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Inspection Expert Herbert Willems: Resolution to Excellence
“Ultrasonic inspection has had phased array technology for ten years. The next advance will be multiplied electronics, using divided, or multi-element, sensors.” - Herbert Willems, December 2018
This forward-looking observation and its timing, on the eve of his retirement, perfectly illustrates the qualities of Herbert Willems, a man who has never stopped thinking about solutions to the toughest problems in one of the most challenging industries to date. Willems is a true visionary. His foresight and skills produced a career of unsurpassed accomplishments.
An Industry is Born
X-Ray testing is considered to be the first commercial non-destructive testing method. In 1895, German physicist Wilhelm Conrad Röntgen discovered X-rays, which earned him the first-ever Nobel Prize. In his first publication on the topic, Röntgen described various uses including possible flaw detection. Other technologies were also developing, in rough concurrence. A notable early technology was magnetic particle testing. Among the first applications of this method was in 1917, for finding cracks in gun barrels by magnetic indications. In 1934, the company Magnaflux, was formed, to offer industrial applications of this technology. Another early form of non-destructive testing was Liquid Penetrant Testing (LPT), primarily used in the second half of the 19th century by the railroad industry, to increase the visibility of defects not ordinarily observable.
State of the Art
The genesis of Ultrasonic Testing (UT) can be found as far back as 1847, in the work of James Prescott Joule, and then later in 1880, by Pierre Curie and his brother Paul Jacques. Consideration of industrial applications of this method began following the sinking of the passenger ship Titanic, in 1912. And, in 1929, a Russian named Sokolov proposed the use of ultrasound for testing castings. The technology has distinct advantages. Because UT is a truly volumetric test, it is capable of determining not only the approximate dimensions and location of a defect, but also the type of defect. It only requires access to one side of the material being tested. And, it will best detect those more critical planar discontinuities such as cracks and incomplete fusion, which may not be possible with radiographic testing.
Willems' First Achievement
Some would say Herbert Willems future contribution to the industry was predefined. He earned his master's degree in physics, from the University of Saarbrücken, Germany, less than 300 kilometers from physicist Wilhelm Röntgen’s birthplace. His path to the company that would become NDT Global began at the Fraunhofer Institute for Non-Destructive Testing, where he worked in the field of ultrasonic materials characterization. In 1994, he started at Pipetronix, as project manager for the development of inline crack inspection using ultrasonic technology.
“Pipetronix was then the leader in ultrasonics,” Willems said. “Most inspections then were completed using MFL [magnetic flux leakage] technologies, which originated in the 1960s. When I started with crack inspection technology; no MFL solution was available for cracks.” In 1995, Willems made his first mark on the industry. “I was involved with the building of the first crack inspection tool based on ultrasonics. The goal was to replace hydrotesting. I also assisted with the development of data analysis algorithms and tools, and I trained people in analysis. In the beginning, data analysis was the big challenge.”
NDT Global is Born
“During my time at Pipetronix, I became convinced that ultrasonics would not achieve its highest potential unless we developed equally powerful data analysis tools,” Willems said. This insight was a key factor in his decision to help launch, in 2000, NDT Systems & Services. At the fledgling company, Willems created data analysis algorithms and the other tools and techniques he knew to be the essential partner of hardware capability. His work constantly pushed against the limitations of computer processing power, data storage capacity, and system reliability.
A Game-Changing Impact on Non-Destructive Pipeline Testing
At NDT Systems & Services, Willems made his second highly important impact on the industry and it was revolutionary. His earlier work on EMAT (electromagnetic acoustic transducer) technology at Pipetronix earned Willems a patent—and created a solution to one of the industry’s most difficult problems. Willems described this problem in a paper he co-authored in 2010, A New ILI Tool for Metal Loss Inspection of Gas Pipelines Using a Combination of Ultrasound, Eddy Current and MFL. “As conventional ultrasonic tools, which are based on piezoelectric transducers, require a liquid coupling medium to couple the ultrasonic energy into the pipe wall, this technology is readily applicable to the majority of liquid pipelines, but not to gas pipelines (unless a batch of liquid is used).”
The abstract states, in part: “In order to apply ultrasonic ILI technology for metal loss inspection to gas pipelines directly, a new tool was developed based on the EMAT (electro-magnetic acoustic transducer) principle by which ultrasound is generated in the surface of the pipe wall through electromagnetic interaction.” Willems and his colleagues observed that the “…simultaneous use of three independent physical methods (ultrasonics, MFL and EC) as realized in the new tool, offers several advantages compared to standard ‘single method’ tools. The redundancy of the data yields an enhanced probability of detection (POD) and in particular a higher probability of identification (POI). For example, lamination's may produce an ultrasonic signal that looks similar to an external metal loss, whereas MFL and EC will not show a signal response in this case. Then the combined information enables a reliable discrimination for this type of anomaly.”
