Ultrasonic sampling phased array testing as a replacement for X-ray testing of weld joints in ship construction

According to European Standard EN 1712 ultrasonic testing of thin-walled welded joints is mandatory for wall thicknesses of more than 8 mm only. Any thinner components do have to undergo X-ray inspection. Besides various advantages of X-ray testing viz. high sensitivity to smallest inclusions, high acceptance in the ship building sector and "automatic" documentation of inspection results, there are also several deficiencies (like radiation protection issues, inspection time expenditure etc.) creating a reasonable request for more cost-effective alternatives. Sampling Phased Array technology introduced by Fraunhofer-IZFP provides significant improvement of flaw detectability also in thin-walled welded joints due to its tomographic approach in processing of signals ob-tained by ultrasonic phased array transducers. It allows high-quality imaging of welded joints and detection of relevant material flaws. Real-time ultrasonic imaging with tomographic quality offers a great alternative to X-ray testing with respect to inspection speed and modern documentation of inspection results. The basic principles of Sampling Phased Array are presented in the paper and several application results ob-tained on welded joints of marine objects are presented.