Managing Pipelines’ Total Stress Landscape With Advancements in In-Line Inspection-Based Bi-Axial Stress Measurement Technology

Abstract Over 15 years ago, pipeline operators requested the development of an in-line inspection (ILI) axial strain measurement tool to support their geohazard management programs. Since then, Axial Strain Measurement Inspection Service (AXISS™) has been employed on over 25,000kms of pipeline with many high strain locations successfully identified and mitigated. Like any new technology, it took the axial strain tool a few years to become a unique, established and proven tool for a pipeline operator to assess geohazards, movement and other strain-related threats. Over the years, the operators’ experience has provided key insights as to where the current technology strengths lie and of course where enhancement with additional information could further enhance their integrity engineer’s more complete understanding of stress and strain-based threats to then develop proactive mitigation strategies and importantly conduct more cost-effective repair programs — ensuring their pipeline’s safe and continuing operation. This paper presents a response to these learned and clearly defined needs. It introduces a new bi-axial stress measurement inspection technology AXISS™ EPS that adopts these needed advancements by providing detailed information on the entire stress landscape of both active loading and residual stresses. This proprietary sensing technology used by this new tool is an evolution of a mature stress measurement technique that has successfully delivered bi-axial stress measurements for steel structures for the last 3 decades in a range of industries including flexible pipeline riser systems in the offshore oil and gas industry as well as nuclear, automotive, aerospace and rail. This paper provides a comprehensive overview of the new bi-axial stress tool technology, its rigorous validation and test results. In addition to that, it gives an insight to some of the novel and unique capabilities it provides to further discriminate the criticality of the pipeline stress condition at any given location along the pipeline driving necessary and timely repair. Furthermore, comparison of this new bi-axial stress/strain data relative to the earlier axial strain inspection data is possible and demonstration of these new capabilities will be described as to benefits it will provide in efficiently and effectively managing pipeline strain-based threats.