OCTL Drill Collars (Slick and Spiral) are manufactured from AISI 4145 H Chromium Molybdenum Alloy Steel and are fully heat treated to a Brinell Hardness range of 285-341 BHN and have a minimum Charpy V-notch Impact strength of 40 ft-lbs. at 70° F and a minimum elongation of 13%. The mechanical properties meet or exceed API 7-1 requirements. The physical properties are guaranteed one inch below the surface at ambient room temperature.
Drill Collars are precision trepanned to close bore tolerance and all bores are drifted to API 7-1. The connections are cut on CNC Machines. All API connections comply with dimensional requirements specified in API 7-1 and guidelines presented in API RP 7G. The thread roots as well as elevator and slip recess upper radii are systematically cold rolled to improve fatigue resistance of the connections by minimizing crack initiation. To improve resistance to galling all connections are phosphatized and coated with an API thread compound. The connections are provided with pressed steel or cast steel thread protectors.