October 2022, Vol. 249, No. 10


Integrity's Newest Ally: PRCI’s Mechanical Damage Strategic Research Priority


By: Anita Vigilante, Communications Specialist, PRCI  

(P&GJ) — A few years ago, a concerned citizen called local authorities to report an unusual odor. Responders followed established protocol and secured the area. The resulting investigation uncovered a buried pipe that was leaking. Documented mechanical damage had failed in a nearby pipeline.

Routine inline inspections over a period of years had not shown evidence of corrosion or cracking. The leak was not detected earlier by soil discoloration, areas of dead vegetation or sheen on nearby water. Thousands of gallons of product had been released and the cost of the response, repair and clean up ran well into the millions of dollars; thankfully, no one was injured or killed.   

Integrity management is at the core of every pipeline program. Even though operators regularly inspect known damage for corrosion or cracking, it can still fail. Only through collaboration and shared experiences can the processes and technology surrounding integrity management be continually improved.  

Research Priorities  

When a committee of American Gas Association (AGA) members was established in 1952 to solve one single industry-wide issue, long-running brittle fracture in natural gas transmission pipelines, the results improved the pipeline industry’s understanding of a significant issue it was facing. Swift success led to asking what other issues could be identified and resolved.   

By sharing information and forming a research partnership, the results were not just suggestions from an ivory tower model: the results were clearly usable  
and adoptable.  

The committee evolved into Pipeline Research Council International (PRCI) with a core research program guided by eight technical committees, each representing its unique perspective of the energy pipeline transportation and storage systems.   

A collaborative research portfolio aligning with industry priorities is produced each year using the leverage generated by members’ resource contributions to produce solutions that ensure the safe, reliable, environmentally sound and cost-effective transportation of energy via pipelines to consumers worldwide. This translates into thousands of issues having been identified and addressed.  

Building upon the core research program, the establishment of Strategic Research Priorities (SRP) further leverages focused efforts and funding to address significant industry challenges while providing the key solutions needed to enhance the safety and integrity of our global pipeline systems. Through collaboration, key strategic industry initiatives and issues such as mechanical damage are identified.  

Through SRPs, PRCI addresses opportunities to develop significant outcomes for the industry and in the interest of the public. PRCI’s approach improves efficiency and engagement by being strategic and intentional, working cohesively as groups to solve problems that cross disciplines, and making impactful advancements in technology and its related research and development (R&D) to improve pipeline safety and performance.  

Mechanical Damage  

Accounting for at least one-third of incidents in energy pipelines, mechanical damage (denting) may occur in construction (pipe handling) because of pipes sitting on rocks at construction, in-service pipe movement or settlement that results in a deformation of the surface of the pipe, ranging from a scratch to a puncture, or damage to the pipe’s protective coating.   

PRCI’s R&D roadmap has been an ongoing work in progress. It focuses on the prevention, inspection, assessment and repair of mechanical damage. A key element of the roadmap is the link between inspection and engineering assessments to ensure that mechanical damage features, which require immediate remediation, are being appropriately addressed. For features not requiring immediate action, enhancements to integrity management (IM) program continual assessment requirements were clearly established.  

The SRP to “Optimize the Detection and Mitigation of Mechanical Damage” is the convergence of multiple PRCI Mechanical Damage research projects to effectively manage deformations identified through condition assessments to ensure repairs are made so mechanical damage is addressed appropriately.   

It provides a basis for Pipeline and Hazardous Materials Safety Administration (PHMSA), establishing the recommended revised dent acceptance criteria by addressing the open recommendation issued to PHMSA in the National Transportation Safety Board’s (NTSB) Pipeline Accident Brief (PAB) 17–01 to:  

Work with pipeline trade and standards organizations to modify the pipeline dent acceptance criteria to account for all the factors that lead to pipe failures caused by dents and promulgate regulations to require the new criteria be incorporated into integrity management programs. (P-17-1)  

Additionally, the SRP is aligned with prior and ongoing R&D funded by PHMSA and provides a significant portion of the research that is the basis for developing the American Petroleum Institute (API) Recommended Practice (RP) 1183, the recognized standard for dent assessment and management  

Results of SRP  

The SRP reviewed and evaluated the performance of current inline inspection (ILI) systems for dents with coincident features (e.g. corrosion, crack, gouges) to support dent integrity assessment, followed by recommendations for assessment process improvement.   

