Materials selection for a reactor

[kissjxp]

I met another problem on the materials selection for a reactor. Please help!

Design temp./pressure for normal operation: 150C/4485 kPag
Design temp./pressure for regeneration: 330C/1550 kPag
MDMT:10C

Operating temp./pressure for normal operation: 76C/4000 kPag
Operating temp./pressure for regeneration: 300C/500 kPag

In the normal operating condition, this reactor has 14 mol% H2. In the regeneration condition, the reactor also has 8 mol% H2 and 500 PPM mol H2S. No free water in this reactor. I read a NACE book, which recommended 321/347SS clad for vessels if both H2S and H2 presented at a temperature above 290C. Considering that this reactor is not in hydrogen service in the regeneration condition based on API941. In this case, do I need to use (CS + clad 321/347SS)? Or Killed carbon steel is fine?

Thanks for your help.

 

[metengr]

Specification of corrosion resistant overlay (CRO) material on substrate materials in pressure vessels should include the worst case process conditions no matter how long or short the duration.