Copper Stainless Steel Reaction

I wish to use hard copper elbows to join aluminum tube frame members.

Copper stainless steel reaction.

Lead and copper are quite close on the nobility table to stainless steel and so the bimetallic corrosion risks should be small. There are three commonly used metals for potable water plumbing pipes including stainless steel copper and brass. These metals are used because of their durability and long lifespans. The elbows must be permanently joined to one frame member at each knock down joint.

In most cases when stainless steel was in the passive state and acted as the cathode the contact accelerated copper corrosion. Iron and steel are generally not a problem unless their mass is similar or smaller than that of the copper. I am constructing a project utilizing a knock down aluminum tube frame. If copper is connected to stainless steel type 304 then the copper will corrode to sacrifice to the stainless steel.

However mixing these metals is not generally advised due to the potential for sudden pipe corrosion and discolored water. The principal metals of concern in terms of direct contact are aluminum and zinc. Any corrosion product if washed onto stainless steel may however result in problems not associated with the bi metallic effect and so not be predicted from the tables. Galvanic corrosion can be controlled by the use of sacrificial anodes isolation of the metals from electrical continuance protective plastic coatings or epoxy coatings or with corrosion inhibitors.

In addition the area ratio of stainless steel to copper altered copper corrosion behavior.