model in the paper. As a result, the computational data were closed to the experimental data. The corrosion damage level and repair plan of the twenty pipes were discussed, and there were three pipes need to repair immediately. The results show that the proposed method can well assess the corrosion degree of the oil and gas pipelines with defects and can provide a scientific basis for the safe operation and emergency management of the oil and gas pipelines enterprise.