1、Designation: D2774 12 An American National StandardStandard Practice forUnderground Installation of Thermoplastic Pressure Piping1This standard is issued under the fixed designation D2774; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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.INTRODUCTIONIn general, thermoplastics pressure piping materials behave as ductile materials under load, meaning
3、that they can undergo considerable deformation without damage. Piping made from such materials hasthe ability to bend under a load without breaking and to deform in other ways, while offering continuedresistance. This flexibility allows ductile thermoplastic pipe to activate through pipe deformation
4、lateral soil forces which create a pipe/soil system capable of safely supportingeven in pipes subjectto little or no internal pressurethe earth and superimposed loads which are encountered in most pipeinstallations. However, proper installation techniques are required to ensure that the necessary su
5、pportat the bottom and passive soil pressures at the sides of the pipe are developed and maintained.Soils in which trenches are dug shall be examined and identified and the trenches prepared andbackfilled in accordance with sound bedding procedures and this practice.1. Scope*1.1 This practice govern
6、s procedures and references ASTMspecifications for underground installation of thermoplasticpressure piping, 63-in. (1372-mm) nominal size and smaller. Itis beyond the scope of this practice to describe these proce-dures in detail since it is recognized that significant differencesexist in their imp
7、lementation depending on kind and type ofpipe material, pipe size and wall thickness, soil conditions, andthe specific end use.1.1.1 This practice assumes that over the range of antici-pated operating conditions, including maximum external load-ing and minimum internal pressure, the soil/pipe system
8、 willoffer sufficient structural stability to resist possible excessivediametrical deformation, or even collapse. In cases, particu-larly with large diameter thinner-walled pipe, for which thevalidity of this assumption may be in question, the selection ofpipe and recommended installation conditions
9、 shall be deter-mined by a qualified engineer.1.1.2 Specific pipe characteristics and end-use requirementsshall dictate addition to, or modification of the proceduresstated or referenced herein.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses a
10、re mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
11、 and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Sections 10 and 11.2. Referenced Documents2.1 ASTM Standards:2D1600 Terminology forAbbreviated Terms Relating to Plas-ticsD2487 Practice for Classification o
12、f Soils for EngineeringPurposes (Unified Soil Classification System)D2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)E11 Specification for Woven Wire Test Sieve Cloth and TestSievesF412 Terminology Relating to Plastic Piping SystemsF1668 Guide for Construction Proce
13、dures for Buried PlasticPipe2.2 AWWA Standard:C 651 Standard for Disinfecting Water Mains33. Terminology3.1 Definitions:1This practice is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.61 on Water.Current edition approved Fe
14、b. 1, 2012. Published March 2012. Originallyapproved in 1969. Last previous edition approved in 2008 as D2774 08. DOI:10.1520/D2774-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume inf
15、ormation, refer to the standards Document Summary page onthe ASTM website.3Available from American Water Works Association (AWWA), 6666 W. QuincyAve., Denver, CO 80235, http:/www.awwa.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor D
16、rive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.1 Definitions are in accordance with Terminology F412,unless otherwise specified. Abbreviated terms are in accor-dance with Terminology D1600. Installation terminology usedin this practice is illustrated in Fig. 1.3.1.2 The term
17、pipe refers to both pipe and tubing, unlessspecifically stated otherwise.3.1.3 protective sleeve, na short section of pipe installedover system piping where there is a transition from relativelyrigid piping or structure to relatively flexible piping or structureto protect the transition region from
18、excessive bending or shearstresses. For example, protective sleeves are installed atconnections between plastic or non-plastic mains and plasticlateral branch or service lines (such as service or branchconnections to tapping tees or saddles), where plastic pipeenters or exits a casing, or where plas
19、tic pipe penetrates abuilding or vault wall.4. Significance and Use4.1 This practice may not apply to products which shall besubject to failure at relatively low strains. For low ductilitymaterials, the installed pipe/soil system shall be sufficientlyrigid to prevent pipe deformations which could st
20、rain thepiping material beyond its safe strain limit.5. Joining5.1 Plastic pipe shall be joined together or to other pipes ofdissimilar material using a number of different techniques.Commonly used procedures, joining materials, and fittings aredefined by various standards. (See Appendix X1.) The te
21、ch-nique used shall be suitable for the particular pipes beingjoined to one another. Manufacturers shall be consulted forspecific instructions not covered by existing specifications.When requesting information, the intended service applicationshall be made known.5.2 Skill and knowledge on the part o
