AD 2000-Merkblatt

AD 2000-Merkblätter are protected by copyright. The rights of use, particularly of any translation, reproduction, extract of figures, transmission byphotomechanical means and storage in data retrieval systems, even of extracts, are reserved to the author. Beuth Verlag has taken all reasonablemeasures to ensure the accuracy of this translation but regrets that no responsibility can be accepted for any error, omission or inaccuracy. In cases ofdoubt or dispute, the latest edition of the German text only is valid.

ICS 23.020.30 July 2009 edition

The AD 2000-Merkblätter are prepared by the seven associations listed below who together form the “Arbeitsgemeinschaft Druckbehälter”(AD). The structure and the application of the AD 2000 Code and the procedural guidelines are covered by AD 2000-Merkblatt G 1.

The AD 2000-Merkblätter contain safety requirements to be met under normal operating conditions. If above-normal loadings are to beexpected during the operation of the pressure vessel, this shall be taken into account by meeting special requirements.

If there are any divergences from the requirements of this AD 2000-Merkblatt, it shall be possible to prove that the standard of safety ofthis Code has been maintained by other means, e.g. by materials testing, tests, stress analysis, operating experience.

Fachverband Dampfkessel-, Behälter- und Rohrleitungsbau e.V. (FDBR), Düsseldorf

Deutsche Gesetzliche Unfallversicherung (DGUV), Berlin

Verband der Chemischen Industrie e.V. (VCI), Frankfurt/Main

Verband Deutscher Maschinen- und Anlagenbau e.V. (VDMA), Fachgemeinschaft Verfahrenstechnische Maschinenund Apparate, Frankfurt/Main

Stahlinstitut VDEh, Düsseldorf

VGB PowerTech e.V., Essen

Verband der TÜV e.V. (VdTÜV), Berlin

The above associations continuously update the AD 2000-Merkblätter in line with technical progress. Please address any proposals forthis to the publisher:

Verband der TÜV e.V., Friedrichstraße 136, 10117 Berlin.____________

Special casesCalculation of pressure vessels

Experimental design methodAD 2000-Merkblatt

S 5

Contents

0 ForewordThe AD 2000 Code can be applied to satisfy the basic safetyrequirements of the Pressure Equipment Directive, princi-pally for the conformity assessment in accordance withmodules “G” and “B + F”.

The AD 2000 Code is structured along the lines of a self-contained concept. If other technical rules are used in ac-cordance with the state of the art to solve related problems,it is assumed that the overall concept has been taken intoaccount.

The AD 2000 Code can be used as appropriate for othermodules of the Pressure Equipment Directive or for differentsectors of the law. Responsibility for testing is as specifiedin the provisions of the relevant sector of the law.

1 ScopeThis AD 2000-Merkblatt describes an experimental proce-dure for testing the strength of structures or partial struc-tures that cannot be calculated using the formulas given in

AD 2000 Code series B. The method described here is lim-ited to:

– the stress case I in accordance with AD 2000-MerkblattW 10;

– the range PS × V < 6000 bar · I and PS × DN < 3000 bar,if no additional calculations are used;

– component loading, that is predominantly static in ac-cordance with AD 2000-Merkblatt S 1.

The method of experimental design described in this Merk-blatt is not to be applied:

– to pressure equipment operated in long-term stressing,

– for dimensioning for additional stresses resulting fromthermal influences and external forces, which may haveto be considered separately,

– for testing the strength of structures the stability of whichis in danger.

This AD 2000-Merkblatt is not to be applied to plate heat ex-changers.

0 Foreword1 Scope2 General3 Symbols and units4 Test programme5 Requirements for the test specimen

prior to the bursting pressure test

6 Test medium and safety requirements to be appliedduring the test

7 Test method and required bursting pressure8 Conditions for a positive evaluation result of

the bursting pressure test9 Test report

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2 General2.1 This AD 2000-Merkblatt shall only be applied in con-junction with AD 2000-Merkblatt B 0. The approved materi-als are those listed in AD 2000-Merkblatt B 0, Table 2.

2.2 With regard to its strength-relevant dimensions to betested, to the manufacturing procedure, materials and testscope, the test specimen shall correspond to the pressureequipment. If partial areas of the pressure equipment are tobe calculated by means of formulas, then the required wallthicknesses determined in accordance with the dimension-ing formulas shall be adhered to.

2.3 The test specimen used for the bursting pressure testshall not be reused after the bursting pressure test even if itshows neither deformations nor cracks or leakages.

