ASNT NDT Methods Exam Solved 100% 2023

Acoustic Emission Testing.. Acoustic Emission (AE) refers to the generation of transient elastic waves produced by a sudden redistribution of stress in a material. When a structure is subjected to an external stimulus (change in pressure, load, or temperature), localized sources trigger the release of energy, in the form of stress waves, which propagate to the surface and are recorded by sensors. With the right equipment and setup, motions on the order of picometers (10 -12 m) can be identified. Sources of AE vary from natural events like earthquakes and rockbursts to the initiation and growth of cracks, slip and dislocation movements, melting, twinning, and phase transformations in metals. In composites, matrix cracking and fiber breakage and debonding contribute to acoustic emissions. AE's have also been measured and recorded in polymers, wood, and concrete, among other materials. Detection and analysis of AE signals can supply valuable information regarding the origin and importance of a discontinuity in a material. Because of the versatility of Acoustic Emission Testing (AET), it has many industrial applications (e.g. assessing structural integrity, detecting flaws, testing for leaks, or monitoring weld quality) and is used extensively as a research tool. Acoustic Emission is unlike most other nondestructive testing (NDT) techniques in two regards. The first difference pertains to the origin of the signal. Instead of supplying energy to the object under examination, AET simply listens for the energy released by the object. AE tests are often performed on structures while in operation, as this provides adequate loading for propagating defects and triggering acoustic emissions. .Tt Questions: 1. The most common range of acoustic emission testing is : - ANSWER-100-300 kHz 2) Discontinuities that are not readily detectable by acoustic emission testing are: - ANSWER-rounded inclusions The kaiser effect refers to: - ANSWER-the behavior where emission from a source will not occur until the previous load is exceeded. Kaiser effect is an absence of acoustic emission at loads not exceeding the previous maximum load level when material undergoes repetitive loading patterns. Discontinuities created in material during previous steps do not move or expand until former stress is exceeded resulting in Kaiser effect. The felicity effect is useful in evaluating: - ANSWER-fiber-reinforced plastic components Felicity effect is an effect in acoustic emission that reduces Kaiser effect at high loads of material. Under Felicity effect the acoustic emission resumes before the previous maximum load was reached. The total energy loss of a propagating wave is called: - ANSWER-Attenuation The Kaiser Effect is useful in distinguishing: - ANSWER-mechanical noise from growing discontinuities The term "counts" refers to the : - ANSWER-number of times a signal crosses a preset threshold The acoustic emission signal amplitude is related to: - ANSWER-the band pass filters. Threshold settings are determined by the: - ANSWER-background noise level Background noise can be reduced by : - ANSWER-electronic filtering Electromagnetic Testing - ANSWER-Electromagnetic Testing (ET), as a form of nondestructive testing, is the process of inducing electric currents or magnetic fields or both inside a test object and observing the electromagnetic response. If the test is set up properly, a defect inside the test object creates a measurable response. The term "Electromagnetic Testing" is often intended to mean simply Eddy-Current Testing (ECT). However with an expanding number of electromagnetic and magnetic test methods, "Electromagnetic Testing" is more often used to mean the whole class of electromagnetic test methods, of which Eddy-Current Testing is just one. Eddy-Current Testing (ECT) is used to detect near-surface cracks and corrosion in metallic objects such as tubes and aircraft fuselage and structures. ECT is more commonly applied to nonferromagnetic materials, since in ferromagnetic materials the depth of penetration is relatively small. Remote field testing (RFT) is used for nondestructive testing (NDT) of steel tubes and pipes. Magnetic flux leakage testing (MFL) is also used for nondestructive testing (NDT) of steel tubes and pipes. At present RFT is more commonly used in small diameter tubes and MFL in larger diameter pipes over long travel distances. Wire rope testing is MFL applied to steel cables, to detect broken strands of wire. Magnetic particle inspection (MT or MPI) is a form of MFL where small magnetic particles in the form of a powder or liquid are sprayed on the magnetized steel test object and gather at surface-breaking cracks. Eddy Currents are circulating electrical currents induced in conductive materials by : - ANSWER-an alternating magnetic field The method used to generate eddy currents in a test specimen by means of a coil can most closely be compared with the action of a: - ANSWER-transformer Eddy current testing relies on the principle of : - ANSWER-electromagnetic induction When the electrical current in an