This International Standard 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 priciples of this International Standard may 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. They are designated by symbols B, C and D. Quality level B corresponds to the highest requirement on the finished weld. The quality levels refer to production quality and not to the fitness-for-purpose (see 3.2) of the product manufactured. This International Standard applies to: — unalloyed and alloy steels; — nickel and nickel alloys; — titanium and titanium alloys; — manual, mechanized and automatic welding; — all welding positions; — all types of welds, e.g. butt welds, fillet welds and branch connections; — the following welding processes and their defined sub-processes in accordance with ISO 4063: — 11 metal-arc welding without gas protection; — 12 submerged-arc welding; — 13 gas-shielded metal-arc welding; — 14 gas-shielded welding with non-consumable electrodes; — 15 plasma arc welding; — 31 oxy-fuel gas welding (for steel only). Metallurgical aspects, e.g. grain size, hardness, are not covered by this International Standard.