In industries, safety and accuracy are the key. And non destructive testing (NDT) plays an essential role in ensuring that the materials and structures remain strong, long-lasting, and fault-free.
What is non destructive testing? From the buildings we live in to the vehicles we travel, non destructive testing helps to detect hidden flaws that could compromise performance or safety. Whether it’s detecting hidden cracks or evaluating the strength of materials, NDT provides valuable insight into unseen features.
Let’s dive deeper to explore what is non-destructive testing, the methods involved, and the tools used to carry out these assessments.
What Is Non Destructive Testing?
Do you need to identify the characteristic differences, welding flaws, and imperfections without causing any damage to the original part? Then non destructive testing (NDT) is the perfect solution.
This is also called non destructive inspection (NDI), non destructive analysis (NDA), or non destructive evaluation/examination (NDE).
Non destructive testing refers to the method to check the internal structures of materials without causing any damage or affecting their performance or functionality. It identifies defects and irregularities by detecting changes in thermal (heat), acoustic (sound), optical (light), electricity, magnetic, and other properties.
Using advanced technologies and equipment, NDT checks a material’s internal and surface structure, condition, and characteristics, including defect type, quantity, shape, nature, position, size, distribution, and any changes within the test specimen. Beyond being a testing method, NDT is a monitoring tool to identify process defects, contributing to cost reduction and improved efficiency.
This is widely used in various industries such as construction, automotive, manufacturing, aerospace, and more. Simply, when a non-destructive inspection is performed, three main types of defects are typically assessed: internal issues, exterior issues, and specification deviations. The procedures are based on industry standards with specific codes and specifications for different sectors. Moreover, they are an essential part of the company’s risk control strategy.
What is Destructive and Non Destructive Testing?
Destructive testing (DT) and Non destructive testing (NDT) have a lot of similarities but primarily differ in how they affect the material or component being tested.
Destructive Testing: The material or component is damaged or destroyed during the testing process to assess its durability, strength, and performance. It is carried out before the product is put into service and is limited to testing only a few samples.
Non Destructive Testing: The material or component being tested remains undamaged and can be used after testing. It allows the examination of an entire batch, identifying discontinuities and defects in a component.
Characteristics of Non Destructive Testing
Nondestructive testing (NDT) of concrete structures evaluates the strength and defects of concrete structural components in their original position directly and quantitatively without causing any damage. Compared to destructive testing, nondestructive methods are distinguished by the following characteristics:
Nature of testing: Non destructive testing ensures the object being inspected remains fully functional.
Comprehensives: This testing enables a fully comprehensive inspection of the object when needed, something destructive testing cannot provide.
Full process applicability: Destructive testing is usually limited to raw material inspection, whereas nondestructive testing can be applied at every stage of the process—from raw materials to intermediate stages and finished products. It can also be used to inspect equipment in operation without impacting its performance.
Types of Non Destructive Testing Methods
There are many non destructive testing methods, but only a few are commonly used today.
Visual Testing
The most popular non destructive testing across all industries is visual testing as it is the most basic form. It is a quick method of tracking quality products just by looking at the material and finding defects that are visible. This is done at every step of the production or maintenance process to detect any cracks, damage, corrosion, or more with simple instruments.
Visual testing,
- Requires minimal equipment
- Helps in identifying issues rapidly
- Can be applied to a wide range of materials
An example of visual testing is in the construction industry, where it is used to inspect concrete structures like bridges or buildings. Inspectors visually examine the surface for signs of cracks, spalling, or signs of corrosion, ensuring the stability of the structure using simple tools like flashlights or magnifying glasses.
This testing is limited to detecting only surface defects and has the possibility of misjudging flaws.
Liquid Penetrant Testing
This is one of the common non destructive testing methods that identifies surface-level defects. This method particularly identifies surface cracks and other imperfections that are not easily seen by the naked eye.
The specially formulated penetrant is applied to the surface of the material and the liquid seeps into any surface-breaking defects, such as cracks or gaps. After a time, a developer is applied to draw out the penetrant, making the flaws visible.
