A coupling connects two pipes. If their measurements vary, the fitting is called a reducing coupling, reducer, or an adapter. There are 2 kinds of couplings: "typical" and "slip". A daily coupling has a little ridge or quit internally, to stop more than-insertion of the pipe, and so beneath-insertion of http://shanetqjdv.articlesblogger.com/12183263/facts-about-valves-and-fittings-revealed