WHAT IS Non-destructive examination？
Non destructive examination (NDE), also known as non-destructive testing (NDT), refers to the process of inspecting, testing, or evaluating materials, components, or structures without causing any damage or permanent alteration to them. NDE techniques are used to assess the integrity, quality, and performance of objects, identify defects, discontinuities, or anomalies, and ensure their safety and reliability. Here are some commonly employed non-destructive examination techniques
- Visual Inspection (VT)
- Ultrasonic Testing (UT)
- Radiographic Testing (RT)
- Magnetic Particle Testing (MT)
- Liquid Penetrant Testing (PT)
- Eddy Current Testing (ECT)
- Thermography
- Acoustic Emission Testing (AE)
Visual Inspection (VT)
Visual Inspection (VT) is a non-destructive examination technique that involves direct visual examination of an object’s surface to identify surface defects, irregularities, or visual indications of potential issues. It is one of the most basic and widely used methods of inspection in various industries.
During visual inspection, a qualified inspector visually examines the object using their eyes, along with appropriate lighting and magnification tools if needed. The goal is to detect any visible defects, such as cracks, corrosion, wear, pitting, surface roughness, discoloration, or any other anomalies that may affect the integrity or functionality of the object.
Visual inspection can be performed at different stages of an object’s life cycle, including during manufacturing, assembly, maintenance, or periodic inspections. It is often used as a preliminary inspection technique to identify obvious defects or abnormalities before employing more advanced non-destructive examination methods.
Advantages of Visual Inspection (VT) include
Ultrasonic Testing (UT)
Ultrasonic Testing (UT) is a non-destructive examination technique that utilizes high-frequency sound waves to inspect and evaluate the internal structure and condition of materials and components. It is widely used in various industries to detect defects, measure thickness, and assess material properties.
The UT process involves the following key steps:
Generating and transmitting sound waves: A transducer is used to generate ultrasonic waves, typically in the frequency range of 0.5 to 25 MHz. These waves are transmitted into the material being inspected.
Wave propagation and interaction: The ultrasonic waves travel through the material and interact with its internal structure. When encountering interfaces, such as boundaries between different materials or internal defects, the waves can be reflected, refracted, diffracted, or scattered.
Receiving and analyzing the reflected waves: The same transducer used to generate the waves also serves as a receiver for the reflected waves. The received signals are then processed and analyzed to determine the properties and conditions of the material being inspected.
Defect detection and characterization: By analyzing the time-of-flight and amplitude of the reflected waves, UT can detect and characterize various types of defects, such as cracks, voids, inclusions, delaminations, and thickness variations.
Ultrasonic Testing offers several advantages:
Magnetic Particle Testing (MT)
Magnetic Particle Testing (MT), also known as magnetic particle inspection (MPI), is a non-destructive examination technique used to detect surface and near-surface defects in ferromagnetic materials. It is particularly effective for identifying defects such as cracks, laps, seams, and other discontinuities that can affect the integrity and performance of the material.
The process of Magnetic Particle Testing involves the following steps:
Magnetization: The object being inspected, typically made of ferromagnetic material such as iron, nickel, or steel, is magnetized using a magnetic field. This can be achieved by using a permanent magnet, an electromagnetic yoke, or a coil.
Application of magnetic particles: Magnetic particles, either in a dry or wet form, are applied to the surface of the magnetized object. These particles are usually iron-based and have magnetic properties.
Particle accumulation: The applied magnetic particles adhere to the surface of the object, forming visible indications at locations where magnetic field distortion occurs due to the presence of defects or discontinuities.
Inspection and interpretation: Trained inspectors examine the surface of the object under proper lighting conditions. The accumulated magnetic particles create visible indications, such as lines or clusters, revealing the presence and characteristics of defects. The inspector evaluates the size, shape, and distribution of the indications to determine the nature and severity of the defects.
Magnetic Particle Testing offers several advantages
Liquid Penetrant Testing (PT)
Liquid Penetrant Testing (PT), also known as dye penetrant inspection or liquid penetrant inspection (LPI), is a non-destructive examination technique used to detect surface-breaking defects in non-porous materials. It is an effective method for identifying cracks, fractures, laps, porosity, and other surface discontinuities that may compromise the integrity of the material.
