Vac Resid Pipe Spec 1

[clsengr]

Is there a good reference/article indicating the temperature range for vacuum bottoms pipe spec break? Specifically, I need to know where I can change from 1-1/4 Cr - 1/2 Mo to CS. (We are adding exchangers for a new pre-heat train.)

 

[gedomin]

Last year story: An incident at a refinery, in California... Loss of containment.
Cause was a pipe section of wrong material at a Vacuum Pipestill bottom. Upon investigation, a CS section was found installed by mistake, where proper alloy should be Cr-Mo (maybe 1.25/0.5 or higher).

Material selection depends also on crude type: Sulfur and Naphthenic Acids content.
You might estimate corrosion rates from registered records at your site, for CS components, at various temperatures, for the same or similar service. This would help you to decide...Do not extrapolate.
What I could say: CS performance is commonly OK below 400 degF when product sulfur is lower than 3.5%, coming from a virgin crude.