CEN/TC 269/WG 1 - Water-tube boilers

This document specifies the requirements for the design and calculation of water-tube boilers as defined in EN 12952-1.
The purpose of this document is to ensure that the hazards associated with water-tube boilers are reduced to a minimum by the proper application of the design according to this part of EN 12952.

1.1   Firing systems
This document specifies requirements for liquid and gaseous fuel firing systems of steam boilers and hot water generators as defined in EN 12952-1:2015.
These requirements also apply to firing systems of chemical recovery boilers (black liquor boilers) with the additions and amendments specified in Annex A.
These requirements also apply to gas turbines in combination with fired/unfired heat recovery steam generators with the additions and amendments specified in Annex B.
NOTE 1   This document is not applicable to coil type boilers (flash boilers/small boilers) that use burners in accordance with EN 12953-7 for single burner installations.
NOTE 2   This document is not applicable to the storage of liquid fuels and to transfer stations of long-distance gas pipelines.
1.2   Fuels
This document specifies requirements which cover the use of liquid and gaseous fuels as defined in this document. Fuels deviating from standardized commercially available types can require additional or alternative safety measures. For black liquor these safety measures are given in Annex A.

1.1   Firing systems
This document applies to pulverized fuel firing systems of steam boilers and hot water generators and commences at the filling equipment for the boiler bunkers or for the pulverized fuel storage system and ends at the ash extraction plant. For multifuel firing systems using separate or combined burners, these requirements apply to the pulverized fuel firing part involved. For other fuels or firing systems used in combination, other requirements apply, e.g. EN 12952-8:2022.
1.2   Fuels
These requirements cover the use of pulverized fuels (e.g. coke, anthracite, bituminous coal or hard coal, lignite or brown coal, petrol coke, oil shale and pulverized bio mass) ranging from low to high volatile matter content.
1.3   Operation
Requirements for operational equipment apply for steam boilers and hot water generators with permanent supervision by properly trained persons.
As firing systems using pulverized fuel can be designed either as direct-firing or as indirect-firing systems, operational requirements have to be differentiated. Annex A summarizes the operational requirements for firing systems including the pulverizing system.

1.1   Firing systems
This document applies to atmospheric fluidized-bed and grate firing systems of steam boilers and hot water generators. These systems commence at the fuel bunkers and end at the ash extraction plant. For combination of various firing systems, the individual requirements of each system apply, especially those included in EN 12952-8:2022 and EN 12952-9:2022.
If several fuels are burnt simultaneously or if a fuel quality varies considerably (e.g. moisture content), additional safety measures can be necessary, especially with respect to limitation of the fuel flow into the firing system and ensuring proper air supply to the individual fuels.
Pressurized firing systems can require enhanced safety measures, which are not given in this European Standard.
1.2   Fuels
This document covers the use of solid fuels. Pulverized fuel fired in an entrained air flow (burner) system is covered by EN 12952-9:2022.
Solid fuels covered are:
•   all coal qualities, e.g. lignite or brown coal, sub-bituminous or hard brown coal, bituminous coal or hard coal, pitch coal, anthracite, coke, coal culm, coal sludge;
•   other fossil solid fuels (e.g. peat, oil shale);
•   biomass solid fuels (e.g. wood, wood wastes [bark], pellets, energy plants [miscanthus], harvest wastes [straw] and briquettes);
•   municipal waste solid fuels (e.g. garbage, sewage sludge, refuse derived fuels [RDF]);
•   industrial waste solid fuels (e.g. petrol coke, soot, tyres, paper wastes, coated wood chips, spent wood, animal product wastes).
Fuel blends from two or more groups, or fuels of unconventional or unknown quality can require special safety measures which can be proved either by practical experience gained from comparable fuels, or by suitable tests, e.g. in accordance with EN 14034-2:2006+A1:2011. Such measures specified and documented by the manufacturer.
Fuels on which the design is documented in the operating instructions (see 11.2). This includes the fuel data for 100 % input of the basic fuel and the data for any supplementary fuels together with their maximum thermal input percentage.
1.3   Operation
The requirements for operational equipment in Clause 4, Clause 5, Clause 6, Clause 7, Clause 8, Clause 9, Clause 10 and Clause 11 apply to steam boilers and hot water generators with permanent supervision by properly trained personnel familiar with the special conditions of the firing systems and the type of fuel.

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

This part of this European Standard specifies the requirements for safety devices against excessive pressure in water tube boilers as defined in EN 12952-1.

