We are experiencing pitting corrosion along the weld seam of
copper/nickle (90/10) 1" resistance welded tubes used in a heat
exchanger -- the pits are on the inside of the tubes that contain
demineralized water heated to 150 deg F.
Does anyone have any good references or experiences to help us
understand this problem and find a solution?
The water may be demineralised but that doesn't mean its 100% pure.
Surprisingly low levels of certain contaminants can cause pitting
especially in regions where metal has been under mechanical or heat
Is there any way you could apply a heat stable paint on the inside
surface of the pipes?
Phil Smith wrote:
You might start by looking at the Copper Development Association (CDA)
Get a cup of coffee or tea to sip, because
it loads slowly these days. There are sections on Copper Nickel in
general and on marine applications. Also look at the Nickel Institute
since they also cover cupronickel.
A good starting point at CDA is:
It has a couple articles. The DKI pamphlet says resistance welding
should not be a problem. The Corrosion 2000 article by Powell & Michel
talks a lot about film formation. If your weld has a funny film, then
it could pit.
What have you got for flow velocity, sulfide content, and other