Long range ultrasonic testing (LRUT) is a non-destructive testing (NDT) technique
using low frequency ultrasonic guided waves to inspect plates and pipes efficiently for
corrosion and other degradation. This technique is widely used in industry for
inspecting long distance oil and gas pipelines. The main advantages are that 100%
coverage of the pipe wall may be achieved over many metres from a single test location.
Minimal access is required to the pipe to perform the inspection and inaccessible
lengths, e.g. road crossings, may be examined from accessible locations. TWI and its
subsidiary Plant Integrity Ltd have been at the forefront of this technology since its
introduction in the late 1990s and carry out a large programme of research and
development to improve the performance of this method. This paper presents an
overview of the main developments currently being investigated and how they are being
introduced into the field test equipment. An important part of this development
programme is the enhancements to the electronics used to perform the tests, so that the
advantages identified in the experimental work may be implemented for use in plants.
At the heart of this is the use of field programmable gate arrays (FPGA) for more
efficient control of such systems to reduce size and weight while improving both system
performance and flexibility.