Galvanic corrosion?

digger_2

My new flat plate heat exchanger is constructed with stainless steel. Can we screw copper FIP adapters directly to the ss threaded nipples on the HX without galvanic corrosion down the road?

BobbyG

digger

[url=http://www.bellgossett.com/literature/files/7140.pdf]http://www.bellgossett.com/literature/files/7140.pdf

Here's a link to a service manual for brazed plate heat exchangers.  It doesn't really talk about connection and electrolysis.  From my limited understanding about electrolysis (galvanic corrosion) ...

In a closed heating system the water becomes electrically neutral and there isn't new water being introduced so it reaches a equilibrium point with electrical charges on the atoms - so no further damage and whatever initial damage is very minimal.

If memory serves me - your using a boiler with heat exchanger to heat radiant tubing loops that are non-oxygen barrier.  In this case, it will be similar to a closed heating system - only with oxygen coming and going freely through the pex tubing - I think once the oxygen enters and there aren't any ferrous items(Cast iron) for the oxygen to attack - it will reach a equilibrium point and nothing bad will happen to the non-ferrous (copper and stainless steel) materials - one thing to watch for is non-ferrous items like the lining of the expansion tank, prv and anything that may be ferrous.  I've seen the small items like the expansion tank get eaten up pretty quickly.  Don't give the oxygen anything to eat because it/they will become very aggressive.



(I know this isn't your situation) - but for a water heater for the domestic water side to transfer to heating water - then there is a constant change in water - so there could be more atoms (valence electrons) with - charge seeking bonds, but I think from stainless to copper isn't as bad (nothing to worry about) as say copper to steel but would like other opinions myself.



I'm curious to hear what others say about this because my experience is really limited....



Hope this helps.

Jim Hankinson

Galvanic corrosion

Energy Kinetics has been using SS exchangers for 30 years to make hot water and isolate systems. They've used copper and brass half-unions for easy install and removal for at least 20 years with no issues.