Non-Destructive Testing in Real-time as a Damage Identification Strategy

Non-destructive testing (NDT) is an act of monitoring the physical properties of a material, part, or component while causing no damage to the original structure. A specially designed testing and analysis technique is used for this purpose.

Non-Destructive Testing General Overview

Non-destructive evaluation is one of the most essential entities for structural health monitoring . SHM as such is the intelligent combination of traditional surveillance of structure’s in­tegrity with novel, data-based, and automatized innovative technologies. It covers areas as safety-critical as aerospace, civil and mechanical engineering infrastructures, marine, power generation and other industries.

The NDT market is huge: by size, methods to choose from, and applications that need an NDT. In 2021, the global NDT market was valued at 17.9 billion USD. With the expected CAGR of 7.7 % from 2022 to 2030.

Current and Future Market Drivers

The industrial segment’s semi-homogeneous development (i.e., electronics, robotics, automotion physical technologies) are becoming a base ground for the companies that offer NDT systems and services. Especially the growing adoption of robotics in sectors such as weight handling, medical (live x-ray, robotic surgery, etc), transportation sectors has opened novel opportunities for NDT systems to shine.

Obstacles and Challenges in the NDT Market

In recent years, the market demand for NDT is growing much more rapidly than the advancements in technology and personnel. The commercially available methods of NDT, usually have to be carried out by a highly qualified workforce. Add to that the usual NDT certification needs from government and the ability for the market to properly satisfy the demand grows in difficulty.

In fact, this process brings the market in a stagnation phase when even the potential market boosters (the demand for better technology), become less aware of the advantages of the new tech for their applications and structures. As the adoption of new NDT technologies often doesn’t come with many training facilities for the internal staff and the equipment costs are higher than what the final user is used to, brings some reluctance to invest in adoption of new, more productive technologies.

Opportunities in the Market of NDT

Other than the obvious added value a non-invasive and non destructive knowledge can give to the user of an application (part, process, component or material), the new applications of the world such as The advent of global digitization, AI, Machine learning are also pushing the potential capacity of NDT and inspection equipment keeping a good part of the market to innovate and improve their NDT methods, and another part of the market to come up with new solutions through R&D, help of academia and tech startups.

Some of the Key Market Players responsible for a big part of the market growth for many years have been the likes of: General Electric (US) , Eddyfi (Canada) , Nikon Metrology (Belgium) , Cygnus Instruments Ltd. (UK) , MISTRAS Group (US) , YXLON International (Germany) , Sonatest (UK) , Olympus Corporation (Japan).

The co-dependency between Structural Health Monitoring and Non-destructive testing lies in the fact that the process of implementing a damage identification strategy is what SHM does and Non-destructive testing is the tool for collecting and using the data on geometric properties of these structures (i.e changes to the internal conditionals of the material). The idea is to create a maintenance strategy based on properly augmented assumptions. A wide variety of highly effective local non-destructive evaluation tools are available for such monitoring, and they are used by.

The need for Non-destructive testing per End User Industry?

As mentioned above, NDT comes for rescue, especially for monitoring structures that have to stay in certain shape and form through their lifetime. Developing a maintenance strategy is precisely dependent on the inspection methods the owner or user of these structures/ap­plications will use. Be it a concrete structure, composite material, or a chemically aggressive environment – if you want to increase security and the capacity of your application – you need to deeply consider what inspection method is best for the application in place.

Non-destructive testing is considered the belle of the ball when it comes to maintenance and inspection strategies. As this testing method does not influence the physical properties of an application, naturally, there have been developed various competing NDT methods in terms of cost, speed, accuracy in the detection of anomalies (in terms of the size of an anomaly, location, the current normal state of the application, etc.), ability to detect anomalies in various environments.

