Most of the world’s drilling rigs rely on the rotary kelly to transmit the torsional energy from the rotary table to the drillstring and, ultimately, to the bottom of the hole. The rotary kelly’s ability to perform this function over a prolonged period of time is a result of the mechanical properties of the steel and the specifications to which it is manufactured.
Heat-treating and machining features prolong service life
Each DRILCO rotary kelly is heat-treated along its entire length for uniform toughness and durability. A hardness range of 285 to 341 BHN, and a Charpy V-notch impact value of 40 ft.lbf are guaranteed 1 in below the surface at room temperature. Each rotary kelly meets the mechanical properties listed in API Spec 7.
Machined flats and upsets ensure tight tolerances and a high-quality drive section. These features will retard wear on the rotary kelly itself, in addition to prolonging the service life of the rotary kelly drive-bushing rollers.