Weld Defects Flashcards
(79 cards)
What is a defect?
A flaw(s) by nature or by accumulated effect, render a pile or product unable to meet minimum acceptance standards/specifications.
What is a discontinuity?
An interruption of the typical structure of a material.
Is a discontinuity a defect?
Not, if it meets standards.
What am I? Amount a joint is out of alignment at the root.
Misalignment (hi-lo)
What is the cause, prevention and repair of a misalignment?
Cause: Carelessness/ joining different thicknesses
Prevention: Workmanship/ Transition angle not exceeding 2.5 to 1
Repair: Grinding
What am I? A groove cut at the toe of the weld and left unfilled.
Undercut
What is the cause, prevention and repair of a undercut?
Cause: High amperage, electrode angle, long arc length, rust
Prevention: set machine on scrap metal to correct parameter/ clean metal before welding
Repair: Weld with smaller electrode.
_____ typically has an allowable limit. On a plate, it is normally the lesser of 0.8 mm or 5%. Anything deeper than 1 mm must be repaired.
Undercut
What am I? The weld surface is below the adjacent surfaces of the base metal.
Insufficient Fill or Under Fill (groove weld)
What is the cause, prevention, and repair for insufficient fill or under fill?
Cause: Improper welding techniques
Prevention: Proper welding technique for weld type/ position. Use stripper beads before the cover pass.
Repair: Simply weld to fill.
What am I? The weld surface is below the adjacent surfaces of the base metal at the weld root.
Insufficient Fill on the Root Side/ AKA: Suckback
What is the cause, prevent and repair for Insufficient fill on the root side (suckback)?
Cause: Improper joint preparation/ excessive weld pool heat
Prevention: Correct cause.
Repair: Backweld to fill.
What are other causes for insufficient fill at the root?
Welding a root pass too wide can cause the bead to sag (overhead position), or some liquids like water/molten steel, try to cover as much surface area possible.
What are the 4 steps to removing a root pass by grinding?
- Recreate groove geometry
- recreate root opening with saw/ die grider and 1/16- 1/8” cut off wheel
- Open groove angle
- Feather start and stop smoothly
What am I? Concavity or convexity of a fillet weld which exceeds the specified allowable limits.
Excessive concavity or convexity (fillet weld)
What is the cause, prevent and repair for excessive concavity or convexity?
Cause: amperage/travel speed
Prevention: Observe proper parameters/techniques
Repair: Grind off or weld on.
What am I? The amount of a groove weld which extends beyond the surface.
Reinforcement (can be face and root)
To prevent excessive reinforcement by standard, reinforcement should be flush to ____ (pipe) or flush ___ on plate or structural shapes.
1/16” pipe or 1/8” plate
What is the cause, prevent and repair for excessive reinforcement?
Cause: Travel speed and amperage too low.
Prevention: Set amperage and travel speed on scrap plate
Repair: Remove excessive reinforcement and feather the weld toes to a smooth transition.
To prevent insufficient reinforcement, under fill may be up to ___ of metal thickness, not exceeding ____ as long as the thickness is made up in the opposite reinforcement.
5%, not exceeding 1/32”
What is the cause, prevent and repair for Insufficient reinforcement.
Cause: on root: too little filler metal will cause thinning of filler metal. In Oh position: too hot/too wide will cause dropping of open root puddle.
Prevention: proper welding technique. use backing/ consumable inserts. Backwelding
Repair: Increase face reinforment
What am I? When the weld exhibits less than a 135 degree transition angle at the weld toe.
Improper welding contour
What is the cause, prevent and repair for improper weld contour?
Cause: poor welding technique.
Prevention: use proper technique. Weave or whip motion.
Repair: Weld face must be feather into the base plate.
What am I? When the face of the weld extends beyond the toe of the weld.
Overlap
