 Kelly Kellys are made from 4145H modified alloy steel in accordance with API Spec.7-1 latest edition, which are quenched and tempered along full length. A hardness range of 285 to 341 BHN and a minimum impact value of 54 Joules as per ASTM A 370 Charpy-V, these values are guaranteed one inch below the surface. Kelly bars are inspected by an ultrasonic unit over their full length and full section. The wall thickness of each flat of the drive section is verified ultrasonically. All kellys’ connectons are fitted with pressed steel thread protectors on both ends and each kellys would be shipped with steel scabbard for marine transportation.  Specification for Square Kelly  Specification for Hex kellys 
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