1、Designation: A 674 05Standard Practice forPolyethylene Encasement for Ductile Iron Pipe for Water orOther Liquids1This standard is issued under the fixed designation A 674; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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 practice covers materials and installation proce-dures for polyethylene encasement to be applied to under-grou
3、nd 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 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the us
4、er 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:2D 149 Standard Test Method for Dielectric BreakdownVoltage and Dielectric Strength of Solid Electrical Insu-lat
5、ing Materials at Commercial Power FrequenciesD 882 Standard Test Method for Tensile Properties of ThinPlastic SheetingD 1709 Standard Test Methods for Impact Resistance ofPlastic Film by the Free-Falling Dart MethodD 1922 Standard Test Method for Propagation Tear Resis-tance of Plastic Film and Thin
6、 Sheeting by PendulumMethodD 4976 Standard Specification for Polyethylene PlasticsMolding and Extrusion 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
7、:3.1.1 polyethylene encasementpolyethylene material, intube or sheet form, that is used to encase ductile iron pipe.3.1.2 securing overlapany one of various methods ofholding polyethylene encasement in place at the point ofoverlap until backfilling operations are completed. This may beaccomplished w
8、ith adhesive tape or plastic tie straps.3.1.3 linear low-density polyethylene filmFilm extrudedfrom virgin linear low-density polyethylene raw material.3.1.4 high-density, cross-laminated polyethylene filmFilmextruded from virgin high-density polyethylene raw material,which is then molecularly orien
9、ted by stretching. Two single-ply layers of the film are then laminated together with theirorientations at 90 to one another to form the final product.4. Requirements4.1 Materials:4.1.1 Linear low-density polyethylene filmLinear low-density polyethylene film shall be manufactured of virginpolyethyle
10、ne material conforming to the requirements ofSpecification D 4976 shown in Table 1.4.1.1.1 ThicknessLinear low-density polyethylene filmshall have a minimum thickness of 0.008 in. 0.20 mm.4.1.2 High-density cross-laminated polyethylene filmHigh-density cross-laminated polyethylene film shall be manu
11、-factured of virgin polyethylene material conforming to therequirements of Specification D 4976 shown in Table 2.4.1.2.1 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 listed in
12、Table 3.4.3 ColorPolyethylene film may be supplied with itsnatural color, colors including white and black, or black(weather-resistant) containing not less than 2 percent carbonblack with an average particle diameter of 50 nm or less. A1This practice is under the jurisdiction of ASTM Committee A04 o
13、n IronCastings and is the direct responsibility of Subcommittee A04.12 on Pipes andTubes.Current edition approved Nov. 1, 2005. Published December 2005. Originallyapproved in 1972. Last previous edition approved in 2000 as A 674 - 00.2For referenced ASTM standards, visit the ASTM website, www.astm.o
14、rg, 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 Water Works Association (AWWA), 1401 New YorkAve., NW, Suite 640, Washington, DC 20005.1Copyright ASTM
15、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.minimum of 2 percent of a hindered-amine ultraviolet inhibitoris required in any natural or colored film except black filmcontaining 2 percent or more carbon black.4.4 Marking requirementsThe polyethy
16、lene film suppliedshall be clearly marked, at a minimum of every 2 ft along itslength, containing the following information:(a) Manufacturers name or registered trademark(b) Year of manufacture(c) ASTM A 674(d) Minimum film thickness and material type (LLDPE orHDCLPE)(e) Applicable range of nominal
17、pipe diameter size(s)(f) WarningCorrosion ProtectionRepair 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 Ge
18、neral:5.1.1 The polyethylene encasement shall 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 toinstal
19、lation of the polyethylene encasement. During 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 wit
20、hminimum space between the polyethylene and 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 preventdamage to the polyethylene due to backfilling operation
21、s.Overlaps and ends shall be secured by the use of adhesive tapeor plastic tie straps.5.1.3 For installations 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
22、plastic tie strapsat the joint overlap. It is also recommended that circumferentialwraps of tape or plastic 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 PipeThis practice includes three different methods
23、forthe installation of polyethylene encasement. Method A and Bare for use with polyethylene tubes and Method C is for usewith polyethylene sheets.5.2.1 Method A (see Fig. 1):5.2.1.1 Cut the polyethylene tube to a length approximately2 ft 0.6 m longer than the length of the pipe section. Slip thetube
24、 around the pipe, centering it to provide a 1-ft 0.3-moverlap on each adjacent pipe section, and bunching it accor-dion fashion lengthwise until it clears the pipe ends.5.2.1.2 Lower the pipe into the trench and make up the pipejoint with the preceding section of pipe. A shallow bell holemust be mad
25、e at joints to facilitate installation of the polyeth-ylene tube.5.2.1.3 After assembling the pipe joint, make the overlap ofthe polyethylene tube. Pull the bunched polyethylene from theTABLE 1 Linear Low-Density Polyethylene CharacteristicsRaw Material Used to Manufacture Polyethylene Encasement Ma
26、terialGroup, density, and dielectric strength in accordance with the latest revision ofSpecification D 4976Group 2 (Linear)Density 0.910 to 0.935 g/cm3Dielectric strength, volume resistivity 1015ohm-cm, minPolyethylene Encasement MaterialTensile strength 3600 psi (24.83 MPa), min (ASTMD 882)Elongati
