Chloride Limits for Pitting and Cracking of 300 Stainless Steels Series in an Acid Gas Removal lant

摘要

The effect of chloride on the pitting and cracking propagation of UNS S30403 and UNS S31603exposed to sour service was studied. Laboratory testing to simulate the extreme ends ofprocess conditions found in our acid gases removal plant were conducted. The typical Gasprocess conditions vary from 110oF (43℃) to 300oF (149℃) with high and low loads of H_2S andCO_2 in equilibrium with a solution of an acid gas selective solvent and water. This study covereda range of chlorides from 0 to 500 ppm. Cyclic polarization and potentiostatic Electrochemicaltechniques were used to determine the limits of chlorides required to cause stable pittingleading to cracking. Cracking was confirmed by means of 30-days exposure testing of stressedcoupon. Conducting cracking testing at several applied stress levels to better resemblingapplied stresses at the plant piping and vessels are planned