Ultrasound Corrosion Scanning or known as C-Scan is a form of automated ultrasonic testing. It uses high frequency sound energy to conduct examinations and record measurements of wall thickness. C-scan can be used for internal detection of corrosion, lamination, and other planar flaws.

Some of the advantages often associated with C-Scan include is provides a permanent record of the location and thickness readings. Only one surface need be accessible. Nonhazardous to operations or to nearby personnel and has no effect on equipment and materials in the vicinity. Portable and highly automated operation. Various views of the defect (i.e. “C” scan, “B” scan, 3D, and spreadsheet displays of actual recorded data). The C-scan is used in corrosion mapping and by techniques other than just ultrasonic. It is not limited to showing amplitude but is also used to display changes in measured wall thickness or qualitative measurements in the extent of corrosion.

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Corrosion mapping is an ultrasonic technique which maps and identifies variations in material thickness due to corrosion. It is an advanced method of ultrasonic testing. Corrosion is the deterioration of a metallic material by chemical (or electrochemical) attack. This is normally caused by the environment (most often water), and sometimes by another material. There are several types of corrosion:

  1. Uniform corrosion that extends evenly across the surface
  2. Pitting corrosion that is uneven and has smaller deep areas (pits)
  3. Exfoliation corrosion that moves along layers of elongated grains
  4. Inter-granular corrosion that grows along grain boundaries

Ultrasonic corrosion mapping is the preferred method for critical pipelines generally on petrochemical sites or offshore platforms. Ultrasonic mapping provides the owner of a pipe line with a detailed C-Scan image of the inspection surface via the means of a semi- automated scanning system.