1、BRITISH STANDARD BS2782-11: Method 1108A: 1989 Methods of testing Plastics Part11: Thermoplastics pipes, fittings and valves Method1108A: True impact rate (TIR) boundaries of pipes IMPORTANT NOTE. Before reading this method it is essential to read BS2782-0, issued separately.BS2782-11:Method1108A:19
2、89 This British Standard, having been prepared under the directionof the Plastics StandardsPolicy Committee, waspublished under the authorityof the Board of BSI andcomes into effect on 29September1989 BSI12-1999 Committee reference PLM/9 Draft (ref.88/39503) formed partof86/37965DC ISBN 0 580 17439
3、5 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Plastics Standards Policy Committee (PLM/-) to Technical CommitteePLM/9, upon which the following bodies were represented: The following bodies were also represented in the drafting of th
4、e standard, through sub-committees and panels: British Gas plc Health and Safety Executive British Plastics Federation Institution of Civil Engineers British Plumbing Fittings Manufacturers Institution of Gas Engineers Association Institution of Production Engineers British Valve and Actuator Manufa
5、cturers Institution of Water and Environmental Association Management (IWEM) Department of the Environment (Construction National Association of Plumbing, Heating and Industries Directorate) Mechanical Services Contractors Department of the Environment (Property Plastics and Rubber Institute Service
6、s Agency) Plastics Land Drainage Manufacturers Department of Transport Association Electricity Supply Industry in England Royal Institute of Public Health and Hygiene and Wales Water Authorities Association Engineering Equipment and Materials Water Companies Association Users Association Water Resea
7、rch Centre British Adhesives and Sealants Association Institute of Plumbing British Board of Agrement Land Drainage Contractors Association Heating and Ventilating Contractors Ministry of Agriculture, Fisheries and Food Association RAPRA Technology Ltd. Amendments issued since publication Amd. No. D
8、ate of issue CommentsBS2782-11:Method1108A:1989 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definition 1 3 Principle 1 4 Apparatus 1 5 Test pieces 3 6 Conditioning 3 7 Procedure 3 8 Determination of results 4 9 Test report 4 Figure 1 Suitable type of
9、 impact testing apparatus 2 Figure 2 Chart for true impact rate (TIR) for test at20 C 5 Table 1 Mass of striker 3 Table 2 Number of longitudinal lines to be drawn on pipe test pieces 3 Publications referred to Inside back coverBS2782-11:Method1108A:1989 ii BSI 12-1999 Foreword This British Standard
10、has been prepared under the direction of the Plastics Standards Policy Committee. It describes a method for determining the resistance of plastics pipes to impact by a falling striker expressed as an estimate of the true impact rate (TIR) of a batch of pipes when tested under specified conditions. I
11、t is intended for specification or production quality control purposes, particularly but not exclusively for pipes made of unplasticized polyvinyl chloride. It has been published in Part11 of BS2782 to enable cross-reference by revisions of British Standard specifications for thermoplastics pipes fo
12、r non-pressure applications, specifically BS4660, BS4576 and BS5255, to avoid duplication of associated appendices. Account has been taken also of similar requirements currently embodied in methods of test appended to BS5481 and BS3505, in particular in the range of pipe sizes and nominal striker ma
13、sses accommodated by this method, to enable cross-reference by those standards in due course. In drafting this standard consideration has been given to the method described in ISO3127:1980 “Unplasticized polyvinyl chloride (PVC) pipes for the transport of fluids Determination and specification of re
14、sistance to external blows” prepared by Technical CommitteeTC138 of the International Organization for Standardization (ISO). This standard differs from the International Standard in that this method is not restricted in scope to PVC pipes and does not impose a specification. Consideration has also
15、been given to current work by that international Technical Committee on the preparation of a method applicable to a variety of materials and providing for both similar and alternative test temperatures and TIR percentage levels, but the ISO work is not yet completed and the sampling requirements, al
16、ternative temperature and TIR levels proposed thereby have not been generally adopted or used for the purposes of British Standards for impact tests on plastics pipes. Part11 of BS2782 comprises a series of methods of test normally applied to the whole range of thermoplastics pipes, fittings and val
