What are the most common weld defects?

The ten we most commonly detect are cracks, lack of fusion, incomplete penetration, porosity, slag inclusions, undercut, overlap, excessive reinforcement, burn-through and distortion.

Which standard applies to weld inspection?

Structural welding and inspection in Australia is generally carried out to AS/NZS 1554, which sets acceptance criteria for weld quality and NDT.

How are weld defects detected?

Visual inspection catches surface defects, while ultrasonic, magnetic particle and dye penetrant testing detect surface and internal flaws depending on the material and defect type.

Defects & Failure

Top 10 Weld Defects

Welds are only as strong as their defects allow. Here are the ten most common weld defects and how they're detected.

1 April 2026 2 min read

Why Weld Defects Matter

Weld defects reduce strength and can initiate cracks and failures. Inspection to AS/NZS 1554 catches them before load is applied.

The Top 10

The defects we most commonly detect:

Cracks
Lack of fusion
Incomplete penetration
Porosity
Slag inclusions
Undercut
Overlap
Excessive reinforcement
Burn-through
Distortion

Related Services

NDT Australia provides these services Australia-wide. Get certified, mobile inspection with clear reporting and fast turnaround.

Weld Inspection UT MPI PT

Frequently Asked Questions

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