UNIT I: OVERVIEW OF NDT
PART A
1. What do you mean by Non-Destructive Testing (NDT)?
Inspecting or testing the materials and components in such a way that
allows the materials or components without changing or destroying their
usefulness.
2. What is purpose of NDT inspection?
It is used to find out the size and locate surface and surface flaws and defects.
3. Give the importance of using NDT.
Material or parts which fail to achieve the design requirements or projected life
due to undetected defects may require expensive repair or early replacements.
4. Give the reason for using NDT methods for inspection.
1. Accident prevention and reduce costs.
2. To improve product reliability.
3. To determine the acceptance to a given requirement.
4. To give the information on repair criteria.
5. List the merits of NDT methods.
1. 100% testing on actual components are possible.
2. Repeated checks over a period of time are possible.
3. Very little preparation is sufficient.
4. Most test methods are rapid.
6. List the limitations of NDT methods.
1. Measurements are indirect.
2. Usually qualitative measurements.
3. Skilled judgement and experience is required.
7. What are the mechanical tests conducted for a material?
Impact Test, Hardness Test, Toughness test, Load Test, Brittleness Test, and
Fatigue Test.
8. Give the basic elements requirement for NDT
1. A probing medium.
2. Modification of probing medium.
3. A sensitive detector.
4. A means of indicating or recording or the detectors signal.
9. What are the common NDT methods usually involved?
1. Visual Test.
2. Liquid penetrant test
3. Magnetic particle test
4. Eddy current test
5. Ultrasonic test
6. Radiographic test.
10. List the scientific techniques available for enabling material characterization.
1. Macroscopic Observation.
2. Microscopic Observation.
3. Optical microscopy.
4. Electron microscopy.
5. Diffraction technique (X ray).
6. Spectroscopic techniques.
11. What are the defects that can be detected by Unaided visual inspsection
1. General condition of the components.
2. The response of crack.
3. The surface porosity.
4. Potential source of mechanical weakness. (Sharp notches, misalignments)
12. Describe the function of an optical microscope.
• An optical microscope is a combination of lenses used to magnify the image of a
small object.
• The object is placed close to the lens to obtain as high a magnification as
possible.
PART B
1. Differentiate between destructive and non-destructive testing.
2. With a case study, discuss the applications of material characterization.
3. Discuss in detail about the different types of Borescopes used in visual inspection
method with precise diagrames.
4. Summarize the factors influencing the selection of NDT methods.
5. Illustrate the non - destructive testing methods and applications of each technique.
6. Explain the working principle and types of visual inspection technique with suitable
sketch.
7. Describe the applications of visual inspection along with its advantages and
disadvantages.
8. Explain the various types of discontinuities with examples.
PART C
1. Generalize about the attractive features and primary limitations of destructive
testing methods.
2. Explain any two destructive tests in brief.
3. Compare and contrast the principles, characteristics detected, advantages,
limitations and applications of visual inspection, liquid penetrant testing, magnetic
particle testing and thermography testing methods.
4. Compare and contrast the principles, characteristics detected, advantages,
limitations and applications of eddy current testing, ultrasonic testing, acoustic
emission testing and radiography testing methods.
UNIT II - SURFACE NDE METHODS
PART A
1. What are the principal methods available in Penetrant Tests?
1. Water washable method.
2. Post Emulsifiable method
3. Solvent Removal method.
2. Give the properties of Penetrants.
1. They spread over the surface easily.
2. Should remain in the defect but remove easily from the surface.
3. List the types of Penetrants:
1. Visual Penetrant Test.
2. Fluorescent Penetrants.
4. What do you mean by visible Penetrants?
It contains a red dye that provides high contrast against the white developer
background.
5. What do you mean by Fluorescent Penetrants?
It contains dye or several dyes that fluoresce when exposed to UV radiation.
6. What is the role of developers in LPT?
The role is to pull the trapped penetrant material out of the defects and spread it
out on the surface of the part.
