Helpful Questions for Mechanical Inspectors and Quality Engineers

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1. What is quality control?

2. What is welding?

3. What is steel?

4. What is difference between metals and materials?

5. How many types of steels are there mainly?

6. What are the types of alloys? List out any three or four?

7. What is the difference between CS & alloy steel?

8. What is the effect of oils, paints & rust found in the welding area?

9. How do you control hydrogen cracking?

10. What is environmental cracking?

11. What is corrosion and erosion?

12. Where do you get the preheating requirement?

13. How do you ensure it?

14. Where do ensure pre heating?

15. What is inter pass temperature?

16. Where do get the inter pass temperature requirements?

17. How do measure it?

18. What is heat input?

19. How do calculate the heat input?

20. Where do ensure the heat input? Draw a picture?

21. What is the welding parameter effecting heat input?

22. What is PWHT?

23. What is the difference between stress relieving & PWHT?

24. What is the difference between normalizing & annealing?

25. How many thermocouples are required during PWHT?

26. What are the types of thermo couples?

27. How do attach it to the job?

28. Where do attach the thermo couples? Explain it?

29. What is the heating bandwidth?

30. How do control the chimney effects?

31. What is you action, if you found power failure during PWHT heating cycle?

32. How do you ensure the PWHT satisfactory or not?

33. What is the hardness?

34. Where do ensure it?

35. What is the weight of hammer to carryout the polide hardness tester?( as per NACE-472)

36. What is your course of action? If you find the diameter of indent are oblong more than 0.1 units during hardness testing.

37. How much distance required at least between indentations?

38. What is color-coding?

39. List how many types of flanges available?

40. What are the inspections required for spectacle flanges?

41. What are the inspections required for valves installation?

42. What is minimum wall thickness? How much is it?

43. What is a quality audit?

44. What is the purpose of quality audits?

45. What is code?

46. What is specification?

47. What is standard?

48. How much verticality acceptable during vessel erection?

49. Which code is stringent?( ASME SEC IX or API – 1104)

50. What is gauge plate?

51. What is size of gauge plate?

52. What is length of gauge plate?

53. Why gauge plate is required?

54. Where do use the gauge plate?

55. What are the pipefittings?

56. How do ensure height of elbow for 20 D X 6”NPS?

57. Do you know 90 deg; four cuts miter bends sizes of sides?

58. What is inert gas?

59. Why backing gas or purging gas is required?

60. How many variables are there to control the welding defects?

61. What is definition of plate/ sheet / strip?

62. Can you explain low hydrogen baking procedure?

63. What is mean for low hydrogen electrode?

64. Why baking is required?

65. What is P&ID?

66. What is isometric drawing?

67. What is difference between ASTM & ASME materials?

68. How do calculate the carbon equivalent?

69. What is HAZ?

70. How do find the development angle for cone?

71. How many types of dished ends?

72. Which thickness is more in case of hemisphere dished end and shell?

73. What is factor of safety?

74. What is plasticity & elasticity?

75. Can you explain stress and strain diagram?

76. Which inspection is required to identify the SA516 Gr.B & SA 515 Gr.B test unidentified specimens?

77. How many types of weld joints?

78. How do measure the strain rate during hydro test?

79. How is microstructure of the duplex stainless steel at room temperature?

80. What cold cracking and hot cracking?

81. How many types of crystal structures?

82. What is IGC?

83. Do you know the bolt tighten sequence? Draw a diagram?

84. Why orifice plate is required?

85. What are the inspections required @ orifice plate inserted?

86. What is good engineering practice for L/S & C/S orientations?

87. What is a lethal substance?

88. How do know the requirement of PWHT?

89. How do know the requirement of impact test?

90. Do you know how types of valves classifieds?

91. How many types of manually operated valves?

92. What is course of action, while hydro testing found 25 mm stretch at TP and

20 mm at zero pressure?

