Effect of pitting corrosion depth on the performance of L360 pipeline under high acid conditions

In Puguang high-sulfur gas field, wet gas gathering and transportation process is adopted in the ground system. Carbon steel pipelines suffer the pitting corrosion caused by coexistence of elemental sulfur and H₂S/CO₂ in the harsh operation conditions. In this paper, corrosion samples with different pitting corrosion depth were prepared at fixed pitting corrosion density in the laboratory to quantitatively evaluate the effect of pitting corrosion defects on mechanical properties of pipelines. Then, the effects of pitting corrosion depth on tensile strength, yield strength, stress corrosion cracking resistance and hydrogen induced cracking resistance were tested in simulated working conditions. It is indicated that the tensile strength, yield strength, modulus of elasticity and elongation of the pitting corrosion samples decrease with the increasing of pitting corrosion depth, and the above parameters decrease sharply at the appearance of pitting corrosion on samples. The impact power of pitting corrosion samples and the intensity factor of crack tip stress field decline exponentially as the pitting corrosion gets deeper.