1、Designation: F2023 10An 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 F2023; the number immediately following the designation indica
2、tes 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 () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method describes the general requ
3、irements forevaluating the long-term, chlorinated water, oxidative resis-tance of cross-linked polyethylene (PEX) tubing produced inaccordance with Specification F876 or PEX tubing/fittingsystems in accordance with Specification F877 used in hot-and-cold water distribution systems by exposure to hot
4、, 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 chloramines) are also used for protection
5、of potable water. Free-chlorine is the most common disinfectant in use today. A PPI researchproject examined the relative aggressiveness of free chlorine and chloram-ines on PEX pipes, both at the same 4.0 ppm concentration and the sametest temperatures. The results of the testing showed pipe failur
6、e timesapproximately 40% longer when tested with chloramines compared totesting with free chlorine, at the tested conditions. Based on these results,the data suggests that chloramines are less aggressive than free chlorine toPEX pipes.1.2 Guidelines and requirements for test temperatures, testhoop s
7、tresses, and other test criteria have been established byprior 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 s
8、ystem can be evaluated with the PEX tubing.When testing PEX tubing 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 sha
9、ll be representative of the piping product(s)and material(s) under 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
10、(PP), multilayer (polymer-metal composite), copper, andstainless 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 th
11、at typicallyfound in potable water systems across the United States.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
12、this specification. Thisstandard does not purport to address all 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.
13、 Referenced Documents2.1 ASTM Standards:2D1600 Terminology for Abbreviated Terms Relating toPlasticsD2122 Test Method for Determining Dimensions of Ther-moplastic Pipe and FittingsF412 Terminology Relating to Plastic Piping SystemsF876 Specification for Crosslinked Polyethylene (PEX)TubingF877 Speci
14、fication for Crosslinked Polyethylene (PEX)Plastic Hot- and Cold-Water Distribution SystemsF948 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 Fluids1This test method is
15、 under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved Aug. 1, 2010. Published August 2010. Originallyapproved in 2000. Last previous edition approved in 2009 as F2023 09. DOI:10.1520/F202
16、3-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of thi
17、s standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Methods of Extrapolation of Hydrostatic Stress RuptureData to Determine the Long Term Strength of Thermo-plastic Pipe3ISO 13760 Plastic Pipe for the Conveyance of Fluids Under
18、PressureMiners RuleCalculation Method for Cumu-lative Damage32.3 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 DefinitionsDef
19、initions are in accordance with Termi-nology F412 and abbreviations are in accordance with Termi-nology D1600, 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
20、single crack emanating fromthe interior 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 obvio
21、us localized deformation of thematerial 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
22、 the interior surface of the tubingwall, 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 m
23、icroscope or other similar device 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
24、 system, make up theinterior water 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-1
25、6 or Model Q of ISO 9080.Where applicable, 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 analyz
26、e time-to-failure datafrom different 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 condition
27、s of stress ortemperature, or both.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 n
28、ormal vision.4. Summary of Test 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
29、 required to allow accurate data 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
30、extrapolated value(s) provides a 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
31、conditions of installation and use 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.
32、 As such, the extrapolated values do not constitute arepresentation that a PEX tube or system with a given3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from Plastics Pipe Institute (PPI), 105 Decker Court, Su
33、ite 825,Irving, TX 75062, http:/www.plasticpipe.org.5Available from American Water Works Association (AWWA), 6666 W. QuincyAve., Denver, CO 80235, http:/www.awwa.org.FIG. 1 Pictorial Illustration of Failure TypesF2023 102extrapolated time-to-failure value will perform for that periodof time under ac
34、tual use conditions.6. Apparatus6.1 Pressurized Flow-Through Test SystemAsystem com-prised of the necessary pump(s), fittings, piping, heaters,sensors, and meters that is capable of maintaining the requiredtest pressures within the tolerance specified in 9.1.3, therequired test temperatures within t
35、he tolerance of 9.1.2, andflow the test-fluid through the specimens continually at a flowrate within the tolerance specified in 9.1.4. Cyclic pressurevariations, such as those produced by some pumping systems,shall not produce pressure excursions that exceed the tolerancestated in 9.1.3.6.1.1 Recirc
36、ulating 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-fluid shall be monitored at a sufficient frequency to ensurethat it continuously meets the test-fluid parameters and waterquality c
37、riteria. 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 passes the test-fluid through the specimens only once andis discarded.6.2 Specimen HoldersTest specimens shall be supportedto minimi
38、ze or eliminate externally induced stresses. Speci-mens shall be allowed to freely expand bi-directionally7. Sampling, Test Specimens, and Test Units7.1 SamplingSelect at random, a sufficient amount oftubing to satisfy the specimen requirements of this test method.When testing as a system, randomly
39、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 fitting joints.7.2.1 Dimensions MeasurementMeasure and record thecritical dimensions for tubing and fittings. For tubing, measureth
40、e average outside diameter and wall-thickness in accordancewith Test Method D2122. For fittings, measure those dimen-sions critical to the function of the joint, as well as minimumbody wall thickness.7.3 Testing as a SystemWhen testing PEX tubing andrelated system components (such as fittings) as a
41、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 accordance with the manufac-turers instructions or theASTM specification when applicable.7.4 Minimum Required Test UnitsA minimum of
42、 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 reliability of the analysisof the resultant data will be benefited by obtaining additionaldata points at each temperature/hoop stres
43、s 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 data points. As analternate, obtain time-to-failure data for the temperature/hoopstress combinations of the three-temperature ma
44、trix 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 only one stress, refers to the lowest test temperature.7.4.2 Test Temperature SelectionTemperatures of 239F(115C), 221F (105C), a
45、nd 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 used, but the maximum test temperature shall notexceed 239F (115C).NOTE 4Prior testing indicates that for the test temperatures sta
46、ted 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 hoop stresses correspond to test pressures of 40 psig(275.9 kPa) to 100 psig (689.7 kPa). If a selected test hoop stress producesSta
47、ge 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 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
48、/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 ratio, DR, andDo= average outside diameter, in. (mm).8. Calibration and Standardization8.1 Measuring EquipmentAll measuring and
49、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 Fluid9.1 Internal Test FluidThe test fluid shall be reverseosmosis (RO) or deionized (DI) water prepared in accordancewith 9.1.1.9.1.1 RO or DI Water Test-Fluid PreparationTest fluidprepared from RO or DI water shall have a pH in the rangefrom 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 th
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