Long Range Ultrasonic Testing (LRUT) is an advanced nondestructive examination technique that was developed for testing large volumes of material from a single test point. What differentiates this from more traditional methods of ultrasonic testing is that, with LRUT, a liquid couplant between transducers and the surface is not required. For this reason LRUT is one of the fastest inspection tools for carrying out pipeline surveys for corrosion and other damage mechanisms.

LRUT is performed using a system which is made up of a low frequency flaw detector, a pulser receiver unit, some transducer rings, and a laptop computer which contains the software that controls the system. To begin, the transducer rings are fixed around a pipe, through which they will then generate a series of low frequency guided waves. It's the uniform spacing of the ultrasonic transducers around the circumference of the pipe allows for the guided waves to propagate symmetrically along the pipe axis, providing complete, 100% coverage of the pipe wall, including areas such as at clamps and sleeved or buried pipes. The waves are then reflected back to the transducer whenever they reach a change in wall thickness, which is how the process is able to detect corrosion, metal loss, or discontinuities.

LRUT is an invaluable nondestructive testing technique that has applications throughout the oil and gas industry. It is widely used in the inspection of pipes in areas such as road and river crossings, power plant tubing, risers, offshore topside pipework, jetty lines, and refinery pipework for the detection of issues such as corrosion under insulation. It has also found widespread use in situations where pipes or tubes are not accessible to other detection methods such as for pipes buried in soil, those encased in a sleeve, or those positioned at a high elevation.

Related Topics

• Internal Rotating Inspection System (IRIS)
• Phased Array Ultrasonic Testing (PAUT)
• Rapid Ultrasonic Gridding (RUG)
• Time of Flight Diffraction (TOFD)

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