1、 Reference number ISO 8521:2009(E) ISO 2009INTERNATIONAL STANDARD ISO 8521 Second edition 2009-08-15 Plastics piping systems Glass-reinforced thermosetting plastics (GRP) pipes Test methods for the determination of the apparent initial circumferential tensile strength Systmes de canalisations en mat
2、ires plastiques Tubes en plastiques thermodurcissables renforcs de verre (PRV) Mthodes dessai pour la dtermination de la rsistance en traction circonfrencielle initiale apparente ISO 8521:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy,
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7、20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedISO 8521:2009(E) ISO 2009 All rights reserved iiiContents Page Foreword iv 1 Scope1 2 Terms and definitions .1 3 Principle2 3.1 General .2 3.2 Method A 3 3.
8、3 Method B 3 3.4 Methods C, D and E.3 3.5 Method F.3 4 Apparatus.3 4.1 For method A .3 4.2 For method B .5 4.3 For method C .6 4.4 For method D .6 4.5 For method E .6 4.6 For method F7 5 Test pieces .8 5.1 For method A .8 5.2 For method B .8 5.3 For method C .9 5.4 For method D .10 5.5 For method E
9、.11 5.6 For method F12 5.7 Number of test pieces.13 6 Conditioning 14 7 Test temperature .14 8 Procedure.14 8.1 For method A .14 8.2 For method B .14 8.3 For method C .15 8.4 For method D .15 8.5 For method E .15 8.6 For method F15 9 Calculation .16 9.1 For method A .16 9.2 For method B .16 9.3 For
10、methods C, D and E17 9.4 For method F17 10 Test report17 ISO 8521:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is norm
11、ally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in t
12、he work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. 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
13、 International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication 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
14、 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 patent rights. ISO 8521 was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the transport of fluids, Subcommittee SC 6, Reinfor
15、ced plastics pipes and fittings for all applications. This second edition cancels and replaces the first edition (ISO 8521:1998), of which it constitutes a technical revision. INTERNATIONAL STANDARD ISO 8521:2009(E) ISO 2009 All rights reserved 1Plastics piping systems Glass-reinforced thermosetting
16、 plastics (GRP) pipes Test methods for the determination of the apparent initial circumferential tensile strength 1 Scope This International Standard specifies six test methods for the determination of the initial circumferential tensile wall strength per unit of length of glass-reinforced thermoset
17、ting plastics (GRP) pipes. NOTE Another commonly used term for “circumferential tensile strength” is “hoop tensile strength” and the two expressions can be used interchangeably. The burst test (method A) is suitable for all types and sizes of pipes. It is considered the reference method. However, al
18、l the methods in this International Standard have equal validity. If correlation of any of the methods B to F can be established by a comparative test programme, then that method can be considered as the reference method. The split disc test (method B) might not be suitable for pipes with helically
19、wound reinforcing layers. The strip test (method C), the modified strip test (method D) and the restrained strip test (method E) are suitable for pipes with a nominal size of DN 500 and greater. The notched plate test (method F) is primarily intended for use with helically wound pipes of nominal siz
20、e greater than DN 500 with a winding angle other than approximately 90. Results from one method are not necessarily equal to the results derived from any of the alternative methods. If required, the initial circumferential tensile modulus can be determined by method A. 2 Terms and definitions For th
21、e purposes of this document, the following terms and definitions apply. 2.1 initial circumferential tensile wall strength cA * , cB * , cC * , cD * , cE * , cF *ultimate circumferential tensile force per unit length in the circumferential direction (the upper-case subscripts denote the method of tes
