1.1 General 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 0,5bar 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 AnnexI 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. 1.2 Boiler assembly For the purpose of this European Standard, the boiler assembly includes: the water-tube boiler including all the pressure parts from the feedwater inlet (including the inlet valve) up to and including the steam and/or hot water outlet (including the outlet valve or, if there is no valve, the first circumferential weld or flange downsteam of the outlet header); all superheaters, reheaters, economizers, that are not capable of isolation from the main system by interposing shut-off valves, associated safety accessories and interconnecting piping; additionally, the piping that is connected to the boiler involved in services such as draining, venting, desuperheating, etc., up to and including the first isolating valve in the tubing line downstream of the boiler; reheaters which are independently fired, and are separately provided with their safety accessories including all control and safety systems. The following equipment and components can be integrated in the assembly at the discretion of the manufacturer: isolatable superheaters, reheaters, economizers and related interconnecting piping; the heat supply or firing system; the means of preparing and feeding the fuel to the boiler including the control systems; the means of providing the boiler with feedwater including the control system; the pressure expansion vessels and tanks of hot water generating plant. 1.3 Other plant equipment The boiler supporting structural steelwork, the thermal insulation and/or brickwork and the casing; the means of providing the boiler with air including the forced draught fans and air pre-heaters which are heated by the gases of combustion; the facilities for moving flue gases through the boiler up to the stack inlet, including the induced draught fans and the air pollution reducing equipment located in the flue gas removal path; all other equipment necessary for the operation of the boiler plant. 1.4 Exclusions This European Standard does not apply to the following types of boiler plant: boilers other than stationary boilers; shell type boilers; electrical boilers; nuclear primary circuits, the failure of which can cause an emission of radioactivity.