Over a long enough period of time, regular exposure to UV radiation will discolor the pipe and may weaken its physical integrity. The pipe can be stored outside unprotected for up to 6 months. The factory issued bags that the pipe comes in will protect it from UV damage indefinitely. If the pipe is being installed outside in an unsheltered location, the installer will need to use the black UV rated pipe. The UV pipe is physically identical to the regular pipe, but is protected with a thin layer of PE to absorb UV radiation. This outer layer must be peeled off the pipe at the ends prior to fusion-welding. The fittings and weld area must be wrapped or painted to protect from long-term UV exposure. Information on outdoor installation can be found on page 4.17 of the catalog. The UV pipe can be found on pages 6.5 and 6.6 of the catalog.