93. How many types reducers are there?

94. What is the difference between concentric reducer and eccentric reducer?

95. How do verify that correct piping material?

96. How do identify the correct flanges and fittings?

97. How do check the correct pipe schedule?

98. What is the tolerance of pipe?

99. What is an expansion loop?


1. What is welding inspector role before welding, during welding & after welding?

2. What are the welding variables?

3. How many types of welding variables?

4. What is difference between essential variables & non-essential variables?

5. What is the supplementary variable?

6. What are the essential variables for QW-353?

7. What are the essential variables for QW-356?

8. What is QW-253?

9. What is QW-256

10. What is “A” number and “F” number?

11. UNS 31254 Super austenitic stainless steel ‘P’ number is 8, what is ‘A’ number?

12. How much misalignment is acceptable? Where do you know it?

13. If you have dissimilar thickness, how do you accept the misalignment?

14. If you have 3/4”-32” dia piping, how many tests required for welder qualifications? How it is?

15. If I have 36 mm thickness job, my welders are max.qualified 12mm.shall completed by them?

16. What is heat input?

17. Where do you ensure? Draw picture?

18. How do we ensure it?

19. Why do we need to control/monitor it?

20. What is interpass temperature?

21. Where do ensure inter pass temperature?

22. How do you ensure inter pass temperature?

23. What is the inspection tools you familiar?

24. How can you check the fit up? Explain?

25. What type of cleaning required within groove & near by groove? How long?

26. What is bridge tacks?

27. Where it is required?

28. How much welding shall be completed before welding interruption?

29. If not what to do?

30. What is your action, if inter pass temperature more 50 c than the specified?

31. What is PQR?

32. What is WPS?

33. What is WPQ?

34. What is QW-484 format?

35. What is QW-482 format?

36. What is QW-483 format?

37. What is mandrill size during bend test?

38. What is the purpose to do the bend test?

39. What is Qw-451?

40. What is QW-452?

41. What type of qualification required for > 24” pipe?

42. What is the difference between pipe and tube?

43. What doesn’t mean 2” tube and 2” pipe?

44. Can you list out the pipeline construction codes?

45. How do ensure the soundness of welding?

46. How much weaving is acceptable?

47. Why tensile strength test is required?

48. Why bend tests are required?

49. Why fillet break test is required?

50. Why macro test is required?

51. What is difference between macro & micro test?

52. Why notch toughness test is required?

53. How much ovality is acceptable for pipes?

54. One welder is qualified for plate welding with 3G according to AWS D 1.1; shall we allow him to carry the plate welding with 3G of ASME SEC IX?

55. How much area of cleaning is required from the weld groove as a good engineering practice?

API 1104
1. How much misalignment is acceptable?
2. How much undercut is acceptable?
3. How much reinforcement is acceptable?
4. How many test specimens required for <4” dia, WQT?
5. How many test specimens required for 6” PQR?
6. What are ranges for diameters?
7. What are ranges for thickness?

8. How much length of crack is to be repaired?
9. What are limitations of API 1104 code?
10. What is table-02?
11. What is table-03?
12. What is table-04?

ANSI B 31.3

1. What are the services existing in this code?
2. How much gap is required between socket welds?
3. How do you ensure the gap?
4. What is minimum size of fillet for socket weld?
5. What is a minimum fillet size for slip on flanges at inside & out side?
6. What is a cover fillet size for branch connection?
7. What is a fillet size for reinforcement pad?
8. Where do we ensure hardness?
9. Why hardness test is required?
10. How much weight of hammer required?
11. What to do it? If we get oblong more than 0.1 units.
12. How much hardness, test bar shall be selected for hardness testing?
13. Why do need to do the hydro testing?
14. What are the pressure gauges ranges for hydro testing?
15. How many pressure gauges required during hydro test?
16. What is the difference between random and spot radiography?
17. What is penalty clause for random radiography?
18. What is the purpose of tell tale holes?
19. Which location it is required? Explain with different orientations?
20. Why backing strip is required while welding saddle L/S or RF pad L/S?
21. What is table-330.1.1?
22. What is table-331.1.1?
23. What is table-341.1.1?
24. How much misalignment is acceptable?


