I am replacing the copper tubing from my dishwasher to the water supply. Using compression fittings do I need to solder or use any adhesive on the “donut” infront of the nut before I connect them and turn back on the water supply?
I like to use a teflon based paste such as GASOILA or SLIC-TITE on the face of the ferrule (donut). Be sure to tighten it up good because you need to compress that ferrule tight on the pipe.
Rather then using compression I would look to a flaire connection for several reasons. 1- Flair is much stronger. 2- Flair can take much more vibration than a cheap compression ring. 3- Flair connections are used on high pressure and temperature connections like an air conditioning compressor and High pressre steam controllers.