Cl SCC in 300SS

[Krausen]

Question on Chloride Stress Corrosion Cracking in 300SS material - working in oil refinery industry, looking to retube a naphtha furnace with new 317/L tubes. Some materials engs have expressed concern with CL SCC potential. The Process engs are claiming aqueous chlorides are not possible in normal operation of furnace inside these tubes. However, there is concern that transient operations may introduce chlorides inside these new 317/L tubes and cause Cl SCC. I understand many refineries have retubed furnaces with 300SS material though, so this must be managed somehow? The 300SS tubes are preferred option since they allow for higher operation temperatures over long term & have higher allowable stresses under both the elastic & rupture (creep) design basis (per API530).

 

[EdStainless]

This service is world of its own.
There are tons of papers out there about it.
Any sensitization (such as in welds) is fatal.
You can do this with 300 SS materials, but you have to have safeguards to PREVENT the introduction of water.
At temperatures of 150-250C, low ppm levels of Cl, low pH, and any S and the SCC will initiate quickly.
Such as times measured with a stopwatch and not a calendar.

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