This series of standards applies to welding of metallic materials in the manufacture and maintenance of railway vehicles and their parts. With respect to the railway environment, this series of standards defines the certification and quality requirements for the welding manufacturer to undertake new building and repair work. It then provides an essential link between performance requirements defined during design, and achieves appropriate quality welds during production and the demonstration of the required quality by inspection. This link is achieved by defining a weld performance class during design, which is based on safety and stress factors relevant to railway operation. Quality levels of imperfections are assigned to weld performance classes to ensure a certain level of performance intended during design. Based on these weld performance classes, certification levels for production as well as inspection and testing and qualifications for welding personnel of the manufacturer are specified. This standard deals with welding steel and aluminium alloys including castings. This part of the series provides general recommendations and definitions for welding railway vehicles and associated components. Except for specific provisions which are laid down contractually, this standard applies to all assemblies, sub-assemblies or parts welded by any welding process, either manual, partly mechanized, fully mechanized or automatic welding as defined in EN ISO 4063. This series of standards does not deal with product qualification. Items of equipment subject to specific regulations are not relevant to the scope of this series of standards, e.g. air reservoirs according to EN 286-3 and EN 286-4.