Liquid Penetrant Testing,
- Identifies surface defects easily.
- Used on a wide range of materials.
- Efficiently tests large areas and surfaces.
An example of using liquid penetrant testing is in the aerospace industry. Liquid penetrant testing is used to inspect aircraft engine parts like turbine blades and exhaust nozzles. It helps detect surface cracks caused by high stress and temperatures by revealing flaws through visible indications.
This method of testing is time-consuming and the depth of defects is less known.
Radiographic Testing
To detect internal defects, radiographic testing is one of the efficient methods. It uses radiation to detect defects with X-rays and gamma rays.
Radiography testing offers a different view of materials and helps find hidden details from the naked eye. Technicians place the object between the radiation source and a recording media. And then short-wavelength electromagnetic waves are used to produce images that highlight variations in material density and thickness.
This testing method,
- Test complex structures
- Helps identify the shape and size of internal defects
- Detect defects like cracks, thinning, corrosion, porosity, and more.
Radiographic testing is used in the oil and gas industry to inspect pipelines. It helps detect internal defects like cracks, corrosion, or weld imperfections in the pipeline, ensuring its strength and safety before it is put into service.
This method requires skilled personnel for accurate result analysis and is less effective for detecting planar and surface defects.
Ultrasonic Testing
This testing process is done using high-frequency sound waves. This method works by sending sound waves into a material and analyzing the returned echoes to learn about the internal structure of the part. This is used on almost all materials, especially steel, and other metallic things.
The sound is generated using specialized ultrasonic testing equipment, such as an ultrasonic probe or gauge, with a frequency range of 0.1 to 15 MHz. The ultrasonic waves travel through a material and change behavior depending on the defects or surfaces they find.
Ultrasonic Testing,
- Highly accurate and sensitive
- Detects surface and subsurface defects
- Applied through a variety of techniques
Ultrasonic testing (UT) can be used to inspect aircraft fuselages and wing structures. The ultrasonic transducers are placed on the surface of the aircraft structure and emit high-frequency sound waves that travel through the material. When these waves find any internal defects, they bounce back to the transducer, and the reflected signals are analyzed to identify the size and location of the flaw.
This method requires a skilled NDT specialist to apply the technique.
Magnetic Testing
Magnetic Particle Inspection (MPI), also known as Magnetic Particle Testing (MT), Magnetic Testing, or Particle Inspection, is an old method of non-destructive testing. It is used to detect surface discontinuities in ferromagnetic (magnet-sensitive) materials. Additionally, this technique can identify defects just below the surface, such as cracks, pores, tapers, cold laps, and fissures.
The process involves magnetizing the area to be inspected to create a magnetic field leakage at irregularities. This leakage attracts ferromagnetic particles to the defect, making it visible. To enhance visibility, the surface is often coated with fluorescent ferromagnetic particles, known as a revealer.
This testing,
- Detect surface defects and subsurface defects to an extent
- Works through thin surface coatings
- Provides immediate results
An example of Magnetic Testing is the inspection of welds on a steel pipeline for defects such as cracks or inclusions. The weld is cleaned, and magnetized, and then the ferromagnetic particles are applied. These particles gather at defects, making them visible for evaluation.
The issue is that this method does not work with non-magnetic materials and only tests small areas at a time.
Eddy Current
Eddy Current testing is an electromagnetic testing method that can be performed on conductive materials. It is created through a process called electromagnetic induction. It can assess coating and material thickness, as well as determine materials and their heat treatment conditions.
When a conductor, such as copper wire, carries alternating current, it generates a magnetic field that expands as the current increases and diminishes as the current decreases. Bringing another conductor close to this changing magnetic field generates an electric current in the second conductor. These generated currents, known as eddy currents, move in circular loops. The term “eddy currents” is inspired by the circular motion of fluids or gases that rotate around obstacles under certain conditions.
Eddy Current,
- Can operate as a non-contact process
- Suitable for parts with complex geometries.