NDT is getting a noticeable growth in popularity for the past decade, among both technicians/en­gineers as well as business developers and product leads for the simple reason that it saves millions of dollars in repair costs. The costs of avoiding NDT can be unbearable, especially for safety-critical applications. It is scary to imagine the failure consequences in a chemical plant(refinery, insecticides production), oil or gas pipelines, and other industries carrying high operational risk. Other than the potential damage to human health/life and the environment, the financial consequences in all these cases, are relevant to consider as well.

Especially with the fact that most of these failures are possible to prevent by implementing timely NDT methods, the consumer of NDT solutions, when evaluating the need to invest has the following risk and cost-management bullet points:

• Cost Reduction: When a product or process tends to fail or break, the costs of manufacturing or operation are naturally increased – with a proper NDT solution in place, it is possible to avoid unnecessary spending
• Product loss: A failure in one of the aspects of an operation can compromise the whole production line/batch of products or the whole structure
• Time loss: Planned downtime, or time dedicated for maintenance are the obvious time-related obstacles that can be prevented with the NDT solution, however, when a failure is substantial, it borrows time from future normal operations as well by damaging the schedule of multiple parties involved.
• Repair costs: These are often necessary, and logical, however with a proper NDT solution it is possible to stretch the time in between repair/replacement as well as make the repair less costly by early detection and predictive maintenance
• Fines and penalties: Certain failures are unacceptable as they may endanger human life, the environment, contractual obligations, or government rules – thus those failures are necessary as well as more economical to prevent, rather than face the consequences

Let’s take a closer look at some of the industries where the biggest NDT consumers are.

Aerospace & Defence

Aerospace & Defence: Aerospace and Defence parts constructed with flaws, or in continuous operations while faulty – can result in high losses of important cargo, assets, and surely human life! The smallest breach in a material, part or component can easily and quickly become a big problem as the items of this industry are under high operational pressure. There is some Destructive Testing involved in the industry as well, such as loading components until military and passenger aircraft production models fail, however during the operational life-cycle as well as prior to granting an aircraft an operational status – the more importantly used testing methods are non-destructive ones, as they determine the need for maintenance, or confirm the operational state of the asset.

Main NDT methods for the aerospace industry are

• Ultrasonic testing (Resonance, Phased Array, Immersion)
• Radiographic Testing (X-ray fluorescence)
• Magnetic particle testing
• Penetrant testing
• Leak detection

Oil and Gas

In the US energy market, the oil and gas industry is responsible for roughly 50% of NDT service consumption. These are the exploration or production companies of oil and gas onshore, onshore and offshore contractors of the oil and gas, the owners as well as drilling and production equipment manufacturing companies in the industry. The industry is in constant need of NDT solutions due to the volume of essential materials transported and stored through the pipelines. It is crucial to make sure no cracks voids or faulty welds are unattended, or even worse not detected. Prior to having the pipelines and tools in-field to operate – some destructive tests may be carried out to ensure the material characterization: this is a part of the material research to exhibit the best final option for use in harsh environments.

The main NDT methods for the Oil&Gas industry are:

• Ultrasonic techniques (possible to receive frequencies from within)
• Radiography (electromagnetic radiation (gamma rays) or X-ray)
• Thermography (differences of the pipeline and the surrounding temperature)
• Acoustic emissions (detecting rarefaction waves produced by leaks in pipelines. Whenever there is a fluid leak, negative pressure waves start propagating within the pipeline in both directions.

Civil engineering / Heavy Construction:

Non-destructive testing of materials in civil engineering is one of the main focus industries for DNT service providers. They are mainly active in Strength testing, Flow Detection, and Research within this industry. In heavy construction and civil engineering, modern diagnostics methods can be classified as destructive, semi-destructive, and non-destructive depending on the level of their invasiveness. Materials like fiber-cement, wood, concrete, and steel, are the essential parts of these constructions, thus also subject to NDT during their construction, but most importantly during their service life. These are constructions like bridges and tunnels made up of tons of material usually rather large, and carrying heavy loads of high importance, meant for long-term operation. All the load, environmental conditions, and material specifications (i.e. corrosion, weld cracks, etc.) – make NDT an essential part of the civil engineering and heavy construction industry. Experts in the industry claim that When the destructive testing results of i.e. concrete specimens do not meet the expectations of clients for in situ monitoring , the non-destructive ones come to the rescue for verifying the actual strength of the material.