22、t used) NOTE It is expressed in newtons per millimetre of circumference. ISO 8521:2009(E) 2 ISO 2009 All rights reserved2.2 burst pressure p ultinternal pressure at bursting NOTE It is expressed in bars 1)or megapascals. 2.3 bursting failure by rupture of the pipe wall 2.4 ultimate tensile force F u
23、lttensile force at failure NOTE It is expressed in newtons. 2.5 width b width of the test piece in the notched area NOTE It is expressed in millimetres. 2.6 winding angle angle between the direction of the continuous reinforcement and the longitudinal axis of the pipe NOTE It is expressed in degrees
24、. 2.7 helical wound cross wound filament wound pipes made with a balanced winding angle 3 Principle 3.1 General It is assumed that the following test parameters are set by the standard making reference to this International Standard: a) for method A, the length between end sealing devices (see 5.1);
25、 b) for methods B, C, D and E, the width of the test piece (see 5.2, 5.3, 5.4 and 5.5); c) for methods C and E, the total width of the test piece (see 5.3 and 5.5); d) for method F, the dimensions of the plate to be tested (see 5.6); e) the number of test pieces (see 5.7); 1) 1 bar = 0,1 MPa 10 5N/m
26、 2= 0,1 N/mm 2 . ISO 8521:2009(E) ISO 2009 All rights reserved 3f) the requirements for conditioning (see Clause 6); g) the test temperature (see Clause 7). 3.2 Method A The initial circumferential tensile wall strength, cA * , is determined by an internal pressure test. Cut lengths of pipe are subj
27、ected to an increasing internal pressure which, within a specified time, causes bursting (see 2.3). The test conditions are such that a mainly uniaxial circumferential stress is obtained. 3.3 Method B The initial circumferential tensile wall strength, cB * , is determined by a split disc test. Rings
28、 cut from the pipe are subjected to an increasing tensile force, by means of a split disc positioned within the ring, until rupture occurs within a specified time. 3.4 Methods C, D and E The initial circumferential wall strength, cC *or cD *or cE * , is determined by a strip test. Strips cut from th
29、e pipe wall in the circumferential direction, and if necessary, shaped to incorporate notches at defined locations, are subjected to an increasing tensile force until rupture occurs within a specified time. 3.5 Method F The apparent initial circumferential wall strength, cF * , is determined by a no
30、tched plate test. Plates cut from the pipe wall are subjected to an increasing tensile force until rupture occurs within a specified time. 4 Apparatus 4.1 For method A 4.1.1 Hydrostatic pressurizing system, capable, for pipes up to DN 500, of causing failure of the test piece between 1 min and 3 min
31、 after commencing the pressurization. For some nominal sizes greater than DN 500, the duration of the test will, for practical equipment reasons, need to be increased. Where increasing the testing time results in lower burst pressures, this shall be evaluated by comparing results of different test d
32、urations. The pressurizing system shall prevent air from entering the test piece during pressurization to failure. 4.1.2 Pressure measuring device, capable of measuring the applied internal pressure to an accuracy of 2,0 %. 4.1.3 End sealing devices for the test pieces, capable of inducing in the te
33、st piece, during the test, a mainly uniaxial state of stress in the circumferential direction in the test piece (see Figure 1). 4.1.4 Dimension measurement devices, capable of measuring the necessary dimensions of the test piece to an accuracy of 0,1 mm. 4.1.5 Test piece support, if needed, to minim
34、ize deformation due to the weight of the test piece and its contents. ISO 8521:2009(E) 4 ISO 2009 All rights reserved4.1.6 Strain measurement, if circumferential tensile modulus of the pipe wall is to be determined, strain gauges of the foil type, single element suitable for the anticipated strain l
35、evel and of a length appropriate for the pipe diameter. 4.1.7 Flexible membrane (if used as a barrier system to prevent weeping), which does not reduce the stress in the pipe wall by more than 1 %. The flexible membrane may be of a different material from the pipe, e.g. elastomeric or thermoplastic
