Sch 40 PVC caps are used to cap off the end of PVC pipe lines. Caps are designed to fit on the end of your pipe and cannot be used to cap off fittings. Sch 40 PVC caps are domed at the top to allow for pressure applications. Sch 40 PVC caps are manufactured with glue or threaded connections. Threaded caps can be used with male adaptors or pipe nipples.