CEN/TC 269/WG 2 - Shell boilers

This document specifies requirements for the inspection during and after construction, documentation and marking of shell boilers as defined in EN 12953-1.
NOTE   For other components, such as water tube walls, reference will be made to the EN 12952 series.

This European Standard specifies requirements for the workmanship and construction of shell boilers as defined in EN 12953-1.
NOTE 1   For other components such as water tube walls, see the EN 12952 series.
NOTE 2   For economizers and superheaters, see EN 12953-4 or EN 12952-5.

This Part of this European Standard specifies requirements for the design and calculation of pressure parts of shell boilers as defined in EN 12953 1.
NOTE   For other components such as economisers, superheaters, tube walls, headers, reference should be made to EN 12952 series.

1.1   General
This European Standard applies to shell boilers with volumes in excess of 2 litres 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.
The purpose of this European Standard 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. This protection will be achieved by the proper application of the design, manufacturing, testing and inspection methods and techniques incorporated in the various parts of this European Standard. Where appropriate, adequate warning of residual hazards and the potential for misuse are given in the training and operating instructions and local to the equipment concerned (see EN 12953-7 and EN 12953-8).
It is the manufacturer's responsibility, in addition to complying with the requirements of this standard, to take into consideration special measures which could be necessary in order to achieve by manufacturing the required level of safety in accordance with the EU Directive 97/23/EC (PED).
NOTE 1   Further requirements relating to operating instructions in prEN 12953-13 and to hazard analysis in
CEN/TS 764-6 should be taken into consideration.
This European Standard specifies requirements for both directly fired and electrically heated boilers including Low Pressure Boilers (LPB, see 3.6) as well as for heat recovery 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 by this European Standard are intended for land use for providing steam or hot water (typical examples are shown in Figures 1 to 6).
For Low Pressure Boilers (LPB) less stringent requirements concerning design and calculation are acceptable. Details are defined in the respective clauses.
NOTE 2   For boilers operating at a pressure on the gas-side greater than 0,5 bar the rules of this standard equally apply. However, it is generally considered that additional design analysis, inspection and testing may be necessary.
Where a particular boiler is a combination of shell and water-tube design then the water-tube standard series EN 12952 is used in addition to this European Standard. One such example of this combination is shown in Figure 3.
This European Standard 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. If welded ends are used, the requirements specified herein begin or end at the weld where flanges, if used, would have been fitted.
1.2   Exclusions
This European standard does not apply to the following types of boilers and equipments:
a)   water-tube boilers;
b)   non stationary boilers, e.g. locomotive boilers;
c)   thermal oil boilers;
d)   boilers where the main pressure housing is made of cast material.
e)   pumps, gaskets, etc.
f)   brickwork setting and insulation, etc.
NOTE   Stainless steel boilers are covered by EN 14222.

This European Standard specifies the following materials for the pressure bearing parts of shell boilers and equipment of shell boilers (e.g. valves), subjected to internal and external pressure including integral attachments (non pressure bearing parts):
   flat products (plate) and parts formed from flat products (e.g. shell, furnace, dished ends);
   tubes and parts formed from tubes (e.g. bending, elbows, reducers, fittings);
   forgings and cast products ;
   bolting materials;
   welding consumables.

This European Standard identifies the requirements for the manufacturer to provide operating instructions for pressure equipment supplied in accordance with EN 12953-1 when placed on the market.
NOTE   Where the equipment or assembly will reach the final user in a Member State which requires translation of operating instructions, manufacturers should be aware of this requirement.

This European Standard specifies the following materials for the pressure bearing parts of shell boilers and equipment of shell boilers (e.g. valves), subjected to internal and external pressure including integral attachments (non pressure bearing parts):
   flat products (plate) and parts formed from flat products (e.g. shell, furnace, dished ends);
   tubes and parts formed from tubes (e.g. bending, elbows, reducers, fittings);
   forgings and cast products ;
   bolting materials;
   welding consumables.

This document applies to shell boilers with volumes in excess of 2 l 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.
For the purpose of this document the following pressurized parts are included:
—   the shell boiler as one entity of pressure equipment including all the pressure parts from the feedwater/hot water inlet (including the inlet valve) up to and including the steam/hot water outlet (including the outlet valve or, if there is no valve, the first circumferential weld or flange downstream of the shell boiler or if applicable the outlet header);
—   all superheaters, economizers and interconnecting piping;
—   additionally, the piping that is connected to the boiler involved in services such as draining, venting, desuperheating, etc., up to the first isolating valve or, if there is no valve, the first circumferential weld or flange downstream of the shell boiler or if applicable the outlet header/piping.
This document does not apply to the following types of boilers and equipments:
a)   water-tube boilers;
b)   non stationary boilers, e.g. locomotive boilers;
c)   thermal oil boilers;
d)   boilers where the main pressure housing is made of cast material;
e)   pumps, gaskets, etc;
f)   brickwork setting and insulation, etc.
NOTE 1   Further information on shell boilers is given in Annex A.
NOTE 2   Stainless steel boilers are covered by EN 14222:2021.

This part of this European Standard specifies the minimum requirements for safety related equipment for shell boilers as defined in EN 12953-1, to ensure the boiler operates within the allowable limits (pressure, temperature, etc.) and if the limits are exceeded the energy supply shall be interrupted and locked out without manual (human) intervention at the boiler.
NOTE 1   The maximum time of operation without manual (human) intervention should be defined for each boiler system.
NOTE 2   Annex C (informative) gives recommendations of operation and testing of the boiler system with a maximum time of operation without manual (human) intervention of 72 hours.

This European Standard specifies requirements for limiters (or limiting devices) which are incorporated into safety systems for shell boilers as defined in EN 12953-1. A limiter (or limiting device) can be either: - a safety accessory as defined in the Pressure Equipment Directive, Article 1, clause 2.1.3, and needs to include the safety logic and final actuator, or - one element of a safety system, for example, a self-monitoring water level sensor used as part of a safety accessory as defined in the Pressure Equipment Directive, Article 1, clause 2.1.3. The overall boiler protection function needs to be provided in association with additional safety logic (where appropriate) and a final actuator. The design requirements and examination of functional capability for the limiters are covered in this European Standard. For an explanation of the extent of the limiter (or limiting device) see Figure A.1.

This Part of this European standard applies to shell boilers as defined in prEN 12953-1. This Part of the standard specifies rules for the workmanship and construction of shell boilers.

This European Standard covers the following materials for pressure parts of shell boilers subjected to internal and
external pressure and their integral attachments:
  flat products;
  tubes; and
  forgings.

This Part of the European Standard specifies requirements for the workmanship and construction of water-tube
boilers as defined in EN 12952-1.

This Part 2 covers the following materials for use in cast iron pressure parts of water-tube boilers and their integral attachments covered by this European Standard and the following materials manufactured from ferritic and austenitic steels: - plates; - wrought seamless tubes; - electric resistance welded and induction welded tubes; - submerged, plasma and TIG arc-welded tubes; - forgings; - castings.