The non-destructive testing inspection of welds in nozzles can be a difficult application to get right, ensuring all defect types of interest can be properly detected and located within the weld. The use of Phased Array Ultrasonic Testing (PAUT) gives many benefits compared to radiography and is widely adopted as the method of choice for these complex configurations. However, there are many technical challenges that Level III inspectors and operators must consider when designing and carrying out PAUT weld inspection. The main obstacle, compared to standard weld inspection, comes from the varying geometry of the parent pipe or vessel as you rotate around the nozzle. This 'saddle' geometry sees the probe move from axial to circumferential alignment as it rotates 90 degrees around the nozzle. The change reciprocates with rotation around the full circumference.
As the probe moves around the nozzle, the front and backwall curvature changes, and beam-set interaction with the weld area will be affected. Beams will become 'skewed' in the first leg in positions outside of the 0, 90, 180, and 270 clock locations. With conventional Ultrasonic Testing (UT) methods, many passes of the weld may be necessary with rastering as well as skewing of the probe motion essential.
In this article we will look at the use of advanced phased array electronics and software as well as dedicated array probes and scanners to give the most comprehensive and efficient inspection approach to ensure success.
Read more at Eddyfi.com.