Performance enhancements in an ultrasonic guided wave pipe inspection system

This thesis was submitted for the award of Master of Philosophy and was awarded by Brunel University LondonSound has the ability to travel over long distances in structures whose geometry can act as a guide for the sound waves. This phenomenon can be exploited in the use of long range testing of structures, such as oil and gas distribution networks, Storage tank facilities, oil and gas exploration platforms to ships hulls and bridges. Specifically, this technology can be utilised to inspect structures where safety critical evaluation of its structural integrity is of paramount importance to both human and environmental considerations. Therefore, any technique that can aid the inspection process of flaw detection in a structure and possibly reduce the risk of catastrophic failures in industrial installations is highly desirable. With more and more companies relying on reliable ways to effectively screen for defects in metal pipe lines and structures, namely in the Oil and Gas industries, a solution was found in the use of Ultrasonic Guided Waves (UGWs). These types of Guided Waves have been found to be useful over recent years in the Non-Destructive Testing (NDT) of industrial pipelines. This technology relies on the ability to transfer pre-determined analogue signals into suitable ultrasonic wave modes capable of travelling through test samples, to record any ultrasonic responses that are reflected from anomalies within the sample, these signals are then analyzed using advanced digital signal processing techniques to detect defects. This research work was carried out with a view to enhance the performance of a commercially available system, marketed as TeletestFocusTM, which is designed and manufactured by TWI. Improvements have targeted the ultrasonic transducers and the embedded electronics that control their use. Improvements to the existing PZT shear mode transducer design were implemented, which resulted in significant improvement in its output characteristics. An experimental setup and testing procedure was developed to facilitate the transducer characterisation. A new transducer manufacturing process was introduced that dramatically reduced production times and improved variations between individual assemblies. Evaluations on the performance of the previous embedded electronics units (Mk1, Mk2 and Mk3) were accessed. As a result of this evaluation a new embedded electronics unit (Mk4) was designed and manufactured. Newer technologies, namely a more advanced FPGA, interpolation DAC’s, Ethernet data transfer protocols and reduced component sizes were introduced to improve the functionality and efficiency of the system but also reduce the overall size of the data collection system. A new approach to the system layout was implemented with new manufacturing processes employed to reduce weight and achieve a reduction in costs. The design improvements to the next generation of TeletestFocusTM Mk4 significantly enhanced data collection and analysis, compared to the previously available Mk3, unit of over 300%. Improvements to the transducer design also culminated in a 250% increase in output performance. Enhancements to both the electronics unit and transducer resulting from this research enables system operators to cover more test locations within a given time period, therefore, increasing efficiency and reducing costs