7. How do you classify the Developers:
1. Dry powder.
2. Water suspendable.
3. Non aquous type (visible type)
4. Non aquous type (Fluorescent type)
5. Water soluble type.
8. Give the merits and demerits of Dry Developers:
Merits: 1. Indication tends to remain brightness.
2. Easy to apply.
Demerits: 1. Does not form contrast background.
2. Difficult to assure the coating of the entire part surface.
9. Give the merits and demerits of Suspendable Developers:
Merits:
1. Ease of coating entire part.
2. Indications are bright.
3. White coating of good contrast can be produced.
Demerits:
Indications weaken and become diffused after some time.
10. Give the merits of Non aqueous Developers:
Merits:
1. Easy to apply.
2. White coating of good contrast can be produced.
3. Indications show up rapidly.
4. Provides highest sensitivity.
11. What is meant by Magnetic Particle Testing?
It uses magnetic fields and small magnetic particle (Iron fillings) to detect flaws in
parts. The part must be a ferromagnetic material.
PART B
1. Discuss the physical principles of liquid penetrant testing with precise diagram.
Also bring out the advantages and limitations of liquid penetrant testing.
2. (i) Explain the Post-emulsifiable lipophilic and solvent removable methods in
liquid penetrant testing using a process flow diagram.
(8)
3. (ii) List the various types of penetrant. (5)
4. Explain the various types of developers along with their characteristics.
5. Explain in detail about the following
a. Surface preparation methods. (7)
b. Excess penetration removal methods. (6)
6. Explain the following
a. Principal requirements of penetrants. (7)
b. Properties of penetrants. (6)
7. Discuss about water washable and post-emulsifiablehydrophilic methods in
liquid penetrant testing using a process flow diagram.
(10)
8. Differentiate the Fluorescent Penetrants and Visible Penetrants (3)
9. Describe the various defects and discontinuities in LPT.
(10)
10. List the applications of LPT. (3)
11. Discuss the various ways of magnetizing components in Magnetic Particle
Testing
12. List the various limitations of Magnetic Particle Testing.
PART C
1. Explain in detail about the equipment used in the determination of magnetic field
strength and direction.
2. List and explain the steps involved in inspecting crankshafts using the wet particle
magnetic particle inspection method.
3. Explain the various detectable discontinuities during metal forming, heat
measurement, machining and welding.
UNIT - III THERMOGRAPHY AND EDDY CURRENT TESTING
PART A
1. Define Thermography.
It is a method of inspecting Electrical and Mechanical equipment by obtaining heat
distribution pictures.
2. What are the broader applications of thermography?
Inspection of Electrical equipment, Mechanical equipment,and Refractory lined
structures.
3. Outline the applications of Thermography in various electrical systems.
Fault findings in Fuse boards, Distribution boards, Bus bar systems, Control panels,
High and Low voltage systems, UPS, Battery systems, PLC, Motor controls and
Transformers.
4. List the applications of Thermography in mechanical systems.
Fault findings in Misalignment and component looseness, Bearing defects, Cracks,
Internal Flaws, Improper Lubrication, Refractory and Insulation faults.
5. What are the advantages of Non-Contact Thermal measurements?
Target in Motion, Target electrically hot, Current conducting Equipments,
Component present in Hazard to personnel, Target Fragile, Target temperature
changing, Target remote.
6. What are the methods available for checking in Thermography?
Contact: Liquid Crystal Thermography. Remote: Infrared Thermography.
Remote : Radio Thermography.
7. What is meant by Infrared Thermography?
Infrared Thermography is equipment or method which detects infrared energy
emitted from object, converts it into temperatures and displays images of
temperature distributions.
8. What do you mean by contact Infrared Thermography?
It is the method which is based on the properties of liquid crystals to change the
colour depending upon the temperature.
9. What do you mean by Liquid Crystal Thermography (LCT)?
Thermographic Liquid Crystals (TLC) are materials that change their reflected
colour as a function of temperature when illuminated by white light.
10. List the types of liquid crystals.
Liquid Crystal types are 1. Encapsulated 2. Unencapsulated.
11. List the characteristics of Infrared thermography.
It is not visible as its wave length is longer than the visible light.
