Bj-Hughes Inc.

Terry E Stuckey

Edward J McFadden

A pneumatically operated rotary power slip assembly which is mountable in a rotary drilling table. It includes a stationary housing having an annular opening therethrough adapted for mounting generally coaxially with the pipe opening in the rotary table. The stationary housing has a conduit therein for transmitting pressurized fluid. The assembly includes a rotary housing having an annular opening therethrough, which housing is adapted for mounting generally coaxially with the opening in the rotary table and for rotation therewith. The stationary housing is provided with a pair of inflatable annular seals which, together with the rotary housing, form two axially spaced apart annular ducts between said housings upon inflation of the seals. The rotary housing supports at least one generally radially extendable and retractable slip, which slip is arranged to engage a pipe inserted through the rotary housing in the radially inwardly extended position and for releasing the pipe in the radially outwardly retracted position. At least one pneumatic cylinder is mounted in the rotary housing and arranged for moving the slips radially inwardly and outwardly upon actuation thereof. Additional conduits are provided in the rotary housing for communicating with each of the aforesaid ducts and transmitting pressurized fluids to the pneumatic cylinder for operation of the aforesaid slips. The apparatus includes valve means for controlling alternate flow of fluids through the ducts to control operation of the pneumatic cylinder to move the slip radially inwardly and outwardly. There is thus provided a rotary power slip assembly which is removably inserted in a rotary drilling table wherein the pneumatic cylinder rotates with the slips such that the slips can be positioned in any position around the full circumference of the opening through the drilling table. The seal arrangement for transmitting fluid pressure to the pneumatic cylinder permits operation of the cylinder in any position, as aforesaid.

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Houston, TX, United States of America

Terry E Stuckey