456A Weld Quality Control 2

Question 1

What is ultrasonic testing (UT) and what are its advantages over radiographic testing?

Accepted 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

Answer

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?

Accepted 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

Answer

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?

Accepted 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

Answer

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?

Accepted 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

Answer

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?

Accepted Answer

Maximum 1 mm (1/32 in.) depth for statically loaded structures; more restrictive limits apply to dynamically (cyclically) loaded structures and critical connections

Answer

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.

Red Seal Welder 456A Practice Test

Red Seal Welder 456A Practice Test

456A Weld Quality Control 2