1. What is the principle of radiography?
2. What is difference between the radiography films and radiographs?
3. What is the penetrameter?
4. How do you ensure the quality of radiographs?
5. What is density?
6. What is contrast?
7. How much contrast variations are acceptable?
8. How do you ensure the density of radiographs?
9. How much densities are acceptable?
10. What is ungeometrical sharpness?
11. For example below 2” thickness how much ug is it?
12. How do you control it?
13. What is NDT?
14. Why do we need to do it?
15. What is isotope?
16. What is the unit for radioactive material?
17. What is the present unit for radioactive material?
18. How do you ensure the black scatter radiation?
19. What is table -276?
20. What is half-life of isotope?
21. What is half-life of IR-192?
22. What is half-life of CO-60?
23. How much sensitivity is required?
24. What doesn’t mean 2% sensitivity?
25. What doesn’t mean 2-2T sensitivity?
26. What is your course of action, if you found instead of ASTM pentameters. DIN pentameters used?
27. Where do you place the penetrameters?
28. If contrast varies more than plus 30% & minus 15% through body of penetrameters, how do you give judgments?
29. How many methods of radiation exposures?
30. How do you ensure the cording area?
31. What are safety devices to ensure radiation?
32. How do ensure the person exposed radiation?
33. How many exposures required for DWDI?
34. How many penerameters required during panoramic exposure? Where have to place it?
35. How do select the penetrameter material?
36. How do select the penetrameter for dissimilar materials?
37. How many penetrameter strips are there?
38. How many wires are there in one strip?
39. What is the penetrameter material of wire for ASTM 3D?
40. How do select the penetrameters? Explain?
41. What are planner defects?
42. What are volumetric defects?
43. What is meant for elongated indication?
44. What is meant for rounded indication?
45. What is elongated indication?
46. How do control the back scattering?


1. What is principle of ultrasonic testing?
2. What is rate of search unit movement?
3. How do calibrate the equipment?
4. What is sensitivity of UT?
5. How many types of waves?
6. How many types of search units?
7. What are the angles for angle probe?
8. How much recommended range frequency is required for search unit?
9. What is DAC?
10. What is aqeostic impedance?
11. Why couplant is required during scanning?
12. How do select the coolant?
13. What is a piezoelectric effect?
14. What is reverse piezoelectric effect?
15. How do select the probe diameter?
16. How do select the frequency of probe?
17. How do select the angle of probe?


1. What is principle of LPT?
2. What are the parameters to be ensured before starting?
3. Do you know how many methods of testing?
4. Can you explain how do carryout the testing?
5. Do you know, what is table-672?
6. Do you know what dwell time is?
7. How do remove the excess penetrant?
8. How do ensure that excess penetrant has removed?
9. When do start inspection after developing?
10. How do ensure the test method is satisfactory?
11. What is the surface temperature?
12. What are limitations of LPT?
13. What is reverse bleeding action?


1a.What is principle of MPT?
1. What are the parameters to be ensured before testing?
2. What is ferromagnetic property?
3. How many methods are there to magnetizatize?
4. How many types of yokes are there?
5. What is lifting power of magnetic yoke?
6. What is maximum distance between yokes?
7. How much current is required for AC electromagnetic yoke?
8. How do ensure that you method is finding good results?
9. Why do demagnetize the substrate?
10. What is the maximum space between poles?
11. What are limitations of MPT?


1. What is relative humidity?
2. What is surface profile?
3. What is blotting test?
4. How do you measure surface profile?
5. How many grades of surface cleanliness?
6. How do you ensure the surface cleanliness?
7. What is dew point temperature?
8. What is wet bulb temperature?
9. How many rotations per minute required while rotate the whirling hygrometer?
10. What temperature is measured as soon as whirling has stopped?
11. Why wind direction is required before whirling the hygrometer?
12. What type of water is required to wet the wick?
13. Why not to expose hygrometer direct to sun or heat source while rotating?
14. What are the adhesion tests?
15. Do you know good weather conditions?
16. List out the duties of Gr.2 inspector?
17. List out the duties of Gr.3 inspector?
18. Do you know contractors malpractices?
19. What are the causes of paint faults?
20. What are the paint faults?
21. What is the difference between dry blisters and osmotic blisters?
22. What is chalking? What is cause?
23. What is pot life?
24. What is induction time?
25. What is cissing?
26. What is difference between holidays and pin holing?
27. How do ensure the wet film thickness?
28. How do ensure the dry film thickness?
29. What are the tests for drying and curing?
30. How do ensure the opacity?
31. How do ensure the density?
32. How do ensure the viscosity?
33. What are the paint and paint film tests?
34. What are the artificial weathering tests?
35. What are the methods of surface preparations?
36. What are the methods of arresting corrosion?
37. What is galvanic series?
38. How many methods are cathodic protections to steel?
39. What is difference between painting and coating?
40. What is maximum pressure for air compressor?


1. What is an anchor?
2. Where is an anchor required?
3. What is guide?
4. What is stopper?
5. When shims are required?
6. What is a sliding support?
7. What is requirement of seal welding?
8. Can Teflon tape use prior to seal welding?

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