There are no specific test standards for AD 2000 B 7 Gasket Parameters. However, an estimation is provided below. The 2015 edition of "AD 2000-Merkblatt B 7" refers to EN 13555 as a test standard(1) and uses table 9 from VDI 2200(2) for the conversion method. Please note that VDI 2200 states that such a conversion is invalid due to the different measurement methods. "Only the method according to DIN EN 1591-1 and AD 2000 in conjunction with DIN EN 1591-1 and FE analysis can be used for providing stability, leak tightness and TA Luft proof."(3)
(1)Arbeitsgemeinschaft Druckbehälter: AD 2000-Merkblatt B 7, Berechnung von Druckbehältern, Schrauben, Seite 4, 188.8.131.52, April 2015.(2)Verein Deutscher Ingenieure e. V.: VDI 2200, Tight flange connections - Selection, calculation, design and assembly of bolted flange connections, page 36, table 9, June 2007.(3)Verein Deutscher Ingenieure e. V.: VDI 2290, Emission Control - Sealing constants for flange connections, page 8, June 2012.(4)Please note that factor m = QSmin / p was defined by DIN V 2505 which was superseded by EN 1591-1 where m is no longer used.(5)Arbeitsgemeinschaft Druckbehälter: AD 2000-Merkblatt B 7, Berechnung von Druckbehältern, Schrauben, Seite 6, Tabelle 1, April 2015.
The AD 2000-Merkbltter are prepared by the seven associationslisted below who together form the ArbeitsgemeinschaftDruck-behlter (AD). The structure and the application of the AD2000 Code and the procedural guidelines are covered by AD2000-Merk- blatt G 1.
The AD 2000-Merkbltter contain safety requirements to be metunder normal operating conditions. If above-normal loadings are tobeexpected during the operation of the pressure vessel, this shallbe taken into account by meeting special requirements.
If there are any divergences from the requirements of this AD2000-Merkblatt, it shall be possible to prove that the standard ofsafety ofthis Code has been maintained by other means, e.g. bymaterials testing, tests, stress analysis, operatingexperience.
The AD 2000 Code is structured along the lines of aself-contained concept. If other technical rules are usedinaccordance with the state of the art to solve related prob-lems,it is assumed that the overall concept has beentaken intoaccount.
The AD 2000 Code can be used as appropriate for othermodules ofthe Pressure Equipment Directive or for different sectors of thelaw. Responsibility for testing is asspecified in the provisions ofthe relevant sector of thelaw.
1.2 The calculation only applies for components dimen-sioned onthe basis of non-time-dependent design strength values (see 6.2 and6.3 of AD 2000-Merkblatt B 0) and sub-jected to cyclic loads onlyin the form of pressure fluctuations. Additional cyclic loadings,for example loads due to rapid
AD 2000-Merkbltter are protected by Copyright. The rights ofuse, particularly of any translation, reproduction, extract offigures, transmission byphotomechanical means and storage in dataretrieval Systems, even of extracts, are reserved to the author.Carl Heymanns Verlag has taken all reason-able measures to ensurethe accuracy of this translation but regrets that no responsibilitycan be accepted for any error, omission or inaccuracy. Incases ofdoubt or dispute, the latest edition of the German text only isvalid.
1.7 If the number of pressure fluctuations to be expectedduringoperation exceeds the allowable number of load cycles calculatedaccording to this AD 2000-Merkblatt, it is necessary to change thedesign or conduct a detailed calculation according to AD2000-Merkblatt S 2 to satisfythe cyclic loading conditions.
1.9 A reduction in the permitted number of stress cycles is notrequired at low operating temperatures within theapplication limitsof Stress Categories II and III in accor-dance with AD2000-Merkblatt W 10.
2.4 The allowable number of load cycles calculated ac-cording toAD 2000-Merkblatt S 1 is influenced by thedimensioning and designof the pressure vessel. In thecase of frequent load cycles withconsiderable cyclicloading, calculations according to AD2000-Merkblatt S 2are more practical, however, to assessappropriate modi-fications measures. As a rule, this yields agreater allow-able number of load cycles than the calculation toAD2000-Merkblatt S 1.
5.1 The fatigue life of cyclically loaded componentslargelydepends on the dimensioning and design. Specialcare shall be takenhere to ensure that designs with highstress or strain concentratione.g. due to abrupt wallthickness transitions, are avoided. Table 3contains anassessment of frequently used weld details inpressurevessels. In the case of rigorous requirementsregardingcomponent lifetime, the weld designs of class K 1arerecommended. If necessary, more rigorous requirementsshall beimposed on the design than are given in AD 2000-Merkblatt HP 1(compare stress factors in Table 3).Suitable design shall makepossible testing and inspectionas specified in clause 7.
5.2 To assess the life expectancy of designs not given inTable3, the anticipated value shall be fixed by means of correspondingestimates on the stress concentration fac-tor (see clause 4 of AD2000-Merkblatt S 2). In suchcases, however, it is practical toconduct a detailed calcu-lation according to AD 2000-Merkblatt S 2.This generallyapplies to cam closures and clasp-bolted joints, forex-ample.
