EN 12814-3-2014 en Testing of welded joints in thermoplastics semi-finished products - Part 3 Tensile creep test《热塑半成品焊缝试验 第3部分 焊接接头拉伸蠕变试验》.pdf

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1、BSI Standards PublicationBS EN 12814-3:2014Testing of welded joints inthermoplastics semi-finishedproductsPart 3: Tensile creep testBS EN 12814-3:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 12814-3:2014. It supersedes BS EN 12814-3:2000 which is withdra

2、wn.The UK participation in its preparation was entrusted to Technical Committee PRI/80, Welding thermoplastics.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Us

3、ers are responsible for its correct application. The British Standards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 78955 7ICS 25.160.40Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority o

4、f the Standards Policy and Strategy Committee on 28 February 2014.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS EN 12814-3:2014EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12814-3 February 2014 ICS 25.160.40 Supersedes EN 12814-3:2000English Version Testing of

5、welded joints in thermoplastics semi-finished products - Part 3: Tensile creep test Essais des assemblages souds sur produits semi-finis en thermoplastiques - Partie 3: Essai de fluage en traction Prfen von Schweiverbindungen aus thermoplastischen Kunststoffen - Teil 3: Zeitstand-Zugversuch This Eur

6、opean Standard was approved by CEN on 30 November 2013. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

7、 concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN memb

8、er into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, Fra

9、nce, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES K

10、OMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12814-3:2014 EBS EN 12814-3:2014Contents Page Foreword 3 Introduction .4 1 Scope 5 2 Normative

11、references 5 3 Terms and definitions .5 4 Symbols and designations .5 5 Principle of the test6 6 Sampling procedures 7 7 Dimensions of test specimens .7 8 Cutting and preparation of test specimens 9 9 Mechanical testing 10 10 Test equipment . 10 11 Determination of the long-term welding factor 11 12

12、 Test report . 13 Annex A (informative) Resistance to slow crack growth . 15 Annex B (informative) Whole pipe tensile creep rupture test 18 Annex C (informative) Minimum creep rupture time of the parent material (ttm) for applicability of the long-term welding factor . 21 Annex D (informative) Testi

13、ng of socket joints . 22 Bibliography . 25 EN 12814-3:2014(E)BS EN 12814-3:2014Foreword This document (EN 12814-3:2014) has been prepared by Technical Committee CEN/TC 249 “Plastics”, the secretariat of which is held by NBN. This European Standard shall be given the status of a national standard, ei

14、ther by publication of an identical text or by endorsement, at the latest by August 2014, and conflicting national standards shall be withdrawn at the latest by August 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/

15、or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 12814-3:2000. The main changes with respect to the previous edition are listed below: a) addition of a NOTE for an alternative test using a whole pipe welded sample (Clause 5) making r

16、eference to Annex B (informative), Whole pipe tensile creep rupture test; b) addition of a NOTE for the sampling procedures (Clause 6) in case of socket joints with reference to Annex D (informative), Testing of socket joints. EN 12814, Testing of welded joints of thermoplastics semi-finished produc

17、ts, is divided into the following parts: Part 1: Bend test; Part 2: Tensile test; Part 3: Tensile creep test (the present document); Part 4: Peel test; Part 5: Macroscopic examination; Part 6: Low temperature tensile test; Part 7: Tensile test with waisted test specimens; Part 8: Requirements. Accor

18、ding to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,

19、 Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. EN 12814-3:2014(E)BS EN 12814-3:2014Introduction The design of welded thermoplastics constru

20、ctions under static load is based on the long-term creep rupture with behaviour, specifically the resistance to slow crack growth of the thermoplastics material and the welds. For design purposes, the relevant characteristic values for the welded joints are the “long-term tensile welding factors” to

21、 which this European Standard provides the test method. The long-term tensile welding factors are normally used in conjunction with the creep rupture curve of the parent material, given for example in EN 1778, when designing welded semi-finished products under static load. The long-term tensile weld

22、ing factor(s), the crack behaviour and the appearance of the fracture surface provide information on the quality of the weld. NOTE The behaviour of the failure obtained during the tensile creep test can be related to the notch sensitivity of the parent material. An example of a test to provide infor

23、mation about the notch sensitivity of parent material is given in Annex A. EN 12814-3:2014(E)BS EN 12814-3:20141 Scope This European Standard specifies the dimensions, the method of sampling and the preparation of the test specimens, and the conditions for performing the tensile creep test perpendic

24、ular to the weld in order to determine the long-term tensile welding factor. A tensile creep test may be used in conjunction with other tests (e.g. bend test, tensile test, macrographic examination, ) to assess the performance of welded assemblies, made from thermoplastics materials. The test is app

25、licable to welded assemblies made from thermoplastics materials filled or unfilled such as tubes and fittings, sheets, plates and profiles, but not reinforced, irrespective of the welding process used. 2 Normative references The following documents, in whole or in part, are normatively referenced in

26、 this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 13100-1, Non destructive testing of welded joints of thermoplastics semi-finish

27、ed products Part 1: Visual examination EN ISO 899-1, Plastics Determination of creep behaviour Part 1: Tensile creep (ISO 899-1) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 test temperature temperature of the medium surrounding the test s

28、pecimen during the test 3.2 test stress test load divided by the minimum cross sectional area of the test specimen 3.3 creep rupture curve regression curve through the geometric mean values of failure times 3.4 minimum failure time ttmcreep rupture time of the parent material to ensure that the test

29、 method is applicable 3.5 ductile fracture large scale deformation of material from fracture surfaces 3.6 brittle fracture little or no deformation of material from fracture surfaces 4 Symbols and designations Symbols and designations are given in Table 1. EN 12814-3:2014(E)BS EN 12814-3:2014Table 1

