1、Designation: F 2023 08An 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 chloramines) are also used for protect
5、ion 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 a the same 4.0 ppm concentration and the sametest temperatures. The results of the testing showed pipe fai
6、lure 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, testhoo
7、p stresses, 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 waterdistributio
8、n system 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
9、shall 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),polypropyle
10、ne (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
11、 that 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,
12、of 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
13、.2. Referenced Documents2.1 ASTM Standards:2D 1600 Terminology for 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 8
14、77 Specification for Crosslinked Polyethylene (PEX)Plastic Hot- and 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:1This test method is under the jurisdiction of ASTM Committee
15、F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved March 1, 2008. Published April 2008. Originallyapproved in 2000. Last previous edition approved in 2005 as F 2023 05.2For referenced ASTM standards, visit the ASTM website, ww
16、w.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ISO
17、9080 Thermoplastic Pipe for Transport of FluidsMethods of Extrapolation of Hydrostatic Stress RuptureData to Determine the Long Term Strength of Thermo-plastic Pipe3ISO 13760 Plastic Pipe for the Conveyance of Fluids UnderPressureMiners RuleCalculation Method for Cumu-lative Damage32.3 Plastics Pipe
18、 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 Termi-nology F 412 and abbreviations are in ac
19、cordance 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 interior of the tubing to the outside surface
20、 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 thematerial visible with the unaided eye, see Fi
21、g. 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 tubingwall, see Fig. 1.3.1.3.1 DiscussionStage
22、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 device yielding thesame level of magnification. O
23、nly 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 water supply system of a commercial or resident
24、ialstructure.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 applicable, application of Miners Rule in acc
25、ordancewith 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 different temperatures and stresses to extrapolat
26、e 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 both.3.1.8 oxidation reduction potential (ORP)
27、, 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 Method4.1 The PEX tubing or tubing/fitting a
28、ssemblies 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 analysis andtime-to-failure extrapolations.
29、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 relativeindication of the resistance of the
30、 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 use is dependentupon a number of factors incl
31、uding 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 values do not constitute arepresentation that a P
32、EX 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, Suite 825,Irving, TX 75062, http:/www.plasticpipe.org.5Available from American
33、 Water Works Association (AWWA), 6666 W. QuincyAve., Denver, CO 80235, http:/www.awwa.org.FIG. 1 Pictorial Illustration of Failure TypesF2023082extrapolated time-to-failure value will perform for that periodof time under actual use conditions.6. Apparatus6.1 Pressurized Flow-Through Test SystemAsyst
34、em 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 9.1.4, therequired test temperatures within the tolerance of 9.1.3, andflow the test-fluid through the specimens continual
35、ly at a flowrate within the tolerance specified in 9.1.5. Cyclic pressurevariations, such as those 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 t
36、he 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 criteria. A portion of the total system volume shall bepurged and replaced wit
37、h 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 minimize or eliminate externally induced stresses. Speci-mens shall be allowed to f
38、reely 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 select a sufficient quantityof fittings.7.2 Test Specimen SizeThe PEX tubing
39、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, measurethe average outside diameter and wall-thickness in accordancewith Test Method D
40、 2122. 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 system, theother components shall be attached to the PEX tubing in thesame m
41、anner 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 six testunits is required. A test unit is comprised of two or moreindividua
42、l 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 stress condition.7.4.1 Test Unit DistributionTime-to-failure data pointsshall be
43、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 matrix of PPITN-16, see Note 3. Hoop stresses shall be separated by a least80
44、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), and 203F (95C) have been utilizedin prior testing of PEX, see Note 4. Adjacen
45、t 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 stated in7.4.2, hoop stresses to yield Stage III failures within reasonable tes
46、tingtimes 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 producesStage I or Stage II failures, the stress will need to be reduced to produceStag
47、e 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/P 5 Do/t! 2 1 (2)where:S = stress in the circumferential or hoop direction,
48、 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 testingequipment having an effect on the accuracy or validity of thecalibrat
49、ions 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, 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 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 the chosen free-c
