Non destructive testing
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This document provides an overview of non-destructive testing (NDT) and compares it to destructive testing. It discusses the objectives of NDT, which include detecting defects without damaging components. Various applications of NDT are mentioned, such as inspection during and after manufacturing, as well as in-service inspections. Advantages of NDT include reusing tested components and portability of equipment. Visual inspection is introduced as the simplest NDT method, involving examining components using the naked eye or optical aids.
Non destructive testing
- 1. Unit-1 OVERVIEW OF NDT By GODWIN PITHALIS N E
- 2. ME6019 NON DESTRUCTIVE TESTING AND MATERIALS OBJECTIVES: To study and understand the various Non Destructive Evaluation and Testing methods, theory and their industrial applications. UNIT I OVERVIEW OF NDT NDT Versus Mechanical testing, Overview of the Non Destructive Testing Methods for the detection of manufacturing defects as well as material characterisation. Relative merits and limitations, Various physical characteristics of materials and their applications in NDT., Visual inspection – Unaided and aided.
- 3. UNIT II SURFACE NDE METHODS Liquid Penetrant Testing - Principles, types and properties of liquid penetrants, developers, advantages and limitations of various methods, Testing Procedure, Interpretation of results. Magnetic Particle Testing- Theory of magnetism, inspection materials Magnetisation methods, Interpretation and evaluation of test indications, Principles and methods of demagnetization, Residual magnetism. UNIT III THERMOGRAPHY AND EDDY CURRENT TESTING (ET) Thermography- Principles, Contact and non contact inspection methods, Techniques for applying liquid crystals, Advantages and limitation - infrared radiation and infrared detectors, Instrumentations and methods, applications. Eddy Current Testing-Generation of eddy currents, Properties of eddy currents, Eddy current sensing elements, Probes, Instrumentation, Types of arrangement, Applications, advantages, Limitations, Interpretation/Evaluation
- 4. UNIT IV ULTRASONIC TESTING (UT) AND ACOUSTIC EMISSION (AE) Ultrasonic Testing-Principle, Transducers, transmission and pulse- echo method, straight beam and angle beam, instrumentation, data representation, A/Scan, B-scan, C-scan. Phased Array Ultrasound, Time of Flight Diffraction. Acoustic Emission Technique –Principle, AE parameters, Applications UNIT V RADIOGRAPHY (RT) 10 Principle, interaction of X-Ray with matter, imaging, film and film less techniques, types and use of filters and screens, geometric factors, Inverse square, law, characteristics of films - graininess, density, speed, contrast, characteristic curves, Penetrameters, Exposure charts, Radiographic equivalence. Fluoroscopy- Xero- Radiography, Computed Radiography, Computed Tomography OUTCOMES: Upon completion of this course, the students can able to use the various Non Destructive Testing and Testing methods understand for defects and characterization of industrial components
- 5. In this type of testing, the component or specimen to be tested is destroyed and cannot be reused. After testing, the component or specimen either breaks or remains no longer useful for future use. As the name suggests, destructive testing (DT) includes methods where the component or specimen is broken down in order to determine physical and mechanical properties such as strength, toughness, ductility and hardness. Destructive testing is more suitable and economical for mass production, as the cost of destroying a small number of pieces is negligible. It is not economical to do destructive testing where only one or very few items are to be produced.
- 6. Tensile test Compression test Shear test Hardness test Impact test Bending test Fatigue test Creep test Torsion test Chemical analysis, etc
- 7. NDT stands for Non-Destructive testing As its name implies, non-destructive testing means testing of materials without destroying them. A non-destructive test is an examination of an object which will not produce any kind of damage or destruction to the sample and after testing the material can be reused.
- 8. Non-Destructive testing is the process of inspecting, testing or evaluating materials, components or assemblies for discontinuities, or differences in characteristics without destroying the serviceability of the part or system. In other words, when the inspection is completed, the part can be used. NDT is a procedure which covers the inspection and/or testing of any material, component or assembly by means which do not affect its ultimate serviceability.
- 9. Material sorting Material characterization Property monitoring Thickness measurement Defect detection/ location Defect characterization Major task of NDT is to detect and identify the range of defects. Main objectives (i) To detect internal or surface flaws (ii)To measure the dimensions of the specimen (iii) To determine material structure or chemistry (iv) To evaluate material’s physical or mechanical properties.
