1、STD.BS1 BS EN 1778-ENGL 2000 Lh24bb 083L2bL O98 = BRITISH STANDARD Characteristic values for welded thermoplastics constructions - Determination of allowable stresses and moduli for design of thermoplastics equipment The European Standard EN 17781999 has the status of a British Standard ICs 83.080.2
2、0; 83.140.01 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS EN 1778:2000 STD-BSI BS EN 1776-ENGL 2000 - 1b24bb9 0833262 T24 been prepared under the direction of the Sector Amd.No. Committee for Materials and Chemicals, was published under the authority of the Standards Com
3、mittee and comes int effect on 15 February ZOO0 O BSI 02-2000 BS EN 1778:2000 Date Comments National foreword This British Standard is the official English language version of EN 17781999. The UK participation in its preparation was entrusted to Technical Committee PRI/80, Weldmg thermoplastics, whi
4、ch has the responsibility to: - aid enquirers to understand the text; - present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed - monitor related international and European developments and promulgate them in the
5、UK A list of organizaions represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “Inte
6、mational Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a
7、British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 52, an inside back cover and a back cover. The BSI copynght notice displayed in this document indicates when the do
8、cument was last issued ISBN O 580 35862 3 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1778 October 1999 ICs 83.080.20: 83.140.01 English version Characteristic values for welded thermoplastics constructions - Determination of allowable stresses and moduli for design of thermoplastics eq u i
9、 p me n t Valeurs caractristiques des constructions thermoplastiques soudes - Dtermination des contraintes admissibles et des modules pour la conception du matriel thermoplastique Charakteristische Kennwerte fr geschweite Themoplast- Konstruktionen - Bestimmung der zulssigen Spannungen und Moduli fr
10、 die Berechnung von Thermoplast-Bauteilen This European Standard was approved by CEN on 2 September 1999. CEN members are bound to comply with the CENICENELEC Internal Regulations which stipulate the conditions for giving this Europem Standard the status of a national standard without any alteration
11、. Up-to-date lists and bibliographical references concerning sich national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by trmslation
12、under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as tie official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland. Ireland, Italy,
13、Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION EUROPISCHES KOMITEE FOR NORMUNG COMIT EUROPEN DE NORMALISATION Central Secretariat: rue de Stassart, 36 8-1050 Brussels O 1999 CEN All rights of exploitation in any form a
14、nd by any means reserved worldwide for CEN national Members. Ref. No. EN 1778:1999 E STD-BSI BS EN 1778-ENGL 2000 lib24bb9 08312b4 8T7 Page 2 EN 1778: 1999 Foreword This European Standard has been prepared by Technical Committee CEN/TC 249, Plastics, the Secretariat of which is held by IBN. This Eur
15、opean Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2000, and conflicting national standards shall be withdrawn at the latest by April 2000. According to the CENEENELEC Intemal Regulations, the national
16、 standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Annex
17、 A (normative) contains the neccessary creep strength diagrams, the creep modulus diagrams as well as the reduction factors. In annex B (informative) explanations and calculation examples are included. Introduction Because most components are subjected to multiaxial loading, the creep strength diagr
18、ams for pipes are taken as a basis for the allowable design stresses. The diagrams have been confirmed by results from many years of measurements and by experience (see I). Extrapolation of creep strength curves to higher temperatures is not permitted. The use of the creep strength curves for dumbbe
19、ll tensile test pieces is not correct practice because of the reasons mentioned above. A large number of reduction factors A2 for the action of the medium taking into account material, stress and temperature have been included. The reduction factors A2 for the action of the medium and the weld facto
20、rs f, were determined independently of each other. Investigations established the validity of the multiplicative connection between the weld factor f, and reduction factor AZK (reciprocal value of factor for resistance to chemicats fcRO (see 2 and 3). I Scope This standard specifies a methodology fo
21、r determination of the characteristic values necessary for the design of welded constructions for example vessels and tanks, ventilation ducting, containers and apparatus. It is assumed that due regard is paid to the standards and Codes of Practice listed in clause 2 as far as the choice of material
22、s and their processing are concerned. The data is applicable for static loading. The relevant EN standards or IS0 standards are applicable to the design calculations, dimensions, construction and testing of the various structures. This standard applies to a wide range of thermoplastics materials, fo
23、r example: Polyethylene (PE), Polypropylene (PP), Polyvinyl Chloride (PVC) and Polyvinylidene Fluoride (PVDF). Annex A gives minimum properties for specific grades of these materials. The use of other thermoplastics is permitted, provided that their creep properties exceed the minimum values given i
24、n annexA for the known materials. Properties should be determined in accordance with the relevant IS0 and EN standards. This allows the introduction of thermoplastics with improved properties as appropriate data becomes available. OBSI 02-2000 STD*BSI BS EN L778-ENGL 2000 Lb24669 083L2b5 733 Page 3
25、EN 1778: 1999 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendment
26、s to, or revisions of, any of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. prEN 12202 Plastics piping systems for hot and cold water - Polypropylene (PP) Plastics - D
27、etermination of creep behaviour - Part 2: Flexural creep by three-point-loading IS0 899-2 IS0 1167 Thermoplastics pipes for the conveyance of fluids - Resistance to internal pressure - Test method Thermoplastics pipes for industrial applications under pressure - Determination of the chemical resista
28、nce factor and of the basic stress - Part 1 : Polyolefin pipes Thermoplastics pipes for industrial applications under pressure - Determination of the chemical resistance factor and of the basic stress - Part 2: Pipes made of halogenated polymers Thermoplastics pipes for the transport of fluids - Met
