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1、Introduction to Nondestructive Testing For IPPS1AgendaIntroduction to NDTOverview of Seven Most Common NDT MethodsApplications2The use of nondestructive techniques to determine the integrity of a material, component, or structure.To inspect or measure without doing harm.Definition of NDT3Methods of
2、NDTVisualMagnetic ParticleX-rayLiquid PenetrantUltrasonicEddy CurrentChemical Composition4What are Some Uses of NDT Methods?Flaw Detection and EvaluationLeak Detection Location DeterminationDimensional Measurements Estimation of Mechanical and Physical Properties Fluorescent penetrant indication5Whe
3、n are NDT Methods Used?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 treatingTo verify proper assemblyTo inspect for in-service damageThere are NDT application at almost any stag
4、eThere are NDT application at almost any stage in the production or life cycle of a component. in the production or life cycle of a component.6Seven Most Common NDT Methods Visual Liquid Penetrant Magnetic Particle X-ray Eddy Current Ultrasonic Chemical Composition7Most basic and common inspection m
5、ethod.Tools include fiberscopes, borescopes, magnifying glasses and mirrors.Visual Inspection8A liquid dye is applied to the surface of the part and allowed time to seep into surface breaking defects.The excess liquid is removed from the surface of the part. A developer (powder) is applied to pull t
6、he trapped penetrant out the defect and spread it on the surface where it can be seen. Visual inspection is the final step in the process. The penetrant used is often loaded with a fluorescent dye and the inspection is done under UV light to increase test sensitivity.Liquid Penetrant Inspection9Magn
7、etic Particle InspectionThe part is magnetized. Finely milled iron particles coated with a dye pigment are then applied to the specimen. These particles are attracted to magnetic flux leakage fields and will cluster to form an indication directly over the discontinuity. This indication can be visual
8、ly detected under proper lighting conditions. 10Magnetic Particle Crack Indications 11RadiographyThe radiation used in radiography testing is a higher energy (shorter wavelength) version of the electromagnetic waves that we see as visible light. The radiation can come from an X-ray generator or a ra
9、dioactive source. High Electrical PotentialElectrons-+X-ray Generator or Radioactive Source Creates RadiationExposure Recording DeviceRadiation Penetrate the Sample12Film RadiographyTop view of developed film X-ray filmThe part is placed between the radiation source and a piece of film. The part wil
10、l stop some of the radiation. Thicker and more dense area will stop more of the radiation. = more exposure= less exposureThe film darkness (density) will vary with the amount of radiation reaching the film through the test object.13Radiographic Images14Conductive materialCoilCoils magnetic fieldEddy
11、 currentsEddy currents magnetic fieldEddy Current Testing15Eddy Current TestingEddy current testing is particularly well suited for detecting surface Eddy current testing is particularly well suited for detecting surface cracks but can also be used to make electrical conductivity and cracks but can
12、also be used to make electrical conductivity and coating thickness measurements.coating thickness measurements. Here a small surface probe is Here a small surface probe is scanned over the part surface in an attempt to detect a crack.scanned over the part surface in an attempt to detect a crack.16Hi
13、gh frequency sound waves are introduced into a material and they are reflected back from surfaces or flaws.Reflected sound energy is displayed versus time, and inspector can visualize a cross section of the specimen showing the depth of features that reflect sound. fplatecrack0246810initial pulsecra
14、ck echoback surface echoOscilloscope, or flaw detector screenUltrasonic Inspection (Pulse-Echo) 17Chemical Composition orPositive Material Identification (PMI)Optical emission systems (OES), also called arc/spark, uses an arc or a spark to vaporize the sample, exciting the atoms and ions into emissi
15、on of radiation. This emitted radiation then passes through an optical fiber and is dispersed into its spectral components. A photo-multiplier tube (PMT) measures the range of wavelengths emitted x-ray fluorescence (XRF) uses X-rays emitted from an X-ray tube or a radioisotope to excite the atoms of
16、 the sample material. An electron is ejected, causing a second to fall into its void and energy is released. A detector within the instrument uses the energy level to determine the element. 18Common Application of NDTInspection of Raw MaterialInspection Following Secondary ProcessingIn-Services Dama
17、ge Inspection19Inspection of Raw ProductsForgingsCastingsExtrusionsPlate20MachiningWeldingGrindingHeat treatingPlatingInspection Following Secondary Processing21CrackingCorrosionErosion/WearHeat DamageInspection For In-Service Damage22Power Plant InspectionProbeSignals produced by various amounts of
18、 corrosion thinning.Periodically, power plants are shutdown for inspection. Inspectors feed eddy current probes into heat exchanger tubes to check for corrosion damage.Pipe with damage23Wire Rope InspectionElectromagnetic devices and visual inspections are used to find broken wires and other damage
19、to the wire rope that is used in chairlifts, cranes and other lifting devices. 24Storage Tank InspectionRobotic crawlers use ultrasound to inspect the walls of large above ground tanks for signs of thinning due to corrosion.Cameras on long articulating arms are used to inspect underground storage ta
20、nks for damage. 25Aircraft InspectionNondestructive testing is used extensively during the manufacturing of aircraft. NDT is also used to find cracks and corrosion damage during operation of the aircraft.A fatigue crack that started at the site of a lightning strike is shown below. 26Jet Engine Insp
21、ectionAircraft engines are overhauled after being in service for a period of time. They are completely disassembled, cleaned, inspected and then reassembled. Fluorescent penetrant inspection is used to check many of the parts for cracking. 27Sioux City, Iowa, July 19, 1989A defect that went undetect
22、ed in an engine disk was responsible for the crash of United Flight 232. Crash of United Flight 23228The 17 year old disk had undergone routine maintenance and six times had been subjected to flourescent penetration inspections. Investigators concluded that human error was responsible in improperly
23、identifying the fatigued area before the accident.United Flight 23229Pressure Vessel InspectionThe failure of a pressure vessel can result in the rapid release of a large amount of energy. To protect against this dangerous event, the tanks are inspected using radiography and ultrasonic testing.30Rai
24、l InspectionSpecial cars are used to inspect thousands of miles of rail to find cracks that could lead to a derailment. 31Bridge InspectionThe US has 578,000 highway bridges.Corrosion, cracking and other damage can all affect a bridges performance.The collapse of the Silver Bridge in 1967 resulted i
25、n loss of 47 lives.Bridges get a visual inspection about every 2 years.Some bridges are fitted with acoustic emission sensors that “listen” for sounds of cracks growing. 32NDT is used to inspect pipelines to prevent leaks that could damage the environment. Visual inspection, radiography and electrom
26、agnetic testing are some of the NDT methods used. Remote visual inspection using a robotic crawler. Radiography of weld joints. Magnetic flux leakage inspection. This device, known as a pig, is placed in the pipeline and collects data on the condition of the pipe as it is pushed along by whatever is being transported. Pipeline Inspection33For More Information on NDTThe Collaboration for NDT Education The American Society for Nondestructive Testing 34For More Information on NDTFor More Information on NDTChinese Society for Non-destructive Testing (ChSNDT) 35
