SPEAR Russian patent published in 2011 - IPC E21B31/18 

FIELD: mining.

SUBSTANCE: invention relates to gas-and-oil production, namely, to spears intended for elimination accident with flanges of drilling and oil well tubings. Proposed spear comprises hollow case with connection thread, guide cone and lateral openings accommodating radially spring-loaded gripping slips fitted on axles to turn and move thereon. Proposed spear differs from know designs in that slips have face surfaces and case surfaces in contact with the latter located in the plane parallel to fastening axis and feature comb-like shape with mating ledges and recesses. Note here that rack recesses represent inverse trapezoids while ledges have rectangular shape.

EFFECT: reliable operation, higher lifting capacity, reduced repair costs.

2 cl, 2 dwg