1、Designation: A674 10Standard Practice forPolyethylene Encasement for Ductile Iron Pipe for Water orOther Liquids1This standard is issued under the fixed designation A674; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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. Scope1.1 This practice covers materials and installation proce-dures for polyethylene encasement to be applied to under-ground
3、installations of ductile iron pipe. It may also be used forpolyethylene encasement of fittings, valves, and other appur-tenances to ductile iron pipe systems.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI uni
4、ts that are provided for information onlyand are not considered standard.1.2.1 Important SI values are provided in brackets. Also,certain important SI values appear without brackets or paren-theses.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its u
5、se. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength o
6、f Solid Electrical Insulating Materialsat Commercial Power FrequenciesD882 Test Method for Tensile Properties of Thin PlasticSheetingD1709 Test Methods for Impact Resistance of Plastic Filmby the Free-Falling Dart MethodD1922 Test Method for Propagation Tear Resistance ofPlastic Film and Thin Sheeti
7、ng by Pendulum MethodD4976 Specification for Polyethylene Plastics Molding andExtrusion Materials2.2 ANSI/AWWA Standards:3C 600 Installation of Ductile Iron Water Mains and TheirAppurtenancesC 105/A21.5 Polyethylene Encasement for Ductile-IronPipe Systems3. Terminology3.1 Definitions:3.1.1 high-dens
8、ity, cross-laminated polyethylene filmFilmextruded from virgin high-density polyethylene raw material,which is then molecularly oriented by stretching. The finalproduct is then formed by two single-ply layers of the film thatare then laminated together with their orientations at 90 to oneanother usi
9、ng molten, high-density, virgin resin.3.1.2 linear low-density polyethylene filmFilm extrudedfrom virgin linear low-density polyethylene raw material.3.1.3 polyethylene encasementpolyethylene material, intube or sheet form, that is used to encase ductile iron pipe.3.1.4 securing overlapany one of va
10、rious methods ofholding polyethylene encasement in place at the point ofoverlap until backfilling operations are completed. This may beaccomplished with adhesive tape or plastic tie straps.4. Requirements4.1 Materials:4.1.1 GeneralAll films shall be manufactured of virginpolyethylene material as non
11、-virgin polyethylene materialsmay be susceptible to accelerated environmental degradation.4.1.1.1 RequirementsThe sections that follow list thematerial requirements for linear low-density and high-density,cross-laminated polyethylene film. In each category, the filmshall meet all of the listed requi
12、rements.4.1.2 Linear low-density polyethylene filmLinear low-density polyethylene film shall be manufactured of virginpolyethylene material conforming to the requirements ofSpecification D4976 shown in Table 1.4.1.2.1 ThicknessLinear low-density polyethylene filmshall have a minimum thickness of 0.0
13、08 in. 0.20 mm.1This practice is under the jurisdiction of ASTM Committee A04 on IronCastings and is the direct responsibility of Subcommittee A04.12 on Pipes andTubes.Current edition approved Oct. 1, 2010. Published November 2010. Originallyapproved in 1972. Last previous edition approved in 2005 a
14、s A674 - 05. DOI:10.1520/A0674-10.2For 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.3Available from American Wa
15、ter Works Association (AWWA), 1401 New YorkAve., NW, Suite 640, Washington, DC 20005.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.3 High-density cross-laminated polyethylene filmHigh-density cross-laminated polyethylene film s
16、hall be manu-factured of virgin polyethylene material conforming to therequirements of Specification D4976 shown in Table 2.4.1.3.1 ThicknessHigh-density cross-laminated polyeth-ylene film shall have a minimum thickness of 0.004 in. 0.10mm.4.2 Tube SizeThe tube size for each pipe diameter shall beas
17、 listed in Table 3.4.3 ColorPolyethylene film may be supplied in its naturalcolor, white, black or weather resistant black containing notless than 2 % carbon black with a particle diameter of 90 nmor less. A minimum2%ofahindered-amine ultravioletinhibitor is required for all films other than the wea
18、ther-resistant black film with carbon black. Where other colors arespecified for purposes of identification, the pigmentation shallnot contain any regulated substances.4.4 Marking requirementsPolyethylene film shall beclearly marked at a minimum of every 2 ft 0.6 m along itslength with print that do
