November 11, 2020
DPM-FAQSeries Topic 2: How to read the Make-up Torque Then Tension Combined Load Curve?
At torque levels up to the make-up torque (MUT) of the tool joint, the Make-up Torque then Tension combined load curves are used to determine the tensile capacity.
Once the pipe is run downhole, we refer to the premium values of the pipe body. The green shaded area is the safe working zone of the pipe. At recommended MUT, the available operational tension in the pipe is the horizontal line that cuts across the intersection of the Premium Pipe curve and Rec MUT line. In this example, the available operational tension at 47,000 ft-lbs (Rec MUT) is 340,000 lbs. In the event that more torque is required, the connection can be made up to the maximum make up torque which in this example is 54,800 ft-lbs. This then reduces the available operational tension to 160,000 lbs.
Do note that if there is insufficient torque applied during makeup, shoulder separation would occur with seal failure. Always ensure the connection is made up to the Recommended make-up torque.