Pipeline operators analyze in-line inspection (ILI) reported features to determine if excavation is required to investigate a feature through direct examination in the ditch. Pipeline excavations require considerable resources and planning. In addition, excavations may cause disturbance to the land owner or cause varying impacts to the operation of the pipeline. Therefore, it is important to ensure that the excavation decisions are made effectively. While operators do review the key performance indicators on how the integrity programs are performing, currently there is no established definition or measure in the pipeline industry to evaluate the effectiveness of a dig program. Defining and measuring dig effectiveness would allow pipeline operators to identify areas to focus on, such as further research and development, opportunities for improvement, and potential optimization of the ILI-based corrosion management program, while maintaining safety and reliability.
This paper presents a method developed by TC Energy to measure dig effectiveness to evaluate the ILI-based corrosion management program. Effectiveness of digs depends on many aspects of the corrosion management program. First, a definition of dig effectiveness that reflects the objectives of the ILI program needs to be established. The method was developed using inhouse historical dig data for external corrosion features that required mitigation based on analysis of ILI data. The focus of the study included the probabilistic evaluation of excavations to baseline what can be expected in a dig program and have a process to evaluate factors that may affect dig effectiveness. The field measurements of digs completed for corrosion driven leak and rupture threats were gathered and analyzed to evaluate the effectiveness of different dig populations and to determine what bounds should be placed to monitor dig effectiveness. The advantages of measuring dig effectiveness using field results as opposed to other metrics such as repair ratio was also demonstrated in this paper. Examples of understanding areas of improvement by using the dig effectiveness are discussed.
Pipeline operators have the potential to incorporate the methodology presented in this paper in the integrity management program to enhance safety and identify areas of focus with the goal of increasing the effectiveness of the corrosion management program.