Sunday, 5 June 2011

Basic knowledge of Non-Destructive Testing (NDT) and Destructive Testing (DT)

1.  What is Non-Destructive Testing (NDT)?
NDT is the testing of materials to detect internal and surface defects or discontinuities using methods which do not damage or destroy the material under test

2.    What is the different between Defects or discontinuities?
Discontinuities: Any imperfection or interruption in the normal physical structure or configuration of a product (cracks, laps, inclusion, etc). Discontinuity may or may not affect the usefulness of the product

Defect:  A discontinuity whose size, shape, orientation, location or properties makes it detrimental to the useful service of the product in which it occurs or exceeds the accept/reject criteria for the given design. Defect is a type of discontinuity.

3.    What are the major 5 NDT methods?

The major 5 NDT Methods are:
a.    Ultrasonic Testing
b.    Radiography Testing
c. Magnetic Particle Testing
d.   Dye Penetrant Testing
e. Eddy Current Testing

4.    For detection of surface weld defects or discontinuities what are the NDT methods commonly used?

The NDT methods are commonly used to detect the defect/discontinuities on surface weld:
a.    Visual Testing (VT)
b.    Penetrant Testing (PT)
c.    Magnetic Particle Testing (MT)
d.   Eddy Current Testing (ET)

5.    For detection of internal weld defects or discontinuities, material what are the NDT methods commonly used?

The NDT methods to detect internal weld defect/discontinuities:
a.    Radiographic Testing (RT)
b.    Ultrasonic Testing (UT)

6.    What are the factors affecting the choice of NDT method

Depends on many factors and conditions
a.    Cost
b.    Type of defect sought
c.    Type of material to be tested
d.   Position and location of defect
e.    Availability of equipment
f.     Availability of qualified operators
g.    Working conditions and location
h.    Sensitivity required
i.      others

7.    What is Destructive Testing (DT)?
Destructive Testing is the testing of materials to detect internal and surface defects or discontinuities by methods which damaging or destroying the material under test

8.    What are the DT (Destructive Testing) methods widely applied?
The DT methods widely used are as follows:
a.    Tensile Test
b.    Bend Test
c.    Charpy Test
d.   Vicker Test
e.    Fracture Test
f.     Fatigue Test
g.    Creep Test
h.    Replica

Thursday, 2 June 2011

Eddy Current Testing Level I (20 Questions)

Q.1    Generation of eddy currents depends on the principle of:
A.  wave guide theory.
B.  electromagnetic induction.
C.  magneto-restrictive forces.
D.  all of the above.

Q.2    A secondary field is generated by the test object and is:
A.  equal and opposite to the primary field.
B.  opposite to the primary field, but much smaller.
C.  in the same plane as the coil is wound.
D.  in phase with the primary field.

Q.3    When a non-ferromagnetic part is placed in the test coil, the coil's voltage:
A.  increases.
B.  remains constant because this is essential.
C.  decreases.
D.  shifts 90 degrees in phase.

Q.4    Eddy currents generated in a test object flow:
A.  in the same plane as magnetic flux.      
B.  in the same plane as the coil is wound.
C.  90 degrees to the coil winding plane.
D.  Eddy currents have no predictable direction.

Q.5    The discovery of electromagnetic induction is credited to:
A.  Arago.
B.  Oersted.
C.  Maxwell.
D.  Faraday.

Q.6    A standard depth of penetration is defined as the point in a test object where the relative eddy current density is reduced to:
A. 25 percent.
B. 37 percent.
C. 50 percent.
D. 100 percent.

Q.7    Calculate the standard depth of penetration at 10 kHz in copper; σ = 5.7 • 107 mhos per meter.
A. 0.1 mm
B. 0.02 mm
C. 0.66 mm
D. 66 mm

Q.8    Differential coils are usually used in:
A.  bobbin coils.
B.  probe coils.
C. OD coils.
D. any of the above.

Q.9    When using a probe coil to scan a test object,______
A.  the object must be dry and polished.
B.  the object must be scanned carefully to insure inspection coverage.
C.  the object must be scanned in circular motions at constant speeds.
D.  the probe must be moving at all times to get a reading.

Q.10    A "spinning probe" would most likely be a (an):
A. bobbin coil.
B. ID coil.
C. OD coil.
D. probe coil.

Q.11    A "feed-through" coil is:
A. a coil with primary/secondary windings connected so that the signal is fed through the primary to the secondary.
B. an encircling coil.
C. an OD coil.
D. both B and C.

Q.12  When inspecting a tubular product with an encircling coil, which statement is not true?
A. OD discontinuities can be found.
B.  Axial discontinuity locations can be noted.
C. Circumferential discontinuity locations can be noted.
D. ID discontinuities can be found.