The process of Liquid Penetrant Testing involves the following steps:
Pre-cleaning: The surface of the object being inspected is thoroughly cleaned to remove any dirt, grease, oil, or other contaminants that could interfere with the test results.
Application of penetrant: A liquid penetrant, which is a low-viscosity colored or fluorescent dye, is applied to the surface of the object. The penetrant is allowed to dwell on the surface for a specific period, typically known as the dwell time, to allow it to seep into any surface defects through capillary action.
Penetrant removal: Excess penetrant on the surface is carefully removed, leaving only the penetrant that has entered the surface defects.
Application of developer: A white or contrasting developer, in the form of a powder or suspension, is applied to the surface. The developer helps to draw out the penetrant trapped in the defects, making them visible.
Inspection and interpretation: Trained inspectors examine the surface under appropriate lighting conditions. The presence of indications, such as colored bleed-out or fluorescent indications, indicates the presence of surface defects. The inspector evaluates the size, shape, and intensity of the indications to determine the nature and severity of the defects.
Liquid Penetrant Testing offers several advantages:
Eddy Current Testing (ECT)
Eddy Current Testing (ECT) is a non-destructive examination technique used to detect surface and near-surface defects in conductive materials. It relies on the principle of electromagnetic induction to identify variations in electrical conductivity, magnetic permeability, or both.
The process of Eddy Current Testing involves the following steps:
Generating eddy currents: An alternating current is passed through a coil or probe, which creates a magnetic field around it. This magnetic field induces eddy currents in the material being inspected.
Eddy current interaction: The eddy currents circulating within the material create their own magnetic fields. When the eddy currents encounter variations in the material, such as surface cracks, corrosion, or material thickness changes, changes in the electrical conductivity or magnetic permeability occur, resulting in alterations to the eddy current flow.
Probe response and signal analysis: The coil or probe used for generating the eddy currents also serves as a receiver. It detects the changes in the eddy current flow and produces signals that are analyzed. The signals can be displayed on a screen or processed using specialized equipment.
Defect detection and characterization: Trained inspectors interpret the signals to identify indications of defects. The characteristics of the signals, including their amplitude, phase, frequency, and distribution, provide information about the nature, size, and location of the detected defects.
Eddy Current Testing offers several advantages:
Thermography
Thermography, also known as infrared thermography or thermal imaging, is a non-contact inspection technique that uses infrared radiation to create images of the temperature distribution on the surface of objects. It is commonly employed to detect anomalies, assess thermal patterns, and identify potential issues in a wide range of applications.
The process of Thermography involves the following steps:
Infrared camera setup: An infrared camera, also called a thermal imaging camera, is used to capture the infrared radiation emitted by the object’s surface. The camera is equipped with sensors that detect the temperature variations and convert them into a visual representation.
Image acquisition: The infrared camera is directed towards the object, and it captures the infrared radiation emitted from the surface. The camera may scan across the surface or focus on specific areas of interest. It records the temperature data for each pixel, creating an image known as a thermogram.
Image analysis and interpretation: The captured thermogram is analyzed by a trained operator or interpreter. They evaluate the temperature patterns and variations to identify anomalies or areas of interest. Hot spots, cold spots, thermal gradients, and temperature differentials are assessed to understand the condition of the object or system being inspected.
Reporting and action: Based on the analysis, the interpreter generates a report highlighting the findings, including any abnormalities or potential issues. This information is used to guide further investigation or corrective actions.
Thermography offers several advantages
Acoustic Emission Testing (AE)
Acoustic Emission Testing (AE) is a non-destructive examination technique that utilizes the detection and analysis of acoustic signals emitted by a material or structure under stress or undergoing deformation. It is used to monitor the behavior of materials, detect active defects, and assess the structural integrity of various components.
