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Development of Coded Excitation Technique for Non-Metallic Pipes Inspection

Project Code: 34765

Start date and planned duration: January 2022, 36 months


The overall aim of this project is to develop an ultrasonic inspection technique which can enhance the signal to noise ratio in highly attenuating materials, and validate the technique with samples of interests to the industries. More specifically this project has the following objectives:

  • Develop an ultrasonic technique that is able to measure the thicknesses of the pipe and of each layer, and demonstrate it on the selected TCP and RTP pipes
  • Develop an ultrasonic technique that is able to detect flaws like delamination, thinning, fibre-breakage etc in the pipe and demonstrate it on the selected TCP and RTP pipes
  • Produce a user friendly interface to acquire and analyse the data.

Project Outline

Non-metallic pipes have been gaining popularity in the oil and gas industry in recent decades due to the advantages of their corrosion resistant properties, strength to weight ratio and cost. They are typically made of reinforced thermoplastic materials commonly known as reinforced thermoplastic pipe (RTP) or thermoplastic composite pipe (TCP). Up to now, there is no standard governing the NDT inspection of such pipes. Even design standard like ‘DNV-GL-F119 Thermoplastic Composite Pipes’ allows the NDT inspection to be replaced by well-documented production controls due to the lack of effective NDT methods.

There are important design variations in non-metallic pipes, as compared to their metallic counter-parts, and the flaw types are a lot more complex too. That is also why there is no NDT strategy that can cover all the failure modes. In the past, micro-wave inspection and digital X-ray have achieved good results in covering a number of flaws with dimensions of a few mm. However, both techniques require costly instrumentation, with one unit typically costing ~£200k up to a few hundred thousand pounds. In addition, radiography techniques demand stringent site safety requirements.

In the field of non-destructive testing of metallic structures, the trend is shifting from radiography to ultrasound, which is inherently safe from radiation and usually uses much cheaper instrumentation. A conventional ultrasonic inspection device costs only a few thousand pounds; even an advanced phased array unit is significantly below a hundred thousand pounds. Over the past decades, ultrasonic inspection has replaced most of the radiography inspection in the oil and gas industry for post-manufacturing and on-site inspections. Comprehensive international standards are also available to govern the use of ultrasonic inspection in sentencing metallic structures.  

This project focuses on coded excitation technique in ultrasonic inspections of TCP and TRP pipes. With this technique low energy input (10V) is able to achieve an equivalent signal-to-noise ratio to a conventional 220V energy input in metallic structures. In this project, various samples will be supplied both by the sponsors and internally through the ACA section. The project will start by establishing the optimum signal-to-noise ratio in the plastic pipe samples using various coding, and then correlate the thickness degradation to the detected signals. If successful, the project will proceed to look at other failure modes like delamination, cracks etc.

Industry Sectors

-      Power

-      Oil & Gas

-      Construction

 Benefits to Industry

  • It will provide an effective, inherently safe and affordable technique to inspect challenging materials with high attenuation.

For more information please email: