Session: MF-05-01 Fitness-For-Service and Failure Assessment-1

Paper Number: 155829

155829 - Wrought Tee Intersections Operating in the Creep Range, Part Ii: Actions to Procure Serviceable Tees 

Abstract: 

Over the last decade hundreds of events in wrought tee intersections designed to ASME B16.9 and stamped as a fitting to A- or SA-234 have been documented by industry. These components are frequently installed in main steam and hot reheat systems, operate in the creep range, are specified to be grade 22, grade 91 or grade 92, and have experienced extensive damage, cracks or leaks in ~40,000 to 150,000 hours of operation. 

Part I addressed the damage mechanisms, identified several common vulnerabilities, and called into question the serviceability of these components for long-term operation. Part II explores the mitigation strategies for new plant or replacement tees, including aspects of design, fabrication, and inspection. Several actions are detailed that must be incorporated into a robust technical purchase specification to address the shortcomings regarding the complex network of codes and standards to which these tees are typically designed and fabricated. The presented recommendations account for the constraints in the supply chain or the present piping configuration, such as for a replacement tee. Lastly, opportunities are identified for refinement and enhancements to the minimum requirements in existing codes and standards that will be essential to achieving acceptable serviceability in the time-dependent range.

Presenting Author: Ian Perrin Triaxis Power Consulting, LLC

Presenting Author Biography: Dr. Perrin has over twenty-five years of problem solving and technical consulting experience within the power generation industry. He has knowledge of a variety of plant systems including: gas turbines, steam turbines, heat recovery steam generators, boilers, and balance of plant equipment. Dr. Perrin has extensive expertise in material damage mechanisms, material modeling, non-linear solid mechanics, and component life assessment.

With a passion for providing accurate, practical, and dependable advice, Dr. Perrin leads complex multidisciplinary failure investigations, advises on component serviceability, contributes to research organizations such as EPRI, and works with industry bodies such as ASME Boiler and Pressure Vessel Codes and Standards.

Authors:

Ian J. Perrin Triaxis Power Consulting, LLC
John A. Siefert EPRI
Thomas Sambor EPRI
Patricia Becker EPRI