The process of Acoustic Emission Testing involves the following steps:
Sensor placement: Acoustic emission sensors, also known as transducers or receivers, are strategically placed on the surface of the object or structure being tested. These sensors are sensitive to the ultrasonic waves generated by the material during deformation or stress.
Stress application: The object or structure is subjected to stress, which can be in the form of mechanical loading, pressure changes, temperature fluctuations, or any other source of energy that induces deformation.
Acoustic emission detection: As the material undergoes deformation or damage, acoustic waves are generated and propagate through the object. The sensors detect these waves and convert them into electrical signals.
Signal analysis: The acquired signals are processed and analyzed using specialized equipment and software. Various parameters, such as amplitude, frequency, duration, and location of the acoustic events, are evaluated to determine the nature and severity of the detected emissions.
Interpretation and assessment: Trained analysts interpret the results to identify active defects, such as cracks, delaminations, and material degradation. The location of the emissions can provide insights into the specific regions of the structure that require further investigation or maintenance.
Acoustic Emission Testing offers several advantages
Advantages of NDE
Non-Destructive Evaluation (NDE) offers several advantages compared to traditional destructive testing methods. Here are some key advantages of NDE:
What is the difference between NDT and NDE?
NDT stands for Non-Destructive Testing, while NDE stands for Non-Destructive Evaluation. Although the terms are often used interchangeably, there can be a subtle difference in their meaning depending on the context.
Non-Destructive Testing (NDT) refers to the process of inspecting or examining materials, components, or structures without causing damage to them. NDT techniques are applied to assess the integrity, quality, or performance of an object or system. The primary objective of NDT is to detect and identify defects, discontinuities, or anomalies that may affect the functionality or safety of the inspected item. NDT methods include techniques such as ultrasonic testing, radiographic testing, magnetic particle testing, liquid penetrant testing, eddy current testing, thermography, and acoustic emission testing, among others.
Non-Destructive Evaluation (NDE), on the other hand, encompasses a broader scope. NDE refers to the process of assessing the condition, integrity, and performance of materials, components, or structures using non-destructive techniques. While NDE includes the detection and identification of defects or anomalies (as in NDT), it also involves a more comprehensive evaluation of the material’s properties, structural behavior, and overall fitness for a specific purpose. NDE techniques may involve advanced methods of data analysis and interpretation to provide quantitative information about the material or structure being evaluated. NDE can include techniques such as stress testing, modal analysis, vibration analysis, fatigue testing, and structural health monitoring.
In summary, NDT is primarily focused on the detection and identification of defects or anomalies, while NDE encompasses a wider range of techniques and aims to evaluate the condition, performance, and fitness for purpose of materials or structures. The distinction between NDT and NDE can vary depending on the context and industry, and the terms are often used interchangeably in practice.
WHERE IS NDE USED (NDE Application)?
Non-Destructive Evaluation (NDE) techniques are used in various industries and applications where the assessment of material integrity, structural performance, and quality assurance is essential. Here are some common areas where NDE is applied:
Aerospace
NDE is extensively used in the aerospace industry for inspecting aircraft components and structures, such as wings, fuselages, engine parts, and landing gear. It helps detect defects, fatigue cracks, corrosion, and other damage that could compromise the safety and reliability of aircraft.
Automotive
NDE plays a crucial role in automotive manufacturing and maintenance. It is used for quality control and inspection of components like engine parts, welds, suspension systems, and body structures. NDE techniques help ensure the structural integrity and performance of vehicles.
Oil and Gas
NDE techniques are used in the oil and gas industry for inspecting pipelines, storage tanks, pressure vessels, and offshore structures. It aids in identifying defects, cracks, corrosion, and leaks that could cause environmental damage or jeopardize operational safety.
Nuclear Power
NDE plays a critical role in the nuclear power industry for inspecting reactor components, fuel rods, steam generators, and other nuclear plant equipment. It helps detect flaws, cracks, and degradation that could impact the safety and reliability of nuclear facilities.
Manufacturing
NDE is widely used in various manufacturing processes to ensure the quality and integrity of products. It is employed for inspecting welds, castings, forged components, and other fabricated parts to identify defects, discontinuities, and material inconsistencies.