This European Standard specifies requirements for the inspection during construction, documentation and marking of water-tube boilers as defined in EN 12952-1.

This European Standard specifies the requirements for the product forms for use in pressure parts of water-tube boilers and for parts welded on to pressure parts:
   plates;
   wrought seamless tubes;
   electrically welded tubes;
   submerged, plasma and TIG arc-welded tubes;
   forgings;
   castings;
   rolled bars;
   welding consumables;
   fasteners;
   seamless composite tubes.

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 0,5 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.
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
a)   The boiler supporting structural steelwork, the thermal insulation and/or brickwork and the casing;
b)   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;
c)   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;
d)   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:
a)   boilers other than stationary boilers;
b)   shell type boilers;
c)   electrical boilers;
d)   nuclear primary circuits, the failure of which can cause an emission of radioactivity.

This part of this European Standard specifies the organisation and content of operating instructions for water-tube boilers and auxiliary installations as defined in EN 12952-1 when placed on the market.
To what extent the following aspects are used for the establishment of an operating instruction depends on the stipulated scope of delivery and of the requirements by contract regarding plant operation and maintenance.
NOTE   The manufacturer’s scope of supply may be either pressure equipment, or pressure equipment and “auxiliary” plant such as motors, pumps and fans.

This European Standard is applicable to water-tube boilers as defined in EN 12952-1:2001.
This European Standard specifies procedures for calculating the creep and/or the fatigue damage of boiler components during operation. These calculations are not required to be carried out by the manufacturer as part of his responsibilities within this European Standard.

This Technical report gives guidance for the involvement of an inspection body independent of the manufacturer of shell boilers as defined in EN 12952 1.

This European Standard specifies the requirements for the design and calculation of water-tube boilers as defined in EN 12952-1.
The purpose of this European Standard is to ensure that the hazards associated with water-tube boilers are reduced to a minimum by the proper application of the design according to this part of EN 12952.

This European Standard specifies requirements for the workmanship and construction of water-tube boilers as defined in EN 12952-1:2001.

This European Standard specifies requirements for the inspection during construction, documentation and marking of water-tube boilers as defined in EN 12952 1.

This European Standard specifies the requirements for the product forms for use in pressure parts of water-tube boilers and for parts welded on to pressure parts:
-   plates;
-   wrought seamless tubes;
-   electrically welded tubes;
-   submerged, plasma and TIG arc-welded tubes;
-   forgings;
-   castings;
-   rolled bars;
-   welding consumables;
-   fasteners;
-   seamless composite tubes.

This standard applies to shell boilers as defined in prEN 12953-1. This Part of the standard specifies rules for the design and calculation of shell boilers.

This European Standard applies to water-tube boilers with volumes in excess of 2 l for the generation of steam and/or hot water at an allowable pressure greater than 0,5 bar and with a temperature in excess of 110°C as well as other plant equipment. The purpose of this EN is to ensure that the hazards associated with the operation of water tube boilers are reduced to a minimum and that adequate protection is provided to contain the hazards that still prevail when the water tube boiler is put into service.

1.1  General
This European Standard 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.
1.2  Boiler plants
A boiler plant consists of:
a)     the shell boiler including all pressure parts from the feedwater inlet (including the inlet valve) to the steam
       and/or hot-water outlet (including the outlet valve). This includes economisers, 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;
b)     isolated economisers, superheaters and associated connecting pipes;
c)     expansion vessels and/or expansion tanks for plants for hot water production;
d)     thermal insulation and/or refractory and cladding;
e)     installations for heat supply and heating;
f)     installations for processing and feeding the fuel into the boiler;
g)     installations for the air supply of the boiler including the fans;
h)     installations for the feedwater supply of the boiler;
i)     all control and safety systems.
This European Standard specifies requirements for both directly fired and electrically heated boilers including low
pressure boilers (LPB, see 3.7) as well as for waste-heat boilers with a gas-side pressure not exceeding 0,5 bar1)
of cylindrical design, constructed from carbon or carbon manganese steels by fusion welding and a design pressure
not exceeding 40 bar1). The boilers covered by this European Standard are intended for land use for providing steam
or hot water (typical examples are shown in Figures 1.2-1 to 1.2-5).

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

This Part of the European Standard applies to water-tube boilers as defined in prEN 12952-1:1997. This part describes procedures for calculating the creep and/or the fatigue damage of boiler components during operation. These calculations are not required to be carried out by the manufacturer as part of his responsibilities within this standard.