Q.13  An absolute coil measurement is made  
A. by comparing one spot on the test object to another.
B. without reference to or direct comparison with a standard.
C. only with probe coils.
D. by comparative measurement to a known standard.

Q.14  When coils in a differential arrangement are affected simultaneously with the same test object variables, the output signal
A. is directly proportional to the number of variables.
B. is "0" or near-"0."
C. is indirectly proportional to the number of variables.
D. is primarily a function of the exciting current.

Q.15Which coil type inherently has better thermal stability?
A. Bobbin
B. Absolute
C. OD                                                                                                                          
D. Differential

Q.16  A hybrid coil is composed of two or more coils. The coils -
A. must be aligned coplanar to the driver axis.
B. may be of widely different dimensions.
C. must be impedance-matched as closely as possible.
D. are very temperature sensitive.

Q.17  Proper selection of test coil arrangement is determined by:
A. shape of test object.
B. resolution required.
C. sensitivity required.
D. all of the above.

Q.18  A coil's resistance is determined by:
A. wire material.
B. wire length.
C. wire cross-sectional area.
D. all of the above.

Q.19  Inductance is analogous to:
A. force.
B. volume.
C. inertia.
D. velocity.

Q.20  The unit of inductance is the:
A. henry.
B. maxwell.
C. ohm.
D. farad.



Wednesday, 1 June 2011

Asnt PT Level 1 sample question.

Liquid Penetrant Testing Method (40 Questions)

1. Which one of the following conditions will affect the rate and the extent a liquid penetrant will enter cracks, fissures, and other small openings?
a. the hardness of the specimen being tested
b. the surface condition of the specimen being tested
c. the color of the penetrant
d. the conductivity of the specimen being tested

2. Which of the following is a commonly used classification for penetrant?
a. post-emulsifiable penetrant
b. nonferrous penetrant
c. chemical etch penetrant
d. nonaqueous penetrant

3. A generally accepted method for removing excess nonwater-washable penetrant is:
a. repeatedly dipping the test specimen in a cleaner
b. soaking the test specimen in hot detergent water
c. blowing the excess penetrant off the surface of the part with compressed air
d. wiping and cautiously cleaning the test specimen with a cleaner-dampened cloth

4. All of the following parts can be tested by the liquid penetrant method except:
a. an iron casting
b. an aluminum forging
c. a part made from a porous plastic material
d. a part made from a non-porous material

5.  Which of the following discontinuities can be found by the penetrant test method?
a. a surface crack
b. a subsurface crack
c. an internal inclusion
d. none of the above

6.  Which of the following is generally the more acceptable method for cleaning parts prior  to penetrant testing?
a. sand blasting
b. wire brushing
c. grinding
d. vapor degreasing

7. All of the following methods are commonly used to clean parts prior to penetrant testing except:
a. vapor degreasing
b. liquid solvent
c. power wire brushing
d. alkaline cleaner

8. Cutting oils may be effectively removed from parts before penetrant testing by:
a. pre-heating
b. vapor degreasing
c. washing with water
d. all of the above

9.  The most common type of contaminant in fluorescent penetrant fluid is:
a. metal filings
b. oil
c. detergents (from cleaning)
d. water

10. Black light, with a proper functioning filter in place, used for fluorescent penetrant inspection can cause permanent damage to:
a. human tissues
b. human eyes
c. human blood cells
d. none of the above

11. All of the following basic inspection principles apply to the penetrant methods except-                        
a. the penetrant must enter the discontinuity in order to form an indication
b. indications glow when illuminated with a black light
c. a longer penetration time is required for smaller discontinuities
d. if the penetrant is washed out of the discontinuity, an indication will not be formed  by that discontinuity

12. Subsurface discontinuities can be best detected by:
a. the post-emulsification penetrant method
b. the visible dye penetrant method
c. the fluorescent, water-washable penetrant method
d. none of the above

13. Visible penetrant may be applied by:
a. brushing
b. spraying
c. dipping
d. none of the above

14. The first step in conducting a liquid penetrant test on a surface that has been painted is to :
a. carefully apply the penetrant over the surface
b. completely remove the paint
c. thoroughly wash the surface with a detergent
d. wire brush the surface to roughen the smooth surface coating of paint

15. When using a post-emulsification penetrant, it is necessary to apply the emulsifier:
a. before applying the penetrant
b. after the water wash operation
c. after the dwell time has elapsed
d. after the develonment time has elapsed

16. When conducting a water-washable liquid penetrant test, the wet developer is applied:
a. immediately after the penetrant has been applied
b. immediately before the penetrant is applied
c. after removal of the penetrant
d. after removal of the emulsifier

17. The term used to describe the action of a particular developer in soaking up the penetrant in a discontinuity, so as to cause the maximum bleed-out of the liquid penetrant for increased contrast and sensitivity, is known as:
a. blotting
b. capillary action
c. concentration
d. attraction

