Eddy current transducer with sensing coils placed orthogonally and connected in differential mode was introduced to evaluate fatigue cracks in clad pipeline circumferential welds. A dedicated embedded electronic hardware was developed to drive the transducer and measure the electrical complex impedance of the coils, and was specifically designed for operation under autonomous in-line inspection tool. In the laboratory experiments, an automated inspection was performed with the goal to evaluate transducer’s detectability, and different scanning speed was tested to reproduce in service situation. The results have confirmed that the introduced eddy current transducer is a potential solution for fatigue crack detection in clad circumferential weld root, while the hardware developed presented a reasonable SNR reaching the data rate required to be incorporated in an autonomous in-line inspection tool.

The area close to the submerging point of off-shore steel catenary risers is difficult to access for inspections, since neither divers or climbers can work safely under the severe splash conditions. Hence, there is a need for technologies that allow remote or automated inspection of the so-called splash zone. Systems based on long range ultrasonic guided waves (GW) are an interesting option, especially if permanently-attached sensors are used to monitor the region continually. Operation with conventional piezoelectric sensors usually requires removal of the external coatings which are usually present, and this can lead to additional corrosion problems. In this work a GW system based on electromagnetic acoustic transducers was developed and tested on pipes covered with a 3 mm thick polyethylene coating. Initial studies of the transducer configuration were performed using finite-element analysis and then validated experimentally. A prototype sensor array was manufactured and then used for inspection of machined defects, initially in dry conditions in the laboratory and later in a full-scale test in an 15m depth water tank. In these given lift-off conditions, the system was capable of detecting defects corresponding to a 2.5% cross section area loss at a distance of 8m.

This paper presents the conceptual design and prototype validation stages of the development of an in-line inspection tool that is based on circumferential guided waves generated by shear horizontal electromagnetic-acoustic transducers (EMATs). By combining the data from these sensors with information from accelerometers and an odometer, the tool can evaluate the integrity of the pipeline non-destructively and record the longitudinal and circumferential position of wall thinning areas and geometrical features or anomalies. This paper focuses on the identification of pipeline features, which is a key aspect in avoiding false-positive calls during real inspections. The performance of the tool in detecting and identifying such features in near-operational conditions in a defect-free qualification pipe loop is evaluated.