BUTT WELD Socket Weld Outlet utilizes the basic Welding Outlet ® however the branch affixes by way of a socket inside the olet. The bore matches the outlet bore, and the existence of a counter bore roughly the size of the OD of the outlet provides a socket where the pipe can sit, facilitating installation and welding. The Socket Weld Outlet® is considered a socket fitting, and manufactured in 3000#, 6000# and 9000# classes.