One of the little known problems of working with copper plumbing is that the copper pipe should never touch a piece of galvanized metal, be it a pipe strap or a passing heating duct. There is an electrolytic reaction between the two metals, especially in the presence of heat, that will eat holes in the copper water pipe. Always use plastic or copper straps with copper pipe.
Also copper and steel pipe must never be in contact with each other. They must be joined by a Dielectrical Couplings.