The annular sealing device in an annular BOP or diverter. Also, the elastomer packing element used in valves or lubricators to effect a seal.
Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards
Seal on a packer (3.26) or bridge plug (3.2) that blocks fluid communication by sealing on the ID of the conduit.
Source: API SPEC 11D1, Packers and Bridge Plugs, Upstream Segment, Second Edition, July 2009. Global Standards
Sealing element between the rotating control device and the drill string.
Source: API SPEC 16RCD, Specification for Drill Through Equipment—Rotating Control Devices, Upstream Segment, First Edition, February 2005. Global Standards