any re-fridge engineers

[solarman216]

I have a problem that so far cannot solve, Drinks fridge has condensate drain on top of unit into a plastic tank with high pressure pipe from compressor dipped in it to evaporate the liquid (standard practice) problem with this one is about 12 months and the copper pipe suffers corrosion and perforates, I have replaced this pipe coil twice now and it is showing signs of leaking again (last time I painted it but guess the paint was destroyed by the high temp) am thinking of heat shrink tube over pipe before forming the coil, but has any one come across this before? I have verified that all items in the fridge are sealed so do not know from where this copper aggressive compound can come from, Rick