Dissimilar metals for flange/bolt connections

[Mesopelagic]

I have had a question from a client, in which he expressed concern that a vessel had used stainless steel bolts on carbon steel red oxide primered channel cover flanges. He was concerned that the dissimilar metals would have corrosion problems. It seems to me that stainless bolts would not have greater corrosion issues than galvanized carbon steel bolts. Am I missing something (carbon contamination perhaps?). Also, this installation is inland and not around any seawater.

Thank you for your thoughts,

Mesopelagic

 

[clay87]

Surely the client is talking about corrosion of the flange, not the fasteners. Assuming normal outdoor installation, your setup sounds fine to me and fairly typical.

 

[CoryPad]

I would say it is not typical to pay extra for stainless steel fasteners that will accelerate the corrosion of a carbon steel vessel. clay87 even shows a photograph of this condition in a post from four days ago:

thread338-349402


Your client is expressing justifiable concern.

 

[cloa]

Vessel?- doesn't he mean like a pressure vessel on land or a boat?

http://www.eng-tips.com/threadminder.cfm?pid=1529

Use translation assistance for Engineers forum

Note the rules include No Student posting

 

[Mesopelagic]

Yes, it is a pressure vessel, it is on land and inland. The fabricator of the vessel substituted the bolts without consulting me, and my inspector did not catch it.


Does galvanic corrosion cause significant problems for inland non-submerged applications?



Thank you all for the posts,

Meso

 

[CoryPad]

Depends on the environmental conditions. If it is only occasionally wet and has low concentration of corrodents like chloride ion, then you may have acceptable life.

 

[TomDOT]

If the primer is intact and thus prevents metal contact between fastener and flange, not much concern. Of course, installation likely damaged the primer enough for metal contact....