Galvanic reaction, Monel metal and Titanium

[corrosionman]

I have just seen a proposed heat exchanger with Titanium ( Grade 2) tubes and Alloy 400 tubesheets. The heat exchanger cools saturated brine. The galvanic action between these metals is much the same as between Stainless steel and Mild steel. Would it be reasonable to expect the titanium tubes to have a short life ??
I cannot believe that the Designer has overlooked this possibility, but I have no experience of titanium.
I would much appreciate any comments.
Corrosionman

 

[EdStainless]

I would expect the galvanic corrosion to attack the Monel, however if this not a high temp application then both alloys have very good corrosion resistance, and the galvanic effect should be minimal.

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Plymouth Tube

 

[shivanighai]

@EdStainless- I have come across the same problem but in application. The Monel and Hastelloy tubesheets (and welds) are seeing some serious corrosion. I tried to do some research on it but couldn't quite find anything. Monel, Hastelloy and Titanium appear to be very close on the anodic index so I am uncertain as to why the Monel and Hastelloy tubesheets are seeing corrosion and not the Titanium tubes. Could it not be galvanic corrosion?

For some background the process is a saturated brine (potash) slurry. Running at fairly high temperatures (250-300F).

 

[EdStainless]

shivanighai,
at the risk of supporting your thread hijacking I'll respond.
I don't think that you are seeing galvanic attack.
I would not expect Monel to like brine service, and Ni-Cr-Mo welds may not be too good either.
At you temps I would even worry about Ti gr2. The CP grades can pit under these conditions.
Full Ti constructions with alloyed grades would be a better solution.

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Plymouth Tube