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1、 Reference number ISO 16241:2005(E) ISO 2005 INTERNATIONAL STANDARD ISO 16241 First edition 2005-02-15 Notch tensile test to measure the resistance to slow crack growth of polyethylene materials for pipe and fitting products (PENT) Essai de traction dune entaille pour mesurer la rsistance la propaga
2、tion lente de fissure des polythylnes pour tubes et raccords (PENT) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without li
3、cense from IHS -,-,- ISO 16241:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing
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6、riat at the address given below. ISO 2005 The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, instruction booklets, technical publications and journals for strictly educational or implementation purposes. The conditions for such re
7、production are: that no modifications are made to the terms and definitions; that such reproduction is not permitted for dictionaries or similar publications offered for sale; and that this International Standard is referenced as the source document. With the sole exceptions noted above, no other pa
8、rt of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale
9、56 CH-1211 Geneva 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 2005 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/99725
10、45001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16241:2005(E) ISO 2005 All rights reserved iii Contents Page Forewordiv Introduction v 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 2 5 Apparatus 2
11、6 Test piece preparation 4 6.1 Test piece geometry . 4 6.2 Test piece preparation 5 6.3 Test piece notching 5 6.4 Number of test pieces. 6 7 Preconditioning. 6 8 Procedure 6 8.1 Calculation of test mass. 6 8.2 Loading the test piece 6 8.3 Checking temperature 7 8.4 Recording time to failure 7 8.5 Ex
12、amination of failed test piece 7 9 Test report . 7 Annex A (informative) Application of the test 8 Annex B (informative) Measurement of extension 9 Annex C (informative) Notch depth 10 Annex D (informative) Recommended minimum requirements for polyethylene 11 Annex E (informative) Precision . 12 Bib
13、liography . 13 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16241:2005(E) iv ISO 2005 Al
14、l rights reserved Foreword ISO (the International Organization 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 sub
15、ject 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 the work. ISO collaborates closely with the International Electrotechnical Commission (I
16、EC) 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 International Standards. Draft International Standards adopted by the technical commit
17、tees 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 of the elements of this document may be the subject of patent rights. ISO shall not be
18、 held responsible for identifying any or all such patent rights. ISO 16241 was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the transport of fluids, Subcommittee SC 5, General properties of pipes, fittings and valves of plastic materials and their accessories T
19、est methods and basic specifications. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16241
20、:2005(E) ISO 2005 All rights reserved v Introduction This test method is based on ASTM F 1473 1, which was originally developed at the University of Pennsylvania. It has been used for assessing and comparing the resistance to slow crack growth of a wide range of polyethylene pipe compounds used prim
21、arily for gas applications in the USA and Europe. The test had been evaluated by ten laboratories in the USA prior to acceptance as an ASTM standard. Further work was then carried out by an ad-hoc group of ISO/TC 138/SC4, Plastics pipes and fittings for the supply of gaseous fuels, to evaluate and r
22、efine the procedure, involving six laboratories in Europe and the USA. Resistance to slow crack growth is an important consideration for polyethylene materials used for pipeline applications and tests to assess this property are incorporated in pressure pipe system standards. The test is also applic
23、able to polyethylene materials used for other pipeline applications as well as to other thermoplastics materials used for other applications. Although seen primarily as a materials test, it has been applied to assess the performance of test pieces cut from pipe and fitting products and butt fusion w
24、elds. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for
25、Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 16241:2005(E) ISO 2005 All rights reserved 1 Notch tensile te
26、st to measure the resistance to slow crack growth of polyethylene materials for pipe and fitting products (PENT) 1 Scope This International Standard specifies a method for determining the resistance to slow crack growth of polyethylene (PE) materials for pipes and fitting products. 2 Normative refer
27、ences 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 291, Plastics Standard atmospheres for
28、conditioning and testing ISO 293, Plastics Compression moulding of test specimens of thermoplastic materials ISO 1872-2, Plastics Polyethylene (PE) moulding and extrusion materials Part 2: Preparation of test specimens and determination of properties ISO 2818, Plastics Preparation of test specimens
29、by machining 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 brittle failure failure with a fracture surface which exhibits no visible permanent material deformation, e.g. stretching, elongation or necking down 3.2 ductile failure failure wit