27、on 800 %, min (ASTM D 882)Dielectric strength 800 V/mil (31.5 V/m) thickness,min (ASTM D 149)Impact resistance 600 g, min (ASTM D 1709 MethodB)Propagation tear resistance 2550 gf, min (ASTM D 1922)TABLE 2 High-Density Cross-Laminated PolyethyleneCharacteristicsRaw Material Used to Manufacture Polyet
28、hylene Encasement MaterialGroup, density, and dielectric strength in accordance with the latest revisionof Specification D 4976Group 2 (Linear)Density 0.940 to 0.960 g/cm3Dielectric strength, volume resistivity 1015ohm-cm, minHigh-Density Cross-Laminated Polyethylene Encasement MaterialTensile stren
29、gth 6300 psi (43.47 MPa), minElongation 100 %, minDielectric strength 800 V/mil (31.5 V/m) thickness, minImpact resistance 800 g, min. (ASTM D 1709 Method B)Propagation tear resistance 250 gf, min. (ASTM D 1922)TABLE 3 Polyethylene Tube Sizes for Push-On Joint PipeANominal Pipe Diameter, in. Recomme
30、nded 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 27464 121 307AThese wrap sizes should work with most push-on joint pipe and fitting bellsizes. Where bell circumferenc
31、es 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, sufficiently large tube or sheetfilm to effectively cover these joints should be ordered.BFor flat sheet polyethylene
32、, see 5.2.3.A674052preceding 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 overlaps the joint at the end of the precedinglength of pipe. Secure the overlap in p
33、lace. 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.5.2.1.4 Repair any rips, punctures, or other damage to thepolyethylene with adhesive tape or with a short length ofpolyethylene t
34、ube cut open, wrapped around the pipe, andsecured in place. Proceed with installation of the next sectionof pipe in the same manner.5.2.2 Method B (see Fig. 3):5.2.2.1 Cut the polyethylene tube to a length approximately1 ft 0.3 m shorter than the length of the pipe section. Slip thetube around the p
35、ipe, 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 5.2.1.5.2.2.2 Before making up a joint, slip a 3-ft 0.9-m lengthof polyethylene tube over the end of the preceding pipe section,bunching it acc
36、ordion 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, overlapping thepreviously installed on each adjacent section of pipe by at least
37、1 ft 0.3 m; make snug and secure each end as described in5.2.1. A shallow bell hole must be made at joints to facilitateinstallation of the polyethylene tube or sheet.5.2.2.3 Repair any rips, punctures, or other damage to thepolyethylene as described in 5.2.1. Proceed with installation ofthe next se
38、ction of pipe in the same manner.5.2.3 Method C (see Fig. 4):5.2.3.1 Flat sheet polyethylene shall have a minimum widthtwice the flat tube width shown in Table 3.5.2.3.2 Cut the polyethylene sheet to a length approximately2 ft 0.6 m longer than the length of pipe section. Center thecut length to pro
39、vide 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 edge ofpolyethylene sheet at approximately 3-ft 0.9-m intervalsalong the pi
40、pe length.5.2.3.3 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 joint, make the overlap asdescribed in 5.2.1.5.2.3.4 Repair any rips, pun
41、ctures, or other damage to thepolyethylene as described in 5.2.1. Proceed with installation ofthe next section of pipe in the same manner.5.3 Pipe-Shaped AppurtenancesBends, reducers, offsets,and other pipe-shaped appurtenances shall be covered withpolyethylene in the same manner as the pipe.5.4 Odd
42、-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 around the body. Make seams by bringing the edgestogether, folding over t
43、wice, and taping down. Handle slackwidth and overlaps at joints as described in 5.2.1. Tapepolyethylene securely in place at valve stem and other penetra-tions.5.5 RepairsRepair any cuts, tears, punctures, or damageto polyethylene with adhesive tape or with a short length ofFIG. 1 Method AFIG. 2 Sla
44、ck Reduction ProcedureMethods A and BA674053polyethylene tube cut open, wrapped around the pipe coveringthe damaged area, and secured in place.5.6 Openings in EncasementMake openings for branches,service taps, blow-offs, air valves, and similar appurtenances,by making an X-shaped cut in the polyethy
45、lene 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 damaged areas in the polyethylene, withtape. Direct service taps may also be made through thepolyethylene, with any resulting damage ar
46、eas being repairedas described previously. The preferred method of making directservice taps consists of applying two or three wraps of adhesivetape completely around the polyethylene encased pipe to coverthe area where the tapping machine and chain will be mounted.This method minimizes possible dam
47、age to the polyethyleneduring the direct tapping procedure. After the tapping machineis mounted, the corporation stop is installed directly throughthe tape and polyethylene as shown in Fig. 5. Experience hasshown that this method is very effective in eliminating damageto the polyethylene encasement
48、by the tapping machine andchain during the tapping operation. After the direct tap iscompleted, the entire circumferential area should be closelyinspected for damage and repaired if needed.5.7 Junctions Between Wrapped and Unwrapped PipeWhere polyethylene wrapped pipe joins a pipe that is notwrapped
49、, extend the polyethylene tube to cover the unwrappedpipe a distance of at least 3 ft 0.9 m. Secure the end withcircumferential turns of adhesive tape. Service lines of dissimi-lar metals shall be wrapped with polyethylene or a suitabledielectric tape for a minimum clear distance of 3 ft 0.9 maway from the ductile-iron pipe.5.8 Backfill for Polyethylene Wrapped PipeBackfill ma-terial shall be the same as specified for pipe without polyeth-ylene wrapping. Take special care to prevent damage
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