ISO 5817 — Weld Quality Levels (B, C, D)
Introduction
EN ISO 5817 defines three quality levels for fusion-welded joints. Each level sets dimensional limits for the imperfections defined in ISO 6520-1, serving as acceptance criteria.
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The 3 Levels
| Level | Description | Typical Application |
|---|---|---|
| D | Moderate | Simple structures, static loads |
| C | Intermediate | General steel construction (EN 1090 EXC2) |
| B | Stringent | Pressure equipment, offshore, nuclear |
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Example Limits
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| Cracks | Not permitted | Not permitted | Not permitted |
| Porosity (max Ø) | 0.5×s (max 5mm) | 0.4×s (max 4mm) | 0.3×s (max 3mm) |
| Undercut | 1.0 mm | 0.5 mm | 0.5 mm (smooth) |
| Lack of fusion | Limited | Not permitted | Not permitted |
| Lack of penetration | Limited | ≤ 0.2×s | Not permitted |
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EN 1090 — Execution Classes
| Class | ISO 5817 Level | Application |
|---|---|---|
| EXC1 | D | Simple structures |
| EXC2 | C | Buildings, pedestrian bridges |
| EXC3 | B | Bridges, fatigue |
| EXC4 | B+ | Nuclear, offshore |
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*Article based on EN ISO 5817:2014. Published on WeldFC Academy.*