Copper Pipe Corrosion/Erosion 5

[umpire]

I am trying to determine why the copper piping in a residential hot water circulation system failed after only three years. The failure occurred in an elbow just upstream of the recirc pump. (I have photos but don't know how to include them.) I don't believe there is anything unusual in the water, and it does not look like galvanic corrosion.

 

[bilge]

Your problem sounds like cavitation, a form of erosion corrosion caused by the formation and collapse of bubbles on the elbows sirface. It is very common on propellers and such.

Possible solutions to the problem: (1) reduce the speed of the fluid flow, (2) use a rubber coating to absorb the impact of the collapsing bubble, (3) go to a stainless steel elbow (but beware of galvanic corrosion).

 

[rustbuster1]

The temp of the system can affect the erosion corrosion rates, especially in soft waters, so check other similar configurations for the next leak. You can upgrade with a cupro-nickel piece and not be concerned about galvanic corrosion, although galvanic corrosion will be unlikely anyway in domestic water even if you do use a stainless steel piece.

 

[Kenneth]

Also see thread338-16852...