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43-453: Non- Destructive Testing (NDT/ NDT testing) Techniques or Methodologies allow the investigator to carry out examinations without invading the integrity of the engineering specimen under observation while providing an elaborate view of the surface and structural discontinuities and obstructions. The personnel carrying out these methodologies require specialized NDT Training as they involve handling delicate equipment and subjective interpretation of

86-676: A comprehensive scheme of certification exists and the method or technique is covered by International, regional or national standards or the new NDT method or technique has been demonstrated to be effective to the satisfaction of the certification body. The certification covers proficiency in one or more of the following methods: a) acoustic emission testing; b) eddy current testing; c) infrared thermographic testing; d) leak testing (hydraulic pressure tests excluded); e) magnetic testing; f) penetrant testing; g) radiographic testing; h) strain gauge testing; i) ultrasonic testing; j) visual testing (direct unaided visual tests and visual tests carried out during

129-430: A failure of a component would cause significant hazard or economic loss, such as in transportation, pressure vessels, building structures, piping, and hoisting equipment. In manufacturing, welds are commonly used to join two or more metal parts. Because these connections may encounter loads and fatigue during product lifetime , there is a chance that they may fail if not created to proper specification . For example,

172-482: A great deal of skepticism. This industry -related article is a stub . You can help Misplaced Pages by expanding it . Magnetic particle inspection Magnetic particle inspection ( MPI ) is a nondestructive testing process where a magnetic field is used for detecting surface, and shallow subsurface, discontinuities in ferromagnetic materials . Examples of ferromagnetic materials include iron , nickel , cobalt , and some of their alloys . The process puts

215-427: A magnetic field into the part. The piece can be magnetized by direct or indirect magnetization. Direct magnetization occurs when the electric current is passed through the test object and a magnetic field is formed in the material. Indirect magnetization occurs when no electric current is passed through the test object, but a magnetic field is applied from an outside source. The magnetic lines of force are perpendicular to

258-405: A national accreditation authority like UKAS ). The Pressure Equipment Directive (97/23/EC) actually enforces central personnel certification for the initial testing of steam boilers and some categories of pressure vessels and piping . European Standards harmonized with this directive specify personnel certification to EN 473. Certifications issued by a national NDT society which is a member of

301-581: A part, the current or magnetic field needed has to be equal to or greater than the current or magnetic field used to magnetize the part. The current or magnetic field is then slowly reduced to zero, leaving the part demagnetized. A popular method to record residual magnetism is by using a Gauss meter. A common particle used to detect cracks is iron oxide , for both dry and wet systems. It is common industry practice to use specifically designed oil and water-based carriers for magnetic particles. Deodorized kerosene and mineral spirits have not been commonly used in

344-405: A part. These are attracted to an area of flux leakage and form what is known as an indication, which is evaluated to determine its nature, cause, and course of action, if any. There are several types of electrical currents used in magnetic particle inspection. For a proper current to be selected one needs to consider the part geometry, material, the type of discontinuity one is seeking, and how far

387-500: A signal to trigger the high-speed camera. These high-speed cameras have advanced recording modes to capture almost any type of destructive failure. After the failure the high-speed camera will stop recording. The captured images can be played back in slow motion showing precisely what happens before, during and after the destructive event, image by image. Building structures or large nonbuilding structures (such as dams and bridges) are rarely subjected to destructive testing due to

430-403: A structure to break or a pipeline to rupture. Welds may be tested using NDT techniques such as industrial radiography or industrial CT scanning using X-rays or gamma rays , ultrasonic testing , liquid penetrant testing , magnetic particle inspection or via eddy current . In a proper weld, these tests would indicate a lack of cracks in the radiograph, show clear passage of sound through

473-400: A transfer function that models the behavior of the system. In NDT, the structure undergoes a dynamic input, such as the tap of a hammer or a controlled impulse. Key properties, such as displacement or acceleration at different points of the structure, are measured as the corresponding output. This output is recorded and compared to the corresponding output given by the transfer function and

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516-570: A true sampling unit is an item that may or may not contain a flaw. Guidelines for correct application of statistical methods to POD tests can be found in ASTM E2862 Standard Practice for Probability of Detection Analysis for Hit/Miss Data and MIL-HDBK-1823A Nondestructive Evaluation System Reliability Assessment, from the U.S. Department of Defense Handbook. Destructive testing In destructive testing (or destructive physical analysis , DPA ) tests are carried out to

559-417: A yoke is limited. These systems used dry magnetic powders, wet powders, or aerosols. After the part has been magnetized it needs to be demagnetized. This requires special equipment that works the opposite way of the magnetizing equipment. The magnetization is normally done with a high current pulse that reaches a peak current very quickly and instantaneously turns off leaving the part magnetized. To demagnetize

602-477: Is a hand-held device that induces a magnetic field between two poles. Common applications are for outdoor use, remote locations, and weld inspection . The drawback of magnetic yokes is that they only induce a magnetic field between the poles, so large-scale inspections using the device can be time-consuming. For proper inspection the yoke needs to be rotated 90 degrees for every inspection area to detect horizontal and vertical discontinuities. Subsurface detection using