It has a characteristic of heating an object. Therefore it is called as Heat Ray. It can
travel through vacuum.
12. What are the measurements carried out using Infrared thermography?
Temperature, stress, moisture,and film thickness measurements.
1.
2.
3.
4.
5.
6.
7.
8.
PART B
Describe in detail about the elements of infrared detection system with a block
diagram.
Explain the principles of thermography testing using the passive approach along
with its applications.
Explain the principles of thermography testing using active approach and mention a
few applications of the same.
List and explain in detail about the laws of thermal imaging in Thermography test.
Classify the various Infrared sensors and explain with a precise diagram about the
working principle of IRsensors.
Illustrate the Contact and Non-Contact inspection methods in Thermography with
precise diagram.
Explain eddy current instrumentation with aid of block diagram.
Explain the different methods used in the generation of magnetic field in eddy
current testing.
PART C
1. Evaluate the procedure for detecting fatigue crack in materials using eddy current
inspection technique.
2. Illustrate the procedure for detecting the surface cracks or material discontinuities
using the eddy current method.
3. Explain in detail, the image processing involved in thermography.
UNIT IV - ULTRASONIC TESTING AND ACOUSTIC EMISSION
PART A
1. Outline the principles of an Ultrasonic Test.
A pulse echo UT inspection system consists of several functional units such as
Pulser, Receiver, Transducer and a display device. The sound energy is introduced
and propagates through the material in the form of waves. When there is a
discontinuity in the wave path, a part of the energy will be reflected from the flaw
surface and it is displayed.
2. Give the properties of acoustic waves:
The wave length is directly proportional to the velocity of the wave
andinversely proportional to the frequency of the wave.
3. Write down the meaning of Attenuation:
The combined effect of scattering and absorption of waves is called attenuation.
4. What is a couplant?
A couplant is a material (usually liquid) that facilitates the transmission of ultrasonic
energy from the transducer into the test specimen.
5. List the UT methods used in Inspection and measurements:
Normal Beam Pulse-echo method, Normal Beam through Transmission, Angle Beam
Pulse-echo method and Angle Beam through Transmission.
6. Write the common formats available for data Transmission in UT tests.
The common formats are A Scan, B Scan and C Scan presentations.
7. List the applications of UT:
1. Weldment testing.
2. Bar, Rods, Sheets, Pipes and Rails testing.
3. Crack detection and Corrosion testing.
4. Plant and Machinery checking.
8. List the advantages of UT.
• Sensitive to both surface and sub-surface discontinuities.
• The depth penetration for flaw detection superior to other NDT methods.
• It is highly accurate.
• Minimum part preparation is required.
• Instantaneous results can be obtained.
• Detailed images can be produced without automated system.
• Non-hazardous to operators.
• Highly portable.
9. Define Acoustic Emission Testing.
Acoustic Emission is defined as the class of phenomenon whereby transient elastic
waves are generated by the rapid release of energy from localized source.
10. Give the applications of AE tests:
1. Inspection during proof testing and online monitoring of pressure vessels.
2. Leakage detection and locations.
3. Investigating processes like fatigue, stress and corrosion.
4. Monitoring underground pipelines and online weld monitoring.
PART B
Describe the principle of ultrasonic testing with a suitable block diagram.
List the advantages and disadvantages of ultrasonic testing.
(5)
Illustrate the principle of pulse echo method with a neat diagram.
Describe the working principle of the following with neat diagrams: (i) PiezoElectric transducer.
(7)
5. Electro Magnetic Acoustic Transducer (EMAT).
(6)
6. Explain the various ultrasonic transducers used in ultrasonic testing methods based
on their applications.
7. Discuss the following ultrasonic inspection techniques with neat diagrams.
1.
2.
3.
4.
8. Straight beam ultrasonic inspection method.
(7)
9. Angle beam ultrasonic inspection method.
(6)
10. Explain the following using appropriate diagrams: (i) A-scan(ii) B-scan(iii) C-scan
11. Explain the various components involved in an acoustic emission test.
PART C
1. Explain the various parameters involved in Acoustic Emission Testing method.
2. List and explain the variables influencing the results of ultrasonic testing.
3. Describe in detail about the suitability of ultrasonic inspection techniques for
inspecting the welding process with precise diagram.
