Session: 06-05-01 Strain Demand

Paper Number: 134022

134022 - Consistently Inconsistent: Lessons From Operators Comparing Multiple IMU Data Sets 

Abstract: 

Operators and regulators have demonstrated an increased awareness of the geohazard threat over the last decade. In response to this threat, many pipeline operators have begun integrating bending strain assessments based on IMU data into their integrity management programs. Bending strain assessments, which provide a direct measure of the pipe condition, can be a valuable tool in any geohazard integrity management program. Unfortunately, many operators encounter challenges or even confusion when they receive results from a bending strain assessment. The results from a bending strain assessment can be difficult to understand and even more difficult to properly sentence, especially if the assessment identifies hundreds of features. These challenges can be compounded if the operator acquires a second IMU data set and elects to perform another bending strain assessment or a comparison assessment between the two data sets. In these situations, operators often observe significant variations in the number of reported bending strain features and the reported strain magnitudes associated with those features. These challenges can rarely be solved by comparing the final reports as the graphical information for the bending strain features is often rendered differently between vendors. This paper presents the results of two case studies where each had multiple bending strain reports based on different IMU data sets. Both case studies demonstrated common challenges experienced by operators. Each assessment had significant differences in the number of reported bending strain features and the locations of those features. In both case studies, the information supplied with the final reports was insufficient to reconcile the differences between the two assessments. After demonstrating these challenges, the paper presents the results of the comparisons when the assessments are performed according to the same criteria and the identified features are fully reconciled. Based on these results, the paper identifies and discusses the causes of the variation in both case studies which includes gage length, signal noise, and analyst judgement. The paper demonstrates how those variables can impact the results of a bending strain assessment, and the lessons learned from this case study. The paper concludes by identifying the necessary reporting requirements for bending strain assessments and makes recommendations on how results from bending strain assessments can be standardized to help operators minimize the future variations.

Presenting Author: Alex Brown TC Energy

Presenting Author Biography: Alex Brown is an engineer working in the Weather and Outside Forces integrity team for TC Energy. Alex graduated from the University of Alaska Fairbanks in 2017. Alex has developed specialized expertise in the evaluation of bending strain data and the use of that technology in the management of geohazard threats.

Authors:

Rhett Dotson D2 Integrity, LLC
Alex Brown TC Energy
Briant Jackson Phillips 66