Effective Anomaly Management Approach for Class Location Change With Engineering Assessment

Abstract Canadian Standard Association (CSA) Z662 allows pipeline operators to perform engineering assessment (EA) to determine the suitability for continued operation of the existing pipeline at the new class location designation instead of pipe replacement or pressure reduction. Canadian Energy Regulator (CER) filing manual guide E provides the filing requirements for class location change EAs. However, there is no clear guideline in CSA Z662 or CER filing manual guide E on how to assess and manage pipeline anomalies (e.g., corrosion and cracking) on a pipeline operating with a class change managed under an EA. CSA Z662-23 Clause 10.7.2 requires evaluation and repair of imperfections per Clause 10.10 and Clause 10.11 for class location change pipeline segments. However, no explicit guidelines are provided regarding which location factor is to be used when the class location changes from a lower class to higher class with an EA. The most common perception is that the location factor based on the new higher class should be used in a class location change scenario. This leads to the question whether a pipeline segment which is designed for a lower class location can have an appropriate response criterion (i.e., acceptable FPR level) based on a higher class location. The authors performed an in-depth analysis to address this question. These results are explained in this paper. The anomaly assessment and response process presented in this paper combines a deterministic FPR based assessment and a probabilistic assessment to effectively manage anomalies on class location change pipeline segments. The proposed process will ensure safe and consistent response requirement for anomalies identified in pipeline segments with class location changes.