Annular Packing Element
A doughnut shaped, rubber/elastomer element that effects a seal in an annular preventer or diverter. The annular packing element is displaced toward the bore center by the upward movement of an annular piston.
Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards