1、Designation: A674 18Standard 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principl
6、es on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Bre
7、akdown Voltage andDielectric Strength of 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 Re
8、sistance ofPlastic Film and Thin Sheeting by Pendulum MethodD4976 Specification for Polyethylene Plastics Molding andExtrusion Materials2.2 ANSI/AWWA Standards:3C600 Installation of Ductile Iron Water Mains and TheirAppurtenancesC105/A21.5 Polyethylene Encasement for Ductile-Iron PipeSystems3. Termi
9、nology3.1 Definitions:3.1.1 high-density, 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
10、 orientations at 90 to oneanother using 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 pip
11、e.3.1.4 securing overlapany one of various 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
12、of virginpolyethylene material, as non-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
13、filmshall meet all of the listed requirements.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 Nov. 1, 2018. Published December 2018. Originallyapproved in 1972. Last prev
14、ious edition approved in 2014 as A674 10 (2014).DOI: 10.1520/A0674-18.2For 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
15、 website.3Available from American Water Works Association (AWWA), 6666 W. QuincyAve., Denver, CO 80235, http:/www.awwa.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with int
16、ernationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.1.2 Linear Low-Density Polyethylene FilmLine
17、ar 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 0.008 in. 0.20 mm.4.1.3 High-Density, Cross-Laminated Pol
18、yethylene FilmHigh-density, cross-laminated polyethylene film shall bemanufactured of virgin polyethylene material conforming tothe requirements 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.0.10 m
19、m.4.2 Tube SizeThe tube size for each pipe diameter shall beas 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 ul
20、travioletinhibitor is required for all films other than the weather-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
21、 minimum of every 2 ft 0.6 m along itslength with print that does not contain hazardous material.Marking shall contain the following information:(a) Manufacturers name or registered trademark.(b) Year of manufacture.(c) ANSI/AWWA C105/A21.5.(d) Minimum film thickness and material type (LLDPE orHDCLP
22、E).(e) Applicable range of nominal pipe diameter size(s).(f) WarningCorrosion ProtectionRepair Any Damage.4.4.1 Marking HeightLetters and numerals used for mark-ing items (a) through (e)in4.4 shall not be less than 1 in. 25.4mm in height. Item (f)in4.4 shall be not less than 112 in.38.10 mm in heigh
23、t.5. Installation5.1 General: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
24、 removed prior toinstallation of the polyethylene encasement. Duringinstallation, care shall be exercised to prevent soil or embed-ment material from becoming entrapped between the pipe andthe polyethylene.5.1.2 The polyethylene film shall be fitted to the contour ofthe pipe to effect a snug, but no
25、t tight, encasement withTABLE 1 Linear Low-Density Polyethylene CharacteristicsRaw Material Used to Manufacture Polyethylene Encasement MaterialGroup, density, and dielectric strength in accordance with the latest revision ofSpecification D4976Group 2 (Linear)Density 0.910 to 0.935 g/cm3Dielectric s
26、trength, volume resistivity 1015ohm-cm, minPolyethylene Encasement MaterialTensile strength 3600 psi (24.83 MPa), for an 8 mil(200m) minimum thickness, or 28.8lbf/in. width (50.4 N/cm width), mini-mum in machine and transverse di-rection (Test Method D882)Elongation 700 %, min in the machine andtran
27、sverse direction (Test MethodD882)Dielectric strength 800 V/mil (31.5 V/m) thickness,min (Test Method D149)Impact resistance 600 g, min (Test Methods D1709Method B)Propagation tear resistance 2550 gf, min in machine and trans-verse direction (Test Method D1922)TABLE 2 High-Density Cross-Laminated Po
28、lyethyleneCharacteristicsRaw Material Used to Manufacture Polyethylene Encasement MaterialGroup, density, and dielectric strength in accordance with the latest revisionof Specification D4976Group 2 (Linear)Density 0.940 to 0.960 g/cm3Dielectric strength, volume resistivity 1015ohm-cm, minHigh-Densit
29、y 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 width), minimum inmachine and transverse direction (TestMethod D882)Elongation 100 %, min in machine and transversedirection (Test Method D88
30、2)Dielectric strength 800 V/mil (31.5 V/m) thickness, min(Test Method D149)Impact resistance 800 g, min. (Test Methods D1709Method B)Propagation tear resistance 250 gf, min. in machine and transversedirection (Test Method D1922)TABLE 3 Polyethylene Tube Sizes for Push-On Joint PipeANominal Pipe Diam
