Inspection and Prioritization Methods for Small Diameter Auxiliary Piping

Abstract

To serve the pumping and storage needs of its customers; Enbridge operates more than 25 terminals and 150 pump stations across North America. In each of these facilities, small diameter (NPS 6 and smaller) piping is used in auxiliary systems including instrumentation, measurement, and product re-injection. Traditionally, in the design of facilities, this small piping has received less attention than large diameter process lines and, during construction, has typically been field run based on standard installation details. This, in conjunction with 65 years of changing design and construction philosophies, as well as asset acquisitions, has resulted in a wide variety of installation configurations across the Enbridge liquids system. The Small Diameter Piping Program in the Facilities Integrity group centrally manages the integrity of all small diameter auxiliary piping across the Enbridge liquids system. Historically, the management and remediation of small diameter systems has been based on addressing specific installation types identified through incident investigations. While generally effective at minimizing re-occurrence, this approach has been limited in its ability to proactively identify installations that should be addressed. In support of our goal of zero incidents, Enbridge has developed a proactive methodology for the inspection and prioritization of small diameter auxiliary piping. Installation types are evaluated on their susceptibility to specific damage mechanisms. An inspection and prioritization model was developed through the combination of internal lessons learned and prioritization methodologies outlined in industry publications, specifically those from the overseas oil and gas industry. This model, sets a standardized process to assign a likelihood of failure (LOF) score to individual small diameter installations of specific types and/or functions. Presently, likelihood of failure scores are used to identify installations requiring remediation, and to most effectively prioritize system-wide remediation activities. Over time, these scores will also be used to demonstrate an overall reduction in the likelihood of failure for small diameter piping in the Enbridge liquids pipeline system.