1、Designation: F 2023 05An American National StandardStandard Test Method forEvaluating the Oxidative Resistance of CrosslinkedPolyethylene (PEX) Tubing and Systems to Hot ChlorinatedWater1This standard is issued under the fixed designation F 2023; the number immediately following the designation indi
2、cates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the general re
3、quirements forevaluating the long-term, chlorinated water, oxidative resis-tance of cross-linked polyethylene (PEX) tubing produced inaccordance with Specification F 876 or PEX tubing/fittingsystems in accordance with Specification F 877 used in hot-and-cold water distribution systems by exposure to
4、 hot, chlo-rinated water. This test method outlines the requirements of apressurized flow-through test system, typical test pressures,test-fluid characteristics, failure type, and data analysis.NOTE 1Other known disinfecting systems (chlorine dioxide, ozone,and chloramine) are currently used for pro
5、tection of potable water;however, free-chlorine is by far the most common system in use today.Disinfecting systems other than chlorine have not been evaluated by thismethod.1.2 Guidelines and requirements for test temperatures, testhoop stresses, and other test criteria have been established byprior
6、 testing of PEX tubing produced by the three mostcommon commercial methods of cross-linking: silane, perox-ide, and electron-beam (see Note 2). Other related systemcomponents that typically appear in a PEX hot-and-cold waterdistribution system can be evaluated with the PEX tubing.When testing PEX tu
7、bing and fittings as a system, it isrecommended that the anticipated end-use fitting type(s) andmaterial(s) be included in the test circuit since it is known thatsome fitting types and materials can impact failure times.Specimens used shall be representative of the piping product(s)and material(s) u
8、nder investigation.NOTE 2The procedures described in this test method (with somemodifications of test temperatures or stresses, or both) have been used toevaluate pipes manufactured from polybutylene (PB), polyethylene (PE),polypropylene (PP), multilayer (polymer-metal composite), copper, andstainle
9、ss steel.1.3 This test method is applicable to PEX tubing andsystems used for transport of potable water containing free-chlorine for disinfecting purposes. The oxidizing potential ofthe test-fluid specified in this test method exceeds that typicallyfound in potable water systems across the United S
10、tates.1.4 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation purposes.1.5 The following precautionary caveat pertains only to thetest method portion, Section 12, of this specification. Thisstandard does not purport to address a
11、ll of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1600 Terminology fo
12、r Abbreviated Terms Relating toPlasticsD 2122 Test Method for Determining Dimensions of Ther-moplastic Pipe and FittingsF 412 Terminology Relating to Plastic Piping SystemsF 876 Specification for Crosslinked Polyethylene (PEX)TubingF 877 Specification for Crosslinked Polyethylene (PEX)Plastic Hot- a
13、nd Cold-Water Distribution SystemsF 948 Test Method for Time-to-Failure of Plastic PipingSystems and Components Under Constant Internal Pres-sure With Flow2.2 ISO Standards:ISO 9080 Thermoplastic Pipe for Transport of FluidsMethods of Extrapolation of Hydrostatic Stress RuptureData to Determine the
14、Long Term Strength of Thermo-plastic Pipe3ISO 13760 Plastic Pipe for the Conveyance of Fluids UnderPressureMiners RuleCalculation Method for Cumu-lative Damage31This test method is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee
15、F17.40 on TestMethods.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 2000. Last previous edition approved in 2004 as F 2023 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual B
16、ook of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
17、 19428-2959, United States.2.3 Plastics Pipe Institute (PPI) Document:TN-16 Rate Process Method for Projecting Performance ofPolyethylene Piping Components42.4 American Water Works Association (AWWA) Docu-ment:1996 WATER:STATS Survey53. Terminology3.1 DefinitionsDefinitions are in accordance with Te
18、rmi-nology F 412 and abbreviations are in accordance with Termi-nology D 1600, unless otherwise indicated.3.1.1 brittle failure (Stage II), nfailure in the tubing wallthat is characterized by little or no material deformation in thefailure area and is the result of a single crack emanating fromthe i
19、nterior of the tubing to the outside surface typicallyresulting in a pinhole leak, see Fig. 1. Brittle failures producedwith this test method shall not be used for data analysis.3.1.2 ductile failure (Stage I), nfailure in the tubing wallthat is characterized by obvious localized deformation of them