- 10. Flaw Detection and Evaluation Leak Detection Location Determination Dimensional Measurements Structure and Microstructure Characterization Estimation of Mechanical and Physical Properties Stress (Strain) and Dynamic Response Measurements Material Sorting Chemical Composition Determination
- 11. NDT allows parts and material to be inspected and measured without damaging them. Because it allows inspection without interfering with a product's final use, NDT provides an excellent balance between quality control and cost-effectiveness. What is NDE: Non destructive evaluation (NDE) is a term that is often used interchangeably with NDT. However, technically, NDE is used to describe measurements that are more quantitative in nature. For example, an NDE method would not only locate a defect, but it would also be used to measure something about that defect such as its size, shape, and orientation. NDE may be used to determine material properties, such as fracture toughness, formability, and other physical characteristics.
- 12. There are NDE application at almost any stage in the production or life cycle of a component. ◦ To assist in product development ◦ To screen or sort incoming materials ◦ To monitor, improve or control manufacturing processes ◦ To verify proper processing such as heat treating ◦ To verify proper assembly ◦ To inspect for in-service damage
- 13. To ensure product integrity and reliability To control manufacturing processes To lower production costs To maintain a uniformity in quality level NDT tests can be performed … (i) During manufacturing (ii) After manufacturing (iii) Even on parts that are already in service
- 14. Inspection of Raw Products Inspection Following Secondary Processing In-Services Damage Inspection Inspection of Raw Products Forgings, Castings, Extrusions,etc.
- 15. Machining Welding Grinding Heat treating Plating
- 16. Cracking Corrosion Erosion/Wear Heat Damage
- 17. Using NDT, an entire production lot can be inspected, or selected samples can be inspected Also different tests can be applied to the same item, either simultaneous or sequentially, and the same test can be repeated on the same specimen for additional verification. It may be added that the NDT equipment is often portable. This permits the use of NDT methods for on-site testing in most locations. NDT does not permanently alter the specimen being inspected, it is a high valuable technique that can save both time and money in product evaluation, trouble shooting, and research. NDT make components more reliable, safe and economical.
- 18. The equipments are easy to handle Defects can be detected without damaging the components Methods are quick and accurate Components can be sorted out on the basis of electrical, magnetic or chemical properties Test results and other information can be conveniently recorded on paper films, cassettes, floppies, DVD, CD. etc
- 19. NON DESTRUCTIVE TEST DESTRUCTIVE TEST Used for finding out defects of materials Used for finding out the properties of the material Load is not applied on the material Load is applied on the material No load applications, so no chance for material damage Due to load application, material gets damaged No requirement of special equipments Special equipments are required Non expensive Expensive Less skill Skill is required e.g: dye penetrate test, ultrasonic, radiography, etc e.g: tensile test, compression test, hardness test, etc
- 20. Visual inspection is the simplest, fastest and most widely used non-destructive testing method. Visual inspection is carried out with naked eye(unaided) or using some optical aids (aided) such as mirrors, magnifying glasses and microscopes etc. Definition: Visual inspection is defined as the examination of material or component for conditions of non- conformance using light and the eyes alone or in conjunction with various aids. Visual inspection often also involves seeing, listening, feeling and sometimes even smelling the component being inspected.
- 21. Visual inspection is commonly employed to support other NDT methods Other NDT methods require visual intervention to interpret images obtained while carrying out examinations. At some point, all NDT methods fall back on visual testing. For Example, LPT uses dyes that rely on the inspectors ability to visually identify surface indications. Digital detectors and computer technology have made it possible to automate visual inspections. This is known as machine vision.
