Cause of leakage of 316L stainless steel hydraulic control pipeline on an offshore platform

The 316L stainless steel hydraulic control pipeline on an offshore platform was leaked. Using macroscopic observation, chemical composition analysis, metallographic inspection, scanning electron microscopy and energy spectrum analysis, and combined with actual working conditions of stainless steel hydraulic control pipeline. The cause of pipeline leakage was analyzed. The results showed that leakage of stainless steel hydraulic control pipeline was caused by the combined effect of surface damage and environmental media. During pipeline installation process, friction occurred between it and adjacent pipelines or equipment, and the passivation film on the outer surface of pipeline was damaged. In the marine atmosphere containing halogen elements, the passivation film was too late to repair, which caused corrosion of outer surface of pipeline. Finally, pitting and perforation occurred under the acceleration of Cl^- to cause leakage of pipeline.