20、aterial visible with the unaided eye, see Fig. 1. Ductilefailures produced with this test method shall not be used fordata analysis.3.1.3 environmental or oxidative failure (Stage III),nfailure in the tubing wall characterized by a large numberof cracks emanating from the interior surface of the tub
21、ingwall, see Fig. 1.3.1.3.1 DiscussionStage III failures may also be identifiedby a color shift in the failure area (typically brown orreddish-brown). Identification of oxidative failure, when notobvious by inspection with the unaided eye, can be performedwith a 253 microscope or other similar devic
22、e yielding thesame level of magnification. Only Stage III environmentalfailures shall be used for data analysis.3.1.4 hot-and-cold water distribution system, na combi-nation of components such as tubing, fittings, valves, and soforth, that when installed as a complete system, make up theinterior wat
23、er supply system of a commercial or residentialstructure.3.1.5 long-term oxidative resistance, nthe extrapolatedtime-to-failure prediction as determined by analysis of time-to-failure test data by multiple linear regression utilizing therate process method of PPI TN-16 or Model Q of ISO 9080.Where a
24、pplicable, application of Miners Rule in accordancewith ISO 13760 can be used to estimate time-to-failure atseveral differing conditions of temperature or stress, or both.3.1.6 multiple linear regression, na three or four coeffi-cient mathematical model used to analyze time-to-failure datafrom diffe
25、rent temperatures and stresses to extrapolate pro-jected time-to-failure at selected temperatures or stresses.3.1.7 Miners Rule, na mathematical method for estimat-ing the cumulative, irreversible damage that results fromexposure to each of several differing conditions of stress ortemperature, or bo
26、th.3.1.8 oxidation reduction potential (ORP), na measure ofthe total oxidizing power of a solution by means of aplatinum-redox electrode. For a further explanation of ORP seeAppendix X2.3.1.9 unaided eye, nobservable without visual enhance-ment beyond correction for normal vision.4. Summary of Test
27、Method4.1 The PEX tubing or tubing/fitting assemblies are exposedto pressurized test-fluid until failure. All time-to-fail data usedfor analysis shall be the result of oxidative degradation (StageIII). A minimum number of test temperature and hoop stressconditions are required to allow accurate data
28、 analysis andtime-to-failure extrapolations.5. Significance and Use5.1 Environment or oxidative time-to-fail data derived fromthis test method, analyzed in accordance with Section 13, aresuitable for extrapolation to typical end-use temperatures andhoop stresses. The extrapolated value(s) provides a
29、 relativeindication of the resistance of the tested PEX tubing or systemto the oxidative effects of hot, chlorinated water for conditionsequivalent to those conditions under which the test data wereobtained. The performance of a material or piping productunder actual conditions of installation and u
30、se is dependentupon a number of factors including installation methods, usepatterns, water quality, nature and magnitude of localizedstresses, and other variables of an actual, operating hot-and-cold water distribution system that are not addressed in this testmethod. As such, the extrapolated value
31、s do not constitute arepresentation that a PEX tube or system with a givenextrapolated time-to-failure value will perform for that periodof time under actual use conditions.6. Apparatus6.1 Pressurized Flow-Through Test SystemAsystem com-prised of the necessary pump(s), fittings, piping, heaters,sens
32、ors, and meters that is capable of maintaining the requiredtest pressures within the tolerance specified in 9.1.4, therequired test temperatures within the tolerance of 9.1.3, and4Available from the Plastics Pipe Institute (PPI), 1825 Connecticut Ave., NW,Suite 680, Washington, DC 20009.5Available f
33、rom American Water Works Association (AWWA), 1401 New YorkAve., NW, Suite 640, Washington, DC 20005.FIG. 1 Pictorial Illustration of Failure TypesF2023052flow the test-fluid through the specimens continually at a flowrate within the tolerance specified in 9.1.5. Cyclic pressurevariations, such as th
34、ose produced by some pumping systems,shall not produce pressure excursions that exceed the tolerancestated in 9.1.4.6.1.1 Recirculating Test SystemA flow-through test sys-tem that repeatedly reconditions the test-fluid and passes itthrough the specimens. For purposes of this test method, thetest-flu