- 22. Visual testing is commonly used To detect surface characteristics such as surface finish, scratches, cracks, colour, wear and corrosion To check alignment of mating surfaces To check of the components To check the evidence of leaking To check internal side defects
- 23. Simple and easy to use Relatively inexpensive Testing speed is high Testing can be performed on components which are in-service Permanent records are available when latest equipments are used Almost all materials can inspect Limitations: Limited to detection of surface flaws The test results depend on skill and knowledge of tester Eye resolution is week Eye fatigue
- 24. Classified on the basis of use of aids used (i) Unaided or direct visual testing (ii) Aided visual testing Unaided or direct visual testing As the name suggests, the unaided visual testing is carried out with naked eye (without using any optical aids) The most important instrument in visual inspection is human eye
- 25. Human eye is the most fascinating and valuable tool in NDT It has greater precision and accuracy than many of the most sophisticated cameras. It has unique focusing capabilities and has the ability to work in conjunction with the human brain so that it can be trained to find specific details or characteristics in a test specimen. It has the ability to differentiate and distinguish between colours and their tones/shades characteristics as well Human eye is capable of assessing many visual characteristics and identifying various types of discontinuities The eye can perform accurate inspections to detect size, shape, colour, depth, brightness, contrast and texture
- 26. As the name suggests, the aided inspection is carried out with the help of optical aids (such as magnifying glasses, microscopes, borescopes, fiberscopes) and a variety of other optical imaging and image enhancement tools. The optical aids are mainly used for (i) Magnification of defects which cannot be detected by unaided visual inspection (ii) Assisting in the inspection of defects (iii) areas where not easily accessible to human eye
- 27. The optical aids used for visual inspection are (i) Magnifying Mirrors (small, angled mirrors) (ii) Magnifying glasses, eye loupes, multi-lens magnifiers, measuring magnifiers (iii) Microscopes(optical and electron) (iv) Boroscopes (v) Fiberscopes and videoscopes (vi) Telescopes (vii) Periscopes (viii) Optical comparators (ix) Optical flats(for surface flatness measurements) (x) Photographic records (xi) Closed-circuit television (CCTV) systems (xii) Machine vision systems (xiii) Image enhancement (computer analysis and enhancement)
- 28. When inspecting areas not easily accessible, a magnifying mirror can be used Depending on the test specimen, the mirror can be of any size. (ii) Magnifying Glass A magnifying glass can be used for closer inspection of suspicious looking areas It generally consists of a simple lens for lower power magnification and double or multiple lenses for higher magnification (iii) Microscopes: Microscope is a multiple element magnifier for providing very high magnified image of small object The simple microscopes consists of a convex lens. The object is placed between lens and focus length of lens, so that an erect, virtual and magnified image is formed. The size of the image of an object depends upon the angle subtended at the eye by the object.(known as visual angle)
- 29. Borescope are optical instrument designed for remote viewing of objects. They are used to inspect the inside of a narrow tube, bore or chamber. Borescopes is a precision optical instrument with built-in illumination Borescopes, also called endoscopes or endoprobes consist of superior optical systems and high intensity light sources. Some Borescopes provide magnification option, zoom controls. Because of the variety of applications, Borescopes are manufactured in rigid, extended, flexible and micro designs.
- 30. Modern fiberscope and videoscopes, due to their small size and flexibility, can provide access to internal areas inaccessible to rigid borescopes. Using these, digital images can be captured and processed in real time. With the aid of laser lights, the area and depth of many surface defects can also be determined. (vi) Telescopes Telescope is an instrument that collects radiation from a distant object in order to produce an image of it. An optical telescope uses visual radiations The telescopes are used for providing visual examination of the inaccessible surfaces.
- 31. Optical comparators are the magnifying devices for visual examination and measurement. A comparator produces 2D enlarged image of an object on a large ground-glass screen. Optical comparators project the image of small parts onto a large projection screen. The magnified image is then compared against an optical comparator chart, which is a magnified outline drawing of the workpiece being gauged.
- 32. Periscope is an instrument used for remote observation of inaccessible areas. In simple periscope, two right angle reflecting prisms are utilized in combination with a series of lenses. The periscopes are commonly used for remote visual inspection in hazardous situation such as radiations areas, toxic environment and for overhead viewing of areas involving obstacles.
- 33. Inspection of cleanliness in machines Checking for corrosion, erosion and deformities of machine components Checking for ruptures, cracks and wear of parts in the equipment. Monitoring of manometers, pressure and temperatures Monitoring of oil level, greasing and greasing apparatus. Monitoring of the operational conditions of systems or machines. Visual Testing of welds Visual Testing of Pumps Visual Testing of hydraulic systems Visual Testing of Belt Pulley Visual Testing of Forging Discontinuities
- 34. Most basic and common inspection method. Tools include fiberscopes, borescopes, magnifying glasses and mirrors. Robotic crawlers permit observation in hazardous or tight areas, such as air ducts, reactors, pipelines. Portable video inspection unit with zoom allows inspection of large tanks and vessels, railroad tank cars, sewer lines.