There are several common engineering composites that are designed to take advantage of manufactured residual stresses. Concrete may be designed with pre-stressed steel tendons. Engineering ceramic composites may be designed with mismatch in thermal properties of the components to produce residual stresses and enhance crack deflection properties. Metal matrix composites may also be designed with mismatch in elastic properties of the component to enhance crack deflection properties.
The objective of this work is to explore the possibility of designing a spiral wound pipe with enhanced mechanical properties. Consider a sheet of steel wound into a spiral in preparation for welding into pipe. Consider then that it is twisted prior to and during welding of the spiral. When the weld solidifies and the torque is released, the pipe would, in principle, maintain some of the stress of the twist. The spiral could be twisted either “inwards” or “outwards” prior to the weld, and the result would be residual tension or compression.
This work is based entirely on theory and analysis. Analyses are performed that predict the residual stresses incurred during the proposed manufacturing technique, and the resulting stresses due in-service conditions. In principle, pipe design and manufacture could be adjusted for either onshore pipelines subject to internal pressure, or offshore pipelines subject to hydrostatic pressures at depth. Both possibilities are considered.