CEN/TC 269 - Shell and 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 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 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 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 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 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 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 requirements for the workmanship and construction of water-tube boilers as defined in EN 12952-1.

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 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 essential requirements for equipment and protective devices for water-tube boiler plant as defined in EN 12952-1, to ensure the boiler operates safely within the allowable limits (pressure, temperature, etc.).
NOTE 1   Additional requirements specially needed for boilers without manual intervention are specified in Clause 7.
NOTE 2   Requirements for equipment for chemical recovery boilers are given in Annex A.

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.

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 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 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 water-tube boilers as defined in EN 12952-1.
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 shall 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 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 European Standard applies to the design of equipment for boiler plants to reduce air pollutants in the flue gases.
NOTE   The effects of explosion are not considered in this Part of the is European Standard.

This draft European Standard covers the safety requirements regarding the storage and use of:
-   liquefied pressurized ammonia for steam boiler plants;
-   liquid ammonia water solution for the reduction of NOx in the flue gas from boiler plants.
Annex A summarizes the operational aspects.

This part of this European Standard specifies the requirements for internal or external grate firing systems commencing at the fuel bunkers and ending at the ash extraction plant. For combination of various firing systems, the individual requirements of each system also apply.
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.

This European Standard covers direct-fired steam and hot water generators, including the auxiliaries. For the purposes of this standard, steam and hot water generators are vessels and pipework systems in which:
¾ steam at a pressure higher than atmospheric pressure is generated for use external to the system;
¾ water is heated to a temperature higher than the saturation temperature at atmospheric pressure for use external to the system.
A steam generator normally consists of the flue gas-heated evaporator, the superheater, the reheater, the feedwater heater, the air heater, the fuel heater, if any, and the fuel burning equipment.
The term 'direct-fired' relates to equipment by means of which the chemical heat in the fuel of known composition is converted to sensible heat. Such equipment can involve stoker firing, fluidized-bed combustion or burner systems.
The auxiliaries include the fuel feeders, the pulverizer, the FD (forced draught) fan, the ID (induced draught) fan, the facilities for removal of the refuse (combustion residues), the steam air heater, the main air heater, the fuel heater, if any, and the dust collector.

This Part of this European Standard specifies a concise procedure for conducting thermal performance tests, using the indirect (losses) procedure for boilers for steam or hot water. Test results are based on either the gross or net calorific value of the fuel.
This concise procedure provides a convenient means for assessing boilers which thermodynamically simple, i.e. having a single major source of heat input and a simple circuit for water, steam or high temperature heat transfer fluid.
NOTE 1   The use of the direct method is not advocated, because the estimated measuring error is three to four times greater than with the indirect method.
NOTE 2   An acceptance test may be required:
a) after the commissioning of new plant or after the recommissioning of modified plant in order to verify compliance with a specification or contractual obligation;
b) whenever the user wishes to determine the current performance of the plant either on a route basis or due to change of load or other operating conditions or when a change of fuel or a modification to the plant is being considered;
c) whenever the user wishes to check combustion conditions.
Regular tests in accordance with this European Standard will enable boiler plant to be monitored in normal operation for opti-mum efficiency in the interests of fuel conservation.
This procedure does not cover condensing boilers. The application of boilers, where heat is extracted from waste gases is specified in annex B.

This European Standard applies to the design of equipment for boiler plants to reduce air pollutants in the flue gases.
NOTE   The effects of explosion are not considered in this Part of the is European Standard.

This part of the European Standard applies to all shell boilers as defined in prEN 12953-1 which are heated by combustion of one or more fuels or by hot gases for the generation of steam and/or hot water. This European Standard applies to those components between the feedwater inlet and the steam outlet of the steam generator. The quality of the steam produced is outside the scope of this standard.

This Part of this European Standard applies to all water-tube boilers as defined in EN 12952-1 which are heated by combustion of one or more fuels or by hot gases for the generation of steam and/or hot water.
This Part of this European Standard applies to those components between the feedwater inlet and the steam outlet of the steam generator. The quality of the steam produced is outside the scope of this standard.
This Part of this European Standard aims to ensure that the boiler is able to be operated to minimize risk to personnel, the boiler and associated plant components located near it.
NOTE   This European Standard does not aim to achieve optimum economic operation. For certain purposes, it will be more appropriate to optimize the chemical characteristics in order to:
- increase the thermal efficiency;
- increase the availability and reliability of the plant;
- increase steam purity;
- reduce the maintenance costs - repair, chemical cleaning, etc.
This Part of this European Standard sets out minimum requirements for the specific types of water to reduce the risk of corrosion, sludge precipitation or formation of deposits which may lead to any damage or other operating problems.
NOTE   This Part of this European Standard has been prepared on the assumption that the user of this European Standard possesses a sufficient knowledge of the construction and operation of the boiler as well as an adequate appreciation of water and steam chemistry.

TC - Request to implement normative comments from BSI after Formal Vote
2013: Originator of XML version: first setup pilot of CCMC in 2012

These requirements apply to oil and gas firing systems of steam and hot water generators. For multifuel firing systems using separate or combined burners these requirements shall apply to the oil and/or gas firing part involved. Where several fuels are burnt simultaneously, improved safety measures may be necessary, especially in respect to limitation of heat input into the firing system and proper air supply to the individual fuels.

This Technical report gives guidance for the involvement of an inspection body independent of the manufacturer of shell boilers as defined in EN 12953 1.

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 Part of this European Standard specifies the requirements for safeguards against excessive pressure in shell boilers
as defined in EN 12953-1.

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 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.

These requirements apply to atmosperic fluidized-bed and grate firing systems. This system commence at the fuel bunkers and at the ash extractions plant. For combination of various firing systems, the individual requirements of each system shall also apply, especially those included in prEN 12952-8 and prEN 12952-9. If several fuels are burnt simultaneously or if a fuel quality varies considerably (e.g. moisture content), additional safety measures may be necessary, especially with respect to limitation of the fuel flow into the firing system and ensuring proper air supply to the individual fuels.

1.1 Firing systems: These requirements apply to pulverized fuel firing systems of steam and hot water generators (boilers) and commence at the filling equipment for the boiler bunkers or for the pulverized fuel storage system and end at the ash extraction plant. For multifuel firing systems using separate or combined burners these requirements shall apply to the pulverized fuel firing part involved. For other fuels or firing systems used in combination other requirements shall apply e.g. prEN 12952-8.

1. Firing systems: These requirements apply to oil and gas firing systems of steam and hot water generators. For multifuel firing systems using separate or combined burners these requirements shall apply to the oil and/or gas firing part involved. Where several fuels are burnt simultaneously, improved safety measures may be necessary, especially in respect to limitation of heat input into the firing system and proper air supply to the individual fuels. 2. Fuels (...) 3. Operation (...)

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 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 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 safeguards against excessive pressure in water-tube boilers as defined in prEN 12952-1.

This Part of the European Standard specifies requirements for the inspection during construction, documentation and marking of shell boilers as defined in EN 12953-1.

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 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.