645-548: Is a type of software testing which attempts to cause a piece of software to fail in an uncontrolled manner, in order to test its robustness and to help establish range limits, within which the software will operate in a stable and reliable manner. Automobiles are subject to crash testing by both automobile manufacturers and a variety of agencies. There has also been extensive destructive testing of passenger and military aircraft, conducted by aircraft manufacturers and organizations like NASA . The 2012 Boeing 727 crash experiment

688-518: Is defined in standard ASTM E-1316. Some definitions may be different in European standard EN 1330. Probability of detection (POD) tests are a standard way to evaluate a nondestructive testing technique in a given set of circumstances, for example "What is the POD of lack of fusion flaws in pipe welds using manual ultrasonic testing?" The POD will usually increase with flaw size. A common error in POD tests

731-434: Is negligible. It is usually not economical to do destructive testing where only one or very few items are to be produced (for example, in the case of a building). Analyzing and documenting the destructive failure mode is often accomplished using a high-speed camera recording continuously (movie-loop) until the failure is detected. Detecting the failure can be accomplished using a sound detector or stress gauge which produces

774-538: Is organized by the American Society for Nondestructive Testing for Level 3 NDT personnel. NAVSEA 250-1500 is another US central certification scheme, specifically developed for use in the naval nuclear program. Central certification is more widely used in the European Union, where certifications are issued by accredited bodies (independent organizations conforming to ISO 17024 and accredited by

817-456: Is quite often enhanced by the use of magnification, borescopes, cameras, or other optical arrangements for direct or remote viewing. The internal structure of a sample can be examined for a volumetric inspection with penetrating radiation (RT), such as X-rays , neutrons or gamma radiation. Sound waves are utilized in the case of ultrasonic testing (UT), another volumetric NDT method – the mechanical signal (sound) being reflected by conditions in

860-474: Is the most commonly used mass-production inspection machine. The machine has a head and tail stock where the part is placed to magnetize it. In between the head and tail stock is typically an induction coil, which is used to change the orientation of the magnetic field by 90° from the head stock. Most of the equipment is built for a specific application. Mobile power packs are custom-built magnetizing power supplies used in wire wrapping applications. Magnetic yoke

903-449: Is to assume that the percentage of flaws detected is the POD, whereas the percentage of flaws detected is merely the first step in the analysis. Since the number of flaws tested is necessarily a limited number (non-infinite), statistical methods must be used to determine the POD for all possible defects, beyond the limited number tested. Another common error in POD tests is to define the statistical sampling units (test items) as flaws, whereas

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946-473: Is used for non-magnetic materials, usually metals. Analyzing and documenting a nondestructive failure mode can also be accomplished using a high-speed camera recording continuously (movie-loop) until the failure is detected. Detecting the failure can be accomplished using a sound detector or stress gauge which produces a signal to trigger the high-speed camera. These high-speed cameras have advanced recording modes to capture some non-destructive failures. After

989-611: The European Federation of NDT ( EFNDT ) are mutually acceptable by the other member societies under a multilateral recognition agreement. Canada also implements an ISO 9712 central certification scheme, which is administered by Natural Resources Canada , a government department. The aerospace sector worldwide sticks to employer based schemes. In America it is based mostly on the Aerospace Industries Association's (AIA) AIA-NAS-410 and in

1032-427: The test article and evaluated for amplitude and distance from the search unit (transducer). Another commonly used NDT method used on ferrous materials 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

1075-687: The European Union on the equivalent and very similar standard EN 4179. However EN 4179:2009 includes an option for central qualification and certification by a National aerospace NDT board or NANDTB (paragraph 4.5.2). Most NDT personnel certification schemes listed above specify three "levels" of qualification and/or certification, usually designated as Level 1 , Level 2 and Level 3 (although some codes specify Roman numerals, like Level II ). The roles and responsibilities of personnel in each level are generally as follows (there are slight differences or variations between different codes and standards): The standard US terminology for Nondestructive testing

1118-470: The NDT inspection/NDT testing results. NDT methods rely upon use of electromagnetic radiation , sound and other signal conversions to examine a wide variety of articles (metallic and non-metallic, food-product, artifacts and antiquities, infrastructure) for integrity, composition, or condition with no alteration of the article undergoing examination. Visual inspection (VT), the most commonly applied NDT method,

1161-443: The application of another NDT method are excluded). NDT is divided into various methods of nondestructive testing, each based on a particular scientific principle. These methods may be further subdivided into various techniques . The various methods and techniques, due to their particular natures, may lend themselves especially well to certain applications and be of little or no value at all in other applications. Therefore, choosing

1204-412: The applied codes and standards. NDT professionals and managers who seek to further their growth, knowledge and experience to remain competitive in the rapidly advancing technology field of nondestructive testing should consider joining NDTMA, a member organization of NDT Managers and Executives who work to provide a forum for the open exchange of managerial, technical and regulatory information critical to

1247-423: The base metal must reach a certain temperature during the welding process, must cool at a specific rate, and must be welded with compatible materials or the joint may not be strong enough to hold the parts together, or cracks may form in the weld causing it to fail. The typical welding defects (lack of fusion of the weld to the base metal, cracks or porosity inside the weld, and variations in weld density) could cause

