Shell boilers

The BS EN 12953 series of standards applies to the design, construction, testing, inspection and operation of electrically heated and directly fired shell boilers (including low pressure and heat recovery boilers) intended for land use with volumes in excess of 2 litres used for the generation of steam and/or hot water at a maximum allowable pressure greater than 0,5 bar and with a temperature in excess of 110 °C. It applies to the generator from the feed-water or water inlet connection to the steam or water outlet connection and to all other connections, including the valves and steam and water fittings.

The purpose of the BS EN 12953 series is to ensure that the hazards associated with the operation of shell boilers are reduced to a minimum and that adequate protection is provided to contain the hazards that still prevail when the shell boiler is put into service. BS EN 12953 Shell boilers series supersedes BS 2790:1992 and BS 1894:1992. You may obtain all parts of BS EN 12953 separately but they are inter-dependent and the design and manufacture of a shell boiler may require the application of more than one part of the standard to ensure that all the necessary requirements are met.

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Key standards

BS EN 12953-1:2002
Shell boilers. General

BS EN 12953-1:2002 specifies design, construction, equipment, operational and water treatment requirements drawn up with a view to ensuring the operating safety of new stationary shell boiler plants.

This European Standard includes the requirements for the prevention of over-heating and inadmissible over-pressurisation.


standard coverBS EN 12953-2:2002
Shell boilers. Materials for pressure parts of boilers and accessories
standard coverBS EN 12953-3:2002
Shell boilers. Design and calculation for pressure parts

standard coverBS EN 14222:2003
Stainless steel shell boilers

standard coverBS 2790:1992
Specification for design and manufacture of shell boilers of welded construction

About BS EN 12953 series

BS EN 12953 covers areas such as:

  • the shell boiler including all pressure parts from the feed water inlet (including the inlet valve) to the steam and/or hot-water outlet (including the outlet valve). This includes economizers, superheaters and associated connecting pipes which are heated by flue gas and are not separated from the main system by intervening shut-off devices. Also included is any piping connecting the boiler to and including the first isolating valve
  • isolated economizers, superheaters and associated connecting pipes
  • expansion vessels and/or expansion tanks for plants for hot water production
  • thermal insulation and/or refractory and cladding
  • installations for heat supply and heating
  • installations for processing and feeding the fuel into the boiler
  • installations for the air supply of the boiler including the fans
  • installations for the feedwater supply of the boiler
  • all control and safety systems.

BS EN 12953 specifies requirements for both directly fired and electrically heated boilers including low pressure boilers as well as for waste-heat boilers with a gas-side pressure not exceeding 0,5 bar of cylindrical design, constructed from carbon or carbon manganese steels by fusion welding and a design pressure not exceeding 40 bar.

The boilers covered are intended for land use for providing steam or hot water. Where a particular boiler is a combination of shell and water-tube design, then the water-tube standard BS EN 12952 is used in addition to this standard. It applies to the boiler proper, from the feedwater inlet connection to the steam outlet connection and to all other connections, including the valves and steam and water fittings.

If welded ends are used, the requirements specified begin or end at the weld where flanges, if used, would have been fitted. It applies to boilers having a capacity of greater than 2i, a maximum allowable pressure greater than 0,5 bar and with a maximum design temperature in excess of 110°C.

The boiler plant comprises, besides the boiler proper, all pieces of equipment necessary for the intended mode of operation, for which requirements have been laid down in the different parts of this standard.

BS EN 12953 does not apply to water-tube boilers, to boilers for railway locomotives, or to marine boilers. It also does not cover brickwork setting and insulation. As with BS EN 12952, these parts may be obtained separately but they are inter-dependent. As such, the design and manufacture of shell boilers requires the application of more than one part in order for the requirements of the standard to be fulfilled.

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