The quality of ultrasonic data collection depends, among other things, on…
(a) The angle of the ultrasonic transducer
(b) The amount of data reduction
(c) The pipeline condition
(d) All of the above
As can be seen from the survey, the question, “The quality of ultrasonic data collection depends, among other things, on…” creates some uncertainty. Nevertheless, the majority of participants chose the correct answer (d).
The quality of the ultrasonic crack measurement depends on many different parameters. In the following, we would like to explain the individual points in more detail.
For a good measurement, it is important that the amplitudes of the recorded ultrasonic waves are high compared to the noise level in the data. This is guaranteed if the wave generated in the wall, ideally, has an angle of 45 degrees. To ensure this, different parameters have to be considered. In particular, the speed of the sound of the steel and the medium present in the pipeline have a significant influence. Taking these parameters into account, the angle at which the sound wave has to be coupled into the steel is determined. If a 45-degree wave cannot be generated in the pipe wall, this affects the signal strength and thus also the data quality.
In order to be able to carry out a reliable ultrasonic crack inspection, the resolution in the circumferential and axial direction plays a very important role. The high resolution applied for ultrasonic crack inspection leads to a relatively large amount of generated data compared to other ILI services. Reliably processing this data on the tool is a challenge for the electronics hardware. Despite these challenges, ROSEN is pursuing the “Full Scan Approach” on this topic, which means there is no reduction of the large amount of data. As a result, all of the data can be taken into account in the evaluation process, bringing qualitative advantages.
Another decisive factor is the pipeline condition. As already mentioned, a strong signal from the defect is paramount for a good measurement. Various deposits in the pipeline or particles in the medium cause less energy to be coupled into the pipe wall. Insufficiently cleaned pipelines can, in the worst case, prevent the recording of usable data, which will lead to a re-inspection. For this reason, the condition of the pipeline is a very important and decisive factor for ultrasonic crack detection.