On what criteria should a defect identified during the visual testing of weld seams be accepted?

Acceptance criteria for a welding imperfection in visual testing

To decide whether a welding imperfection observed during visual testing is acceptable or not, it is necessary to refer to the acceptance criteria provided by the quality welding standard in place:

In general, all these welding quality management standards are based on the EN ISO 5817 standard. Depending on the quality level demanded by the standard, it gives mathematical formulas to apply in order to calculate the permissible tolerances.

The EN ISO 5817 standard sets three levels of quality:

• Basic :                level D
• Normal :           level C
• Strict :                level B

The tolerances for welding imperfection will be all the more stringent as the demanded quality level for the weld seam is significant.

Here is an excerpt from the EN ISO 5817 standard concerning the quality of welds:

It is always important to refer to the welding quality management standard in place because it sets the acceptance criteria for imperfection.

For example, under the EN 1090-2: EXC2 standard (§7.1), the acceptance criteria correspond to the EN 5817 quality level C except for the following welding imperfections:

• Undercut (5011,5012) – overflow (506) – accidental arc strike (601) – open crater shrinkage (2025): quality level D is required
• Lack of inter-run fusion (505) – micro lack of fusion (401): always allowed

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