17、ves. WARNING. This British Standard does not necessarily detail all the precautions necessary to comply with the requirements of the Health and Safety at Work etc. Act1974. Attention should be paid to any appropriate precautions and the method should be operated only by trained personnel. A British
18、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 British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front co
19、ver, an inside front cover, pagesi andii, pages1 to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS2782-11:Method1108A:1989 BSI 12-1999 1
20、1 Scope This British Standard describes a method for determining the resistance of plastics pipes to external blows by a falling striker. It is suitable for application to isolated batches of pipes, to obtain an estimate of the true impact rate (TIR) of the batch, for production quality control or a
21、cceptance purposes. In particular this method determines TIR boundaries at the10% level when tests are conducted at20 C. NOTEThe titles of the publications referred to in this method are listed on the inside back cover. 2 Definition For the purposes of this British Standard method, the following def
22、inition applies. 2.1 true impact rate (TIR) in the analysis of results from an impact test involving a number of discrete blows on one or more test pieces, the total number of failures observed expressed as a percentage of the total number of blows applied NOTEThe criteria applied for failure usuall
23、y means that the test is destructive or likely to impart damage too severe for the test pieces to be serviceable: in practice therefore, test pieces are drawn at random from a batch and the result is only an estimate of the TIR for that batch. 3 Principle Test pieces are subjected at one or more poi
24、nts around their circumference to a blow from a striker of specified mass falling freely from a specified height and the effects of each blow are categorized as a pass or failure relevant to the specified criteria. The proportion of failures is expressed as an estimated TIR, with a90% confidence lim
25、it, for comparison with e.g.specification or acceptance requirements. The severity of the test method can be adjusted to suit different specification requirements, e.g.by changing the mass of the falling striker and/or by changing the height of fall. The boundary criteria given in this method (seeFi
26、gure 2) are not valid for values of TIR other than10%. 4 Apparatus 4.1 Falling weight apparatus, which shall consist essentially of the following (seeFigure 1). a) Main frame, rigidly fixed, supporting a guide, in the form of rails or a tube with perforated walls, sufficiently long for a striker see
27、b) to fall freely through at least2000mm relative to the top of a test piece, such that the guide is rigid and vertical to within1 . b) Striker, which may be weighted and which can fall freely subject to the guide. It shall be equipped with a hardened hemispherical striking surface25mm in diameter w
28、hich shall be free from flats or other imperfections. The combined mass of the striker and any associated weight(s) shall be not less than the nominal mass specified for the type and size of pipe to be tested. Unless otherwise specified in the applicable product specification, the nominal mass of th
29、e striker and any associated weight(s) shall be chosen from those listed in Table 1 and the actual mass of the striker and any associated weight(s) shall be not less than its nominal mass and shall not exceed its nominal mass by more than50g for nominal masses of less than1kg or by more than100g for
30、 nominal masses of not less than1kg and not greater than3kg or by more than200g for nominal masses of greater than3kg. c) Test piece support, comprising a120 vee-block at least200mm long so positioned on the base that the projection of the path of the centre of the hemispherical striker head is not
31、more than2.5mm from either axis of the vee-block. The vee-block and its underlying support or foundation shall not deform or move in response to the impact on the pipe under test. d) Striker release mechanism, such that the striker and any associated weight(s) can fall through a specified height of
32、up to at least2000mm onto the top surface of the test piece. e) Means for adjusting and/or maintaining the height of fall by the striker, e.g.by vertical movement of the test piece support seec), the striker release mechanism seed) or the main frame seea), in order to accommodate different diameters
33、 of pipe. 4.2 Water bath, maintained at20 1 C and large enough to contain test pieces described in clause5.BS2782-11:Method1108A:1989 2 BSI 12-1999 Figure 1 Suitable type of impact testing apparatusBS2782-11:Method1108A:1989 BSI 12-1999 3 Table 1 Mass of striker 5 Test pieces Unless otherwise specif
34、ied in the applicable product specification, each test piece comprises a complete section of pipe having a minimum length of200mm with ends cut cleanly and square to the longitudinal axis and free from discontinuities visible without magnification. Cut the test piece from pipe selected at random fro
