Aramco Specific Evaluations for Welding / Mech. QC candidates 1. Describe the difference between QA/QC? QA provides the objective needed to give a maximum confidence for quality while QC is involved with the monitoring of a process and eliminating the causes of any deficient output with any process, which has effect on quality. 2. What is an essential variable as related to a Weld Procedure Specification (WPS)? Essential variables are those in which a change, is considered to affect the mechanical properties of the weldment and shall require requalification of the WPS. 3. What is the relationship between Procedure Qualification Record (PQR) and a WPS? PQR is a record of the welding data used to weld a test coupon, it contains the result of the tested specimens, while the WPS is the written form of the welding procedure for making a specified kind of weld joint using specified base and filler materials. 4. Heat input (SMAW per ASME SEC IX) is a common of what two electrical characteristics & travel speed? Volts and amperes, heat input = volts x amperes / travel speed. 5. Excessive heat input is mainly attributed to what poor welding techniques during SMAW process? Incorrect welding technique 6. What are 3 potential sources of Hydrogen encountered during SMAW process? • • •
Damp electrodes Moist surface Improper weather condition.
7. What are several likely causes of porosity in carbon steel welds using the SMAW process? • • • •
Excessive moisture in the flux Arc length too long Use of low welding current Damage electrode flux
8. What dimension is measured to determine the size of a concave fillet weld?
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Its height and length 9. What dimension is measured to determine the size of a convex fillet weld? Its throat thickness 10. Where would cracking most likely occur from excessive current input in a single pass weld? Liquation cracking 11. Using GTAW process, describe what happens to a root pass applied without purging/back gauging on SS? It will produce oxidizing, coking to the weld metal. 12. Name 3 of the 5 mechanical tests in ASME IX employed for procedure & performance qualifications? • • • • •
Tension test Guided bend test Filler-weld test Notch-toughness test Macro test
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Mechanical/NDT, assume SMAW process for all questions. 1. How is Magnetic Particle inspection of a weld using wet continuous test method performed? • • • •
Measure and record the temperature of examination surface, temperature shall not exceed 135*F (57 *C ) Clean examination surface and adjacent area within 3 inches ( 76.2 mm ) of the examine area Perform visual inspection of the examination surface for cleanliness and discontinuities Check for remnant magnetic fields exceeding + 2 gauss.
2. Indications with Liquid Penetrant Testing are easily seen if the surface has been prepared by grinding prior to testing? True or False? Why? False, surface discontinuities of the examine area will not be seen or occur 3. Name an NDT method and techniques that employs a reflected sound beam that can be used for the volumetric examination of welds? Ultra sonic test 4. List 3 advantages of RT over other NDT Methods? Advantages: • Permanent record • Little surface preparation • Defect identification very easy • No material limitation • Not so reliant operator skill Disadvantages: • Requires bulky and expensive machinery • Expensive consumables • Cannot detect plate laminations, lack of inter-run fusion or cracks perpendicular to x-ray beam 5. If a product is to be stress relieved, why is it important to use exactly the same RT procedure before and after stress relieving? To ensure the weld has no cracks or defects. 6. A dark narrow area 2-3 mm wide appears on a radiograph all along the edge of the area of the representing the weld. The joint has a 60 Degree double vee groove. What is the indication most likely to be? Slag inclusion
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7. A localized darker density Radiographic image with fuzzy edges in the center of the weld image that may or may not be wider than the width of the root pass images is most likely what ? Burn through 8. Name 5 common film artifacts that may be cause for rejection of the Radiographic film? • • • • •
Film marks Low density Poor identification Fog and processing irregularities Unacceptable technique and set-up
9. When the radiation source is located inside piping with the film located outside, single-wall exposure and single-wall view, name this type of exposure? Panoramic- single wall exposure, single wall viewing (single wall single image) 10.
How do gamma rays compare with x-rays when applied to RT of welds?
x-rays generally produces better quality radiograph and safe, while gamma sources permanently produces radiation and require shielding when not in used. 11. • • • •
Per ASME B31.3, name three of the four Categories of Fluid Service? Category “D” Fluid service Category “M” Fluid service Normal Fluid service (NFS) High Pressure Fluid service
12. Per ASME B31.3 who is responsible for classification of service to a given category? Owner 13. Per ASME B31.3 what are the RT requirements for Socket welds in a severe cycle service? Random RT 14. Relating to the above question, give 2 reasons why random RT of socket welds is recommended even though code does not require RT? •
Gap verification 4
15. Briefly describe good QC practice relating to the installation & bolting of flanges? • • •
Bolt holes shall be aligned within 1.8 mm maximum offset Flange bolts and studs shall be long enough to penetrate completely through the nuts minimum of 3 threads protrusion Bolts nuts faces and nut bearings surfaces shall be lubricated before installation
16. What is an often- overlooked inspection/ NDT requirement on the installation of the orifice flanges? Welds root at orifice flanges shall be ground or machined smooth and flush on the inside of the pipe, and it requires RT. 17. What API documents apply to the replacement of the existing floor for an Aboveground Oil Storage tank? API 653 18. Relating to weld fabrication shop evaluation prior to the beginning of pipe welding for a major project, what are several key items you would look for as the Inspector before you approved the shop for welding? The inspector must considered the following: material specification, welders qualification, WPS Hint: 5M + E formula = Manpower, Methods, Materials, Machines, Measurements, Environment Per SAES – W-011 1. What is the maximum size of low hydrogen (E7018) permitted? 5mm for the 1g/1f position, 4mm other positions For non-hydrogen; 5mm for all positions 2. What are the diameter limitations (per pipe size) for the different welding processes? SMAW 3”- up
GTAW ½” to 10 ‘
GMAW 3”- up
3. What is the requirement (Material, location) for bridges tacks? It should be same materials, electrodes, minimum preheat and should be located above the root area 4. For temporary supports and attachments welded to the pipe, what are requirements related to Materials? NDT? 5
It should be same materials, and PT or MPT 5. What is the minimum amount of time that E-7018 electrodes can be kept out in the field? Up to 4 hours 6. What is the minimum drying temperature and drying time? 260°C- 430°C for 2 hours 7. How many times can electrodes be re-baked? One time only 8. What is the maximum internal misalignment of butt joints? 1.5 mm max. 9. Piping during preparation before fit-ups shall be cleaned/ground nternally/externally for what distance from the edge of the prepared joint? Ground internally/externally for at least 25 mm, and should be clean 10. Moist surfaces require moisture removal and surface to be preheated must be preheated to what distance from the joint edge? 75mm from the joint edge
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