HOIS Highlights 2023-2024
Inspection for SCC cracking: Duplex Stainless Steel Components at Elevated Temperatures (120°C to 150°C)
Background
In the last few years, several cases of Cl’ SCC have been identified in insulated duplex pressured equipment (process piping and pressure vessels), operating at temperatures up to 150°C.
Following removal of the insulation, roughened component surfaces have been observed due to pitting corrosion and contamination/debris underneath the insulation.
Traditional PT and MT has a maximum application temperature between 40°C to 60°C, fluorescent penetrants will begin to lose their fluorescence at 93˚C, which is one of the reasons why dryer temperatures are not to exceed 71˚C per ASTM E-1417 6.6.2. These temperatures are below critical Cl’ SCC temperature for duplex, therefore are not considered an option for in-service inspection for this degradation mechanism. There is therefore a need for an inspection technology for early detection of developing cracks.
The focus of this work will be on crack detection only and will not consider measurement of crack depth.
Progress Update
Various methods of manufacturing SCC in duplex SS have been considered, but it was decided that the trials will be based on sections from a failed duplex stainless steel pump containing stress corrosion cracking.
The design of the trial is currently ongoing.