- Provides immediate results
Eddy current testing is used in the automotive industry to inspect the thickness of metal coatings on car parts. A probe is placed near the coated surface, and the alternating current generates a magnetic field. Eddy currents are induced in the metal, and any variations in the coating thickness affect the flow of these currents, allowing them to detect inconsistencies or defects in the coating without contact.
This works only with electrically conductive materials and requires high-skill personnel for accurate interpretation.
Non Destructive Testing Tools
Non-Destructive Testing (NDT) tools help identify defects, assess material integrity, and ensure safety and quality in various industries. Each tool serves a specific purpose, ensuring material reliability and safety across various industries. Below are a few commonly used non-destructive testing tools.
- Rebound Hammers Tester: A versatile tool that assesses the strength of hardened concrete slabs or rocks. Also, it enhances drilling and blasting by analyzing rock strength, boosting safety and efficiency in mining. Langry’s rebound hammers contain a Bluetooth chip to connect to a portable Bluetooth printer.
- Pull Out Anchor Tester: Measures the pull-out force of anchor rods, steel bars, and expansion bolts. Additionally, these tools assess the compressive strength of concrete and verify anchor installation integrity. Langry’s tools are manufactured with high-strength steel, resisting high pressure.
- Digital Angle Finder: Essential for accurate angle calculations and delivers accurate measurements for both inside and outside angles. Langry’s angle measuring tools are designed with materials to withstand harsh working conditions
- Rebar Detector: Locates and assesses reinforcement bars in concrete structures while determining the position, depth, and space. This tool supports various detection modes and meets the demands of different working conditions.
- Crack Detector: Identifies and evaluates cracks in materials such as metal, concrete, or composites. Crack detectors are essential in industries like construction, manufacturing, and aviation to ensure structural integrity and prevent failure.
- Adhesion Testers: Use to measure the bond strength of adhesion between various construction materials. Langry’s tools are made of high-strength aluminum alloy and are perfect for on-site testing applications.
- Rebar Detector Testing Device: Locate and assess the position, depth, and orientation of reinforcement bars (rebars) within concrete structures. It ensures structural integrity and avoids damage to rebars during drilling or cutting.
- Concrete Floor Thickness Testers: accurately measure the actual thickness of the floor to ensure that the quality meets the design requirements and detect if there is any insufficient thickness or structural weakness due to aging.
These advanced NDT tools are available now at Langry! Enhance your testing capabilities with our reliable and accurate equipment. You can explore our full range of Non-Destructive Testing tools!
Can NDT Ensure Quality and Reliability?
Non destructive testing is a vital and effective tool. However, this raises an important question: Does every project that undergoes nondestructive testing ensure its quality and guarantee no issues throughout its lifespan?
The answer is clear: Not all projects subjected to non destructive testing guarantee that they will be defect-free or free of future problems.
Different methods have their limitations and our evaluation criteria often prioritize to meet minimum requirements for use. More importantly, nondestructive testing relies significantly on the experience and expertise of the inspectors.
The true value of nondestructive testing goes beyond a one-time inspection; it is an integral part of a continuous, cyclical process of improvement. By identifying issues through testing, we trace them back to the production processes that caused them and then enhance those techniques. Additional non destructive testing is carried out, followed by further process improvements. This cycle repeats until the pass rate consistently reaches a high level, thereby enhancing project quality and reducing costs.
Nondestructive testing is essential in design, manufacturing, and operation. However, it should not be viewed solely as a testing method. It functions more as a monitoring tool during both the production and usage phases. Its greatest value lies in its ability to identify defects in the project, which is its core purpose.
Conclusion
If you are unaware of what is non destructive testing, it is a process to evaluate the properties and quality without causing damage.
It is a process used to assess the properties and quality of materials without causing any damage. There are various techniques available, each with its own advantages, and selecting the right one depends on the specific situation. Each method comes with its own set of benefits and limitations, which should be carefully considered. It’s important to evaluate the circumstances thoroughly to determine the most efficient approach, ultimately saving both time and money.
If you’re looking to find the best non-destructive testing solution for your needs, explore our range of NDT services at Langry today. Contact us to get expert advice and ensure the quality and integrity of your materials without any damage.