Pushing the Boundaries
While managing the growth of NDT Systems & Services as it evolved to become NDT Global in 2000, Willems did not let up. He made his third significant impact on the industry in November, 2016. A paper by Herbert Willems and Gerhard Kopp (also of NDT Global), Introduction to Ultrasonic In-Line Inspection of CRA Pipelines demonstrated that successful CRA inspections are now possible. The abstract states in part:
“Pipelines manufactured from corrosion-resistant alloys (CRA) are becoming more common in special applications, in particular with offshore pipelines which are in many cases exposed to a harsh and highly corrosive environment. For many years the inspection of CRA pipelines (solid CRA, clad and lined pipe) was not a high priority. Due to the special composition of these types of lined pipe it also posed specific challenges to inline inspection methods as compared to the inspection of common line pipe.
“In this article, the different types of CRA lined pipe and the relevant characteristics regarding inline inspection (metal loss inspection, crack inspection) are described. Typical damage mechanisms (e.g. pitting corrosion) that may develop during operation is illustrated and the specific capabilities that are available for ultrasonic inline inspection as well as the limitations are explained. Several examples from inspection runs in CRA pipelines are presented demonstrating that reliable inline inspections with good data quality are feasible to a wide extent.”
Removing the Uncertainty
Sizing Crack Indications from Ultrasonic ILI: Challenges and Options, is the title of a paper Willems authored and presented at the 12th annual Pipeline Technology Conference (PTC) in 2017. The paper examined some aspects of ultrasonic inline inspection, regarding the task of crack inspection in particular. One common issue often experienced across the pipeline inspection industry is the uncertainty that comes with crack sizing.
Willems’ interest and expertise in digital tools that extend the power of hardware proprietary ultrasonic modeling software can be found in Willems' fourth contribution to NDT Global and the industry. The paper notes: “Apart from hardware-driven developments, ultrasonic modeling is becoming more and more important as a supporting tool for a better understanding of ultrasonic signal behavior as well as optimizing e.g. the inspection settings.
“Based on the FD approach, the software allows for the precise modeling of many testing situations. In particular, the testing parameters (geometry, defect type, defect size, ultrasonic sensor characteristics, medium etc.) can be easily modified enabling parameter studies in a much faster way as compared to experimental studies. For special situations, it is (still) recommended to verify the modeling results by selected experiments. However, the appropriate usage of ultrasonic modeling can reduce costs and time.”
The New Frontier
“A number of factors will continue to have a large impact on non-destructive testing in the future,” Willems observed. “First is very high-resolution, 5 mm diameter minimum. The second is acquiring this high-resolution data at higher speeds. Costs have greatly improved, compared to 20 years ago. There have been many refinements to this technology, in terms of resolution, speed, reliability, and data storage. All of these refinements address the inspection industry’s key metric: first-run success rate. NDT Global’s goal today is 97%.”
A Prolific Author
Willems has written many highly regarded technical papers, which record his major technical accomplishments. He has been a familiar and respected presence at industries technical conferences worldwide. In particular, as his work on ultrasonic crack detection in pipelines matured, Willems documented its progress in numerous, well written papers.
These papers are widely recognized and cited. His paper, Ultrasonic Crack Detection in Pipelines - Practical Experiences, is typical; it was awarded "Best Paper" at the Internal Corrosion and Mitigation in Pipelines Symposium, held during the 2016 CORCON conference and exhibition. Willems has also authored numerous trade journal articles, in the classic Willems style: coherent, understated, and highly informative.
His Contributions Live On
These highlights are far from all that Herbert Willems accomplished during his remarkable career. Just as noteworthy, he has been a trusted colleague, mentor, and friend to countless people. “Now I’ll have much more time with family and friends, but there are still problems to solve and challenges to meet. I’ll enjoy thinking about them as well, as I remain connected to my family at NDT Global.”
Willems offers some examples of challenges the industry now faces. “Many older pipelines cannot be inspected using standard tools. You’ll see the growth of special-purpose inspection technologies for this purpose." Demand for offshore inspection is growing. This environment is much more challenging. Higher pressures are one problem, and the wide temperature range also causes certain problems. Wax and methane hydrates form in low temperatures. Special tools must be developed for the waxy environment. New solutions are also needed for special offshore pipelines such as cladded pipes. “There is also a trend to standardize inspection and tool specifications, so it will be easier for operators to compare. It took a long time for the pipeline industry to get to this point.” As Willems continues to think about new solutions to problems like these, no one should be surprised if another major industry advance comes from it. After all, in his brilliant and extraordinary career, Herbert Willems has done it four times.