COT Visual Assessment 4 — Questions and Answers
Question 1: During a visual inspection of a weld joint, you notice the weld bead has an irregular, uneven surface with sharp ridges and valleys. This surface condition is best described as:
- Undercut
- Overlap
- Irregular bead profile (Correct answer)
- Porosity
Correct answer: Irregular bead profile
An irregular bead profile refers to a weld surface that lacks uniformity, exhibiting sharp ridges, valleys, or uneven contours. Undercut is a groove melted into the base metal, overlap is weld metal overflowing onto the base metal without fusion, and porosity refers to gas pockets within or on the weld surface.
Question 2: A COT inspector is examining a fillet weld and notices that the weld metal has flowed over the toe of the weld onto the base metal without fusing to it. This discontinuity is called:
- Cold lap (overlap) (Correct answer)
- Undercut
- Incomplete fusion
- Excessive convexity
Correct answer: Cold lap (overlap)
Cold lap, also known as overlap, occurs when molten weld metal flows over the base metal at the toe of the weld but does not fuse to it, creating a notch-like condition. Undercut is a groove in the base metal, incomplete fusion refers to lack of bonding between weld passes or between weld and base metal internally, and excessive convexity means the weld face is too high above the base metal plane.
Question 3: When visually inspecting a groove weld, the inspector finds that the root of the weld does not penetrate completely through the joint thickness. This condition is termed:
- Underfill
- Incomplete joint penetration (IJP) (Correct answer)
- Root concavity
- Shrinkage void
Correct answer: Incomplete joint penetration (IJP)
Incomplete joint penetration (IJP) occurs when the weld metal does not extend through the full thickness of the joint as required. Underfill refers to a depression in the weld face below the adjacent base metal surface, root concavity is a concave condition at the root surface, and a shrinkage void is a cavity formed by solidification shrinkage.
Question 4: A visual inspector observes elongated, worm-shaped porosity aligned along the weld axis in a completed weld. This specific type of porosity is known as:
- Cluster porosity
- Piping porosity (wormhole) (Correct answer)
- Uniformly scattered porosity
- Surface porosity
Correct answer: Piping porosity (wormhole)
Piping porosity, often called wormhole porosity, consists of elongated gas pockets that form in a tubular or worm-like shape, typically oriented along the weld axis. Cluster porosity is a localized grouping of pores, uniformly scattered porosity is distributed randomly throughout the weld, and surface porosity refers to pores open to the weld surface.
Question 5: During visual examination of a completed structural steel weld, the inspector measures the weld face and finds the center of the weld crown is 7mm above the base metal plane on a flat position weld with a specified maximum convexity of 3mm. The correct action is to:
- Accept the weld since convexity adds strength
- Reject the weld for excessive convexity (Correct answer)
- Mark it for radiographic testing before deciding
- Accept it if the weld legs meet the minimum size requirement
Correct answer: Reject the weld for excessive convexity
Excessive convexity is a rejectable condition because an overly high crown creates a stress concentration at the weld toes and does not meet code-specified dimensional requirements. The weld must be rejected and repaired by grinding to bring the convexity within the allowable limit. Convexity does not add usable strength and actually introduces notch effects.
Question 6: A visual inspector is examining a multi-pass weld and finds slag inclusions trapped between the first and second weld passes. What welding practice most likely caused this discontinuity?
- Using too high a travel speed
- Failure to adequately clean slag from the prior pass before depositing the next pass (Correct answer)
- Using too low an amperage setting
- Employing the wrong electrode angle
Correct answer: Failure to adequately clean slag from the prior pass before depositing the next pass
Interpass slag inclusions result when slag from a previous weld pass is not completely removed before the next pass is deposited. The trapped slag becomes embedded in the weld metal and cannot be detected visually in the finished weld without proper inter-pass inspection. All passes must be cleaned of slag before subsequent passes are applied.
COT Visual Assessment 4
During a visual inspection of a weld joint, you notice the weld bead has an irregular, uneven surface with sharp ridges and valleys.
This surface condition is best described as: