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It partially supersedes BS When the reference to this European Standard has been published in the Official Journal of the European Communities OJcompliance with it will confer a presumption of conformity with the essential requirements covered by the standard in respect of the Pressure Equipment Directive.
A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users of this publication are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations.
Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 50, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. Date Comments Li ce ns ed C op y: Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Management Centre or to any CEN member.
A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by Novemberand conflicting national standards shall be withdrawn at the latest by November For relationship with EU Directive ssee informative annex ZA, which is an integral part of this document.
The European Standard EN concerning water-tube boilers and auxiliary installations consists of the following Parts: Materials for pressure parts of boilers and accessories. Design and calculation for pressure parts. In-service boiler life expectancy calculations. Workmanship and construction of pressure parts of the boiler. Inspection during construction; documentation and marking of pressure parts of the boiler. Requirements for equipment for the boiler.
Requirements for firing systems for liquid and gaseous fuels for the boiler. Requirements for firing systems for pulverized solid fuels for the boiler. Requirements for safeguards against excessive pressure.
МКС EN 12952-7:2013
Requirements for limiting devices of the boiler and accessories. Requirements for boiler feedwater and boiler water quality. Requirements for flue gas cleaning systems. Requirements for grate and fluidized bed firing systems for solid fuels for the boiler. Guideline for the involvement of an inspection body independent of the manufacturer. Although these Parts can be obtained separately, it should be recognized that the parts are inter-dependent. As such, the design and manufacture of water-tube boilers requires the application of more than one Part in order for the requirements of the standard to be satisfactorily fulfilled.
NOTE Parts 4 and 15 are not applicable during the design, construction and installation stages. The Annex A is normative.
The Annex B of this European Standard are informative. Requirements for equipment for chemical recovery boilers are given in Annex A, and design examples for hot water generating systems are given in Annex B. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision.
For undated references the latest edition of the publication referred to applies including amendments. Requirements for firing systems for pul- verized solid fuels for the boiler.
Requirements for safeguards against ex- cessive pressure. Requirements for feedwater and boiler water quality. Requirements for flue gas cleaning sys- tems. Requirements for fluidized bed and grate firing systems for solid fuels for the boiler. Requirements for application design and installation. The bodies of the shut-off devices are considered to be within these limits 3.
The electrical safety circuits shall correspond to prEN see safety levels given in Table 4. If any part of the functional test involves delaying the cut-off and lock-out of the heat supply, then the time delay shall not exceed a value specified by the manufacturer.
For boilers fitted with water level limiter, the time delay shall not exceed the time for the water level to fall from the lowest controlled water level to LWL at MCR: Sufficient space shall be provided to permit access to the steam and water spaces and the combustion chamber as well. Internals shall be of such a design as not to obstruct inspection of the component walls, or it shall be possible to remove them.
Inspection access shall be designed as head, hand or inspection holes where manual inspection methods are to be used or, as inspection nozzles where inspection devices are used e. The nozzle or ring height shall not exceed mm, and mm in the case of a tapered design.
In such cases, the nozzle or ring height shall not exceed mm, or mm in the case of a tapered design. For minimum number of openings see table 4. The nozzle or ring height shall not exceed mm, or mm in the case of a tapered design.
EN – Water-tube boilers and auxiliary installations – Part 7: Req –
For minimum num- ber of openings see table 4. The nozzle or ring height shall not exceed 65 mm, or 95 mm in the case of a tapered design. However, they shall be provided only where a hand hole is not possible for design reasons. For minimum number of openings see Table 4. Radial inspection nozzles may be omitted, if connecting tubes can be used in lieu of such nozzles.
In the cylinder, the greatest distance between head holes shall not exceed 3 mm and between hand holes shall not exceed 2 mm. One hand hole each shall be provided near the header ends or in the front faces.
For handholes the gasket bearing width may be reduced to 10 mm. The total clearance between the door frame and the spigot or recess of such doors shall not exceed 3 mm, i.
