Variable bore ram rubber with non-overlapping inserts

摘要

An improved sealing device for variable bore ram blowout preventers of the type that uses a pair of opposed semi-cylindrical ram blocks to urge a pair of resilient sealing elements into sealing circumferential contact with the circumferential surface of a tubular drill string component includes a generally uniform thickness sealing member having in plan view the shape of a semi-circular arch with co-linear rectangular legs which protrude laterally outwards from opposite base ends of the arch. The sealing device includes two identical sealing members, each of which has a plurality of laterally spaced apart metal inserts molded into a resilient matrix. Each insert has a pair of generally flat and parallel upper and lower plates joined by a pedestal disposed perpendicularly between the plates. Five inserts are used; two identical, generally square cross-section end inserts, one each located near the outer lateral end of each leg, two identical, trapezoidal cross-section corner inserts, one each laterally inward of each end insert, and a semi-annular cross-section center arch insert within the center arch section, adjacent the corner inserts. Forcible contact of the front face of each sealing member with a tubular component causes the corners inserts to move laterally away from the end inserts and toward the center insert, thereby forming an effective seal with tubular components of various diameters.