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?0,5mm. 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 ISO13919-1. 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. Several types of loads are considered, e.g. static load, thermal load, corrosion load, pressure load. Additional guidance on fatigue loads is given in AnnexB. The quality levels refer to production and good workmanship. This document is applicable to: a) non-alloy and alloy steels; b) nickel and nickel alloys; c) titanium and titanium alloys; d) manual, mechanized and automatic welding; e) all welding positions; f) all types of welds, e.g. butt welds, fillet welds and branch connections; g) the following welding processes and their sub-processes, as defined in ISO4063: — 11 metal arc welding without gas protection; — 12 submerged arc welding; — 13 gas-shielded metal arc welding; — 14 gas-shielded arc welding with non-consumable tungsten electrode; — 15 plasma arc welding; — 31 oxyfuel gas welding (for steel only). Metallurgical aspects, such as grain size and hardness, are not covered by this document.