European/International Standard EN ISO 5817 has been prepared by ISO/TC 44/SC 10 "Unification of requirements in the field of metal welding", in collaboration with CEN/TC 121/SC 4 "Quality management in the field of welding". The responsible German committee is Joint Committee NA 092-00-04 AA "Qualitätssicherung beim Schweißen (DVS AG Q5)" ("Quality assurance of welding (DVS AG Q5)") at the NAS at DIN. This 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 principles of this standard may also be applied to partial-penetration butt welds. The three quality levels (designated by symbols B, C and D) are given in order to permit application to a wide range of welded fabrication. 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 of the manufactured product. This standard applies to manual, mechanized and automatic welding and for all welding positions. Metallurgical aspects such as grain size, hardness, are not covered by this standard. This standard differs from DIN EN ISO 5817:2006-10 as follows: a) the introduction has been revised; b) the scope now covers several types of load; c) normative references have been updated; d) the terms and definitions in 3.7 (smooth weld transition) and 3.8 (fatigue class) have been added; e) previously missing symbols have been added to clause 4; f) in Table 1, 1.24, the temper colour and 3.1, linear misalignment between plates, have been added; g) Annex C containing additional requirements for welds in steel subject to fatigue has been added; h) the Bibliography has been updated.