The development of a novel inspection approach within AEA Sonamatic BV in the Netherlands using the various inspection software utilities in the Microplus (µ⁺) system ensures early detection of this phenomenon with high reliability and reproducibility. The detection of HHA in the parent metal is possible combining the following two ultrasonic techniques.

1. Backscatter measurement
2. Velocity ratio measurement.

The backscatter technique is based on the detection of ultrasonic backscatter received from the microcrakcs. The advantage of this is that 100% coverage of the surface is possible. Velocity ratio measurements are used to observe the changes in the velocity ratios between the longitudinal and transverse waves. With an advanced calculation program, it is possible to calculate the stage of attack. This is a very reliable result so long as the attacked wall thickness is over 10% of the total wall thickness.

HHA in the weld material is detected using the Ultrasonic Time- Of-Flight Diffraction (TOFD) technique. Both micro and macro cracks are detectable. Monitoring using the above approach is simple and effective as baseline data is stored.

This paper will also discuss the field-results obtained using this approach and highlight the practical advantages in such cases.