The most commonly used methods are:

• Ultrasonic: determines dynamic elasticity modulus
• Radar: position detection of stressing ducks, bars,
• Magnetism: (i.e.profometer, pachometer), size/location of steel-reinforced materials

Non-Destructive Testing Methods: Conventional and not so much

Even though the market is self-evolving, coming up with new simpler, or sometimes, more advanced methods of NDT, there are certain methods that are already accepted by the end users, thus they have become commercially available to choose from. If we would make a simple list of the methods, it would be beneficial to divide them into traditional and advanced methods, and the list may look as follows:

Traditional NDT Method (Visual Testing, Magnetic Particle Testing, Liquid Penetrant Testing, Eddy Current Testing, Ultrasonic Testing, Radiographic Testing).

Advanced NDT Method (Digital Radiography (DR), Ultrasonic Testing ( Specifically Straight and Angle beam testing, Phased array testing, Time-of-flight diffraction testing, Guided wave testing), Pulsed Eddy Current (PEC), Time-Of-Flight Diffraction (TOFD), Alternating Current Field Measurement (ACFM), Automated Ultrasonic Testing (AUT), X-ray inspection, computed tomography (CT) ).

The most commonly used NDT tests performed today are surface tests like dye penetrants or magnetic particle technologies. In power generation, oil and gas, manufacturing, and other industries, Eddy Current testing is a famous one as it is a rather accurate way to inspect tubing, bolt holes, bars, etc.(it is capable of detecting both surface and subsurface defects). In the medical field, the X-ray and other tomography techniques have been used as non-invasive inspection methods, however, their unique properties let them find use in industrial sectors as well (i.e. CT scanning can color-code certain objects according to present cavities or their composite materials), and as X-rays are passed through a material, they can provide real-time imaging of the internal structure of various components and materials)

However, the above most widely in use methods also have some downsides to them according to scientific records and claims of professionals such as;

• Coin tapping – is simple, yet time-consuming, often not accurate.
• Vibration analysis – Live detection is a big pro, but it is hard to detect damage severity
• Thermography – Non-contact, fast detection, needs a vibration-free environment
• Optical – Limited by the information from the surface and/or dusty environment.
• Ultrasound – Time-consuming, suffers attenuation, scattering, and absorption.
• Radiography methods – High resolution, expensive, time-consuming.
• Eddy Current testing – Limited penetration depth, the surface must be accessible
• X-ray inspection industrial CT – Inspects visually hidden areas, however is expensive and needs trained operators

Here’s How we do it:

Today, thanks to the developed understanding of magnetic principles there is a possibility of contactless, non-destructive sensing of several physical parameters(pres­sure, temperature, vibration, magnetic field, etc.) simultaneously. Moreover, using modern physical phenomena and processes, RVmagnetics made it possible to develop miniaturized sensors and read measured quantities from a greater distance.

The whole principle lies in the MicroWire – a miniaturized sensor of physical quantities (temp, pressure, magnetic field, etc.) is essentially a metallic alloy with a glass coating. It is thin and elastic like human hair. The dimensions and glass coating make it possible to integrate the microwire into/onto almost any material and gather local data. The measurements are not deformed or affected by harsh chemical or magnetic environments.

It is also important to mention that just from 1 gram of metallic alloy it is possible to produce 100.000 MicroWire sensors within around 10 minutes, which added to the facts mentioned above, makes the MicroWire a cost-effective, versatile, and precise tool for physical data mining. Add to this the fact that the MicroWire sensing system can gather data 10000×/second and you ensure Predictive Maintenance through real-time measurement.

Now you know one more NDT inspection method to consider for the Maintenance Strategy of your application: contact us for more information about the technology.