With the use of new in-line inspection (ILI) tools, detailed geometrical information for a dent can now be obtained without excavating the pipeline. In addition, widely available general-purpose finite element software and increased processing power have reduced analysis times from days to minutes. These two developments have enabled the creation of a streamlined process referred to as the “Finite Element Dent Analysis Tool” (FE-DAT).
The FE-DAT can be used to perform an elastic analysis for every dent detected in a tool run by taking data directly from a high-resolution ILI tool, building a finite element model, and post-processing the results. With these data, operators are better equipped to determine which dents require mitigation.
Historically, the analysis process outlined above typically involves an analysis consultant performing the assessment at the request of an operator. Through our partnership with ROSEN, the FE-DAT enables the complete analysis to be performed through the ILI vendor, reducing the involvement of and stress placed on the operator.
Proper assessment of the types of damage that occur in pipelines is often challenging, especially considering the potential for a failure occurring. Additionally, operators are often hesitant to shut down operation or remove lines from service unless determined to be absolutely necessary. For this reason, Stress Engineering Services is frequently enlisted by operators to assess the extent and relative risk of pipeline damage.
Our damage-assessment approach is built on our experience from numerous prior evaluations and draws heavily from resources involving finite element methods as well as a database integrating years of full-scale pipeline testing. Our goal is to help pipeline operators better position themselves to appropriately respond to pipeline damage using a sound methodology that permits the continued safe operation of their pipeline systems.
We use testing, analysis, state-of-the-art technology, and a collective integrated approach to help pipeline companies assess threat interaction in their pipeline systems in support of their integrity-management programs. Our engineers and technicians are leading experts in predicting the future performance of potentially interacting threats along the pipeline, including combinations of anomalies such as dents, wrinkle bends, and flaws in seam welds and vintage girth welds.
The pipeline industry has used years of research and experience to develop a set of tools to perform qualitative analyses of pipeline integrity. With the implementation of the Integrity Management Program (IMP) by the Pipeline and Hazardous Material Safety Administration (PHMSA), the analysis methods and results must be defendable and well documented.
To address these requirements, we have combined existing knowledge, analytical techniques, testing, and engineering to create a systematic method for assessing damage to pipelines and generating results. The benefit of this process is the development of field-friendly tools that allow operators to quickly respond to any threat once it has been identified.
At Stress Engineering Services, we take into account the current recommended fracture mechanics model, operational history of the line, and future conditions to perform a comprehensive assessment that addresses both strain and fatigue.
Over time, a pipeline will experience some amount of pressure cycling whose impact needs to be addressed. Performing a pressure cycle analysis requires both a rainflow counter and a fatigue calculator, which is composed of a crack-growth model and a failure algorithm. By utilizing these tools and their extensive analytical expertise, our engineers can perform a pressure cycle analysis for each pipeline segment and determine the remaining life for each flaw within that segment.