This document defines the terms, definitions, quantities, symbols and units that are used throughout the EN 13445 series and gives general information on the design and manufacturing of vessels under this standard. It also contains instructions on how to use the standard (Annex A) as well as an index which covers the whole standard (Annex B). This information is aimed to aid users of the EN 13445 series. This document applies to unfired pressure vessels with a maximum allowable pressure greater than 0,5 bar gauge but may be used for vessels operating at lower pressures, including vacuum. This document is not applicable to pressure vessels of the following types: - vessels of riveted construction; - vessels of lamellar cast iron or any other materials not included in Parts 2, 6, or 8 of the standard; - multilayered, autofrettaged or pre-stressed vessels. This document can be applied to the following pressure vessels, provided that account is taken of additional and/or alternative requirements resulting from the hazard analysis and from rules or instructions specific for: - transportable vessels; - items specifically designed for nuclear use; - pressure vessels with a risk of overheating. NOTE EN 14222 covers electrically fired boilers made from stainless steel and can be used as an example of additional requirements for such vessels. Other European standards apply to industrial piping (EN 13480 series) and to water tube and shell boilers (EN 12952 series and EN 12953 series).