35、m the batch or extrusion production run of pipe to be tested in accordance with the product specification sampling requirements or quality plan as applicable. The number of test pieces required will depend upon any applicable product sampling requirements, upon the size of the pipe under test and wh
36、ether or not each test piece may be subjected to more than one impact (seeTable 2 and clause7), and upon the results obtained (seeclause8). For pipes with nominal outside diameters greater than40mm, draw a straight line along the length of each test piece, randomly positioned on the pipes circumfere
37、nce. Draw further lines parallel to the first line and equidistant around the circumference to bring the total number to that given in Table 2. 6 Conditioning Condition the test pieces at20 1 C in the water bath (see4.2) for at least30min prior to testing. Test each test piece within60s of its remov
38、al from the conditioning bath. If this interval is exceeded by up to5min, return the test piece immediately to the conditioning bath for re-conditioning for a minimum period of5min. If the test piece is not re-immersed within6min of initial removal from the bath, then recondition the test piece for
39、at least30min. 7 Procedure Unless otherwise specified in the applicable product specification, set the impact test machine to give a height of fall of not less than2000mm. Maintain the ambient temperature at20 50 C. Table 2 Number of longitudinal lines to bedrawn on pipe test pieces Nominal mass of
40、striker and any associated weights Tolerance Nominal mass of striker and any associated weights Tolerance Nominal mass of striker and any associated weights Tolerance kg 0.5 0.75 1.00 1.25 1.375 1.50 kg +0.05 +0.05 +0.10 +0.10 +0.10 +0.10 kg 1.75 2.00 2.25 2.50 2.75 3.25 kg +0.10 +0.10 +0.10 +0.10 +
41、0.10 +0.20 kg 3.75 4.00 5.00 5.75 6.25 7.5 kg +0.20 +0.20 +0.20 +0.20 +0.20 +0.20 Nominal outside diameter a Nominal size b Number of circumferentially equidistant lines to be drawn mm u 40 50 63 75 90 110 125 140 160 180 200 225 250 280 315 355 W 400 in u 1“ 2 2“ 3 4 5 6 7 8 9 10 12 14 W 16 3 3 4 4
42、 6 6 8 8 8 12 12 12 16 16 16 24 a Metric series, e.g.nominal size as specified in BS4576, BS4660 or BS5481 or expressed in accordance with BS5556 in terms of size or outside diameter, e.g.d e . b Inch series, as specified in BS3505 or BS5255.BS2782-11:Method1108A:1989 4 BSI 12-1999 Place the first t
43、est piece in the vee-block with one of the marked lines where applicable (seeTable 2) uppermost and subject it to a blow from the falling striker. If the test piece does not fail, as defined by cracking completely through its wall thickness, and subject to the requirements of clause6, rotate it unti
44、l the next line becomes uppermost and in this position strike it again. Repeat the process until each line has been struck once or until the test piece has failed. After testing each test piece, consider whether the results obtained are sufficient to determine a definite result in accordance with cl
45、ause8; if not, test further test pieces in the same manner. When any test piece fails, remove it from the machine, record the number of strikes up to the point of failure and, if appropriate, recommence the test using a further test piece. Use as many test pieces and strikes as necessary to obtain a
46、 conclusion in accordance with clause8. NOTEA minimum of10strikes, without failure occuring, is necessary before testing can be discontinued. 8 Determination of results Refer to Figure 2 to compare the total number of strikes with the number of failed test pieces and interpret the result as follows.
47、 a) If the point of intersection falls within region C, record the result as an estimate of true impact rate (TIR) greater than10%. b) If the point of intersection falls within region A, record the results as an estimate of TIR less than10%. c) If the point of intersection falls on or within the bou
48、ndaries of region B, the result is indeterminate. Continue testing until either a positive result is obtained (seenote) or until it becomes clear that a result in region A is most unlikely and in this case record the result as an estimate of TIR greater than10%. NOTEThis will usually require a seque
49、nce of not less than10 further strikes which produces either no failed test pieces or at least two failed test pieces. 9 Test report The report shall include the following: a) a reference to this method of test, e.g.BS2782:Method1108A:1989 and/or the relevant product standard; b) the identification of the test pieces; c) the result of the test, i.e.whether the estimate of TIR is greater or less than10%; d) a report of any test conditions used other than as given in this method (e.g.a height of fall other than2000mmseeclause7). e
