What is Non-Destructive Testing
Non-Destructive Testing (NDT) refers to a group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage.
Other terms commonly used to describe NDT technology and services are Non-Destructive Examination (NDE), Non-Destructive Evaluation (also NDE) and Non-Destructive Inspection (NDI).
Benefits of Non-Destructive Testing
NDT provides an excellent balance between quality control and cost-effectiveness. Because it does not damage or permanently alter the article being inspected, it is a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research.
By applying NDT techniques, you can extend the lifetime of your productive assets, perform targeted maintenance and repairs only where needed, prevent costly shutdowns due to component failure, and ensure the continuing quality and safety of the assets you manufacture, operate and maintain.
Non-Destructive Testing Methods
- Electromagnetic (ET) testing is used to evaluate electrically conductive materials. This method often relies on a fluctuating magnetic field that generates an electric 'eddy' current. If the electrical resistance to the current's flow is disrupted or inconsistent, this can indicate a flaw in the material.
- Infrared / Thermal (IR) testing, or infrared thermography, is used to measure surface temperatures based on the infrared radiation given off by an object as heat flows through, to or from that object. Used properly, thermal imaging can be used to detect corrosion damage, delaminations, disbonds, voids, inclusions as well as many other detrimental conditions.
- Liquid Penetrant (PT) testing is used to identify flaws in nonporous materials. This method relies on a colored oil- or water-based liquid penetrant that is applied to a surface, then wiped clean. A blotter is then applied and sometimes UV light, highlighting any penetrant that was trapped in unwanted cracks, pores and flaws.
- Magnetic Particle (MT) inspection uses the flow of magnetic particles to detect flaws at or slightly below the surface of ferromagnetic materials such as iron. A magnetic field is generated and iron particles applied to the surface clump together to reveal the flaw.
- Radiographic (RT) testing involves exposing a test object to penetrating radiation so that the radiation passes through the object being inspected and a recording medium placed against the opposite side of that object. For thinner or less dense materials such as aluminum, electrically generated x-radiation (X-rays) are commonly used, and for thicker or denser materials, gamma radiation is generally used.
- Ultrasonic (UT) testing identifies flaws in a material by measuring how audio waves flow through it. These audio waves reflect off the edges of the material or wherever there's an abrupt change in the material's density. This allows the inspector to measure the thickness of a material or create a complex three-dimensional image of the test specimen.
- Vibration Analysis (VA) testing refers to the process of monitoring the vibration signatures specific to a piece of rotating machinery and analyzing that information to determine the condition of that equipment. Three types of sensors are commonly used: displacement sensors, velocity sensors and accelerometers.
- Visual Diagnostic (VT) testing involves the visual observation of the surface of a test object to evaluate the presence of surface discontinuities. VT inspections may be by direct viewing or may be enhanced with the use of remote viewing instruments such as mirrors, borescopes and computer-assisted viewing systems.
- Many other non-destructive testing methods exist and are used to address a wide range of specialized evaluation and inspection needs. As an NDT professional, it's important to maintain an active interest in the latest tools and methods available to meet industry's changing needs.