eddy current coil reverses direction the: - ANSWER-direction of the eddy currents in the test part also reverses. In order to generate measurable eddy currents in a test specimen the specimen must be : - ANSWER-an electrical conductor. The magnetic field generated by eddy currents induced in a test specimen: - ANSWER-opposes the magnetic field that induced the eddy current. In eddy current testing, IACS is a recognized abbreviation for: - ANSWER-International Annealed Copper Standard In eddy current testing, the specimen is coupled to the test coil by: - ANSWER-the coils electromagnetic fields. The penetrations of eddy currents in a conductive material is decreased when the : - ANSWER-test frequency , conductivity of the specimen or permeability of the specimen is increased At a fixed test frequency, in which of the following materials will the eddy current penetration be greatest ? - ANSWER-Lead (7% IACS conductivity) A term used to describe the effect observed due to a change in the coupling between a test specimen and a flat probe coil when the distance of separation between them is varied is: - ANSWER-perpendicular to the major plane of the discontinuity When testing with eddy currents, discontinuities will be most easily detected when the eddy currents are: - ANSWER-perpendicular to the major plane of the discontinuity Which of the following discontinuities is easiest to detect with an eddy current test ? ( Assume that the area of the discontinuity is equal in all five choices listed): - ANSWER-a. A subsurface crack which lies parallel to the direction of the eddy current b. A discontinuity located in the center of a 51 mm (2" ) diameter bar. C. A radial crack that extends to the outer surface of a 51 mm ) 2 in. ) diameter bar. d. A subsurface radial crack located at a depth of 13 mm (0.5 in.) in a 51 mm (2 in. ) diameter bar. A term used to define the timing relationships involved in alternating current signals is : - ANSWER-impedance The impedance of a test coil can be represented by the vector sum of : - ANSWER-inductive reactance and resistance. Dis advantages of using a surface probe coil for the eddy current inspection of small-diameter tubing include: - ANSWER-lift off variations effect. The term " fill factor " applies to: - ANSWER-an encircling coil Which of the following materials would be more likely used as a mounting material for a probe coil ? - ANSWER-a. Aluminum B. Plastic c. copper Nonferromagnetic steel Ferromagnetism is very important in industry and modern technology, and is the basis for many electrical and electromechanical devices such as electromagnets, electric motors, generators, transformers, and magnetic storage such as tape recorders, and hard disks. Which of the following is not a commonly used eddy current testing read-out mechanism ? - ANSWER-A. Signal Generator b. Meter c.Cathode ray tube d. Strip-chart recorder. Reference Standards used for eddy current testing: - ANSWER-must be constructed from the same material of the object being inspected Which of the following conditions is not important when selecting specimens to be used as reference standards ? - ANSWER-If the material is aluminum the surface should be anodized. Which of the following conditions would be the most difficult to detect when eddy current testing a rod using a encircling coil - ANSWER-A small inclusion in the center of the rod. The thickness of non conductive coatings on a conductive base can be most simply measured by: - ANSWER-observing the lift off effect caused by the coating. Some of the products commonly tested using encircling coils are : - ANSWER-rods, tubes and wire. It is often possible to sort various alloys of a nonmagnetic metal by means of an eddy current test when: - ANSWER-there is a unique range of conductivity values for each alloy When conducting eddy current testing on tubing with a system that includes a frequency discriminating circuit which of the following variables would be classified as a high frequency variable ? - ANSWER-Small discontinuities Which of the following is not a candidate for testing by the eddy current method : - ANSWER-a 102 mm (4") thick plate to be tested for discontinuities throughout the plate Ground Penetrating Radar - ANSWER- Guided Wave Testing - ANSWER- Laser Testing Methods - ANSWER- Leak Testing - ANSWER-What is a product leak? This common term is not always well defined. A product leak is material flow from or into a product (a control volume) during a given time, in excess of allowable limits. Which of the following systems or components are not good candidates for leak testing ? - ANSWER-Sintered material components. A helium mass spectrometer (A helium mass spectrometer is an instrument commonly used to detect and locate small leaks using helium ) is used in which of the following NDT techniques or methods - ANSWER-Leak Testing Which of the following is a technique of leak testing ? - ANSWER-Detector Probe Potentially, the most sensitive leak testing technique is the : - ANSWER-Mass Spectrometer Test-- Mass spectrometry works by ionizing chemical compounds to generate charged