30、 Symbols and designations Symbols Designations Units a Minimum measured thickness of test specimen within calibrated and parallel length mm anNominal thickness of test piece mm b Width of calibrated and parallel length of the test specimen mm b1Width of shoulder of the test specimen mm c Depth of th

31、e notch mm DnNominal outside diameter of the tube mm flLong-term tensile welding factor FsValue of the force applied to the welded test specimen calculated from the chosen value of sN Ft Value of the force applied to the unwelded test specimen calculated from the chosen value of t N L Total length o

32、f the test specimen mm LjMinimum distance between the clamping jaws mm L0Calibrated and parallel length of the test specimen mm LwaMaximum width of the weld bead of the test specimen mm r Radius of shoulder of the test specimen mm ttm Minimum failure time h s Value of stress of the welded test speci

33、mens used in the calculation of fl N/mm2t Reference stress. Value of stress of the unwelded test specimens, used in the calculation of fl N/mm2aFor extrusion and hot gas welds only. 5 Principle of the test The test involves subjecting a test specimen to a constant load until fracture occurs. The tim

34、e to fracture is measured and recorded. NOTE An alternative test using a whole pipe welded sample rather that a test specimen cut form the weld is given in Annex B. EN 12814-3:2014(E)BS EN 12814-3:2014The tests are carried out over a range of temperatures and loads, and in a test medium. Only such m

35、edia shall be used which cause no swelling or degradation of the polymer. Examples of available test media are air, water or solutions of demineralised water with detergents. Care should be taken to ensure that the condition of the test medium does not influence the results of the test. The applicab

36、ility of the long-term tensile welding factor for design purposes requires a minimum creep rupture time for the parent material (ttm). Before determining the long-term welding factor for the materials mentioned in Annex C, a tensile creep test should be carried out on the parent material at one of t

37、he test conditions given in Table C.1. The values of creep rupture time should be at least that quoted in Table C.1. Application standards may prescribe higher values for these rupture times depending upon the semi-finished product and material. 6 Sampling procedures Welded and unwelded test specime

38、ns shall be taken from the same test piece. NOTE In the case of socket joints, see Annex D. The test specimens (welded and unwelded) shall be cut perpendicular to the welded joint at least eight hours after welding. For sheets where the extrusion direction is different on either side of the weld, th

39、e unwelded test specimens shall be taken from the side of the test piece which has the lowest creep rupture time. Each test specimen shall be marked in order to identify its original position within the test piece. No heat treatment or mechanical straightening operations shall be carried out on the

40、test specimen. 7 Dimensions of test specimens The dimensions of test specimens according to Figure 1 are given in Table 2 and those according to Figure 2 are given in Table 3. Profiles can be tested if test specimens are in accordance with the dimensions given in Table 2 or Table 3. For tubes having

41、 nominal outside diameter less than 20 mm, the whole tube shall be tested. In this case, the minimum distance between the clamps shall be 200 mm. EN 12814-3:2014(E)BS EN 12814-3:2014Key Lj= L0+ (2xb) Figure 1 Type 1 test specimen for flat and tubular assemblies Figure 2 Type 2 test specimen for flat

42、 and tubular assemblies EN 12814-3:2014(E)BS EN 12814-3:2014Table 2 Dimensions of type 1 test specimens Dimensions in millimetres Dnor anb L0L 20 Dn20 1,5 x an3 x an+ Lw with 120 min L0+ 80 Table 3 Dimensions of type 2 test specimens Dimensions in millimetres Dnor anb min. b1L0L r 20 Dn20 1,5 x an2,

43、5 x an3 x an+ Lwwith 120 min L0+ 80 60 Where the beads are left intact in service, they shall be left intact for the test. Where the beads are removed in service, they shall be removed prior to testing. The minimum value for b shall be 6 mm. The tolerance for b shall be 1 mm. The tolerance for L0sha

44、ll be 2 mm. The variation of b over the length L0shall not exceed 2 % of the average value of b. 8 Cutting and preparation of test specimens The tensile creep test specimens shall be cut with parallel sides as shown in Figures 1 and 2. During cutting, heating of the test specimen shall be minimized.

45、 The cutting operation shall not cause any damage to the test specimen. After cutting, a visual examination of the weld according to EN 13100-1 shall be carried out and recorded. EN 12814-3:2014(E)BS EN 12814-3:20149 Mechanical testing The stress is applied to the test specimen at constant temperatu

46、re, static tensile load and constant ambient conditions. Test specimens shall be conditioned to the test temperature before loading. The variation of the test temperature shall not exceed 1 C. For every stress level and every test temperature, a minimum number of six welded test specimens and six un

47、welded test specimens shall be tested. The test shall be carried out according to EN ISO 899-1. The test conditions shall be chosen in such a way that at least 30 % of the fracture area has undergone brittle failure, as described in Figure 3. To shorten the duration of the test, it is possible to us

48、e an appropriate aqueous surfactant solution as the contact medium for both welded and unwelded test specimens. The test specimens shall be progressively subjected to the test load. The duration of the test shall be taken from the moment of reaching test load until the test specimen fractures. Key 1

49、 area of crack surface that has undergone brittle fracture 2 area of crack surface that has undergone ductile fracture Figure 3 Characteristics of fracture surface The fracture behaviour of welded joints, where fracture occurs in the parent material and is initiated from notch between the parent material and the weld bead (see Figure 3), is closely related to the resistance to slow crack growth of the parent material. The resistance to slow crack growth of the parent material can be determined using the Full Notch Creep Test