3 Symbols and unitsIn addition to the specifications of AD 2000-Merkblatt B 0the following applies:

sy se-c1-c2 mm

sg wall thicknesses measured on thetest specimen mm

n form factor –

Rm (3) mean value of tensile strengthof 3 samples from the same cast N/mm2

Rm minimum value of tensile strengthaccording to the standard N/mm2

SF safety coefficient for calculating PB –

PB required bursting pressure bar

The required safety coefficient to be applied to the burstingpressure for calculating PB is for:

Rolled and forged steel SF = 5,0

Cast steel SF = 6,0

Nodular graphite iron SF = 7,0

Grey cast iron SF = 9,0

Aluminium and alloy/wrought material SF = 5,0

Nickel 1+2, Titanium SF = 5,0

Copper SF = 6,0

4 Test programmeThe procedure for the bursting test shall be specified in atest programme and agreed with the notified body. The testprogramme shall include at least the information listed be-low:

– constructional drawing with the main dimensions and in-formation regarding the material of the test specimen

– manufacturing method

– test conditions, number of test specimens

– description of measurement instrumentation

– evaluation of test results

– criteria for acceptance or rejection of test results

5 Requirements for the test specimen prior to the bursting pressure test

The test specimen shall be taken from regular production.The test specimen shall either be equipped with sufficient

vent connections or sufficient ventilation shall be ensuredotherwise. During the subsequent manufacture no changesshall be made to the manufacturing tolerances, manufactur-ing methods or materials. The mechanical and technologicalquality characteristics of the materials used shall be certifiedin accordance with the requirements of AD 2000 series W.

6 Test medium and safety requirementsto be applied during the test

For safety reasons, the pressure required for the burstingtest shall be applied by means of a fluid having neither cor-rosive nor any other effect on the material (hydraulic test).Since the test can lead to the sudden failure of test speci-mens appropriate safety measures shall be taken.

7 Test method and required burstingpressure

Method: bursting pressure test

This method is applicable to the materials indicated in thescope (see 2.1). The material-related safety coefficient isdefined in clause 3.

Only structures of simple shapes and with soft transitionsshall be tested. This method is of limited suitability for struc-tures with plane surfaces. After the bursting test, the perma-nent deformation for components made of ductile steelsshall not exceed the limits permissible for cold deformationwithin areas of plane surfaces (see AD 2000-MerkblätterHP 7/2 and 7/3).

The required bursting pressure is calculated using the fol-lowing formula (1):

PB = SF × PS × Rm (3) /Rm × K20 /K × (sg /sy)n (1)

where:

n = 1 for curved surfaces (cylinder, sphere) or cones with acone angle of f ≤ 30°;

n = 2 for all other surfaces.

The exponent n or the relevant position in the structure isspecified in the test programme together with the notifiedbody.

Test procedure:

a) When commencing the test, the temperatures of the testspecimen and test fluid should be close to room tempe-rature; during the test the temperature of the test fluidshall be at least 10 °C below the boiling temperature atatmospheric pressure.

b) For the first loading step a pressure corresponding to50 % of the required minimum bursting pressure shall beapplied. Subsequently, the load is increased in incre-ments of 10 % of the required minimum bursting pres-sure. Following each load increase, the pressure shallbe held constant for a sufficient period of time.

8 Conditions for a positive evaluation result of the bursting pressure test

The test specimen shall not show any non-permissible plas-tic deformations (refer to clause 7) or leakages in the pres-surized wall until the required bursting pressure calculatedusing formula (1) is reached.

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If a specimen fails before reaching the required burstingpressure the bursting test may be repeated with a secondspecimen from the same production. If when using this sec-ond specimen the required bursting pressure is reached,then the test may be deemed successful if the reason for fail-ure of the first specimen to fail is comprehensible. However,if the second specimen should also fail, then the construc-tion is to be strengthened correspondingly.

Leakages at flange connections are acceptable during thebursting pressure test if the required bursting pressure isreached. For this it shall be ensured that the flange connec-tions are sufficiently dimensioned in accordance with the re-quirements of AD 2000-Merkblatt B 8 for the maximumallowable pressure PS. It is permissible to use materials ofhigher strength for the bolts than required for their quality inaccordance with the design calculation.

9 Test reportThe pressure equipment manufacturer shall document atleast the following:

– manufacturer registration

– equipment number

– date and place of the test

– description of the apparatus

– details or references to the test method

– calibration of the measurement equipment

– maximum applied bursting pressure PB

– pressure test medium

– calculation of the maximum allowable pressure PS

– summary

– operator’s name and designation of the relevant third party

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Publisher: Source of supply:

Beuth Verlag GmbH10772 BerlinTel. 030/26 01-22 60Fax 030/26 01-12 60info@beuth.dewww.beuth.de

Verband der TÜV e.V.

E-Mail: berlin@vdtuev.dehttp://www.vdtuev.de

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