1290-477: The designed seismic performance of a new building, or the actual performance of an existing building. The tests are, mostly, carried out on a platform called a shake-table which is designed to shake in the same manner as an earthquake. Results of those tests often include the corresponding shake-table videos. Testing of structures in earthquakes is increasingly done by modelling the structure using specialist finite element software . Destructive software testing

1333-414: The direction of the electric current, which may be either alternating current (AC) or some form of direct current (DC) (rectified AC). The presence of a surface or subsurface discontinuity in the material allows the magnetic flux to leak, since air cannot support as much magnetic field per unit volume as metals. To identify a leak, ferrous particles, either dry or in a wet suspension, are applied to

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1376-440: The failure the high-speed camera will stop recording. The captured images can be played back in slow motion showing precisely what happened before, during and after the nondestructive event, image by image. NDT is used in a variety of settings that covers a wide range of industrial activity, with new NDT methods and applications, being continuously developed. Nondestructive testing methods are routinely applied in industries where

1419-870: The known input. Differences may indicate an inappropriate model (which may alert engineers to unpredicted instabilities or performance outside of tolerances), failed components, or an inadequate control system . Reference standards, which are structures that intentionally flawed in order to be compared with components intended for use in the field, are often used in NDT. Reference standards can be with many NDT techniques, such as UT, RT and VT. Several NDT methods are related to clinical procedures, such as radiography, ultrasonic testing, and visual testing. Technological improvements or upgrades in these NDT methods have migrated over from medical equipment advances, including digital radiography (DR), phased array ultrasonic testing (PAUT), and endoscopy (borescope or assisted visual inspection). (Basic source for above: Hellier, 2001) Note

1462-404: The magnetic field needs to penetrate into the part. An AC electromagnet is the preferred method for find surface breaking indication. The use of an electromagnet to find subsurface indications is difficult. An AC electromagnet is a better means to detect a surface indication than HWDC, DC, or permanent magnet, while some form of DC is better for subsurface defects. A wet horizontal MPI machine

1505-476: The number of advancements made during the WWII era, a time when industrial quality control was growing in importance. This ISO 9712 requirements for principles for the qualification and certification of personnel who perform industrial non-destructive testing(NDT). The system specified in this International Standard can also apply to other NDT methods or to new techniques within an established NDT method, provided

1548-410: The prohibitive cost of constructing a building, or a scale model of a building, just to destroy it. Earthquake engineering requires a good understanding of how structures will perform at earthquakes . Destructive tests are more frequently carried out for structures which are to be constructed in earthquake zones. Such tests are sometimes referred to as crash tests , and they are carried out to verify

1591-401: The right method and technique is an important part of the performance of NDT. Successful and consistent application of nondestructive testing techniques depends heavily on personnel training, experience and integrity. Personnel involved in application of industrial NDT methods and interpretation of results should be certified, and in some industrial sectors certification is enforced by law or by

1634-403: The specimen's failure, in order to understand a specimen's performance or material behavior under different loads. These tests are generally much easier to carry out, yield more information, and are easier to interpret than nondestructive testing . Destructive testing is most suitable, and economic, for objects which will be mass-produced , as the cost of destroying a small number of specimens

1677-617: The successful management of NDT personnel and activities. Their annual conference at the Golden Nugget in Las Vegas is a popular for its informative and relevant programming and exhibition space There are two approaches in personnel certification: In the United States employer based schemes are the norm, however central certification schemes exist as well. The most notable is ASNT Level III (established in 1976–1977), which

1720-470: The test object, and form indications (particle collection) on the object's surface, which are evaluated visually. Contrast and probability of detection for a visual examination by the unaided eye is often enhanced by using liquids to penetrate the test article surface, allowing for visualization of flaws or other surface conditions. This method ( liquid penetrant testing ) (PT) involves using dyes, fluorescent or colored (typically red), suspended in fluids and

1763-489: The weld and back, or indicate a clear surface without penetrant captured in cracks. Welding techniques may also be actively monitored with acoustic emission techniques before production to design the best set of parameters to use to properly join two materials. In the case of high stress or safety critical welds, weld monitoring will be employed to confirm the specified welding parameters (arc current, arc voltage, travel speed, heat input etc.) are being adhered to those stated in

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1806-593: The welding procedure. This verifies the weld as correct to procedure prior to nondestructive evaluation and metallurgy tests. Structure can be complex systems that undergo different loads during their lifetime, e.g. Lithium-ion batteries . Some complex structures, such as the turbo machinery in a liquid-fuel rocket , can also cost millions of dollars. Engineers will commonly model these structures as coupled second-order systems, approximating dynamic structure components with springs , masses , and dampers . The resulting sets of differential equations are then used to derive

1849-513: Was conducted and filmed by the Discovery channel . It is now standard procedure to test to destruction the first few production models of new airplanes by loading various components until they fail. The 1951 movie, No Highway in the Sky starring James Stewart and Marlene Dietrich told the story of an eccentric engineer who pioneered research into destructive testing of complete components against

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