Copper is OK, as long as it's well-supported. It has a habit of fatigue-cracking due to vibration, usually at fittings, unless it's bracketed to something solid every few inches.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!