Optimization of Hydrostatic Test Plan for Pipeline Crossing Significant Elevation Difference Terrain

Abstract The purpose of Hydrostatic Testing for new constructed pipeline is to establish the Maximum Operating Pressure (MOP) prior to pipeline operation. There are challenges in conducting hydrostatic tests for pipeline passing through geological areas with significant elevation changes. These challenges include a large number of hydrostatic test sections and associated hydrostatic test risks and costs. A Point Specific MOP approach has been developed to address these issues. This approach considers the pressure variance associated with elevation changes along the pipeline and determines the actual pressure at each point during the hydrostatic testing. It optimizes the test sections to achieve the design capacity and ensures the transient pressure safety. The subject pipeline is a newly constructed liquid transmission pipeline system with approximately 1180 km total length of pipe (nominal diameters of 762 mm/914 mm/1066 mm) and 16 stations (pump stations/trap sites/terminals). This pipeline system passes through geological areas with significant elevation changes (with the biggest elevation change of 1326 m within 50 km, between mountain top and river valley bottom). This paper presents the hydrostatic testing considerations and optimization philosophies of Point Specific MOP approach, and the use of Hydraulic Pipeline Simulator to conduct hydraulic analysis for validation. This paper also discusses the importance of incorporating this methodology during design and hydrostatic test phases, to provide guidance for future pipeline design.