Nondestructive Testing (NDT) Services Information
Non-destructive testing services (NDT) use test methods to examine an object, material or system without impairing its future usefulness. They specialize in NDT methods such as visual inspection, ultrasonics, or eddy current methods. Non-destructive testing (NDT) services may also use the following processes or technologies: acoustic emission, beta gauge, electromagnetic, magnetic (induction or Barkhausen), magnetic particle system, optical (shearography, holography, or magneto optical, penetrant testing, and radiographic or X-ray). Depending on the method and measurement requirements, non-destructive testing companies can perform activities off-line in laboratory environments, as well as in continuous production line or field monitoring applications.
Types of Non-Destructive Testing Services
Common types of NDT services include acoustic emission NDT testing or beta gauge testing, or use eddy current or other electromagnetic techniques. Acoustic emission measures the specific acoustic or vibration response of flaws or features within a mechanical system. If a break, deformation or other failure occurs in a piece of equipment, sensitive acoustic emission sensors can detect the high frequency burst given off during the event. This technique is particularly useful in determining the structural adequacy of tanks and pressure vessels. With beta gauge NDT, the absorption of Beta particles is used to measure the thickness of materials or coatings.
Magnetic and Optical NDT Testing
A non-destructive testing service can use a variety of magnetic and optical techniques. Magnetic NDT testing uses Hall effect and induction methods. In a magnetic particle non-destructive testing system, current flow or an external magnet magnetizes the part. Magnetic poles created at flaws, cracks or other discontinuities attract magnetic particles. Non-destructive testing services can also use eddy current, penetrating radar and other electromagnetic techniques to detect or measure flaws, bond or weld integrity, thickness, electrical conductivity, detect the presence of rebar or metals. The eddy current method is the most widely applied electromagnetic NDT technique. It is also useful in sorting alloys and verifying heat treatment. Eddy current non-destructive testing uses an electromagnet to induce an eddy current in a conductive sample. The response of the material to the induced current is sensed. Since the probe does not have to contact the work surface, eddy current testing is useful on rough surfaces or surfaces with wet films or coatings.
Optically-based non-destructive testing (NDT) services use methods such as laser shearography, magneto-optical, holographic interferometry; or other optical techniques to detect flaws, residual stress or measure thickness.
Non-destructive Testing Radiography
Non-destructive testing (NDT) services with radiographic or X-ray equipment use penetrating X-rays or gamma rays to capture images of the internal structure or a part or finished product. The density and composition of the internal features will alter the intensity or density of these features in the X-ray image. Ultrasonic non-destructive testing (UT) inspection techniques can detect surface and subsurface flaws or to measure thickness. Choices for form factor include bench or rack or cabinet, computer board, portable or handheld or mobile, and monitoring system. Beams of high frequency acoustic energy are introduced into the material and subsequently retrieved.
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