The effects of boundary condition on pipeline walking

Most studies on pipeline walking assume free-end boundary conditions, overlooking the influence of boundary condition imposed by connections to manifold or terminal systems. This paper addresses this limitation by idealising the boundary condition as an elastic-perfectly plastic resistance model, enabling a more realistic analysis of pipeline walking behaviour. An improved analytical solution is derived and is demonstrated through calculation examples. The results reveal that, if the walking activating force Q is within the critical value Q critical , pipeline walking eventually halts. Conversely, if the activating force Q exceeds Q critical , axial displacement continues to accumulate, but at a reduced rate compared to free-ended pipelines. A closed-form equation for the critical activating force Q critical was obtained. The derived analytical solution and the calculation examples provide an improved assessment of offshore pipeline walking and highlight the importance of modelling the boundary condition. These results allow the critical activating force and boundary stiffness to be used directly in practical walking assessments, supporting more reliable design and verification of pipeline end restraints and manifold/terminal connections. • An improved analytical model for pipeline walking with realistic boundary effects is developed. • Boundary condition is modelled as an elastic-perfectly plastic restraint at the pipeline end. • A critical walking activation force is derived to predict long-term axial movement. • The model improves design accuracy for subsea pipelines connected to PLETs/PLEMs.