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Introduction
What is NDT?
Non Destructive Testing is exactly what it sounds to be. Testing of welds, products or components in such a manner that it not destructive, thus will not cause damage to said components. Abbreviated as NDT, also known as NDE (Non destructive Examination), NDI (Non destructive Inspection) dependent on the industry or National Association, it can be an invaluable tool that may save time and money in product evaluation, troubleshooting and research. NDT can be pivotal in all areas of manufacturing and service industries such as Oil and Gas, Mining, Building and Civil, Rail and Railway Components, Structural and Pressure Equipment Fabrication, Aerospace and more.
The most frequently used NDT techniques are Magnetic Particle Inspection (MT), Dye Penetrant Inspection (PT), Radiographic (RT), Ultrasonic (UT), Eddy Current (ET) and Visual Testing (VT).
NDT has progressed over the years and now has more advanced methods which can provide even more information, with greater recording and condition monitoring capabilities. These methods use proven technology from the traditional NDT methods, and further utilise modern technological advances.
Advanced methods include Phased Array Ultrasonic Testing (PAUT), Time of Flight Diffraction (TOFD) , Eddy Current Array (ECA), Acoustic Emission (AE), Electro-Magnetic Acoustic Transducer (EMAT - UT), Alternating Current Field Measurement (ACFM), Digital Radiography (DR), and many more.
We will go through a few of the conventional NDT methods below. If you require further information, or information about ANDT (Advanced NDT) methods, get in touch with us.
Conventional Non-Destructive Testing
Visual Testing (VT)
Magnetic Particle Testing (MT)
Magnetic Particle Testing (MT)
Visual inspection (VT), the most commonly applied NDT method, is quite often enhanced by the use of measuring equipment and/or gauges, magnification, borescopes, cameras, or other optical arrangements for direct or remote viewing. Visual Testing can often indicate where further inspection methods should be employed for more accurate investigation and characterisation of identified discontinuities
Magnetic Particle Testing (MT)
Magnetic Particle Testing (MT)
Magnetic Particle Testing (MT)
Magnetic Particle Testing is used on ferrous materials and involves the application of fine iron particles (either suspended in liquid or dry powder – fluorescent or colored) that are applied to a part while it is magnetized, either continually or residually. The particles will be attracted to leakage fields of magnetism on or in the test object, and form indications (particle collection) on the object's surface, which are evaluated visually.
Penetrant Testing (PT)
Magnetic Particle Testing (MT)
Ultrasonic Testing (UT)
Penetrant Testing involves using dyes, fluorescent or colored (typically red), suspended in fluids and is used for non-magnetic materials, usually metals. Probability of detection for a visual examination by the unaided eye is often enhanced by using liquids to penetrate the test article surface for visualization of flaws or other surface conditions after cleaning and development of bleed-out against a suitable contrasting background
Ultrasonic Testing (UT)
Radiographic Testing (RT)
Ultrasonic Testing (UT)
Sound waves are utilized in the case of ultrasonic testing (UT), where a mechanical signal (sound) induced via particle vibration being reflected by conditions in the test article and evaluated for amplitude and distance from the search unit (transducer). Ultrasonic Testing results are in real time with options of permanent recording, can be cost effective and has excellent sensitivity and detectability for planar reflectors such as Lack of Fusion and cracking.
Radiographic Testing (RT)
Radiographic Testing (RT)
Radiographic Testing (RT)
The internal structure of a sample can be examined for internal flaws and discontinuities with penetrating radiation (RT), such as X-Rays or Gamma radiation. Can be used on almost any material and is generally considered a volumetric method of inspection, and provides permanent records which, when stored correctly, can last for years to come.
Eddy Current Testing (ET)
Radiographic Testing (RT)
Radiographic Testing (RT)
Eddy Current Testing can be used to detect (generally) surface breaking flaws in conductive materials through use of electromagnetic induction. Can be used through non conductive surface coatings, minimising their need to be removed.
Additionally, Eddy Current Testing can also be used for material sorting and conductivity measurement.
