A pigging valve is an alternative to conventional pig launchers. They are capable of launching and receiving foam, steel, and solid-cast pigs in both cylindrical and spherical shapes. Original designs would only allow spherical shapes but machining innovations and technology have allowed for other shapes of pigs such as cups, disc, brushes and also foam pigs can be used.
Pigging valves consist of an opening on the side of the valve that comes apart to allow for insertion or removal of the pig. Pig valves are designed to isolate the pressure portion of the line from the opening to protect the operator.