UNIT V RADIOGRAPHY TEST
PART A
1. List the properties of X rays and Gamma rays:
They are not detected by human senses (cannot by heard, seen, felt etc)
They travel in a straightline with a speed of light.
Their path cannot be changed by electrical or magnetic fields.
They pass through matter until they have a chance to encounter an atomic particle.
They have enough energy to ionize matter and can damage or destroy living cells.
2. Illustrate the principle of Radiography:
This technology makes use of the ability of electromagnetic radiations with short
wave lengths, such as x-rays and gamma rays, to penetrate things. The stronger the
penetrating power, the shorter the wave length. Some of the radiation that passes
through the substance is absorbed by it. The degree of absorption is determined by
the density and thickness of the materials.
3. What is meant by attenuation?
When X-rays or Gamma rays are directed at an object, some photons interact with
matter particles and their energy is absorbed or scattered. Attenuation is the term
used to describe this absorption and scattering.
4. List out the various class of films and its characteristics:
Class I
Extra fine grain, High contrast, Slow speed.
Class II
Fine grain, High contrast, Medium speed.
Class III
High speed
Class IV
Fluorescent screens
5. What is meant by an intensifying screen?
It has been discovered that the use of thin screens/foils made of heavier material
produces intensification. The screen helps to reduce exposure time by utilizing more
effective radiation reaching the film with gamma ray radiation of 70 kv and above.
6. List the general rules for optimum results in radiography?
Source or focal spot size should be as small as possible. An idle source will be a point
source. Source to object distance should be as large as possible. The film should be in
close contact with the object. Source location should be such that the radiation
passes through the object thickness.
7. Define Radiographic Image Density?
The term Radiographic Image Density is a measure of the degree of film darkening.
After taking a radiographic image of a part and processing the film, the
resulting darkness of the film will vary according to the amount of radiation that has
reached the film through the test object. The darker areas indicate more exposure
and lighter areas indicate less exposure.
8. What do you mean by a Penetrameter?
A Penetrameter or Image Quality Indicator (IQI) is a gauge used to establish
radiographic technique or quality level. To get this, IQI must be made up of a
material radiographically similar to the material being radiographed. The identifying
number in the penetrameter is in thousands of an inch.
9. Give short notes on Step type penetrameter
This type of penetrameter is essentially a step wedge having 4 or 5 steps. The
thickness of these steps increases either in geometric or arithmetic progression.
10. What do you mean by Fluoroscopy?
The term Fluoroscopy is synonymous with real time radiography and electron
radiography. Basic equipment for conventional fluoroscopy consists of a source of
radiation, a fluoroscopic conversion screen, mirror and a viewing port. To get the
basic real time image an object is placed between the source of radiation and
fluoroscopic screen that converts the transmitted radiation into visible lights.
1.
2.
3.
4.
PART B
Explain the process of Neutron Radiography and Computed Tomography.
(i). Discuss the safety aspects related to Radiographic Testing.
(7)
(ii). Write short notes on penetrometers and sensitivity in radiography testing. (6)
Illustrate the components of an X-ray generator with a neat diagram.
Discuss the following
(i) Crank-out mechanism for Gamma ray radiographic exposure. (7)
(ii)Gamma source isotopes and their characteristics. (6)
5. Explain the various stages of film processing and development with a flow
diagram.
6. Discuss the four important processes involved in the interaction of X-rays with
matter.
7. Explain in detail about Xerography techniques with suitable diagrams.
8. Explain computed tomography with relevant diagrams.
PART C
1. How are X-rays produced in radiographic testing? Briefly write about two methods
of X-ray production.
2. How computed radiography differs from conventional radiography? Briefly explain
the principle of operation involved in computed radiography.
3. Classify X-ray films used in industrial radiography and brief about the construction
of an X ray film with a simple line diagram.