Welding and fabrication
ISO 5817: Welding, fusion-welded joints in steel, nickel, titanium and their alloys, quality levels for imperfections
The standard most often used to decide whether a weld is acceptable.
Reference noteThis page is an independent plain-language summary written by QUALITAS TR. It does not reproduce the standard. Always work from the current official edition, available from ISO, the International Organization for Standardization, and national standards bodies such as TSE in Turkey (official page). QUALITAS TR supports organisations against this standard; it does not certify them.
01Purpose
ISO 5817 provides quality levels of imperfections in fusion welded joints in steel, nickel, titanium and their alloys. Three levels are defined: B (stringent), C (intermediate) and D (moderate).
02Scope
Covers material thicknesses above a lower limit and applies to arc welding processes; beam welding is not covered. Imperfections are classified according to ISO 6520-1. For aluminium, ISO 10042 is the equivalent standard.
03Main requirements
- Limits for surface imperfections such as cracks, porosity, undercut, excess weld metal and incomplete root penetration
- Limits for internal imperfections
- Limits for geometric imperfections such as misalignment and incorrect throat
- Multiple imperfections
- Guidance on application for fatigue loaded structures in an informative annex
04Typical applications and industries
Chosen by the design code or product standard: EN 1090-2 links execution classes to quality levels, for example. See our weld imperfections guide.
05Audit and inspection considerations
- Is the quality level specified for each joint?
- Is the evaluation done after final treatment?
- Are NDT acceptance levels consistent with the quality level?
06Common nonconformities
- Quality level not specified, inspector improvises
- Undercut and excess reinforcement above limits
- Incomplete root penetration in single sided welds
07How QUALITAS TR can support
Our welding inspection evaluates welds against the specified ISO 5817 quality level.