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UT Inspection of Welds in Accordance with Code AWS D1.1: Part 2. Effect of Surface Conditions

When performing contact ultrasonic testing (UT), the surface condition of the inspected item is an important variable. Surface conditions include: cleanliness, contour and waviness, and roughness. Requirements for surface cleanliness are formulated in subdivision 6.26.3 of AWS D1.1 (AWS, 2010). Recommended waviness value needs to be less than 1.5 mm (0.06 in.) over a 50 mm (2 in.) span (ASNT, 2007). However, no criteria are given for acceptable roughness of scanning surfaces. A rough surface affects the examination in many ways, including, but not limited to: causing difficulty in moving the search unit; reducing the energy of the refracted beam due to scattering and increasing thickness of the couplant; causing a change in the mode transfer; and causing reverberation of the sound in the pockets on the surface, resulting in a wide front surface echo and increased dead zone.

References
  • ASNT, Nondestructive Testing Handbook, third edition: Vol. 7: Ultrasonic Testing, American Society for Nondestructive Testing, Columbus, Ohio, 2007, p.224.
  • AWS, AWS D1.1/D1.1M, Structural Welding Code – Steel, American Welding Society, Miami, Florida, 2010.
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