• HI-TORQUE™ (HT™) Connection


    The Grant Prideco™ HI-TORQUE™ connection is a patented, high-performance, rotary shouldered connection available in sizes from 2 3/8 to 6 5/8". The HI-TORQUE connection incorporates a double-shouldered design.

    A secondary internal shoulder on the nose of the pin offers an additional friction surface and mechanical stop. The primary external shoulder still serves as the connection's sealing surface. As shown in this figure, the HI-TORQUE design has an extended pin base, pin nose, and box counterbore. These sections are carefully engineered to provide additional elastic deformation during make-up. This ensures that the contact forces are properly proportioned between the two shoulder surfaces. The additional torsional strength provided by the HI-TORQUE design offers several advantages and unique solutions in drill string design.


    A HI-TORQUE™ connection offers significantly higher torsional capacity than standard API connections of similar size. This additional strength provides an extra margin of safety when drilling in high-risk situations or rugged conditions.

    Torsional Yield Strength

    Slim Profile
    Another advantage of HI-TORQUE's increased torsional strength is the ability to use a streamlined tool joint that is suitable for the pipe's torsional strength. This figure illustrates the smaller OD and larger ID for HI-TORQUE connections compared to standard API connections with identical torsional capacity. Using a streamlined HI-TORQUE tool joint allows a larger diameter drill pipe to be used. This provides increased bit weight in horizontal drilling, improved hydraulic efficiency, better hole cleaning, and more drill pipe buckling strength without sacrificing torsional strength or fishability. For instance, using a HI-TORQUE connection on 5 1/2" pipe will provide 35% more drill pipe buckling strength than a 5" drill pipe with an NC5O connection, and will add only 21% string weight. With HI-TORQUE connections, the ability to fish inside an 8 1/2" hole and have torsional capacity matched with the pipe is maintained. Drilling fluid pressure loss is decreased and annular velocities are increased because of the larger pipe. HI-TORQUE connections can provide a superior solution for any drilling situation requiring a low-profile tool joint such as extended reach, horizontal, or slim hole drilling programs. HI-TORQUE's increased torsional strength gives the tool joint a more streamlined profile that remains matched with the torsional strength of the pipe. Compared with an API NC profile with equal torsional strength, HI-TORQUE offers greater flexibility on OD and ID to provide solutions to today's drilling challenges.

    Because of its increased torsional capacity, the HI-TORQUE connection greatly extends the life of the joint by tolerating more OD wear. For example, an NC38 on 3 1/2" 13.30 lb/ft G-105 drill pipe is downgraded to Class 2 when the OD wears below 4 21/32". At this diameter, the tool joint is less than 80% as strong as Premium Class pipe. The HT38 connection can tolerate wear down to a diameter of 4 3/8"; before its torsional strength falls below 80% of the pipe strength.

    Wear Allowance Comparison


    HI-TORQUE™ Connection Mechanical Characteristics

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