Ultrasonic Rail Testing: Challenges and Solutions

Despite the booming automotive industry over the past century, railroads are still a pretty big deal. In the United States alone, there are more than 538 railroads and over 155,000 miles (or 250,000 kilometers) of operational rail. China, which comes in second after the US in terms of railway length, boasts greater than 62,000 miles (or 100,000 km) of track in its networks.

Every inch of those railways needs to be kept in pristine condition in order to ensure the safety of the thousands of passengers and crew members who ride aboard those trains every day, as well as that of the precious cargo that companies choose to ship by rail. Developing flaws must be caught early on in order to prevent catastrophic failures down the line. Regular ultrasonic rail testing can go a long way towards detecting such flaws; however, analysts must overcome a variety of challenges—not the least of which is the sheer expanse of railway in need of inspecting—in order to ensure no stone (or railhead) is left unturned.

The Challenges of Ultrasonic Railway Inspections

Every testing material and environment presents unique challenges for NDT analysts to overcome. With railway testing, one of the biggest challenges analysts face is the need for absolute accuracy—even the smallest overlooked flaw can compromise an entire section of railing. Particularly dangerous anomalies such as buckling can result in a train derailment if not addressed early in development. And because of today’s heavier train loads and increased commerce and traffic, such flaws develop more frequently than ever—and are as easy as ever to miss.

Another challenge inspectors face when conducting railway ultrasonic testing (UT) is the logistics associated with scanning wide networks of rail. While inspection cars can cover wide swaths of ground in a short amount of time, they cannot pinpoint the exact nature or location of developing flaws from a distance, and may not detect minute flaws at all. Walking sticks, meanwhile, offer more precise readings but are not ideal for covering a lot of ground at once.

Additionally, standard UT tends to offer fixed beam angles that do not permit added angles during testing. Such unyielding techniques increase the likelihood of missed flaws that can morph into severe anomalies if they aren’t addressed during the early stages of development.

PAUT: An Innovative Solution

Just as every situation presents unique problems to solve, so too do innovative NDT advancements offer unique solutions for each case. One common solution to the challenges mentioned above is to utilize inspection cars and walking sticks in tandem—the inspection cars head out first to scan large sections of rail, and then their readings are used to determine which areas require a closer look with the walking sticks.

However, in most cases, both inspection cars and walking sticks are still limited by the technology they use, as many are equipped with only standard UT. While ultrasonic testing is by far one of the most effective methods for testing rails, there is an advanced ultrasonic solution that can more aptly address the inherent challenges of railway NDT: phased array ultrasound, or PAUT.

With conventional UT, it’s nearly impossible to diverge from a fixed beam position, and analysts cannot achieve multiple angles with a sole scan. PAUT, on the other hand, allows analysts to angle the wave beam in multiple directions, covering more of the testing radius and spotting defects that would have likely been missed using fixed-angle testing. And while some railway cars and walking sticks do offer the ability to angle beams in different directions, PAUT has yet another advantage over both, as they do not typically offer the sheer level of customization possible with PAUT instrumentation.

Portable PAUT units equipped with advanced software and cutting-edge probes make it easier than ever to gather incredibly detailed data and analyze it quickly and efficiently, streamlining the overall inspection process and minimizing the margin for human error. Bipolar pulsers in more advanced PAUT instruments can easily be used to inspect complex surfaces such as railheads and welds that are typically harder to test using other NDT methods. The pulsers push ultrasonic waves below the surface of thick welds, reading and measuring even the most minute irregularities within the structure with relative ease.

Improving Ultrasonic Rail Testing With Advanced Technology

While even standard ultrasonic rail testing is among the most efficient methods of railroad NDT, few techniques offer the accuracy, adjustability, and ease of analysis that advanced PAUT instruments can provide.

To get the most out of a PAUT initiative, however, it’s important to invest in high-quality equipment from a trustworthy NDT manufacturer that can provide your analysts with the innovative software and instrumentation they’ll need to conduct the most comprehensive inspections possible. The more effective your nondestructive testing process is, the more confidently you can guarantee the safety of the crew and passengers whose wellbeing hinges on the quality of your railway.

Zetec is an experienced NDT company that provides innovative UT solutions, including PAUT instrumentation and software for railway inspections. For a custom inspection plan and reliable instruments, contact us today.