36、sheet or a flexible coating. Key 1 end sealing device 2 elastomeric seal 3 test piece 4 tie bar for carrying end thrust Figure 1 Typical arrangement for pressure testing pipes (method A) ISO 8521:2009(E) ISO 2009 All rights reserved 54.2 For method B 4.2.1 Test machine, of the type capable of produc
37、ing a progressive separation of the split disc and incorporating the following components: a) a fixed or virtually fixed part; b) a moveable part; c) a drive mechanism, capable of imparting a constant speed to the moving part so that rupture can be reached between 1 min and 3 min after initial loadi
38、ng; d) a load indicator, capable of measuring the force applied. This shall be virtually free from inertia at the specified rate of testing and shall indicate the force to an accuracy of within 1 % of the measured value. 4.2.2 Rigid split discs, as shown in Figure 2, capable of making even contact w
39、ith the internal diameter of the test piece. The diameter of the two segments of the split disc shall be not less than 98 % of the internal diameter of the pipe with which they are intended to be used. 4.2.3 Dimension measuring devices, capable of measuring the necessary dimensions of the test piece
40、 to an accuracy of 0,1 mm. Key 1 toggle 2 saddle 3 shear pin aDirection of loading. bSeparation. cRounded edges. Figure 2 Typical arrangement for the split disc test (method B) ISO 8521:2009(E) 6 ISO 2009 All rights reserved4.3 For method C 4.3.1 Test machine, of the type with constant separating sp
41、eed, incorporating the following components: a) a fixed, or virtually fixed, part with a grip to hold one end of a test piece; b) a moveable part, incorporating a second grip to hold the other end of the test piece. The grips holding the ends of the test piece shall do so as far as possible without
42、slipping and/or crushing; NOTE Grips that tighten automatically can be used. c) the fixed and moving parts and their associated grips shall enable the test piece to be aligned when a force is applied, so that the axis of the test piece is coincident with that of the force; d) a drive mechanism capab
43、le of imparting a constant speed to the moving part, so that failure can be reached between 1 min and 3 min after initial loading; e) a load indicator capable of measuring the force applied. The mechanism shall be virtually free from inertia lag at the specified rate of testing and shall indicate th
44、e force to an accuracy of within 1 % of the measured value. 4.3.2 Dimension measuring device(s), capable of measuring the necessary dimensions of the test piece to an accuracy of 0,1 mm. 4.4 For method D 4.4.1 Test machine, conforming to 4.3.1 (see also Figure 6). 4.4.2 Dimension measuring device(s)
45、, capable of measuring the necessary dimensions of the test piece to an accuracy of 0,1 mm. 4.5 For method E 4.5.1 Test machine, conforming to 4.3.1 (see also Figure 3). 4.5.2 Dimension measuring device(s), capable of measuring the necessary dimensions of the test piece to an accuracy of 0,1 mm. 4.5
46、.3 Restraining fixture, capable of preventing the test piece from bending. The radius of curvature of the support plate shall be half the nominal size, DN, expressed in millimetres, 5 %. An example of such a fixture is shown in Figure 3. ISO 8521:2009(E) ISO 2009 All rights reserved 7Key 1 bolt 2 cl
47、amping plate 3 test piece 4 pivot R = 0,5 d iaDirection of loading. bAdjustable distance. Figure 3 Typical arrangement for restrained-strip test with a split support (method E) 4.6 For method F 4.6.1 Test machine, conforming to 4.3.1. 4.6.2 Load indicator, capable of indicating the force applied to
48、the test piece to an accuracy of 1 % of the indicated value. 4.6.3 Means of measuring the necessary dimensions of the test piece to an accuracy of 0,1 mm and the winding angle, , to an accuracy of 1. ISO 8521:2009(E) 8 ISO 2009 All rights reserved5 Test pieces 5.1 For method A The test piece shall b
49、e a cut length of pipe whose length between the end sealing devices shall be as specified in the referring standard. 5.2 For method B The test piece shall be a ring cut from a pipe; see Figure 4. The width of the test piece shall not exceed the width of the split disc. The width of the test section, b, shall be a minimum of 15 mm. NOTE For larger diameter and/or higher pressure pipes, the width of the test section might, for practical equipment reasons, need to be r
