Description
Kelly is a kind of drill rod in the shape of a six-sided square cross section. It is made of AISI 4145H alloy steel in accordance with the specification of API and SY/ T 6509 standard. The raw material is conducted integrate heat treatment to achieve the excellent thermal performance. With concern to its thread, it is treated with cold rolling, copper plating and phosphating.
Kelly is at the top of the drill string, performing the function of drive. In the rotary table drilling rig, kelly can cooperate with the kelly bushing and rotary table to transfer the rotary torque to the drill rod and the drill rod in return makes the drill bit rotate. Meanwhile, the kelly should also bear the hanging weight of the drill string.
