This European Standard applies to water-tube boilers with volumes in excess of two litres for the generation of steam and/or hot water at a maximum allowable pressure PS greater than 0,5 bar and with a temperature in excess of 110 °C as well as auxiliary installations (other plant equipment). The purpose of this European Standard is to ensure that the necessary essential safety requirements according to Annex I of the Pressure Equipment Directive are fulfilled in order to guarantee the safety of water tube boilers. This aim will be achieved by: — the proper application of the design, manufacturing, testing and inspection methods and techniques, — the provision of protective measures against hazards, which cannot be eliminated, and — the provision of information on residual hazards and other measures to reduce risk, which are incorporated in the various parts of this European Standard. The requirements of this European Standard take account of pressure-related hazards, which apply to water tube boilers, including failure of pressure-retaining components due to overheating. This standard recognizes that it is not possible to cover all the combinations of situations that might arise.