This paper investigates High Pressure and/or High Temperature (HPHT) design of a pipeline across an escarpment with significant seabed undulations and elevation change from drill center (DC) to riser touch down point (TDP). The pipeline has a tendency to walk towards the riser during pipeline start-up / shut-down (SD) operations due to seabed slope and riser bottom tension in a case study. A hold-back pile at the uphill pipeline end near DC to arrest walking, along with the riser bottom tension applied at the other end of the pipeline, results in significant tensions in the pipeline and substantial spans over escarpment. The pipeline spanning lengths, lateral buckling amplitudes and walking distances and their variations during the start-up / shut-down cycles are presented and discussed. Both wet-insulated single pipe (WISP) and pipe-in-pipe (PIP) options are studied and compared. Interactions among pipeline global walking, spanning and lateral buckling are observed. In-depth understanding of pipeline systematic response will help perform a safe and cost-effective pipeline design.

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