Galvanic Corrosion
Galvanic Corrosion
(OP)
Dear all,
I have a heat exchanger with carbon steel tubesheet.
There is stainless steel weld overlay on tubesheet. The tube is carbon steel. Tube to tubesheet joint is strength weld. My question is there any possibility for galvanic corrosion between CS tube with SS weld overlay ??
Thanks a lot
I have a heat exchanger with carbon steel tubesheet.
There is stainless steel weld overlay on tubesheet. The tube is carbon steel. Tube to tubesheet joint is strength weld. My question is there any possibility for galvanic corrosion between CS tube with SS weld overlay ??
Thanks a lot





RE: Galvanic Corrosion
Can you give any paritculars on your fluid??
You state that the tube to tubesheet overlay is a strength weld??? Normally the strength comes from the tube expansion into the tubesheet, and the weld is a seal weld only. Please explain.
Tube to tubesheet joints like the one you describe are very common in high pressure feed water heaters, which last years, and few of which fail from galvanic corrosion. But, then boiler feed water is not very conductive.
rmw
RE: Galvanic Corrosion
And about the joint type, there are expand only, heavy expand and seal weld and light expand with strength weld.
RE: Galvanic Corrosion
Sorry,, why was SS welding consumables used for a CS - CS joint. Under what premise was the WPS and PQR qualified.
RE: Galvanic Corrosion
If the heat exchanger shell is carbon steel, I would periodically inspect the weld interface between the weld overlaid tube sheet and the carbon steel shell to check for knife line corrosion attack.
RE: Galvanic Corrosion
RE: Galvanic Corrosion
Good catch. Actually, the anode area will be greater than the cathode area because the total surface area of the carbon steel tubes will be greater than the surface area of the overlaid ss tubesheet. Thus, there should be no galvanic corrosion problem. For some reason I had flip flopped the areas.