FAILURE ANALYSIS OF STEAM TURBINE WHEEL DUE TO HOT CAUSTIC STRESS CORROSION CRACKING

We received two sections of 304 stainless steel pipe along with samples of insulation, strapping, two process fluids, and a water sample from the DI system used to mix the fluids for failure analysis.

Cracks in the pipe section - as polished_1

Ion chromatography (IC) testing revealed that the DI water sample contained 9 ppm of chlorides that could cause corrosion. The silicone-based piping insulation also contained both sodium and chlorine. If these elements are trapped against stainless steel in a moist environment, stress corrosion cracking (SCC) can occur, as it did here. For more information, download our Failure Analysis Case Stude Guide