Double Duty Drill Collar & Tool Joint Compound
The lead-free formulation contains copper flake as the only metallic component and is fortified by a unique blend of natural, inorganic, extreme-pressure, and anti-wear additives. For invert or high-pH muds, a special base grease is available.

21 has been designed to utilize the makeup charts in API RP7G. In the more severe drilling situations such as higher speeds, higher penetration rates, deviated holes, or harder formations, drill collars and other rotary shouldered connections should be made up at least 15% over the listed RP7G values.

Applications
21 is recommended for the entire drill string in most drilling conditions. Typical applications would include geothermal wells, high angle holes, problem holes involving high temperature, whip stocks, and horizontal drilling applications. 21 prevents high stress in drill pipe connections which shortens their useful life.
 
Not recommended for oxygen service.