Ultrasonic Testing (UT) of Welds

Welding is the common process of joining materials through melting and fusion, and inspection of structural welds in metals is the single most common application for Ultrasonic Testing (UT). Welding can be done by means of several methods including electric arcs, gas flames, and lasers. For ultrasonic testing, the welding method is not a primary concern.

The most commonly encountered flaw types in welds are cracking, lack of fusion, incomplete penetration, porosity, and slag inclusions. All of these are potentially detectable through ultrasonic testing.

While straight beam techniques can be highly effective at finding laminar flaws, they are not effective when testing many common welds, where discontinuities are typically not parallel to the surface. The combination of weld geometry, the orientation of flaws, and the presence of the weld crown or bead require inspection from the side of the weld using a beam generated at an angle.

Shear wave testing, also known as angle beam inspection, is an ultrasonic testing technique used primarily for weld inspections. Weld inspection is accomplished by introducing shear waves into a plate at a selected angle and manipulating the transducer so as to scan the entire weld.

In typical inspections the sound beam will travel at the generated angle down to the bottom of the test piece and then reflect upward at the same angle. Moving the probe back and forth causes the sound beam to sweep across the full height of a weld. This scanning motion enables inspection of the entire weld volume and detection of discontinuities both at the fusion lines and within the weld body.

We use Olympus Epoch 650 Ultrasonic Flaw Detector, a state of the art digital flaw detector, and Olympus Panametrics angle beam (shear wave) transducers for inspection of welds. With ultrasonic inspection, we are able to detect the following defects in welds:

• Cracks in the weld zone.
• Discontinuities and incomplete penetration of weld joints.
• Lack of fusion in welded joints.
• Porosity in welded joints.
• Slag inclusions in the welded joints.
• Areas with distortion.
• Stratification of weld metal.

marineSOLUTIONS has invested extensively in the training of personnel and assortment of equipment. We come equipped not only with an understanding of shear wave testing, but also with a comprehensive skill-set of conventional and advanced non-destructive testing techniques and provide the highest level of service.