456A Weld Quality Control 2 — Questions and Answers
Question 1: What is ultrasonic testing (UT) and what are its advantages over radiographic testing?
- A hearing test for welders
- A method using high-frequency sound waves to detect internal discontinuities; advantages include immediate results, no radiation hazard, ability to detect planar defects (cracks, lack of fusion), and portability (Correct answer)
- A method using ultrasonic cleaning of welds
- A surface-only inspection method
Correct answer: A method using high-frequency sound waves to detect internal discontinuities; advantages include immediate results, no radiation hazard, ability to detect planar defects (cracks, lack of fusion), and portability
UT sends high-frequency sound waves through the weld using a transducer. Internal discontinuities reflect the sound back, and their location, size, and orientation can be determined. Advantages over RT include: no radiation hazard, immediate results, superior detection of planar defects (cracks, lack of fusion), portability, and ability to inspect thick sections.
Question 2: What is magnetic particle testing (MT/MPI) and what type of discontinuities does it detect?
- Testing the magnetic properties of filler metals
- Applying magnetic particles to a magnetized workpiece to detect surface and near-surface discontinuities such as cracks, incomplete fusion, and porosity in ferromagnetic materials (Correct answer)
- Measuring the magnetic field strength of the welding arc
- Testing whether the base metal is magnetic
Correct answer: Applying magnetic particles to a magnetized workpiece to detect surface and near-surface discontinuities such as cracks, incomplete fusion, and porosity in ferromagnetic materials
Magnetic particle inspection (MPI) magnetizes the test area and applies iron particles (dry or in a liquid suspension). Discontinuities at or near the surface disrupt the magnetic field, attracting and holding particles in visible patterns (indications). It detects surface and near-surface cracks, lack of fusion, and similar discontinuities in ferromagnetic materials only.
Question 3: What is a welder qualification test under CSA W47.1?
- A written exam on welding theory
- A practical test where a welder produces test welds on a specific joint configuration, position, and process; the welds are then tested (bend, RT, or UT) to verify the welder can produce acceptable quality (Correct answer)
- An eye exam to check the welder's vision
- A safety certification course
Correct answer: A practical test where a welder produces test welds on a specific joint configuration, position, and process; the welds are then tested (bend, RT, or UT) to verify the welder can produce acceptable quality
Under CSA W47.1, welder qualification requires producing test weld coupons using the specific process, position, and joint type being qualified. Test specimens are cut from the coupon and subjected to guided bend tests, RT, or UT to verify they meet acceptance criteria. Qualification is valid for a specific process, position range, and material thickness range.
Question 4: What is dye penetrant testing (PT/LPI) and when is it used?
- Dyeing the weld for appearance
- Applying a visible or fluorescent dye to detect surface-breaking discontinuities by capillary action; used on non-ferromagnetic materials and when MPI cannot be used (Correct answer)
- Testing the colour of the weld metal
- A method for measuring weld penetration depth
Correct answer: Applying a visible or fluorescent dye to detect surface-breaking discontinuities by capillary action; used on non-ferromagnetic materials and when MPI cannot be used
Liquid penetrant inspection (LPI/PT) applies a dye (visible red or fluorescent) to the surface, which is drawn into surface-breaking discontinuities by capillary action. After removing excess penetrant and applying a developer, the dye bleeds back out of flaws, making them visible. It works on any non-porous material, including non-ferromagnetic metals where MPI cannot be used.
Question 5: What is the acceptance criteria for undercut in a structural fillet weld according to CSA W59?
- Any undercut is acceptable
- Maximum 1 mm (1/32 in.) depth for statically loaded structures; more restrictive limits apply to dynamically (cyclically) loaded structures and critical connections (Correct answer)
- Maximum 5 mm depth
- Undercut is only measured on groove welds
Correct answer: Maximum 1 mm (1/32 in.) depth for statically loaded structures; more restrictive limits apply to dynamically (cyclically) loaded structures and critical connections
CSA W59 limits undercut depth based on loading type and member category. For statically loaded structures, undercut generally must not exceed 1 mm (1/32 in.) depth. For cyclically loaded (fatigue-sensitive) structures, limits are more restrictive and may be as low as 0.25 mm (0.01 in.). Undercut creates stress concentrations that reduce fatigue life.
Question 6: What documentation must accompany a completed structural weld per CSA W47.1 and W59?
- Only the welder's name
- Welder identification/qualification records, WPS used, NDE reports, material test reports (MTRs), fit-up inspection records, and any non-conformance reports (Correct answer)
- Only photographs of the finished weld
- No documentation is required if the weld passes visual inspection
Correct answer: Welder identification/qualification records, WPS used, NDE reports, material test reports (MTRs), fit-up inspection records, and any non-conformance reports
Complete weld documentation under CSA W47.1/W59 includes: welder identification marks and qualification records (valid for the process/position), the WPS number and parameters used, all NDE reports (VT, RT, UT, MT, PT as required), base and filler material certifications (MTRs), fit-up and preheat inspection records, and any non-conformance/repair documentation.
456A Weld Quality Control 2
What is ultrasonic testing (UT) and what are its advantages over radiographic testing?