19、es not contain hazardous material.Marking shall contain the following information:(a) Manufacturers name or registered trademark(b) Year of manufacture(c) ASTM A674(d) Minimum film thickness and material type (LLDPE orHDCLPE)(e) Applicable range of nominal pipe diameter size(s)(f) WarningCorrosion P
20、rotectionRepair Any Damage4.4.1 Marking heightLetters and numerals used for mark-ing items a through e in Section 4.4 shall not be less than 1 in.25.4 mm in height. Item f in Section 4.4 shall be not less than112 in. 38.10 mm in height.5. Installation5.1 General:5.1.1 The polyethylene encasement sha
21、ll prevent contactbetween the pipe and the surrounding backfill and beddingmaterial but is not intended to be a completely airtight orwatertight enclosure. All lumps of clay, mud, cinders, etc.which may be on the pipe surface shall be removed prior toinstallation of the polyethylene encasement. Duri
22、ng installa-tion, care shall be exercised to prevent soil or embedmentmaterial from becoming entrapped between the pipe and thepolyethylene.5.1.2 The polyethylene film shall be fitted to the contour ofthe pipe to effect a snug, but not tight, encasement withminimum space between the polyethylene and
23、 the pipe. Suffi-cient slack shall be provided in contouring to prevent stretchingthe polyethylene bridging irregular surfaces, such as bell-spigot interfaces, bolted joints, or fittings, and to preventTABLE 1 Linear Low-Density Polyethylene CharacteristicsRaw Material Used to Manufacture Polyethyle
24、ne Encasement MaterialGroup, density, and dielectric strength in accordance with the latest revision ofSpecification D4976Group 2 (Linear)Density 0.910 to 0.935 g/cm3Dielectric strength, volume resistivity 1015ohm-cm, minPolyethylene Encasement MaterialTensile strength 3600 psi (24.83 MPa), for an 8
25、 mil(200m) minimum thickness, or 28.8lbf/in. width (50.4 N/cm width),minimum in machine and transversedirection (ASTM D882)Elongation 700 %, min in the machine andtransverse direction (ASTM D882)Dielectric strength 800 V/mil (31.5 V/m) thickness,min (ASTM D149)Impact resistance 600 g, min (ASTM D170
26、9 MethodB)Propagation tear resistance 2550 gf, min in machine andtransverse direction (ASTM D1922)TABLE 2 High-Density Cross-Laminated PolyethyleneCharacteristicsRaw Material Used to Manufacture Polyethylene Encasement MaterialGroup, density, and dielectric strength in accordance with the latest rev
27、isionof Specification D4976Group 2 (Linear)Density 0.940 to 0.960 g/cm3Dielectric strength, volume resistivity 1015ohm-cm, minHigh-Density Cross-Laminated Polyethylene Encasement MaterialTensile strength 6300 psi (43.47 MPa), for a 4 mil (100m) minimum thickness, or 25.2 lbf/in.width (44.1 N/cm widt
28、h), minimum inmachine and transverse direction(ASTM D882)Elongation 100 %, min in machine and transversedirection (ASTM D882)Dielectric strength 800 V/mil (31.5 V/m) thickness, min(ASTM D149)Impact resistance 800 g, min. (ASTM D1709 Method B)Propagation tear resistance 250 gf, min. in machine and tr
29、ansversedirection (ASTM D1922)TABLE 3 Polyethylene Tube Sizes for Push-On Joint PipeANominal Pipe Diameter, in. Recommended PolyethyleneFlat Tube Width, in. cmB3 14 364 14 366 16 418 20 5110 24 6112 27 6914 30 7616 34 8618 37 9420 41 10424 54 13730 67 17036 81 20642 81 (206)48 95 24154 108 27460 108
30、 27464 121 307AThese wrap sizes should work with most push-on joint pipe and fitting bellsizes. Where bell circumferences are larger than the sheet sizes shown, the bellareas should be carefully wrapped with cut film sections, effectively lapping andsecuring cut edges as necessary; or, alternatively
31、, sufficiently large tube or sheetfilm to effectively cover these joints should be ordered.BFor flat sheet polyethylene, see 5.3.3.A674 102damage to the polyethylene due to backfilling operations.Overlaps and ends shall be secured by the use of adhesive tapeor plastic tie straps.5.1.3 For installati
32、ons below the water table or in areassubject to tidal actions, or both, it is recommended thattube-form polyethylene be used with both ends sealed asthoroughly as possible with adhesive tape or plastic tie strapsat the joint overlap. It is also recommended that circumferentialwraps of tape or plasti
33、c tie straps be placed at 2 ft 0.6 mintervals along the barrel of the pipe to help minimize the spacebetween the polyethylene and the pipe.5.2 Polyethylene InstallersThe polyethylene encasementshall be installed by personnel trained or experienced in theproper application of the encasement as descri
34、bed in thisstandard. At all times during construction of the pipeline,precautions shall be taken to prevent damage to the encasementfilm.5.3 Methods of InstallationThis practice includes threedifferent methods for the installation of polyethylene encase-ment. Method A and B are for use with polyethy
