Experimental Study of Chloride Stress Corrosion Cracking In Stainless Steel

Nowadays, material and stress problems have become a significant issue that is causing many problems such as Stress Corrosion Cracking (SCC). “Stress corrosion Cracking” (SCC) is a general term describing stressed alloy failures that occur by the propagation of cracks in corrosive environments. Chloride stress corrosion cracking (CLSCC) is one the most common reasons why austenitic stainless steel pipe work and vessels deteriorating in oil & gas industry. A pressure vessel known as knock out drum is typically used to separate gas-liquid mixture in the gas processing plant. Cracking failure was reported for a knockout drum in PETRONAS Gas Berhad Kerteh. The accumulation of salts under insulation and also residual stress were suspected to trigger this CLSCC. The aim of this project is to study the impact of sodium chloride concentration and impact of applied strain towards the crack initiation of 304L and 316 stainless steel test specimens. The test specimens were prepared and machined into C-ring geometry accordingly to ASTM G38-01 standard. Then they were stressed by tightening with bolt and nut into 0.4% and 1% strain. All C-ring specimens were submerged in a beaker at temperatures 55°C with different sodium chloride solution concentrations at 1000 PPM and 10000 PPM respectively. The crack initiation on the C-ring specimens was observed and analyzed weekly. The results from 304L stainless steel C-ring samples show early sign of rusting. Meanwhile, there is no change to the 316 C-ring specimens. These experiments are ongoing. The expected result is that 304L C-ring materials should crack in the duration of 60 days.