Article Article
In Situ Metallography Applications in the Pipeline Industry

The Merriam-Webster Dictionary defines metallography as “a study of the structure of metals, especially with the microscope.” The structure of a steel visible at high magnification can reveal information about how the steel was formed or heat-treated, the general “quality” of the steel, whether any observed discontinuities originated during manufacturing or while the component was in service, and the extent to which properties may be consistent across the wall thickness. Microstructural features such as grain size, the amount and distribution of inclusions, and the types and amounts of different microstructural phases are known to influence a material’s properties. In some cases, the observed attributes are qualitatively characterized. In other cases, manual or digital image analysis facilitates quantitative descriptions of attributes such as grain size, the percent of a selected phase, or inclusions that are present. Typically, small sections are cut from the pipe or other component and metallographic sample preparation and examination are performed in a laboratory. When destructive sampling is impractical, the specimen preparation, visual examination, and related photo documentation can be performed nondestructively in the field. That process is known as “in situ metallography” and is the subject of this paper.

DOI: https://doi.org/10.32548/2021.me-04240

References

API, 2018, Specification 5L: Line Pipe, 46th ed., American Petroleum Institute, Washington, DC

DOT/PHMSA, 2019, 49 CFR Parts 191 and 192: Pipeline Safety: Safety of Gas Transmission Pipelines: MAOP Reconfirmation, Expansion of Assessment Requirements, and Other Related Amendments, Final Rule, Docket No. PHMSA-2011-0023, Amdt. Nos. 191-26; 192-125, US Department of Transportation, Pipeline and Hazardous Materials Safety Administration, Washington, DC

Gibbs, J., N. Switzner, J. Kornuta, R. Gonzalez, M. Rosenfeld, and P. Veloo, 2021, “Comparison of In-Situ Material Verification Non-Destructive Testing to Laboratory Destructive Testing of Lap-Welded Pipe,” Pipeline Pigging and Integrity Management (PPIM), 22–26 February, Houston, TX

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Switzner, N., P. Veloo, M. Rosenfeld, T. Rovella, and J. Gibbs, 2020b, “An Approach to Establishing Manufacturing Process and Vintage of Line Pipe Using In-Situ Nondestructive Examination and Historical Manufacturing Data,” Proceedings of the 2020 13th International Pipeline Conference, Vol. 3: Operations, Monitoring, and Maintenance; Materials and Joining, 28–30 September, https://doi.org/10.1115/IPC2020-9589

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