A coupling connects two pipes. If their sizes vary, the fitting is named a lowering coupling, reducer, or an adapter. There are 2 forms of couplings: "standard" and "slip". An everyday coupling has a little ridge or cease internally, to prevent more than-insertion of a pipe, and therefore beneath-insertion of http://messiahapdqe.review-blogger.com/10608144/not-known-factual-statements-about-valves-and-fittings