molecules or molecule fragments and measuring their mass-to-charge ratios. Establishing differential pressure between the test object and environment is an essential element in which of the following NDT methods ? - ANSWER-Leak testing Which of the following best describes the type of leak test used when the interior of the test object is evacuated and a tracer gas is applied to the exterior, while the leak detector is connected to the evacuating system. ? - ANSWER-Dynamic leak test Assuming no significant leakage, if the temperature increased during a pressure drop leak test, the pressure in the system under test would : - ANSWER-increase If the sensitivity of the halogen leak detector is constant throughout a test, which of the following is true upon completion of the test - ANSWER-The instrument and the test procedure were cabable of detecting leakage of a certain size during the test All leak detection methods are dependent upon: - ANSWER-gas or fluid flow In and evacuated system, sensitivity of a pressure change leak test is dependent not only on the pressure change observed, but also on the degree of outgassing . Outgassing is best defined as: - ANSWER-the release of gas from materials in a vacuum Liquid Penetrant Testing - ANSWER-Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). The tendency of a liquid penetrant to enter a discontinuity is primarily related to : - ANSWER-capillary forces Liquid penetrant testing is a non-destructive method that can be used for: - ANSWER-locating discontinuities open to the surface Which of the following is not a characteristic that applies to liquid penetrant testing ? - ANSWER-a. This method can accurately measure the depth of a crack or discontinuity b. This method can be used for on-site testing of large parts. C. This method can be used to find shallow surface discontinuities. d. This method can be made more or less sensitive by using different penetrant materials. The property of a dye used in penetrant materials to emit light in the range of wavelengths different from the wavelength of light that excites the emission is called ; - ANSWER-a. emissivity b. irradiation c. spectrum blocking D. fluorescence. When using a fluorescent, post-emulsifier penetrant the length of time the emulsifier is allowed to remain on the part is critical for detecting shallow discontinuities. The optimum length of time should be: - ANSWER-experimentation. A red penetrant indication against the white background is most likely to be seen when: - ANSWER-visible dye penetrants are used The most widely-accepted method for removing excessive water-washable penetrant from the surface of a test specimen is by; - ANSWER-using a water spray rinse. Which of the following penetrant systems is generally considered the least sensitive / - ANSWER-water -washable, visible dye. When performing a liquid penetrant test using solvent-removable visible dye penetrant, there are several ways to remove excess penetrant from the surface of the part. Which of the methods listed below is generally regarded as the most suitable for giving accurate test results ? - ANSWER-a. Squirting solvent over the surface with no more than 10 psi pressure. b. Wiping with a solvent -soaked cloth then wiping with a dry cloth. g with a solvent-dampened cloth, then wiping with dry cloths D. Wiping with dry wipes , then wiping with a solvent-dampened cloth and finally wiping with a dry cloth. A problem with retesting a specimen that has been previously tested using liquid penetrant is that the - ANSWER-penetrant residue left in discontinuities may not readily dissolve and the retest may be misleading. A commonly used method of checking the overall performance of a penetrant material system is to: - ANSWER-compare two sections of artificially cracked specimens 12. The function of emulsifier in the post-emulsified penetrant process is to : - ANSWER-react with the surface penetrant to make the penetrant water-washable 13. Which of the following statements does not apply to developers used during penetrant testing ? - ANSWER-Developers are normally highly fluorescent 14. The penetrant indication for a cold shut on the surface of a casting will normally be: - ANSWER-a smooth continuous line. A crack-type discontinuity will generally appear as: - ANSWER-a continuous line, either straight or jagged In a penetrant test, scattered round indications on the surface of apart could be indicative of - ANSWER-porosity Which of he following are typical nonrelevant indications found in penetrant testing - ANSWER-Indications due to part geometry or part designe configurations Which of the statements below best states the results of sandblasting for cleaning surfaces to be penetrant tested? - ANSWER-Discontinuities may be closed The penetrant indication of a forging lap will normally be a : - ANSWER-thin continuous line Aluminum ally test specimens that have been tested by the liquid penetrant method should be thoroughly cleaned after testing because: - ANSWER-the alkaline s in wet developers and most emulsifiers could cause surface pitting, particularly in the moist atmosppheres