Possibly requiring you to install a  new fixture such as a bathtub faucet, Bathtub faucets are simple screw-on  faucets. The pipe cap screws on over a steel or copper pipe. The faucet  contains a threaded connection point that fits over the pipe cap.  
                                   
If you are installing a new pipe cap along with the bathtub faucet, tighten it  using a wrench. If the pipe cap is loose, leaks can develop. Screw on the  faucet in a clockwise movement until it is tight. Remove a bathtub faucet by  twisting it counter-clockwise until the faucet loosens and comes off. Turn on  the water supply to the bathtub and test for leaks. If the faucet leaks, it is  not tight enough. If you cannot screw down the faucet tight enough by hand to  prevent leaks, use a wrench but cover the opening with a thin, soft cloth to  avoid scratching your new faucet. 
                               
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