a sealing device used to close off the annular space around the kelly in drilling with pressure at the surface, usually installed above the main blowout preventers. A rotating head makes it possible to drill ahead even when there is pressure in the annulus that the weight of the drilling fluid is not overcoming; the [...]

a ram device used to close the annular space around the polished rod or sucker rod in a pumping well.

a sealing component for a blowout preventer that closes the annular space between the pipe and the blowout preventer or wellhead.

1. One of several valves installed at the wellhead to prevent the escape of pressure either in the annular space between the casing and drill pipe or in open hole (i.e., hole with no drill pipe) during drilling completion operations. Blowout preventers on land rigs are located beneath the rig at the land’s surface; on [...]