Causes of Hydrogen Blistering for 20G Steel in Wet Hydrogen Sulfide Environment

The causes of hydrogen blistering for corrosion monitoring coupons were analyzed.The coupons were located in the entrance pipeline from medium pressure gas cooler outlet to raw gas compressor outlet separator,in a united station natural gas processing unit of the Tarim oilfield.The physiochemical properties of 4 pieces of corrosion monitoring coupons on the scene and 1 piece of 20G pipeline test piece in-store were analyzed,and the HIC performance of 20G pipeline test piece was tested.The results showed that the chemical composition and metallographic microstructure of tested piece of pipeline met the standard requirements for 20G material.The hydrogen blistering of corrosion monitoring coupons was mainly caused by the high concentration of H2S in the pipeline.Metallographic section crack thickness sensitive rate of pipeline test piece exceeded the standard requirements,There is a high risk of hydrogen-induced cracking.Therefore,when 20G material is used in the condition,the corrosion monitoring and testing of wall thickness needs to be strengthened,Installing desulfurization device or adding corrosion inhibitor to slow down the corrosion before the wet hydrogen sulfide medium into the pipeline showed be considered for extending the service life of the pipeline.