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Although cast iron pipe is naturally resistant to corrosion, occasionally the pipe wall will deteriorate through a form of corrosion called graphitization. Previously, graphitization has been detected and assessed in the field by visual inspection, while quantification of the damage depth has been possible only in the laboratory.
Southwest Research Institute (SwRI) developed a tool for on-site inspection and quantification of graphitization that will simplify inspection procedures and accommodate a larger sample. This commercial graphitization meter is nondestructive and can be operated by a field technician as part of normal inspection procedures.
An existing meter was also adapted, using eddy current to measure the thickness of the graphitized layer of cast iron. This technique distinguishes between the conducting (good material) and non-conducting (graphitized material) parts of the pipe wall. Graphitization depth up to 10 mm can be measured.
The adapted meter provides very reliable estimates of corrosion depth on naturally occurring graphitization when damage is in the 0-3 mm (0-0.12 inch) range. In this range, the error is less than 0.3 mm. A number of units have been purchased by NGA members and are being used reliably in the field.
For more information about our nondestructive evaluation (NDE) capabilities, cast iron graphitization measurement device technology, or how you can contract with SwRI, please contact Jay Fisher, Ph.D., at jfisher@swri.org or (210) 522-2028.
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| Sensor Systems and Nondestructive Evaluation (NDE) Technology Department | Mechanical Engineering Division | SwRI Home | |
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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions. |
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January 03, 2013 |
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