ISO 5817 is the standard that sets acceptance limits for imperfections in fusion-welded joints in steel, nickel and titanium alloys. The equivalent standard for aluminium is ISO 10042.
The standard defines three quality levels:
| Level | Meaning | Where it is used |
|---|---|---|
| B | The strictest level | High fatigue loading, pressure, safety-critical parts |
| C | Intermediate level | General steel structures and most machinery manufacturing |
| D | The least strict level | Non-critical, lightly loaded welds |
Which level applies is decided by the designer or the customer; it must be written on the drawing or in the specification. If no level is given, ask before starting the inspection.
Imperfections most often checked in visual inspection
- Cracks: Not accepted at any of the three levels.
- Porosity and gas pores: Limited by size and frequency; tightest at level B.
- Undercut: Depth is limited relative to thickness.
- Excess weld metal and excess penetration: Height is limited relative to the weld width.
- Incomplete penetration and lack of fusion: Generally not accepted at levels B and C.
- Linear misalignment: Limited as a proportion of thickness.
- Throat thickness of fillet welds: Deviation from the design value is limited.
For exact limit values refer to the current edition of the standard; limits vary with the type of imperfection and the part thickness.
Related reading: AWS D17.1 explained · Weld records on Gulf oil & gas projects · What is a WPS?
Which of these is in your records?
Knowing the list is easy. The real question is which one is missing from your own records. These gaps slip past when files are read by eye, and auditors look for them first. Upload your weld photo to NTB SpecPro and quickly see which points may carry risk, the likely reason and a suggestion.
Making inspection easier
Measuring every imperfection on the shop floor, comparing it with the limit in the standard and writing it into the report takes time. The NTB SpecPro welding module marks possible imperfections from a photo, gives an evaluation suggestion for the level you select and prepares the PDF inspection report. The evaluation is always checked and approved by authorized inspection personnel.
Free tool: Weld consumable weight calculator
Prepared by NTB SpecPro process quality engineering; reviewed by an engineer holding the International Welding Engineer (IWE) qualification. Questions: info@ntbspecpro.com
More articles