35、id shall be monitored at a sufficient frequency to ensurethat it continuously meets the test-fluid parameters and waterquality criteria. A portion of the total system volume shall bepurged and replaced with fresh test-fluid continually.6.1.2 Single-Pass Test SystemA flow-through test systemthat pass
36、es the test-fluid through the specimens only once andis discarded.6.2 Specimen HoldersTest specimens shall be supportedto minimize or eliminate externally induced stresses. Speci-mens shall be allowed to freely expand bi-directionally7. Sampling, Test Specimens, and Test Units7.1 SamplingSelect at r
37、andom, a sufficient amount oftubing to satisfy the specimen requirements of this test method.When testing as a system, randomly select a sufficient quantityof fittings.7.2 Test Specimen SizeThe PEX tubing specimens shallbe 12 to 18 in. (300 to 460 mm) in length between fittingclosures or between fit
38、ting joints.7.2.1 Dimensions MeasurementMeasure and record thecritical dimensions for tubing and fittings. For tubing, measurethe average outside diameter and wall-thickness in accordancewith Test Method D 2122. For fittings, measure those dimen-sions critical to the function of the joint, as well a
39、s minimumbody wall thickness.7.3 Testing as a SystemWhen testing PEX tubing andrelated system components (such as fittings) as a system, theother components shall be attached to the PEX tubing in thesame manner as in actual service. For fittings, the particularfitting style shall be installed in acc
40、ordance with the manufac-turers instructions or theASTM specification when applicable.7.4 Minimum Required Test UnitsA minimum of six testunits is required. A test unit is comprised of two or moreindividual time-to-failure data points at the same temperatureand hoop stress condition. Statistical rel
41、iability of the analysisof the resultant data will be benefited by obtaining additionaldata points at each temperature/hoop stress condition.7.4.1 Test Unit DistributionTime-to-failure data pointsshall be obtained at 2 test hoop stresses at each of a minimumof 3 test temperatures for a minimum of 12
42、 data points. As analternate, obtain time-to-failure data for the temperature/hoopstress combinations of the three-temperature matrix of PPITN-16, see Note 3. Hoop stresses shall be separated by a least80 psi (0.55 MPa).NOTE 3When using the PPI TN-16 matrix, Temperature T3, whichrequires testing at
43、only one stress, refers to the lowest test temperature.7.4.2 Test Temperature SelectionTemperatures of 239F(115C), 221F (105C), and 203F (95C) have been utilizedin prior testing of PEX, see Note 4. Adjacent test temperaturesshall be separated by at least 18F (10C). Other test tempera-tures may be us
44、ed, but the maximum test temperature shall notexceed 239F (115C).NOTE 4Prior testing indicates that for the test temperatures stated in7.4.2, hoop stresses to yield Stage III failures within reasonable testingtimes are between 160 psi (1.10 MPa) and 400 psi (2.76 MPa). For a trueSDR9 tube, those hoo
45、p stresses correspond to test pressures of 40 psig(275.9 kPa) to 100 psig (689.7 kPa). If a selected test hoop stress producesStage I or Stage II failures, the stress will need to be reduced to produceStage III failures at all temperatures.7.4.2.1 Relationship of Internal Pressure to Hoop StressThe
46、hoop stress in the tubing wall is calculated by thefollowing expression, commonly known as the ISO equation:2S/P 5 DR 2 1 (1)or2S/P 5 Do/t! 2 1 (2)where:S = stress in the circumferential or hoop direction, psi(MPa),P = internal pressure, psig (kPa),t = minimum wall thickness, in. (mm),DR = dimension
47、 ratio, DR, andDo= average outside diameter, in. (mm).8. Calibration and Standardization8.1 Measuring EquipmentAll measuring and testingequipment having an effect on the accuracy or validity of thecalibrations or tests shall be calibrated or verified, or both,before being put into service.9. Test Fl
48、uid9.1 Internal Test FluidThe test fluid shall be reverseosmosis (RO) or deionized (DI) water prepared in accordancewith 9.1.1, or potable water (tap water) prepared in accordancewith 9.1.2.9.1.1 RO or DI Water Test-Fluid PreparationTest fluidprepared from RO or DI water shall have a pH in the range
49、from 6.5 to 8.0 and contain 2.5 ppm to 5 ppm (milligrams perlitre) of free-chlorine. The chosen pH shall be maintained to60.2 and the chosen free-chlorine concentration shall bemaintained to 60.2 ppm. The pH and free-chlorine concentra-tion combination shall yield a minimum ORP of 825 mV forthe test fluid, see Note 5.9.1.2 Tap Water Test Fluid PreparationTap water shallhave a pH in the range from 6.5 to 8.0 and contain thenecessary free-chlorine to maintain an ORP of 825 6 30 mV,see Note 5.NOTE 5At the time this test method was originall
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