Specialist Applications

Long Range Ultrasonic Testing

What is Long Range Ultrasonic Testing?

Also known as Guided Wave Testing (GWT), Long Range Ultrasonic Testing (LRUT) is an advanced inspection technique that is used to detect, locate and classify defects in pipe structures. Unlike traditional methods that test a very localised area, a temporary collar of ultrasonic transducers is mounted to the pipe and generates guided waves in both directions that propagate along the structure to identify defects over long distances. 

How it Works

Image 1: Guided Wave Propagation in a Pipe (Courtesy of Guided Wave Ultrasonics Ltd)

Test Results

The below image is an example of a defect to show how LRUT can determine axial distance, circumferential position, and Cross-Sectional Change / Severity of an indication or defect. This information allows secondary, high-resolution inspection techniques to be used efficiently to target precise areas of interest.

Image 2: Signal Propagation  from an indication (Courtesy of Guided Wave Ultrasonics Ltd)

Key Features and Benefits

  • Non-Destructive: LRUT is completely non-destructive and can be used while pipelines are in-service.

  • Long-Distance Coverage: The ability to cover long lengths of pipe and screen 100% volume to detect corrosion or erosion from a single test location. This significantly reduces inspection time, costs, and manpower, making it a highly efficient and cost-effective solution.

  • Provides Severity and Location of Indications: The data provided can be used to make fast fitness for service assessments and when more detailed data is required, it enables the laser focus of inspection resources to any areas of interest. 


  • Transmission Pipelines: LRUT is widely used in the oil and gas industry for the inspection and monitoring of pipelines. It allows for the detection of defects, such as wall thinning, corrosion, and cracking, enabling proactive maintenance and preventing costly leaks or failures.

  • Corrosion Under Insulation: Many process systems require the pipework to be insulated, which can accelerate corrosion and make visual assessments very time-consuming and costly. Long Range Ultrasonic Screening requires only a small section of insulation or lagging to be removed to inspect a long section of pipe while still in service. This is a very efficient way to screen for Corrosion Under Insulation (CUI). 

  • Contact Point Corrosion or Corrosion Under Pipe Supports: CPC/CUPS is one of the leading causes of failure in piping within the Oil, Gas, and Chemical Process Industries. Long Range Ultrasonic allows for the rapid screening of multiple contact points per test to identify any problems hidden from visual inspection. If a contact point is identified we follow up that area with a PA-CAT inspection to quantify the remaining wall loss before any remediation can take place safely.

Read more about our CPC/CUPS solution for Screening and Assessment


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