Medical
NDE techniques are utilized in medical imaging and diagnostics, such as X-rays, ultrasound, and magnetic resonance imaging (MRI). These techniques help visualize internal structures, identify abnormalities, and assist in medical diagnoses.
Construction and Infrastructure
NDE is applied in the construction industry for assessing the quality and integrity of buildings, bridges, dams, tunnels, and other infrastructure projects. It helps detect structural defects, concrete delamination, reinforcement corrosion, and other potential weaknesses.
Marine and Offshore
NDE techniques are applied in the marine and offshore industry to inspect ship hulls, offshore structures, pipelines, and underwater components. It helps identify corrosion, fatigue cracks, structural weaknesses, and ensures the safety and performance of maritime assets.
NDE CODES AND STANDARDS
There are several codes, standards, and guidelines that govern the practice of Non-Destructive Evaluation (NDE) to ensure consistency, reliability, and safety in various industries. Here are some widely recognized NDE codes and standards:
ASNT
ASNT(American Society for Nondestructive Testing) is a professional society that focuses on the advancement of NDT. While ASNT does not develop codes and standards directly, it provides resources and publications that support NDT professionals in following established standards and best practices.
ASTM
ASTM(American Society for Testing and Materials) International develops and publishes standards for a wide range of industries, including NDT. ASTM standards cover various NDT methods, such as magnetic particle testing (ASTM E1444), liquid penetrant testing (ASTM E1417), and ultrasonic testing (ASTM E317).
ASME
ASME (American Society for Mechanical Engineers)develops codes and standards for various engineering disciplines. It includes standards related to NDT, such as the Boiler and Pressure Vessel Code (Section V – Nondestructive Examination), which provides guidelines for NDT methods like radiographic testing, ultrasonic testing, and liquid penetrant testing.
API
The API(American Petroleum Institute) develops standards and recommended practices for the oil and gas industry. It includes standards related to NDT, such as API 570 (piping inspection), API 510 (pressure vessel inspection), and API 653 (storage tank inspection).
What Is the Difference Between Destructive Testing and Non-Destructive Testing?
Destructive Testing (DT) and Non-Destructive Testing (NDT) are two distinct testing methods used to evaluate the properties, integrity, and performance of materials, components, and structures. Here’s the difference between the two:
Destructive Testing (DT)
Non-Destructive Testing (NDT)
Table summarizing the key differences between DT and NDT
| Destructive Testing (DT) | Non-Destructive Testing (NDT) | |
|---|---|---|
| Purpose | Understand behavior, strength, and limitations | Assess quality, integrity, and performance |
| Sample Integrity | Sample is destroyed or permanently altered | Sample is preserved and can be returned to service |
| Information Obtained | Detailed information on mechanical properties, failure modes, performance limits | Defect detection, flaw evaluation, material properties assessment |
| Examples | Tensile testing, bend testing, impact testing, fracture toughness testing, fatigue testing, hardness testing | Ultrasonic testing, radiographic testing, magnetic particle testing, liquid penetrant testing, eddy current testing, visual inspection, thermography |
| Usability | Renders sample unusable after testing | Sample can remain in service or be returned to service after inspection |
Key Differences
Both DT and NDT have their respective advantages and applications. DT is often used for material characterization, performance evaluation, and quality control during the development and manufacturing stages. NDT, on the other hand, is employed for in-service inspection, maintenance, and ongoing monitoring to ensure the integrity and safety of materials, components, and structures without causing any harm.
Why Global Clients Choose Us?
By choosing us, global clients gain access to an unparalleled combination of global reach, top-notch quality, competitive pricing, customization options, exceptional customer service, and on-time delivery. We strive to exceed expectations and establish long-term partnerships built on trust and satisfaction.
Customers Good Feedback
GOOD WORDS FROM GOOD PEOPLE
Mary R
Mary R
Mary R
Leave you Enquiry
Request an Appointment
Still not sure which NDT is right? Get a free initial consultation right now. Our team will analyze your needs and recommend the most suitable sensor for you