31、eter, 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 27464 121 307AThese wrap sizes should work with most push-on joint pipe and fitting bell sizes.Lay fla
32、t tube widths are minimums for each size of pipe. Tube widths used may beas much as two sizes wider than shown. Where bell circumferences are larger thanthe sheet sizes shown, the bell areas should be carefully wrapped with cut filmsections, effectively lapping and securing cut edges as necessary; o
33、r, alternatively,sufficiently large tube or sheet film to effectively cover these joints should beordered.BFor flat-sheet polyethylene, see 5.4.5.A674 182minimum space between the polyethylene and the pipe. Suffi-cient slack shall be provided in contouring to prevent stretchingthe polyethylene bridg
34、ing irregular surfaces, such as bell-spigot interfaces, bolted joints, or fittings, and to preventdamage 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 installations below the water table or in areassubj
35、ect 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 plastic tie straps be placed at 2-ft 0.6-minter
36、vals 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 described in thisstandard. At all times during
37、construction of the pipeline,precautions shall be taken to prevent damage to the encasementfilm.5.3 Repairs to EncasementRepair cuts, tears, punctures,or damage to polyethylene with adhesive tape or with a shortlength of polyethylene sheet; or with a tube cut open, wrappedaround the pipe to cover th
38、e damaged area, and secured inplace.5.4 Methods of InstallationThis practice includes threedifferent methods for the installation of polyethylene encase-ment. Methods A and B are for use with polyethylene tubes,and Method C is for use with polyethylene sheets.5.4.1 Method A (see Fig. 1):5.4.1.1 Cut
39、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 section, and bunching it accor-dion fashion lengthwise until it clears the pipe ends.5.4.1.2 Lower the
40、 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.5.4.1.3 After assembling the pipe joint, make the overlap ofthe polyethylene tube. Pull the bunched polyethylene from the
41、preceding 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 place. Take up the s
42、lackwidth 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.5.4.2 Modified Method A (see Fig. 3):5.4.2.1 This is a modification of Method A, which uses onelength of polyethylene tube for each length of pipe.
43、In thismodified method, one end of the tube is secured with circum-ferential tape to the spigot prior to making the joint. The 12-in.(300-mm) overlap is achieved when bringing the remainingfilm over the joint from the previous length of pipe.5.4.2.2 Cut a section of polyethylene tube approximately1
44、ft (300 mm) longer than the pipe section. Remove all lumpsof clay, mud, cinders, or other material that might haveaccumulated on the pipe surface during storage. Slip thepolyethylene tube around the pipe, starting at the spigot end.Bunch the tube accordion fashion on the end of the pipe. Pullback th
45、e overhanging end of the tube and circumferentiallytape it to the barrel of the pipe behind the insertion line. Afterassembly of the joint, the tape should be as close to the face ofthe bell as possible but not so close to the spigot end that itinterferes with the gasket.5.4.2.3 Take up the slack in
46、 the tube along the barrel of thepipe to make a snug, but not tight, fit. Fold excess polyethyleneback over the top of the pipe and use pieces of tape across thefold to securely hold it. This step is extremely important toavoid the sagging of the film at the bottom of the pipe.5.4.2.4 Dig a shallow
47、bell hole in the trench bottom at thejoint location to facilitate installation of the polyethylene tube.Lower the pipe into the trench and make up the pipe joint withthe preceding section of pipe.5.4.2.5 Move the sling (that is, no chains or metal, usenonabrasive sling material) to the bell end of t
48、he pipe and liftthe pipe slightly to provide enough clearance to easily slide thetube over the remaining barrel of the pipe. Snugly fold over theexcess wrap using tape to hold it in place. Note: Make sure thatno dirt or other bedding material becomes trapped between thewrap and the pipe.5.4.2.6 Secu
49、re the polyethylene in place behind the preced-ing bell by using a circumferential wrap of tape. Make theoverlap of the polyethylene tube by pulling back the bunchedpolyethylene from the preceding length of pipe and ensurethere is at least a 12-in. overlap.5.4.2.7 Carefully backfill the trench according to the proce-dures in AWWA Standard C600. To prevent damage duringbackfilling, allow adequate slack in the tube at the joint.Backfill should be free of cinders, rocks, boulders, nails, sticks,or other mate
