Welder how-to

How to Inspect a Weld for Common Defects

Visual inspection is the first line of quality control.

Updated By the Career Education Institute Curriculum Team
Quick answer

Visual inspection is the first line of quality control. In short: let; check; look, then complete the remaining steps below.

Step by step

  1. Let the weld cool and clean off slag and spatter.

  2. Check the weld size and length against the drawing.

  3. Look for cracks. Any crack is generally rejectable.

  4. Check for porosity (pinholes) on the surface.

  5. Look for undercut along the toes of the weld.

  6. Check for overlap, incomplete fusion and uneven profile.

  7. Mark and repair defects according to the procedure, then reinspect.

Safety reminders for welders

  • Wear a properly shaded welding helmet, flame-resistant clothing and gloves
  • Use ventilation or fume extraction, especially for stainless and galvanized steel
  • Follow hot work permits and keep a fire watch where required
  • Secure gas cylinders upright and away from heat

SMAW (stick) · GMAW (MIG) · FCAW (flux-core) · GTAW (TIG) · Bead · Weld puddle: see the full welder glossary.

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