18. Using a black light lamp with a cracked filter or without the filter in place can cause damage to human eyes because the lamp emits:
a. black light
b. ultraviolet light
c. infrared light
d. none of the above

19. The term used to define the period of time in which the test part is covered with penetrant is:
a. waiting time
b. soak time (drain time)
c. penetration time (dwell time)
d. bleed-in time

20. Usually, the most desirable method of removing excess water-washable penetrant after the dwell time is by using:
a. a low pressure coarse water spray
b. water and brush
c. a solid stream of water
d. water and clean rags

21. When conducting a liquid penetrant test using a post emulsifiable visible dye penetrant, the generally accepted method for applying the wet developer is by:
a. brushing
b. swabbing
c. dipping
d. spraying

22. Which of the following characteristics does not apply to liquid penetrant testing?
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

23. Which of the following discontinuities is most likely to be missed due to improper rinse techniques?
a. a forging lap
b. deep pitting
c. shallow and broad discontinuities
d. the rinse technique will not affect the detection of discontinuities

24. When conducting a fluorescent penetrant test, a commonly used technique for assuring that the excess penetrant has been removed prior to the application of a developer is to:
a. blow compressed air over the surface
b. chemically etch the surface
c. blot the surface with absorbent paper
d. scan the surface with a black light

25. Which of the following surface conditions could have a detrimental effect on a liquid penetrant test?
a. a wet surface
b. a rough weld
c. an oily surface
d. all of the above

26. Liquid penetrant testing is capable of detecting:
a. intergranular stress corrosion cracking discontinuities
b. discontinuities open to the surface
c. subsurface discontinuities
d. all of the above

27. Black light equipment is required when penetrant testing by:
a. the.fluorescent penetrant method
b. the visible dye penetrant method
c. the non-fluorescent penetrant method
d. all of the above

28. The term used to define the tendency of certain liquids to penetrate into small openings such as cracks or fissures is:
a. saturation
b. capillary action
c. blotting
d. wetting agent

29. Excess penetrant (all penetrant except that which is in discontinuities) is removed from the specimen:
a. after the required penetrant dwell time has elapsed
b. before the application of an emulsifier if a post-emulsifier penetrant is used
c. by means of a steam cleaner
d. only when water-washable penetrants are used

30. When using a post-emulsifiable penetrant, the emulsifier time should be:
a. as long as the penetrant dwell time
b. half the penetrant dwell time
c. the same as the developer time
d. only as long as necessary to remove the interfering background

31. When an inspector is working in a darkened area, he/she should become adjusted to the dark before inspecting parts. The generally accepted time period for becoming accustomed to the dark is:
a.  1 minute
b.  5 to 0 minutes
c. 10 to 15 minutes
d.  no waiting period is necessary

32. When applying penetrant by dipping, heating the penetrant prior to dipping:
a. will increase the sensitivity of the test
b. will increase the capillary action of the penetrant
c. will increase the stability of the penetrant
d. is not generally recommended

33. A penetrant inspection cannot find:
a. surface p orosity
b. surface cracks
c. an internal cavity
d. a surface forging lap

34. All of the following materials can be tested by the usual liquid penetrant tests except:
a. unglazed porous cerai
b. titanium
c. high alloy steel
d. cast iron

35. Liquid penetrant testing can be used to detect:
a. discontinuities 1.6 mm (0.06 in.) below the surface
b. internal discontinuities
c. discontinuities open to the surface
d. all discontinuities

36. Which of the following are commonly accepted methods for applying penetrant?
a. dipping the part in penetrant (dipping)
b. pouring the penetrant over the test specimen (flowing)
c. spraying the penetrant on the test specimen (spraying)
d. all of the above

37. A solvent used to clean the surface of a test specimen must possess all of the following characteristics except that the:
a. cleaner must be capable of dissolving oils and greases commonly found on the surface             
b. cleaner must not be flammable
c. cleaner must be free of contaminants
d. cleaner must leave a minimal residue on the surface

38. Which of the statements below best states the danger of sandblasting (without subsequent chemical etching) for cleaning surfaces to be penetrant tested?
a. the discontinuities may be peened over and closed
b. oil contaminants might be sealed in the discontinuities
c. the sand used in the sandblasting operation may be forced into the discontinuity
d. the sandblasting operation may introduce discontinuities

39. The penetrant applied to the surface of a test specimen:
a. seeps into discontinuities
b. is absorbed by discontinuities
c. is drawn into discontinuities by capillary action
d. is drawn into discontinuities by gravity

40. Which of the following statements concerning liquid penetrant testing is correct?
a. fluorescent penetrants will produce red against white discontinuity indications
b. non-fluorescent penetrants require the use of black lights
c. fluorescent indications will be seen when exposed to black light
d. nonfluorescent discontinuities glow in the dark for easy viewing and interpretation