The CT is then constrained to be straight in the injector and then run in hole. The CT is then bent around a given dog-leg or radius of curvature. The CT is then pulled out of hole with a given reel-back tension, held straight in the injector head, bent over the gooseneck, straightened and then wrapped back onto the reel. The computational engine is based on discretizing the cross-section into a grid of polar elements. For a given loading event, the change in stress and strain is computed iteratively for each element.
Plane sections remain plane.
The concept of introducing a reverse bend in the CT was pursued. This would allow the injector to be lifted into the derrick without the CT contacting with an A-frame. In normal operation, CT is plastically deformed when it is wrapped around the reel, unwrapped from the reel or bent over the gooseneck. Thus, additional low cycle f atigue damage could be induced on the CT, if there is any additional plastic deformation, due to heave in the reverse bend. The analyses were initially performed with fixed boundary conditions at the upper injector head and at the subsea package.