Analysis & Testing

1. Finite element analysis (FEA): CAD models of multiple DUO design configurations are put through simulated torsional load cases to evaluate localized stress levels, double-shoulder interaction, load-sharing between taper regions, and the overall expected deformation of the DUO design.
2. Torsional stage loading: Prototype connections are subjected to increasing values of torque loads up to and beyond torsional yield with critical connection geometry measured between at each stage. The DUO connection design has proven to remain well within field inspection tolerances even at extreme torque loads.
3. Cyclical torque loading: Connections are subjected to cyclical torque loads at makeup torque, evaluating the detrimental effects of repeatedly applied loads on connection geometry and threadform. DUO connections have demonstrated excellent galling and deformation resistance even being cycled well past the recommended makeup torque.

Correlated together, the above methods provide a clear picture of the raw torque capability of the DUO connection and validates the initial analytical calculations used in its design.