Paper: Modified Internal Chamfer Coupling

Currently, API specs on 7/8" couplings allow for a wide variation in coupling face widths. The face width is critical when trying to achieve good rod makeup. For example, a larger face width is less likely to rotate due to the larger surface area i.e. more friction. As a result of the high number of rod pin-coupling failures, especially in the 718" section, a coupling with a more effective face width was developed.