CWI Fundamentals 3 — Questions and Answers
Question 1: Which nondestructive examination (NDE) method is most effective for detecting subsurface volumetric discontinuities in a weld?
- Liquid penetrant testing (PT)
- Magnetic particle testing (MT)
- Radiographic testing (RT) (Correct answer)
- Visual testing (VT)
Correct answer: Radiographic testing (RT)
Radiographic testing uses X-rays or gamma rays to reveal internal volumetric flaws such as porosity and inclusions throughout the weld cross-section.
Question 2: A weld symbol with a circle at the intersection of the reference line and arrow indicates:
- A weld all around (Correct answer)
- A field weld
- A flush finish
- A complete joint penetration weld
Correct answer: A weld all around
A circle placed at the junction of the reference line and arrow on a weld symbol signifies that the weld is to be made all around the joint.
Question 3: What is the primary purpose of using shielding gas in GMAW?
- To flux and clean the base metal surface
- To protect the molten weld pool from atmospheric contamination (Correct answer)
- To provide additional filler metal to the joint
- To control arc voltage automatically
Correct answer: To protect the molten weld pool from atmospheric contamination
Shielding gas in GMAW surrounds the arc and weld pool to prevent oxygen, nitrogen, and moisture from contaminating the molten metal.
Question 4: In the context of welding procedure qualification, what does 'essential variable' mean?
- A variable that must be recorded but need not be re-qualified if changed
- A variable whose change requires re-qualification of the welding procedure (Correct answer)
- A variable controlled automatically by the welding machine
- A variable used only during welder performance qualification
Correct answer: A variable whose change requires re-qualification of the welding procedure
An essential variable is one whose change beyond specified limits is considered to affect the mechanical properties and requires re-qualification of the WPS.
Question 5: Which destructive test is used to evaluate the ductility and soundness of a weld by bending the specimen?
- Charpy V-notch impact test
- Guided bend test (Correct answer)
- Hardness test
- Tensile test
Correct answer: Guided bend test
The guided bend test bends a weld specimen around a mandrel to a specified angle, revealing lack of fusion, cracks, or porosity on the tension surface.
Question 6: Electrode classification E7018 indicates a minimum tensile strength of:
- 60,000 psi
- 70,000 psi (Correct answer)
- 80,000 psi
- 90,000 psi
Correct answer: 70,000 psi
The first two digits '70' in E7018 indicate a minimum tensile strength of 70,000 psi (70 ksi) for the deposited weld metal.
Question 7: What is 'undercut' in a weld?
- Weld metal melted and deposited below the base metal surface level
- A groove melted into the base metal along the weld toe that is not filled (Correct answer)
- Excess weld metal extending beyond the weld toe
- A crack forming along the heat-affected zone
Correct answer: A groove melted into the base metal along the weld toe that is not filled
Undercut is a groove burned into the base metal at the toe or root of a weld that is left unfilled by weld metal.
CWI Fundamentals 3
Which nondestructive examination (NDE) method is most effective for detecting subsurface volumetric discontinuities in a weld?