1、BRITISH STANDARD BS ISO 8574:2004 Aerospace Hydraulic system tubing Qualification tests for bent tubes ICS 49.080 BS ISO 8574:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2008 BSI 2008 ISBN 978 0 580 61242 8 National foreword
2、 This British Standard is the UK implementation of ISO 8574:2004. The UK participation in its preparation was entrusted to Technical Committee ACE/69, Aerospace hydraulic systems, fluids and components. A list of organizations represented on this committee can be obtained on request to its secretary
3、. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments/corrigenda issued since publication Date CommentsINTERNATIONAL ST
4、ANDARD ISO 8574 Second edition 2004-05-01 Reference number ISO 8574:2004(E) Aerospace Hydraulic system tubing Qualification tests for bent tubes Aronautique et espace Tubes pour circuits hydrauliques Essais de qualification pour tubes coudsBS ISO 8574:2004ii iii Foreword ISO (the International Organ
5、ization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been establish
6、ed has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
7、 International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Pu
8、blication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such paten
9、t rights. ISO 8574 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 10, Aerospace fluid systems and components. This second edition cancels and replaces the first edition (ISO 8574:1990), which constitutes a minor revision by adding inch-dimensioned tubing
10、and by deleting flexure fatigue testing. BS ISO 8574:2004 blank1 Aerospace Hydraulic system tubing Qualification tests for bent tubes 1S c o p e This International Standard specifies pressure impulse and burst test procedures for determining and classifying the impulse fatigue strengths of bent tube
11、s used in aerospace hydraulic systems. The procedures are intended for qualification purposes of high- and low-pressure system tubing or for the evaluation of new materials for hydraulic system tubing. NOTE Requirements for tubing used in aerospace hydraulic systems are given in ISO 8575. 2 Normativ
12、e references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6772, Aerospace Fluid systems Im
13、pulse testing of hydraulic hose, tubing and fitting assemblies 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 proof pressure static pressure for testing hydraulic system tubing, a prescribed multiple of the nominal system or sub-system press
14、ure 3.2 tube failure leakage or rupture of the tube itself during test NOTE See 6.1.2. 4 Test equipment 4.1 Pressure impulse equipment The test equipment shall be capable of producing the pressure impulse curve specified in ISO 6772 (see 6.3). 4.2 Burst pressure equipment The test equipment shall be
15、 capable of producing the pressure requirements specified in 6.4. BS ISO 8574:20042 5 Test specimens 5.1 Configuration The test specimens shall consist of bent lengths of the relevant tubing of dimensions as specified in Figure 1 and Table 1 (with inch-dimensioned tubing given in Table 2), according
16、 to the case, manufactured using production techniques and requirements, in addition to test fittings and adaptors where required. Except where otherwise specified, the bend radius ( ) of the specimens shall be three times the nominal tube diameter. anominal tubing diameter. Figure 1 Test specimen (
17、S-tube) for the impulse test Table 1 Test specimen lengths for impulse testing metric-size tubing (see Figure 1) Dimensions in millimetres Nominal tube size Total tube length DN size adesignation Nominal diameter DN6 6 65 30 300 DN10 10 65 30 300 DN12 12 90 30 400 DN16 16 140 30 510 DN20 20 140 30 5
18、70 DN25 25 140 30 670 a DN size is the nominal diameter expressed in millimetres. R R= 3 L 1 L 2 +13 0 +6 0 +25 0 BS ISO 8574:20043 5.2 Pre-test checks 5.2.1 The outside diameter and wall thickness of the tubing shall be measured and recorded, together with the ovality of the bend. 5.2.2 Three strai
19、ght samples of the test tubing shall also be checked to determine the basic material properties, i.e. yield tensile strength ( proof strength), ultimate tensile strength and elongation. 6T e s t i n g 6.1 General 6.1.1 Temperature Unless otherwise specified e.g. when testing to ISO 6772 (see 6.3), t
20、esting shall be carried out at ambient temperature unless the fatigue characteristics of the material in question are significantly affected by the extreme temperature limit envisaged. In this case, the temperature spectrum shall be as defined by the particular aerospace requirements. 6.1.2 Fitting
21、failures Failure of a tube fitting or at the fitting sleeve interface shall not constitute a tube failure. In the event of a failure during testing of a tube fitting or at the fitting sleeve interface, the fitting(s) shall be replaced and the tests continued, or a new tube specimen shall be tested.
22、6.2 Proof pressure test Prior to commencement of testing, all specimen tube assemblies shall be subjected to a proof pressure which, unless otherwise specified, shall be twice the system nominal operating pressure. 6.3 Pressure impulse test A minimum of six specimens for each size required to be tes
23、ted, mounted as specified in Figure 1 and Table 1, shall be subjected to pressure impulsing in accordance with ISO 6772. Table 2 Alternate test specimen lengths for impulse testing inch-size tubing (see Figure 1) Dimensions in inches Tube size Total tube length Dash size adesignation Nominal diamete
24、r 0,25 2,5 1,25 12 0,375 2,5 1,25 12 0,5 3,5 1,25 16 0,625 5,5 1,25 20 0,75 5,5 1,25 22 1 5,5 1,25 26 a Dash size is the nominal diameter expressed in 1/16 inch. L 1 L 2 +0,5 0 +0,25 0 +1 0 0,4 0,6 0,8 10 12 16 0,2 % BS ISO 8574:20044 6.4 Burst test At least two specimens of each size required to be
25、 tested, mounted as specified in Figure 1, shall be subjected to hydraulic pressure. The pressure shall be increased at a rate of until the tube bursts. Expansion of the tube before burst is permissible. 6.5 Dimensional check On completion of pressure impulse and burst tests, the specimens shall be
26、sectioned and the wall thickness around the bend(s) checked. 7 Requirements 7.1 Pressure impulse test The required use is dependent on the life of the aerospace vehicle, but as a minimum requirement the results shall demonstrate a life of 200 000 cycles when the specimens are subjected to maximum im
27、pulse pressures as specified for the system. 7.2 Burst test As a minimum requirement, each tube shall withstand, without failure, a burst pressure related to the system operating pressure in addition to any safety factor required for the particular application. (150 000 37 500) kPa/min (20 000 5 000
28、) psi/min BS ISO 8574:20045 Bibliography 1 ISO 8575, Aerospace Fluid systems Hydraulic system tubing BS ISO 8574:2004BS ISO 8574:2004 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presen
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