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Nondestructive Evaluation

 

Cast Iron Graphitization Measurement Device

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  image of SwRI adaption of an existing meter to measure the thickness (up to 10 mm depth) of the graphitized layer of cast iron using eddy current measurements
 

SwRI adapted an existing meter to measure the thickness (up to 10 mm depth) of the graphitized layer of cast iron using eddy current measurements.

 

image of graph showing Error in maximum damage depth estimate using the meter on machined defects of different aspect ratios (diameter to depth ratio)

 

Error in maximum damage depth estimate using the meter on machined defects of different aspect ratios (diameter to depth ratio). Each curve corresponds to one flaw surface diameter.

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.

 

ndesensors.swri.org

  

Contact Information

Jay Fisher, Ph.D.

Electromagnetics

(210) 522-2028

jfisher@swri.org

ndesensors.swri.org

Related Terminology

cladding thickness

computer modeling

corrosion

cracks

eddy current

magnetic sensor

nondestructive evaluation

orientation sensing

pipe wall thinning

position sensing

pulsed eddy current

reliability studies

specialized NDE system development

specialized procedure development

steel pipe inspection

| Sensor Systems and Nondestructive Evaluation (NDE) Technology Department | Mechanical Engineering Division | SwRI Home |

Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 10 technical divisions.

August 07, 2014