Over-dimensioning for predominantly static loading alsoleads toa greater number of allowable load cycles. Simi-larly a greaternumber of load cycles can normally bepermitted by applying AD2000-Merkblatt S 2 (see An-nex 2 of this AD 2000-Merkblatt).
Within the context of the design examination as described in AD2000-Merkblatt HP 511, the relevant third party shallestablish thelocations which shall be tested in particularwith regard to cyclicloading in the tests described in 7.2and 7.3.
party shall ensure that there are no defects present inthepressure vessel or pressure vessel component which maygrowrapidly in size under cyclic loading and which may result infailure of the pressure parts before the allowablenumber of loadcycles has been reached (see AD 2000-Merkblatt HP 5/1).
7.2.2 For the non-destructive test, the provisions ofAD2000-Merkblatt HP 5/3 in conjunction with the generaltable for HP0 shall be observed. If according to this, themethod ofnon-destructive examination is left open, theultrasonic examinationshould be given preference. Loca-tions subject to high loadingsduring operation such as welded-in nozzles, hole edges or crosssectional transi-tions, shall as far as practicable be subjectedcompletely to non-destructive testing. The visual examinationforsurface defects and external visible welding defects shall beperformed with appropriate care.
In the case of corrosion-induced crack formation (fatiguecrackcorrosion, strain-induced crack corrosion), hydro-gen-induced crackformation in compressed hydrogen, orthe presence of a magnetiteprotective layer, the provi-sions of AD 2000-Merkblatt S 2, shallbe applied accord-ingly.
9.3 Should cracks or crack-type defects within themeaning of 5.2and 5.4 of AD 2000-Merkblatt HP 5/3 orother more extensive damageestablished in the tests carried out as described in 9.1 or 9.2,the component orthe structural element concerned shall be replaced,unless continued operation is deemed to be permitted by virtueofappropriate measures to be agreed in accordance withnationalregulations.
10.1 In all cases where the conditions for waiving appli-cationof this Merkblatt as described in 1.4 an 1.5 are notmet, this shallbe indicated to the manufacturer and forthe design examination ofthe relevant third party. In suchcases, measures adapted tooperational needs shall be provided for and, if necessary, agreedbetween the manu-facturer, customer/user and relevant third party.Thesemeasures shall be included in the design-approved draw-ing andin the certificate of the final test, making reference to AD2000-Merkblatt S 1.
In order to take into account thecyclic-strength-reducinginfluence of the component size, thecorrection factor Fdwas taken for welded joints in the endurancerange givenin 7.2.6 of AD 2000-Merkblatt S 2. Dependence onthenumber of load cycles according to AD 2000-MerkblattS 2, formula(17), was dispensed with.
To plot a load cycle curve for unwelded components (sur-facecondition: rolling skin), calculations were conducted according toAD 2000-Merkblatt S 2 for different materials taking account of theinfluence of plasticity and maximummean stress ( = Rp0,2).According to Fig. A 1 of this Annex, it is possible toindi-cate by approximation a mean value curve with constantgradient exponent m = 3,5 on a double-logarithmic scale. This loadcycle curve class K 0 is almost identical with theload cycle curvesfor unwelded component areas accord-ing to the British Standard BS5500 : 94  or, as the casemay be, BS 7608 : 1993  (curves ofclass C).
To check the influence of plasticity in the range of lownumbersof load cycles, calculations were conducted (conservatively)according to AD 2000-Merkblatt S 2 forthe low-strength material HII. Fig. A 4 shows that thereduction through the ke factors (ke> 1) is relatively smallfrom 1000 load cycles on and only takeseffect in classesK 1 and K 2. In view of the scoope (N 1000), aglobalstress increase in elastic-plastic range through kefactorswas therefore dispensed with for reasons ofsimplification.
To simplify the procedure with damage accumulation inthe case ofan operational load regime, no fictitious loadcycle curvesaccording to the Haibach modification as inAD 2000-Merkblatt S 2are contained in the endurance range (N > 2 106).
As compared with the base values of allowable stress amplitudes2a according to AD 2000-Merkblatt S 2, Ta-ble 4 in the range N = 2106 to 108 and in accordancewith the procedure according to AD2000-Merkblatt S 2,9.2, stress amplitudes with N 2 106 at a levelof 50 %of the endurance values 2aD according to Table 2 of this AD2000-Merkblatt are regarded as negligible.
1.1 The following rules on simplified analysis for cyclicloadingapply to pressure-bearing unwelded parts ofpressure vessels made ofspheroidal graphite cast iron according to DIN EN 1563, limited tothe grades EN-GJS-400-15/15U, EN-GJS-400-18/U-LT andEN-GJS-350-22/22U-L, manufactured and tested according toAD2000-Merkblatt W 3/2. 2b1af7f3a8