fitting

Hi all, I’m changing my kitchen sink and need to adjust some drain piping. Before touching anything, I want to make sure putting the drain back does not become too complicated. In attached photos, I would like to get your thoughts if the connection pointed by arrow is threaded or cement? I know...

I've learned that for compression fitting Never apply PTFE tape to the thread The water seal is done by the olive (O-ring) not the thread Suggest replace olive every time if undo the fitting If have to reuse the olive, wrap small amount of PTFE around the olive may help to reseal the fitting...