This document applies to wrought aluminium and aluminium alloy enclosures and their welding. These enclosures are pressurized with dry air, inert gases, for example sulphur hexafluoride or nitrogen or a mixture of such gases, used in indoor and outdoor installations of high-voltage switchgear and controlgear with rated voltages above 1 kV, where the gas is used principally for its dielectric and/or arc-quenching properties with rated voltages. - above 1 kV and up to and including 52 kV concerning gas-filled compartments with design pressure higher than 300 kPa relative pressure (gauge); - above 52 kV concerning all gas-filled compartments. The enclosures comprise parts of electrical equipment not necessarily limited to the following examples: - circuit-breakers; - switch-disconnectors; - disconnectors; - earthing switches; - current transformers; - voltage transformers; - surge arrestors; - busbars and connections; - etc. The scope also covers enclosures of pressurized components such as the centre chamber of live tank switchgear, gas-insulated current transformers, etc.