Axial fatigue load effects on makeup of threaded connections

In this study, the axial dynamic fatigue load effects on friction behaviour during makeup of threaded connections was investigated. Tests were carried out on full-scale NC50 Rotary Shouldered Connections (RSC) used in the oil and gas industries. An equipment was designed and constructed in order to carry out the makeup/breakout tests under axial dynamic load application. The influence of alternate or pulsating loads, with frequencies up to 110 Hz and maximum load amplitude 10 kN was investigated. Steel connections were tested under vibration, with the same compound or without compound, at the nominal makeup torque and at lower torque values (one-third of the nominal makeup torque and about three-quarters of the nominal makeup torque) in order to evaluate the friction behaviour in various operating conditions.