A commonly used process for manufacturing large-diameter tubes for offshore pipeline, riser and tension-leg platform tether applications involves the cold forming of long plates. The plates are bent into a circular shape and then welded. The circumference of the pipe is then plastically expanded to develop a high tolerance circular shape. Collectively, these steps comprise the U-O-E manufacturing process. These mechanical steps cause changes in the material properties and introduce residual stresses in the finished pipe. This paper presents the results of a combined experimental and analytical study of the effect on the U-O-E process on the capacity of the tube to resist collapse under external pressure loading. The U-O-E manufacturing process for a 26 in. (660 mm) diameter, 1.333 in. (33.86 mm) wall thickness pipe was simulated numerically. The numerical process was validated by comparing the predicted stress-strain behavior of the material at two stages in the process with properties measured from actual pipe specimens obtained from the mill. Following the simulation of the U-O-E process the collapse pressure was calculated numerically. The manufacturing process was found to significantly reduce the collapse pressure. A similar pipe for which the final sizing was conducted (simulated) with circumferential contraction (instead of expansion) was found not to have this degradation in collapse pressure.
On the Effect of the U-O-E Manufacturing Process on the Collapse Pressure of Long Tubes
Kyriakides, S., Corona, E., and Fischer, F. J. (February 1, 1994). "On the Effect of the U-O-E Manufacturing Process on the Collapse Pressure of Long Tubes." ASME. J. Eng. Ind. February 1994; 116(1): 93–100. https://doi.org/10.1115/1.2901815
Download citation file: