Square Kelly

Kelly is on the top of drill stem, transmitting torque and supporting drill stem’s suspension weight. It’s the drive section of the whole drill stem. We can manufacture square Kelly and hexagonal Kelly accordingly, which are forged to and refined by AISI4145H alloy steel, quenched and tempered along full length, with its hardness range of 285-341BHN, charpy impact value=54J. The bore eccentricity can reach the minimum thickness of the standard, it’s ensured. Kelly ends and drive section, connections are processed and inspected according to API SPEC 7-1 and SY/T6509-2000. Kelly bars are inspected by an ultrasonic unit over their full length.
By military industry power, our company had designed, developed and manufactured all specifications of kellys in 70th, last century, which made nationalization lasting to this day. Our square kellys and hexagonal kellys (all specification) have won high reputation from our customers, for their high quality and excellent performance.


Square Kelly