Chiller Tube Sheet Corrosion 1

[Hileg]

Does anyone know why chiller copper tubes are able to be pressed into steel tube sheets. Doesn't this create electrolisys? I know plumbers and hvac mechanics are taught to always use a dielectric fitting type connection whenever this combination is formed. Why do chillers not have to conform to this practice? What causes the pitting in tube sheets of chillers? How can pitting be avoided. Please help.

 

[molsen4u]

Pitting is usually created by poor water treatment control. while adverse operating conditions, i.e.-High head/high condenser temps. If pitting is a concern, an eddy current test would be advisable