Thermal Expansion by Lateral Buckling: Structural Reliability Analysis for the Penguins Flowline

The Penguins pipeline is a 60 km PIP system designed to buckle laterally on the seabed. This is an effective way to accommodate thermal expansion. However excessive bending could lead to local buckling or wrinkling of the pipe wall. Existing design criteria based on load-controlled or displacement-controlled conditions are not directly applicable here, because the actual conditions fall somewhere in between. For this reason a structural reliability analysis has been performed for the Penguins flowline, to demonstrate that it is safe to allow the flowline to buckle laterally. Thereby the uncertainties that can affect the peak bending moments and curvatures at the buckles are addressed explicitly i.e. one does not rely on an assumption of load- or displacement control. This paper describes how describes how the various uncertainties are combined to assess the structural reliability. Details of the various inputs, including full-scale tests and finite element analyses addressing both global response and local buckling or wrinkling to develop the capacity and response functions are reported in a companion paper.