30、h a fracture surface which clearly exhibits permanent material deformation with stretching, elongation and necking down 3.3 slow crack growth slow extension of a crack with time which is of a brittle appearance 3.4 remaining ligament remaining cross section after notching and crack growth Copyright
31、International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16241:2005(E) 2 ISO 2005 All rights reserved 4 Princi
32、ple To assess the resistance to slow crack growth of a material, a test piece is cut from a compression-moulded sheet. The rectangular shaped test piece containing a centre notch in one face and side notches in the same plane is subjected to a constant static tensile load at a specified test tempera
33、ture. The time to failure is recorded. NOTE 1 The test may be carried out on test pieces machined from pipe and fitting products or butt welds (see Annex A). The following characteristics are described in this method: the shape and dimensions of the test piece; the notch depth and the depth of the s
34、ide grooves; the number of test pieces; the test temperature of the test pieces; the method of preparation of the test pieces. The following parameters shall be specified by the referring standard (a standard making reference to this International Standard in its own provisions): the test piece thic
35、kness and notch depth if different from the preferred dimensions (see 6.1); the stress to be applied to the test piece for the duration of the test; the number of test pieces if differing from the number specified in 6.4; the test temperature if differing from the value specified in this method (see
36、 5.2). NOTE 2 The applied stress chosen is such as to preclude ductile behaviour by inducing a fracture surface which is flat, exhibiting no visible permanent material deformation (i.e. stretching, elongation or necking down). Such a surface as a result of the gradual extension of the crack with tim
37、e is considered to be akin to slow crack growth. Typically, a load to give a stress level of 2,4 MPa at 80 C will produce a mode of failure related to slow crack growth in polyethylene materials. Alternative stress levels may be used providing a similar mode of failure is produced. 5 Apparatus 5.1 T
38、est rig, consisting of the following. 5.1.1 Test machine, capable of applying, via grips (see 5.1.2) an axial load on the test piece controlled with an accuracy of within 0,5 % of the calculated or applied load, e.g. a lever-loading machine, with a lever arm ratio of around 5:1 to 10:1 be applied di
39、rectly using dead weights or a constant load. 5.1.2 Grips, having a low friction universal action to prevent bending and to ensure that the load is transmitted axially through the test piece. The grips shall be designed to prevent slippage of the test piece (e.g. serrated grips). NOTE Measurement of
40、 the extension of the test piece or movement of the lever arm provides useful information. The rate of extension of the test piece will increase when initiation of the crack has occurred and will increase rapidly when failure is imminent (see Annex B). 5.2 Heating chamber or oven, where the loading
41、frame shall be located with air circulation by a fan or other means to maintain the test piece at (80 1,0) C or an alternative test temperature specified by the referring standard. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical
42、 Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16241:2005(E) ISO 2005 All rights reserved 3 5.3 Temperature measuring device, i.e. calibrated thermometer or a thermocouple, capable of checking conformity to 5.
43、2. NOTE Temperature is a critical parameter and measurement made remote from the test piece may not be indicative of temperature of the test piece. 5.4 Clock or timing device, for recording the elapsed time, which shall automatically stop or record the point when the test piece is deemed to fail by
44、either fracture or excessive displacement of the grips. 5.5 Alignment jig, as shown in Figure 1 or similar, to facilitate the alignment the grips and the test piece when it is being tightened in the grips. Key 1 screw clamps 2 test piece 3 grips Figure 1 Typical arrangement for an alignment jig 5.6
45、Notching apparatus, for notching the test piece (see Figure 2) so that the main notch and any side notches are coplanar and the plane of the notching is perpendicular to the tensile axis of the test piece. A blade of approximate thickness of 0,15 mm to 0,25 mm shall be used for preparing the notch.
46、The notch-machining equipment shall have a blade penetration speed of not more than 0,25 mm/min and be capable of producing a specified notch depth to within 0,1 mm. NOTE The indicated notch depth can be checked by notching and measurement of a dummy test piece. 5.7 Microscope, suitable for measurin
47、g the notch depth and examining the fracture surface. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 19:55:44 MDTNo reproduction or networking permitted without license from IHS
48、 -,-,- ISO 16241:2005(E) 4 ISO 2005 All rights reserved Key 1 test piece 2 razor blade 3 guides Figure 2 Typical arrangement for apparatus for notching test pieces 6 Test piece preparation 6.1 Test piece geometry The test piece geometry is shown in Figure 3, with a preferred nominal width, b, not less than 25 mm and not greater than the width of the grips used, a thickness, h, of a nomina