29、hods of extrapolation of hydrostatic stress rupture data to determine the long-term hydrostatic strength of thermoplastics pipe materials IS0 8584-1 ISOTTR 8584-2 ISOTTR 9080 3 Definitions, symbols and abbreviations K S Al A2K fcRo A2E EC Ec(ai.).D Creep strength at the design temperature and lifeti
30、me in newtons per square millimetres Factor of safety Reduction factor to take account of the effect of specific strength Reduction factor taking into account the effect of surrounding medium (reciprocal value d resistance factor fcRo) Stress dependent chemical resistance factor Reduction factor tak
31、ing into account the effect of surrounding medium on the modulus d elasticity Creep modulus at the design condition (temperature, stress, time) in newtons per square millimetres Allowable creep modulus at the design condition for stability (temperature, stress, time, medium, safety factor) in newton
32、s per square millimetres Allowable creep modulus at the design condition for deformation (temperature, stress, time, medium) in newtons per square millimetres Design temperature in degrees Centigrade Short-term weld factor Long-term weld factor Effective stress in newtons per square millimetres Allo
33、wable stress at the design condition in newtons per square millimetres Number of fractional loadings Proportion of total loading time at each design condition expressed as per cent Service life at the individual working conditions (constant pressure and temperature) taking into account reduction, jo
34、int and safety factors Design life with or without intermittent loading Principal stress in newtons per square millimetres OBSI 02-2000 STD=BSI BS EN L77B-ENGL 2000 1624bb9 08312bb b7T Page 4 EN 1778: 1999 4 Determination of allowable stresses and moduli 4.1 General Design calculations for component
35、s are based on long-term values. Depending on the nature of the loading, there are generally three criteria: 1) Stress; 2) Deformation (e. g. deflection); 3) Stability (e. g. short or long-term buckling). Stress design calculations shall be made with reference to creep strength, as multiaxial states
36、 of stresses are present in most cases. The maximum principal stress shall not exceed the allowable creep strength. The allowable values are derived by using reduction factors (see clause 5), a joint factor (see clause 6) and factors of safety (see clause 7) from the characteristic values of the mat
37、erial. In terms of deformation and stability, the critical design parameter is creep modulus. This can be obtained from creep modulus diagrams depending on time, temperature and stress. In the event of stability problems, allowance shall be made for an appropriate factor of safety (see clause 7). 4.
38、1.1 Design calculation according to strength The allowable stress is obtained from the creep strength, reduction factors, joint factor and the factor of safety. The creep strength K to be used as a basis for design calculations can be obtained for a stated working time and working temperature from t
39、he diagrams in A.1.l or determined in accordance with ISOflR 9080. 4.1 .i .i Creep strength curves The creep strength curves show strength as a function of time and temperature. They were determined from long-term internal pressure tests on pipe specimens filled with water and represent minimum valu
40、es in accordance with IS0 1 167. The minimum creep strength values for other semi-finished products shall be equal to or higher than those determined for pipes. Other materials than those specified in FiguresA.l to A.12 can be taken into consideration if appropriately demonstrable tests are availabl
41、e in accordance with ISO/TR 9080. 4.1 .i .2 Intermittent loading For applications where regularly alternating (intermittent) loading occurs, as an approximation, the theory of linear accumulation of damage can be taken as a basis (Miners rule) (see 4). With this rule, the design life is determined i
42、n relation to the time spent at each design condition, taking into account the appropriate reduction, joint and safety factors. See the example in B.2.2. According to this rule: n wtx c - 100xti i=l OBSI 02-2000 For two fractional loadings: or Page 5 EN 1778:1999 (3) 4.1.2 The creep modulus (E,) is
43、used in the case of thermoplastics instead of the modulus of elasticity used in theoretical mechanics. The creep modulus is dependent on time, stress and temperature. It can also depend on the medium (particularly in the case of substances which have a swelling effect; characteristic values for this
44、 are still to be determined). For the materials used, the creep modulus can be obtained as a function of the stated parameters from the creep modulus curves (Figures A.13 to A.27) or in accordance with IS0 899-2. Design calculation according to stability and bending The creep modulus is used: - in s
45、tability calculations: EC Ec(a1 .)St = AE s - to determine deformations: - Ec Ec(aI.)D - A2 E 5 Reduction factors 5.1 Reduction factor AZ (see 5 and 6) 5.1.1 Reduction factor AK The reduction factor AZK quantifies the effect of the working medium on the creep strength of thermoplastics materials. Th
46、e reduction factor AzK is the reciprocal of the stress dependent resistance factor f, according to IS0 8584-1 or ISOTTR 8584-2). is determined A.1.3 contains the reduction factors for a wide range of chemicals. Other media than those specified in A.1.3 can be taken into consideration, if appropriate
47、ly demonstrable experience with the same or similar liquids, or the same material of construction andlor tests are available in accordance with IS0 8584-1 or ISOTTR 8584-2. 5.1.2 Reduction factor The reduction factor AzE except for mediums causing swelling SAZE = 1 For mediums which cause swelling (
48、see footnote 9 of A.1.3), AzE shall be determined by appropriate tests. 5.2 Reduction factor A, (As a function of temperature and impact strength for separate materials) This factor takes into account the strength of the materials as a function of temperature and is therefore derived from impact str
49、ength values. Table 1 contains values forA,. The values for other materials shall be established in accordance with annex B. OBSI 02-2000 STD*BSI BS EN 3378-ENGL 2000 = 3624669 0833268 442 Process Heated-tool butt welding HS Page 6 EN 1778:1999 PE-HD P P*) PVC-u* PVC-c PVDF fs 099 0,9 0,9 018 0,9 Table 1: Reduction factors Ai Material PE-HD high density PP-H homopolymer PP-B block - copolymer PP-R random - copolymer PVC-NI normal impact strength (PVC-U) PVC-RI raised impact strength (PVC-U) PVC-C chlorinated PVDF-H homopolymer Further explanation can b