The 1295-7 of the gasket material combined with the design of such doors shall 19252-7 adequate to provide an effective and safe sealing assembly. If the shut-off device and the protection device against backflow are not installed in direct connection to each other, pressure relieving shall be possible for the intermediate piping section.
A single once-through steam boiler in which the heat supply is cut 1295-7 automatically in the case of feedwater failure, requires neither a shut-off device nor protection device against backflow if the feed pump is of the positive displacement type where it can be ensured that no dangerous backflow can occur.
For safety reasons 1,15 times of maximum continuous rating is enough. For availability and difference in service conditions a greater margin can be necessary. For once-through steam boilers a feed pump capacity of at least equal to 1,0 times the maximum continuous rating can suffice.
By em, steam operation of all feed pumps from only one steam main shall be permissible. The feed pumps shall be connected to the power sources in such a way that in the case of failure of one power source the remaining feed pumps shall meet the requirements of 5.
Where the pumps are electrically driven one line per feed pump drive can suffice if the line can be switched over to the bus bars; c In the case of steam boiler plant of a unitized arrangement, it shall be permitted 1295-27 rate the second feed pump for 0,5 times the allowable steam output if it is ensured that in the case of failure of the feed pumps rated for the allowable steam output, the heat supply system is, at the same time, automatically adjusted to the reduced steam output.
If water is blown down, the quantity of blow down water shall be fully considered when rating the second feed pump; Li ce ns ed C op y: A common standby circulating pump can suffice for several forced circulation steam boilers of one steam boiler plant, if it can be connected to each em boiler. Except in the case of unitized arrangements such devices shall be located as close as possible to the steam boiler. Where duplicate isolating devices are installed in series, but not adjacent to each other, the intervening tubework shall be provided with means for venting and condensate removal.
Such drains and the nozzles thereof shall be protected against the effects of combustion gases.
EVS-EN – Estonian Centre for Standardisation
Self-closing blowdown devices shall be capable of being locked manually in the closed position unless a further shut-off device is installed in the line. The steam boiler shall be equipped with oil or gas firing system or the design of the heat supply system shall ensure that no unacceptable evaporation of the water inside the steam boiler occurs due to the heat accumulated in the boiler passes upon cut-off of the heat supply. In the case of two-drum boilers with an evaporator tube bundle between them, the outer tubes shall not be considered as downcomers.
One glass water gauge may be replaced by: An indication of the limit values for safety-relevant water level is sufficient.
A glass water gauge located at the water level controller or limiter shall be considered a direct-reading water level indicator. In case a the glass water gauge need not be in the field of vision of the 12925-7 operator responsible for the feedwater.
If the water level indicators are connected by means of common connecting lines or if the water-side connecting tubes are longer than mm, the latter shall have an inside diameter of at least 40 mm. Connecting tubes on the steam side shall be designed so that condensate does not accumulate. Water-side con- necting tubes shall always be arranged horizontally to the water level indicators.
However, when reverse measuring method is used, impulse tubes to transmitters on the steam and water side shall be full of condensate and the transmitters shall rn below the water level.
Impulse tubes to transmitters can have a smaller inside diameter. Where cocks are used, the open position shall be indicated. The lower limit 112952-7 the indicating range of a glass gauge shall be at least 30 mm below the lowest permissible water level LWL also see 5. Cylindrical glass gauges shall be provided with a safety device for protection against damage by bursting glass. Any blowdown operation shall be detectable.
Indirect measuring 129527- may be used. The water level limiter shall respond, at the latest, when the level drops to the lowest permissible water rn LWL. Where required, the low water condition may be tested by simulation. For the protection against water shortage, once-through boilers shall be provided with a limiter flow or temperature limiters in order to prevent the boiler walls 129952-7 becoming overheated.
The shut-off devices in the connecting lines of limiters shall only permit operation of the heat supply system in the open position interlocking.