They sell copper nails at the big box and hardware stores for this purpose. However, imo, any screw or nail will work.

I don't know if there is a code covering this. An inspector would have to be pretty nit picky if he or she dings you for it.

 

I just used the plastic straps they use for pex.

 

I put some 1.5" wide insulation tape on the spot
and then use a heavier/better galvanized 2hole strap set with screws.
Works well for iron pipe too.

 

What is actually touching your pipes is important because of the galvanic effect. What is touching the strap is not so important because of that corrodes a bit, no huge deal.