This work led to feedback sessions with ILI service providers and established uniform dent and dent with coincident features reporting criteria. By standardizing language and definitions, a mutual understanding and efficient communication of features improves the ability to manage mechanical damage.  

Technology providers participated in ILI test trials at PRCI’s Technology Development Center (TDC) to improve upon existing technology, using more than 140 mechanically damaged pipe samples with coincident features such as metal loss, cracks, gouges and dents with coincident features. Results are being used to improve industry standards on mechanical damage inspection and assessments.  

In addition to completing a capstone report that systematized 20 years of mechanical damage research to identify knowledge uncertainties or gaps, pipeline operator data were collected to assess real-world experience and support engineering assessment model validation. Partnering on these collective experiences is critical in avoiding unnecessary replication of work and reducing inefficiencies.  

Results from work completed prior to establishing the Mechanical Damage SRP show that a critical factor in dent assessment is the shape of the deformation. Confirming the ILI performance specifications for measuring deformations was an appropriate inclusion for this SRP.   

Using a process developed through PRCI R&D, applying those measurements determine the “shape factor” of each dent, an important consideration in the dent engineering critical assessment (ECA) process and assessing the remaining fatigue life of a dent.  

Results in Practice  

PRCI’s mission is to collaboratively deliver relevant and innovative applied research to continually improve the global energy pipeline systems. Results from the MD SRP have provided the basis for the development of an ECA process that is included in PHMSA’s standard language for Special Permits, and they have been codified in natural gas pipeline safety regulations.

PRCI’s Technology Development Center validates technology using pull tests, flow loops and a library of damaged pipe samples. (Photo: PRCI)

Recently, an operator conducted the dent ECA on a pipe that required repair according to regulatory requirements to verify pipeline safety. The pipe could not be accessed within the required time limits because of permitting delays. The completed ECAs, based on strain-based damage parameters, verified that the delayed repair schedule did not represent a safety concern pending the issuance of the necessary permits.  

Operators have applied the dent ECA following API Recommended Practice 1183, the industry standard developed for dent assessment and management based on PRCI R&D results, PRCI operators technical knowledge and experience, and Mechanical Damage SRP work product, to identify the dents and dents with coincident features that may require remediation and to identify dents that do not impact integrity.  

Another operator observed that pressure cycle management has become an increased focus for many operators who have segments with dents present. While it has always been an element of engineering assessments for all anomalies, additional emphasis on dent assessment is needed for remaining fatigue life. The processes developed through the Mechanical Damage SRP and R&D programs have provided a consistent assessment of dents beyond the current dent response criteria based on depth.   

A major gas operator applied the results of PRCI Mechanical Damage project on fatigue crack growth behavior of dent with cracks to identify a safe operating period prior to remediation. This increases safety and ensures remediation in a timely fashion.   

Additional benefits of the Mechanical Damage SRP have included increased focus and support between researchers, operators and ILI technology providers in implementing the restraint calculations using shape parameters recently introduced in API 1183.   

This is a new and powerful technique for assessing the potential of fatigue failure of dents even down to depths of less than 1% OD. The technical applications of implementing ILI data to this assessment are not trivial; the pull testing at the TDC and the feedback from ILI technology providers have helped rapidly develop a solution that can be delivered to address this integrity threat to our aging pipeline infrastructure.  

Results from the Mechanical Damage SRP impact high level areas for industry improvement in the IM of mechanical damage, including damage prevention, assessment, inspection technologies and repair. By improving operator management systems, safety is advanced, the environment is protected and pipeline assets have increased reliability and efficiency. Additionally, improving systems and processes can eliminate unnecessary excavations and failures.  

With the commitment and technical expertise of its members, PRCI continues to develop dynamic research programs devoted to identifying, prioritizing and implementing the industry’s core research objectives. As a result, PRCI has become a critical resource for all energy pipelines regardless of where they operate, how they operate or the purpose of their operation.

Learn more at prci.org

Related Articles


{{ error }}
{{ comment.comment.Name }} • {{ comment.timeAgo }}
{{ comment.comment.Text }}