HT Connections

The original double shoulder connection


The Grant Prideco Hi Torque™ (HT™) connection is a patented, high-performance, rotary-shouldered connection available in sizes from 2⅜ to 6⅝ in. The Hi Torque connection incorporates a double-shouldered design.

The HT design has an extended pin base, pin nose, and box counterbore. These sections are carefully engineered to provide additional elastic deformation during makeup. This ensures that the contact forces are properly proportioned between the two shoulder surfaces.

Increased torsional capacity

The HT 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.

Slim profile

The HT connection’s increased torsional capacity enables the use of a streamlined tool joint that is suitable for the pipe’s torsional strength. HT tool joints may feature a smaller outside diameter (OD) and larger inside diameter (ID) compared to standard API connections with identical torsional capacity. Streamlining provides improved hydraulic efficiency without compromising torsional strength or fishability.

Wear tolerance

Because of its increased torsional capacity, the HT connection greatly extends the life of the joint by tolerating more OD wear. For example, an NC38 on 3½-in., 13.30-lb/ft G-105 drill pipe is downgraded to Class 2 when the OD wears below 42132 in. At this diameter, the tool joint is less than 80% as strong as Premium Class pipe. The HT 38 connection can tolerate wear down to a diameter of 4⅜ in. before it reaches the same limit.


Standard HT Configurations for S135 Grade Drill Pipe

Contact your Grant Prideco representative for further tool joint OD and ID configurations.
Pipe OD (in.) Nominal weight (lb/ft) Connection Tool joint OD × ID (in.) Maximum MUT (ft-lb)
3.500 13.30 HT 38 4.750 × 2.438 17,000
3.500 13.30 HT 38 4.875 × 2.563 17,600
3.500 13.30 HT 38 5.000 × 2.563 17,600
4.000 14.00 HT 38 4.938 × 2.563 17,600
4.000 14.00 HT 40 5.250 × 2.688 21,500
4.000 15.70 HT 38 4.875 × 2.563 17,600
5.000 19.50 HT 50 6.625 × 3.500 38,200
5.500 21.90 HT 55 7.000 × 3.750 52,700
5.500 21.90 HT 55 7.000 × 4.000 46,300
5.500 24.70 HT 55 7.000 × 3.750 52,700
5.500 24.70 HT 55 7.000 × 4.000 46,300

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