ISO 5817:2003 (corrected version:2005) provides quality levels of imperfections in fusion-welded joints (except for beam welding) in all types of steel, nickel, titanium and their alloys. It applies to material thickness above 0,5 mm. It covers fully penetrated butt welds and all fillet welds. The principles of ISO 5817:2003 (corrected version:2005) may also be applied to partial-penetration butt welds.