I always install so that the copper and the steel do not touch.
Plumbers UPC tape, plastic wings or inserts, copper unistrut clamps.
Is it ok for copper water lines to be in contact with steel studs, hangers or bx cable or will it cause future corrosion in the copper?
Plumbers often put the plastic inserts between copper and steel but sometimes do not do a completely thorough job of it.
See attached pics from a renovation.
"Touching" is a problem,but not necessarily the one you think it is. The problem is that the copper is going to move back and forth and the metal will wear a hole in it.
Licensed residential and commercial plumber