The Plumber's Choice 1/2 in. Side Beam Rod Connector in Malleable Iron for Threaded Rod

These are better than any other type of insulators, because these are very slim and fit perfectly into the typical bare bore for the pipe size. Slip them on the pipe, push them into the joist bore, tack them in with a screw or two, and the expansion and contraction of the line is instantly silenced. The pipe is now sliding on plastic rails and not chattering across raw wood. Use them across the entire thru-joist run, or at the ends where the run turns and hanging weights are often heavier (and are the most prone to expansion chatter), and you will have a dead quiet pipe run.