Shoulder Yielding Detection During Pipe Makeup

摘要

During makeup, shoulder connections can become deformed by over-torque or contamination in the thread compound. Thernresult is a reduction of the inner diameter of the connection at the shoulder and potential leaking during service. A yieldedrnconnection must be rejected, broken out, and the pin and box diameters and threads inspected for deformation or damagern(VAM book, December 2010) [1]. In most cases, the tubular(s) must be removed from the string and replaced.rnIf over-torque is the root cause for yielding, it is normally easily detected by indication of final torque (dump torque) beingrngreater than the set point value on the torque-turn graph. Currently, yielded connections are detected by the operator visuallyrninspecting the torque-turns graph; a subjective process dependent on the operator’s knowledge and experience.rnA new software process detects yielding in a connection during makeup by evaluating the change in gradient in the delta turnsrnrange (between shoulder contact and final torque) of the makeup graph. The gradient value initially increases to a value thatrnshould remain relatively constant until final torque is achieved. A decrease in the gradient during the delta turns range of thernmakeup is a potential sign of yielding.rnThis paper discusses a mathematical approach for analyzing a makeup in real time and detecting possible yielding based onrnanalysis of the torque-turns gradient in the delta range of the makeup graph.