The natural world can identify corroding metals in gas and oil pipelines. Inspired by this natural detection, engineers have now devised a new scanning method.
The researchers have developed a novel system by simulating the way bats use varying wavelengths of ultrasound to hunt, detect objects, and evade predators. The system integrates two individual types of radiation—that is, gamma rays and fast neutrons—to identify corrosion, which is the leading cause of pipeline leaks.
Pipelines, stretching to thousands of kilometers, are used to transport gas and oil over large distances across the world, and therefore, leaks are considered a major problem, which can cost millions every year. Leaks also carry the risk of injuries and accidents and cause considerable damage to the environment.
Corrosion in oil pipelines is usually quantified using electromagnetic or ultrasonic methods. But these methods are not suitable for pipelines surrounded by insulating layers of plastic or concrete, or for underground pipelines.
The innovative system, created by engineers from the National Physical Laboratory, Lancaster University, and Hybrid Instruments Ltd—a technology company—manipulates the reflected signals, called “backscatter,” of a combination of isolated gamma radiation and fast neutrons.
Both gamma radiation and neutrons exhibit useful complementary properties. Neutrons primarily interact with low-density materials such as plastics. Fast neutrons also have a high penetrating power, making them appropriate for analyzing thick materials. Gamma rays primarily interact with metals and do not always penetrate extremely thick materials of high density.
Both types of radiation create a varying electronic signal, allowing scientists to simultaneously retain information on both types of radiation using an innovative detecting device known as a “Mixed Field Analyzer.” The device was earlier developed by Hybrid Instruments Ltd. and Lancaster University.
The Mixed Field Analyzer generates a pencil-like beam of probing radiation, of gamma and neutrons, which is then focused toward the steel section being analyzed.
In a laboratory, the researchers tested both imaging methods in real time on carbon-steel samples of varying thicknesses and successfully observed the variations in the thickness of the steel.
When an insulating layer was simulated with plastic or concrete, the sensors worked equally well. This indicates that defects in steels, as well as rust and corrosion, are likely to create differences in the backscatter.
These outcomes demonstrate that if these sensors are utilized on real pipelines, then potential problems could be identified and resolved more easily, before oil and gas escape from the pipelines.
The combined beams of neutrons and gamma rays in parallel bouncing back to an array of detectors yield a comprehensive and fast representation of the inner structure of steel. This system works a bit like the chirps made by bats. These chirps are a superposition of different ultrasound wavelengths, which bounce back to the bats’ ears.
Mauro Licata, PhD, Project Researcher, Lancaster University
Licata continued, “As well as highlighting the benefits of combining multiple reflection sensing techniques to detect for problems such as corrosion, our work further illustrates the significant potential that can be had from taking inspiration from, and mimicking, systems that have evolved in the natural world.”
Isolating neutrons and gamma rays backscattered from a steel surface in real time, in a way analogous to the way bats’ brains isolate backscatter ultrasound and thus avoid confusion with their own chirps, could help us isolate flaws in pipe walls more quickly and effectively.
Malcolm Joyce, Professor, Lancaster University and Hybrid Instruments Ltd.
“This is a great example of NPL’s world-leading neutron facilities being used for innovative science with a positive impact,” stated Neil Roberts from the National Physical Laboratory.
The idea is to further develop the new detector system and thus use it to identify faults by pointing it at the pipeline sections from the outside.
But to make the system faster, more research is required in the field of neutron detectors, added the researchers. According to the team, the new technology could even be utilized in other applications, for example, checking the integrity of structures, like bridges.
The study has been described in the paper titled “Depicting corrosion-born defects in pipelines with combined neutron/γ ray backscatter: a biometric approach,” published in the Scientific Reports journal.
The study was funded by Innovate UK and headed by Hybrid Instruments Ltd, in association with Lancaster University.
The authors of the study are M. Licata, M. D. Aspinall, M. Bandala, and M. J. Joyce from Lancaster University; F. Cave, S. Conway, D. Gerta, and H. Parker from Hybrid Instruments Ltd; and N. Roberts and G. Taylor from The National Physical Laboratory.