Threaded plugs and oil plugs: 1/4" to 3/4"

Male threaded plugs, oil plugs and sealing caps for threaded connections

Threaded plugs close off a connection in a compressed air line or oil circuit that you are not using, such as a free port on a manifold block or a fill and drain opening. They belong to the other threaded couplings, next to the parts that do the opposite and join two connections together.

The first criterion is thread size and thread type. The Airpress plugs with external thread come in 1/4", 3/8" and 1/2" and screw into a female thread of the same size. The SKF oil plugs have a G thread, from G1/4 through G1/2 to G3/4. Check the thread type of the opening before you order, because threads of a similar size can look alike without fitting each other.

For a metric connection you want to cover for a while, Facom has M15 caps with matching seals. Think about the seal as well: a plug only closes leak-free with a sealing ring or thread sealant suited to the medium in the line. If the line has to branch rather than close, a threaded tee fitting is the logical alternative.