Square & Hexagonal Kelly for oil&gas drilling

Kelly is main driver of the whole drill string. It transmits torsional energy from the rotary table through the drill string to the bit at the bottom of the hole. Our Kelly is a long square or hexagonal, precision machined heavy steel bar that is supported by the swivel through the rotary table and is connected to the first joint of drill pipe in the drill string.

Straightness of the kelly is very crucial in the manufacturing process, thus straightness inspections are carried out before, during and after each machining operation. The flats are precision-milled to API specifications. All milling processes are performed on specially designed rigid Kelly mills to ensure tight tolerances and high quality drive sections. Each Kelly is furnished with a pressed steel thread protectors.

Kellys are manufactured with one of two drive configurations, square or hexagonal. Square kellys are furnished as forged or machined in the drive section. Hexagonal or fully machined square kellys are machined from full length quenched and tempered round bars.

Square Kelly and hexagonal kellys are fabricated as per requirements of customers. The kellys are made of AISI 4142H-4145H forged or rolled alloy structural steel. Quenching plus tempering thermal treatment will be conducted over the whole length. Its Brinell hardness can reach 285-341 on the basis of such thermal treatment. Charpy impact energy: >or =54J. The formulated process can ensure that the misalignment of the hole reaches the standard wall thickness. Kelly bars are manufactured according to API-7-1 Spec.