35、lene tubes andMethod C is for use with polyethylene sheets.5.3.1 Method A (see Fig. 1):5.3.1.1 Cut the polyethylene tube to a length approximately2 ft 0.6 m longer than the length of the pipe section. Slip thetube around the pipe, centering it to provide a 1-ft 0.3-moverlap on each adjacent pipe sec
36、tion, and bunching it accor-dion fashion lengthwise until it clears the pipe ends.5.3.1.2 Lower the pipe into the trench and make up the pipejoint with the preceding section of pipe. A shallow bell holemust be made at joints to facilitate installation of the polyeth-ylene tube.5.3.1.3 After assembli
37、ng the pipe joint, make the overlap ofthe polyethylene tube. Pull the bunched polyethylene from thepreceding length of pipe, slip it over the end of the new lengthof pipe, and secure in place. Then slip the end of thepolyethylene from the new pipe section over the end of the firstwrap until it overl
38、aps the joint at the end of the precedinglength of pipe. Secure the overlap in place. Take up the slackwidth at the top of the pipe as shown in Fig. 2, to make a snug,but not tight, fit along the barrel of the pipe, securing the foldat quarter points.5.3.1.4 Repair any rips, punctures, or other dama
39、ge to thepolyethylene with adhesive tape or with a short length ofpolyethylene tube cut open, wrapped around the pipe, andsecured in place. Proceed with installation of the next sectionof pipe in the same manner.5.3.2 Method B (see Fig. 3):5.3.2.1 Cut the polyethylene tube to a length approximately1
40、 ft 0.3 m shorter than the length of the pipe section. Slip thetube around the pipe, centering it to provide 6 in. 150 mm ofbare pipe at each end. Make the polyethylene snug, but nottight, as shown in Fig. 2; secure ends as described in 5.1.5.3.2.2 Before making up a joint, slip a 3-ft 0.9-m lengtho
41、f polyethylene tube over the end of the preceding pipe section,bunching it accordion fashion lengthwise. Alternatively, placea 3-ft 0.9 m length of polyethylene sheet in the trench underthe joint to be made. After completing the joint, pull the 3-ftlength of polyethylene over or around the joint, ov
42、erlapping thepreviously installed on each adjacent section of pipe by at least1 ft 0.3 m; make snug and secure each end as described in5.1. A shallow bell hole must be made at joints to facilitateinstallation of the polyethylene tube or sheet.5.3.2.3 Repair any rips, punctures, or other damage to th
43、epolyethylene as described in 5.6. Proceed with installation ofthe next section of pipe in the same manner.5.3.3 Method C (see Fig. 4):5.3.3.1 Flat sheet polyethylene shall have a minimum widthtwice the flat tube width shown in Table 3.5.3.3.2 Cut the polyethylene sheet to a length approximately2 ft
44、 0.6 m longer than the length of pipe section. Center thecut length to provide a 1-ft 0.3-m overlap on each adjacentpipe section, bunching it until it clears the pipe ends. Wrap thepolyethylene around the pipe so that it overlaps circumferen-tially over the top quadrant of the pipe. Secure the cut e
45、dge ofpolyethylene sheet at approximately 3-ft 0.9-m intervalsalong the pipe length.5.3.3.3 Lower the wrapped pipe into the trench and make upthe pipe joint with the preceding section of pipe.Ashallow bellhole must be made at joints to facilitate installation of thepolyethylene. After completing the
46、 joint, make the overlap asdescribed in 5.1.5.3.3.4 Repair any rips, punctures, or other damage to thepolyethylene as described in 5.6. Proceed with installation ofthe next section of pipe in the same manner.5.4 Pipe-Shaped AppurtenancesBends, reducers, offsets,and other pipe-shaped appurtenances sh
47、all be covered withpolyethylene in the same manner as the pipe.5.5 Odd-Shaped AppurtenancesWrap valves, tees,crosses, and other odd-shaped pieces which cannot practicallybe wrapped in a tube, with a flat sheet or split length ofpolyethylene tube. Pass the sheet under the appurtenance andbring up aro
48、und the body. Make seams by bringing the edgestogether, folding over twice, and taping down. Handle slackwidth and overlaps at joints as described in 5.1. Tape polyeth-ylene securely in place at valve stem and other penetrations.5.6 RepairsRepair any cuts, tears, punctures, or damageto polyethylene
49、with adhesive tape or with a short length ofFIG. 1 Method AA674 103polyethylene tube cut open, wrapped around the pipe coveringthe damaged area, and secured in place.5.7 Openings in EncasementMake openings for branches,service taps, blow-offs, air valves, and similar appurtenances,by making an X-shaped cut in the polyethylene and tempo-rarily folding the film back. After the appurtenance is installed,tape the slack securely to the appurtenance and repair the cut,as well as any other dama
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