EN 12952-4:2011

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserrohrkessel und Anlagenkomponenten - Teil 4: Betriebsbegleitende Berechnung der LebensdauererwartungChaudières à tubes d'eau et installations auxiliaires - Partie 4 : Calculs de la durée de vie prévisible des chaudières en serviceWater-tube boilers and auxiliary installations - Part 4: In-service boiler life expectancy calculations27.060.30Grelniki vode in prenosniki toploteBoilers and heat exchangersICS:Ta slovenski standard je istoveten z:EN 12952-4:2011SIST EN 12952-4:2011en,fr,de01-november-2011SIST EN 12952-4:2011SLOVENSKI
STANDARDSIST EN 12952-4:20011DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12952-4
July 2011 ICS 27.040 Supersedes EN 12952-4:2000English Version
Water-tube boilers and auxiliary installations - Part 4: In-service boiler life expectancy calculations
Chaudières à tubes d'eau et installations auxiliaires -Partie 4: Calculs de la durée de vie prévisible des chaudières en service
Wasserrohrkessel und Anlagenkomponenten - Teil 4: Betriebsbegleitende Berechnung der Lebensdauererwartung This European Standard was approved by CEN on 18 June 2011.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
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Calculation of in-service creep damage . 6Annex B (informative)
Calculation of in-service fatigue damage . 10Annex C (informative)
Significant technical changes between this European Standard and the previous edition . 20Bibliography . 21 SIST EN 12952-4:2011

Calculation of in-service creep damage A.1 General This annex describes a procedure for calculating the creep damage of a boiler and its major components during operation. It is based on measured values of pressure and temperature, from which the actual primary stress and the expected lifetime at these conditions may be determined. Design lifetime is not necessarily identical with the operating lifetime. It is therefore necessary to make projections at various stages throughout the operating lifetime of the boiler to determine its expected lifetime. A.2 Symbols and abbreviations In addition to the symbols given in EN 12952-1:2001, Table 4-1, the symbols given in Table A.1 apply. Table A.1 — Symbols Symbol Description Unit fop Membrane stress at operating conditions N/mm2 Top Operated time at operating conditions h Tal Time to reach the theoretical rupture by creep h Dc Creep damage – A.3 Calculation of in-service lifetime and creep damage A.3.1 General The calculation of the usage factor due to creep is a method that retrospectively takes into consideration the previous modes of operation. It is carried out for highly loaded components on the basis of the measured operating temperatures and gauge pressures. In order to limit the number of the required calculations and to more clearly present the results, the pressure and temperature range over which the component has been operated, shall be broken down into increments. The membrane stress fop at the highest loaded point in the component shall be obtained by transposing the design formula using the mean pressure of each pressure increment. If the operating pressure is not measured continuously during operation the separation into increments is not valid and under such circumstances the operating pressure for 100 % load may be used, thus resulting in more conservative predictions. If available, the measured minimum wall thickness may be used. If this was not measured, the guaranteed minimum wall thickness of the material as delivered shall be used. The theoretical lifetime Tal shall be calculated for each rating temperature/pressure. According to Figure A.1, Tal is obtained at the intersection of the stress line fop and the lower limit curve of the scatter band of the creep rupture strength (= 0,8 Rm T tc) at the mean temperature of each temperature increment. The respective portion of the creep damage ûDci k for each incremental temperature/pressure is obtained by the ratio of the operating time Top for this increment divided by the theoretical lifetime Tal for the same increment. SIST EN 12952-4:2011

Key a) lg (Rm) b) lg (T), h Figure A.1 — Diagram for the determination of Tal The operating times in the temperature/pressure increment shall be summarized, taking into account the temperature allowances for measuring uncertainties and for temperature asymmetries in due consideration at this classification. The usage portion for each increment is given by alopkciTTD=û (A.1) The creep damage Dc during the evaluated period shall be obtained from the linear damage rule by summing up the values ûDci k for all temperature increments and, if any, pressure as follows: ∑∑=ikkcicDDû (A.2) A.3.2 Online computerized data storage In the case of on-line data storage by means of a data processing system a separation into increments may be waived. For calculation of the theoretical lifetime Tal the on-line measured values of pressure and temperature including the above mentioned allowances shall be used instead of the mean values of the increments. The increase of creep damage is obtained in this case from the measured time divided by the theoretical lifetime (see Tables A.2 and A.3). The computer programme used shall permit the results to be verified by at least a random test. SIST EN 12952-4:2011

b
d
mm c
es mm ers mm pc bar to °C tc °C fap N/mm2 Tal 103 h 1 HP-line 13CrMo44; 5.1 m AB292,0o24,021,075,5525 530 48,7 208 2 Superheater 2 – header 13CrMo44; 5.1 n AB419,0o39,039,075,5510 525 56,3 186 3 Superheater 2 – outlet line 13CrMo44; 5.1 n AB241,0o17,517,575,5510 525 48,2 304 4 Superheater 2 – outlet header 16CrMo44; 5.1 n AB250,0i 20,028,075,5510 525 47,1 329 7 Fitting at control 20Mo3; 1.2 m AB225,0i 28,020,
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