In previous International Pipeline Conference papers, Weir et al. (IPC 2006) and Weir, Li (IPC 2008) described an approach for determining the location of new remote controlled sectionalizing valves on an existing liquid pipeline system and for new pipeline development that considers a) valve placement to protect major water crossings (defined as 100 feet wide or greater), b) the volume out reduction potential of valve placement to areas of high consequence, and c) a set volume out threshold. High consequence areas include high and other populated areas, drinking water, environmentally sensitive areas, and commercially navigable waterways as defined by 49 CFR 195.450. These papers describe the use of an effectiveness calculation and effectiveness curve that is used to determine a valve location based on a calculated effectiveness score being above a set predetermined threshold.
Effectiveness is a measure of the volume out reduction achieved to one or more high consequence areas by the placement of a remote controlled sectionalizing valve. All other conditions being equal, the effectiveness score is higher for sections of pipeline contained within or having the ability to affect many high consequence areas versus sections of pipe with limited or no potential to affect such areas. As a result, the effectiveness scoring method does not work well for those pipe sections with the potential to impact small but significant high consequence areas or non-major water crossings (i.e. width less than 100 ft) or that do not impact a high consequence area.
Recent incidents and a heightened public awareness about pipelines and measures that are required to alleviate concerns of environmental impacts in the event of a pipeline rupture have necessitated a reevaluation and refinement of the Intelligent Valve Placement approach. This paper outlines enhancements that Enbridge Pipelines has made to its Intelligent Valve Placement approach. These enhancements include a) set valve spacing for high vapor pressure (HVP) pipelines, b) a new definition of major water crossing, c) tighter volume out thresholds, and d) application of a value assessment applied to the placement of valves for pipeline sections in areas that may or may not contain high consequence areas.