WELDING INSPECTOR INTERVIEW QUESTIONS Name & Sign: _____ARJED ALI_
Company__NSHC________ DATE__15-09-2011__
1. Which element could effect the hardness of carbon steel material? CARBON 2. How will you qualify welder for on-plot process piping? BY PERFORMANCE TEST(WQT)PER ASME-IX 3. Write 4 common welding defects in SMAW process? a) POROSITY e) SPATTERS
b) SLAG c) LOP f) ROOT CONCAVITY
d) LOF g) UNDERCUT(ROOT & TOE)
4. What are the causes of weld defect Porosity? Improper baking of Low Hydrogen electrode, inadequate shielding of welding area, improper cleaning of joint surface, inadequate preheating 5. Why pre-heat is done on some pipes before start welding? i.
ii. iii. iv.
It slows the cooling rate in the weld metal and base metal, producing a more ductile metallurgical structure with greater resistance to cracking; The slower cooling rate provides an opportunity for hydrogen that may be present to diffuse out harmlessly, reducing the potential for cracking; It reduces the shrinkage stresses in the weld and adjacent base metal, which is especially important in highly restrained joints; and It raises some steels above the temperature at which brittle fracture would occur in fabrication
6. If welder qualifies on 2G and 5G positions, how many positions he can qualified? All positions
7. Name the 2 types of flux used in SAW____________________ Neutral & basic
8. Which welding process shall be used for all passes for butt welds in piping and setin fittings less than 2 inch NPS? GTAW
9. DMW means____? Dissimilar Metal Weld, such as CS to SS
10. The maximum weekly repair rate for each welder should not exceed________% Weekly Linear Repair rate should not exceed by 2%.
11. Internal misalignment of butt joints shall not exceed ____mm. 1.6mm OR as per approved WPS
12. The maximum allowable SMAW electrode size for low hydrogen electrodes for all positions (except 1G/1F position) would be_____________ 4mm (dia.)
13. A minimum of ______ mm depth shall be removed by grinding or machining from thermally cut or gouged surfaces of air-hardenable materials.(chrome moly steels) 1.5 mm
14. Buttering or weld build-up on the prepared surfaces shall not exceed the lesser of _____ of the base metal thickness or _____ mm without the approval of company. Lesser of the 1/3rd of the base metal thickness or 10mm without company approval
15. How many tack welds required for 4inch diameter pipe joint? Minimum # 3
16. The back purge for low alloy steel shall reduce the oxygen level below____% By 1%
17. Seal welding of threaded connections shall cover all_______________ Exposed threads and shall have a smooth contour between the two surfaces
18. The minimum distance between parallel butt welds shall be _____mm or ______ times the wall thickness of the joint, whichever is ________ 20mm or three (03) times the wall thickness of the joint whichever is greater
19. All socket welds shall be at least minimum ___________pass weld. Two (02) passes
20. Minimum pre-heat temperature for 5Cr-0.5Mo material for any thickness would be________ 250°C
21. How many thermocouples shall be used for 20’’ dia pipe during PWHT? Two
22. PWHT temperature recorders calibration period shall be every________ Three months, May be extended up to 12 months if company approved
23. Maximum hardness limit for P No 1 material would be_________ 200BHN
24. The acceptance criteria for Magnetic particle examination shall be ASME SEC VIII, Appendix number_____ Appendix number-6
25. The acceptance criteria for Liquid penetrant examination shall be ASME SEC VIII, Appendix number_____ Appendix number-8
26. Heat input formula is ________ HI (J/Inch or J/mm) = (Volt X Amp X 60) / Travel speed
27. Potable electrode oven heated to ________deg centigrade minimum. 65°C
28. What are the essential variables in WPS? ‘P’ no, ‘F’ no, ‘A’ no, Base metal thickness, PWHT
29. What are the essential variables in PQR? ‘P’ no, ‘F’ no, ‘A’ no, PWHT
30. Electrode, filler wires and fluxes shall conform to ASME Section ______ Part___ Section II part C
31. Define Low hydrogen consumable? Consumable having less than or equal to 8ml of hydrogen per 100 gm of deposited weld metal
32. ”Tack welds shall be sufficient size to maintain joint alignment’’ The recommended tack thickness is ______ 3.2 to 4.8mm
33. Tack welds shall be sufficient size to maintain joint alignment’’ The recommended tack length is ______ 12.5 to 25.4mm
34. How much required ferrite content in austenitic stainless steel materials? 3% to 10%
35. Minimum calibration for pyrometer should be__________ Six months
36. Minimum holding time for P4 materials during PWHT should be_______ hours if thickness more than 13mm? 2 hours
37. Minimum pre heat temperature for carbon steel materials would be_______ as per JERES-W-011. 20°C
38. PWHT holding time for 25mm thickness of P8 materials should be_________hours? For ‘P’ no 8(Stainless steel), SS material normally PWHT is not required.
39. API SPEC 5L stands for_____________ Specification for line pipe
40. ‘‘If welder welded a joint without JCC card’’, what is your action as a welding inspector? If the welder is actually having JCC card & qualified for the joint he welded, but forget to keep the JCC with him during the time of weld, he may be given one more chance with warning letter. And if doesn’t have the JCC at all, he should be revoked from the project and welded joint shall be cut & re-welded with qualified welder.
41. How much RT % required for P4 materials? 100%
42. Category M equal or less than 600# coverage of RT on onshore piping is______ 100%
43. PMI means_______ Positive material identification
44. Difference between MT and PT? MT:- Only Applicable for ferromagnetic materials & able to detect both surface & sub surface discontinuities, compare to PT examination it takes less time for testing & inspection; Applicable for large temp range. PT:- Applicable for both ferromagnetic & non ferromagnetic materials & able t detect only surface discontinuities, It requires more time; Applicable for small temp range.
45. Can you allow using Nitrogen as a back purging for SS piping? If Yes Why? And If NO reason? No, nitrogen gas is slightly reactive, so the purpose of back purging (making inert atmosphere at the root side) will not be achieved.
46. Unless specified otherwise, the maximum interpass temperature shall be ______°C for P1 and P4 materials. 315°C
47. PWHT required for caustic services? Yes or No? If yes how much % and if no why? Yes, 100%
48. ‘’Welder welded joint without your fit-up inspection’’ What is your action as a welding inspector? If visually accepted that weld joint, then it will be radiographed. Based on RT report the joint will be accepted or rejected. At the same time welder should be given warning for not repeating such mistakes in future.
49. How you will do welder identification and marking after complete of the joint? From the information given close by the joint such: Line no; Joint no; WPS no; Fit-up date, Piping QC sign; Welder no, date of joint welded; Sub con/Con signature. Visual Acc/Rej:
50. All pressure containing welds other than butt welds including branch connections such as weldolets, sockolets and weld bosses shall be 100% examined for what type of materials and what type of NDT? As per JERES-W-011 P3, P4 & P5 materials shall be 100% examined with florescent MT.
