Threaded and coupled connections generally present a non-uniform stress distribution, which is
related to the higher stiffness of the box when compared to the pin. The non-uniform stress distribution
can contribute to fatigue cracks and other failure modes in high pressure oil wells. An API 5CT P110
steel obtained from a seamless pipe was mechanically characterized. FEA models were carried out
to investigate and compare two API casing connections under make-up torque and tensile efforts. A
parametric study was performed using numerical models to determine the influence of some geometric
features on the behavior of the API Buttress threaded connection. The API Buttress connection supported
higher tensile loads than the API Short Round, however both standard connections showed high stress
concentration in the last engaged thread and a non-uniform stress distribution. The manufacturing
of grooves at the first and the last engaged threads proved to be an efficient way to reduce the stress
concentration of Buttress casing connection and could be an alternative to the development of new
products