3/4 Female Npt Pipe Cap 108-E pipe cap fittings are reusable and can be used for applications involving pneumatics, vacuum, and general fluid handling. Our brass fittings are an economical and durable solution to your piping and plumbing needs. Our pipe end caps are widely used in industrial manufacturing applications and corrosion resistance is desired. Additional usage for other types of fluid transfer and handling non potable water, air and fuel.