This document specifies 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 ≥ 0,5 mm. It covers fully penetrated butt welds and all fillet welds. Its principles can also be applied to partial-penetration butt welds. Quality levels for beam-welded joints in steel are presented in ISO 13919-1. Three quality levels are given in order to permit application to a wide range of welded fabrication.