The cast pipe fitting is stainless steel 304 nipple with male National Pipe Taper (NPT) threads for connecting and extending female threaded pipes. The fitting has NPT threads for creating tighter seals than straight threads.Pipe fittings are components used for connecting, terminating, controlling flow, and changing the direction of piping in many different industries. When purchasing pipe fittings, consider the application, as this will affect material type, shape, size and required durability. Fittings are available with threaded or unthreaded fittings in many shapes, styles, sizes, and schedules (pipe wall thickness).