Step 7 · Tighten Compression Nut
Slide the compression nut up to the valve body and hand-tighten it by turning it clockwise. Once it's snug, use two wrenches again, just like during removal. Hold the valve body steady with one wrench to prevent any stress on the pipe. Use the second wrench to tighten the compression nut. The standard is to tighten one-half to three-quarters of a turn past hand-tight. You will feel the ferrule compress and bite into the pipe. Do not overtighten, as this can crack the nut or damage the valve.