Abstract
An increased coefficient of friction (CoF) is beneficial for the torque loading capability of a rotary shouldered drill string connection or other shouldered connections. Increasing the CoF while avoiding fretting or galling damage to the shoulder surfaces will increase the torque required to reach the desired shoulder preload, therefore increasing the torque capacity of the complete connection. This can yield technological advantages compared to standard rotary shouldered connections. Additionally, an increased CoF would broaden options for material selection, as lower strength (and therefore cheaper) materials become available for the same torque due to the lowered axial preload.
Using different surface modification technologies like shot peening, phosphatizing and low-pressure cold spray and combination thereof with and without using thread dopes/lubricants have been identified for increasing the CoF. These technologies are easy to apply to already existing tools and complex surfaces. No redesign or new design is required.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Baker Hughes Company, "Surface modification of metallic surfaces to increase the coefficient of friction", Technical Disclosure Commons, (January 19, 2025)
https://www.tdcommons.org/dpubs_series/7739