EN ISO 5817: Complete Imperfection Table with Quality Levels B, C and D
Introduction
EN ISO 5817:2005 defines the quality levels for imperfections in fusion welded joints in steel. It is the mandatory reference standard for weld inspection of steel structures and safety-critical components across Europe.
Three Quality Levels
| Level | Designation | Typical application |
|---|---|---|
| B | Stringent | Fatigue, pressure, safety-critical |
| C | Intermediate | General steel structures, EN 1090 |
| D | Moderate | Low-risk structures |
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Group 1 — Cracks
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| Longitudinal crack | Not perm. | Not perm. | Not perm. |
| Transverse crack | Not perm. | Not perm. | Not perm. |
| Crater crack | Not perm. | Not perm. | Not perm. |
General rule: Any type of crack is unacceptable at all quality levels.
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Group 2 — Cavities (Porosity)
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| Max. porosity (% proj. area) | 2.5% | 1.5% | 1.0% |
| Max. single pore (d ≤) | 0.3t or 4 mm | 0.2t or 3 mm | 0.1t or 2 mm |
| Wormhole porosity | ≤ 1.5% | ≤ 1.0% | Not perm. |
| Crater pipe (d ≤) | 0.2t or 3 mm | 0.1t or 2 mm | Not perm. |
*t = thickness of thinner part*
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Group 3 — Solid Inclusions
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| Slag inclusion (h ≤) | 0.3t or 3 mm | 0.2t or 2 mm | 0.1t or 1.5 mm |
| Total length (l ≤) | t or 75 mm | 2t/3 or 50 mm | t/3 or 25 mm |
| Copper inclusion | Not perm. | Not perm. | Not perm. |
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Group 4 — Lack of Fusion and Penetration
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| Lack of sidewall fusion | Not perm. | Not perm. | Not perm. |
| Incomplete penetration (h ≤) | 0.2t or 2 mm | 0.1t or 1.5 mm | Not perm. |
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Group 5 — Shape Imperfections
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| Excess weld metal — butt (h ≤) | 1+0.25b or 10 mm | 1+0.15b or 7 mm | 1+0.1b or 5 mm |
| Continuous undercut (h ≤) | 0.2t or 1 mm | 0.1t or 0.5 mm | 0.05t or 0.5 mm |
| Intermittent undercut (h ≤) | 0.2t or 2 mm | 0.1t or 1 mm | 0.05t or 0.5 mm |
| Linear misalignment (hi ≤) | 0.25t or 5 mm | 0.15t or 4 mm | 0.1t or 3 mm |
*b = weld width; a = design throat*
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Group 6 — Miscellaneous Imperfections
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| Spatter | Permitted | Minimal | Not perm. |
| Surface irregularity (h ≤) | 0.5 mm | 0.2 mm | 0.1 mm |
| Root concavity (h ≤) | 0.2t or 2 mm | 0.1t or 1 mm | Not perm. |
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Practical Application: EN 1090-2
| Execution Class (EXC) | ISO 5817 Quality Level |
|---|---|
| EXC1 | D |
| EXC2 | C |
| EXC3 | B |
| EXC4 | B + additional requirements |
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