AISI 316L expanded rolled into carbon steel tube sheet exchangers

[0707]

In high temperature vacuum crude residuum services to resist against Naphtenic corrosion is it correct to have austenitic steel tubes such as AISI 316L expanded rolled into carbon steel tube sheet exchangers? Shell side we have vacuum bottoms residuum, tube side we have steam.

Regards

Luis

 

[EdStainless]

It will work, but often in application that will see significant pressure and/or temperature cycling it is wise to seal weld the tubes to the tubesheet.

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[0707]

Can we assume that there is no possibility of galvanic corrosion?

Tank you

Regards

Luis Marques

 

[bmoorthy]

If the total TAN number is higher(Don't ak me the limits, this info is from my memory) then 317 will work or have 316L with Higher moly (Minimum 2.5%) there are some postings on corrosion of 316L in Naphtenic Acid.

If your question is regarding whether rolling is OK for the service, then it is not objectionable to have fully rolled expanded joint (So long as Appendix A is properly addressed).

 

[MJCronin]

0707

You should consider the difference in expansion between the SS tubes and the CS shell....

I do not know the rule of thumb, but if the SS tube expansion is excessive ( long tubes and/or large temperature cycles) the tubes may "unseat" themselves and you will have continual leaks/repairs

Consult a HX fabricator for the design limits....


-MJC