22、f the installer arerequired using recommended techniques to obtain qualityjoints. Training of new installers shall be made under theguidance of skilled individuals. Detailed written proceduresand visual aids used to train personnel are available frompiping and joining equipment manufacturers.5.3 The
23、 use of fittings and joining procedures which are notcovered by a recognized standard is subject to the judgmentand discretion of the purchaser. Each fitting and joiningprocedure used shall be qualified by investigation, testing, andexperience to establish its suitability and safety for the intended
24、service. Fittings and joints shall have long-term pressurecapabilities equal to or greater than the systems maximumanticipated sustained operating pressure.5.3.1 Thrust transmitting joints such as heat fused or solventcemented, shall be capable of restraining maximum anticipatedpipe pull-out forces
25、generated by any unbalanced forces frominternal pressure or pipe expansion/contraction, or both.5.3.2 Gasketed and other non-thrust transmitting joints shallbe restrained by means of properly engineered external re-straints (thrust blocks) or joint restraint devices (see 7.3).NOTE 1Where there are u
26、nbalanced momentum forces and thrust istransmitted through the joints, consideration shall be given to the designcapacity of each joint in the system to safely resist maximum anticipatedaxial thrust (see 7.3). Where a piping section having thrust transmittingjoints is connected to a piping section h
27、aving non-thrust transmittingjoints, measures shall be taken to anchor or restrain the end of the thrusttransmitting joint section against longitudinal movement so that contrac-tive forces shall not be transmitted and cause disjoining of non-thrusttransmitting joints.6. Trenching-Recommended Install
28、ation Procedure6.1 Trench StabilityDuring trench excavation, ensure thatthe trench sides shall be stable under all working conditions.The trench walls shall be sloped or appropriate supportsprovided to comply with all applicable local, state, and federalrequirements for safety.6.2 Trench WidthThe wi
29、dth of the trench at any pointbelow the top of the pipe shall be sufficient to provide adequateroom for each of the following requirements: (1) joining thepipe in the trench if this is required; (2) snaking of small-diameter, heat fused or solvent cemented pipe from side-to-sidealong the bottom of t
30、he trench, when the effects of contractionare not otherwise accommodated; (3) filling and compactingthe side fills; and (4) checking the elastomeric seal joints.Minimum trench widths shall be permitted to be utilized withmost solvent-cemented and heat-fused pressure pipe materialsby joining the pipe
31、 outside the trench and lowering the pipeinto the trench after adequate joint strength has been attained(see 10.5). This practice shall be permitted to be used forgasket joint pipe, with manufacturers approval, providing careis taken to not disassemble the joints during lowering.6.3 Trench BottomThe
32、 trench bottom shall be prepared forthe direct replacement of the pipe and shall be continuous,relatively smooth, free of rocks, and provide uniform support.For bell-ended or coupled pipe, suitable “bell-holes” shall beprovided at each joint to permit the joint to be assembled andthe pipe to be supp
33、orted properly.FIG. 1 Installation TerminologyD2774 1226.3.1 Where ledge rock, hardpan, or boulders areencountered, it shall be required to pad the trench bottom witha bedding of at least 4-in. (100-mm) thickness of compactedClass I or II material (see Table 1). In situations where rapidmovement of
34、water takes place through this bedding, the ClassI or II material used shall have gradation that prevents loss bymigration of any pipe embedment material (see 9.8).6.4 Trench Depth and Pipe CoverExcavation for pipetrenches shall be to the lines, grades, and dimensions shown onthe contract drawings.
35、Sufficient cover shall be maintained toadequately reduce the traffic or other concentrated and impactloads.6.4.1 Reliability and safety of service shall assume majorimportance in determining minimum cover for any intendedservice. Local, state, or federal codes shall also govern. Pipeintended for win
36、ter water service shall have a minimum coverequal to or greater than the maximum expected frost penetra-tion depth.6.4.2 Aminimum cover of 24 in. (610 mm) for pipe shall berequired when subjected to heavy overhead traffic. In areas oflight overhead traffic a minimum cover of 12 to 18 in. (305 to457
37、mm) is required.6.5 “Trenchless InstallationSome types of thermoplas-tic pressure pipe shall be permitted to be installed usingmethods that do not require excavation.7. Pipe Placement7.1 Pipe Joint AssemblyPipe assembly shall be conductedin accordance with the manufacturers published recommen-dation
38、s. Above ground joining of pipe joined by solventcementing, heat fusion or some other thrust transmittingconnection shall be permitted. After the joint is appropriately“cured” (see Section 10) the pipe is lowered into the trench.This practice shall be permitted to be used for gasket joint pipe,with
39、manufacturers approval, providing care is taken to notdisassemble the joints during lowering.7.2 Pipe BendingAssembled thermoplastic pipe may bebent longitudinally if the bending radius is within limitsprescribed by the manufacturer. There shall be two limits, onefor pipe without joints and the othe
40、r for pipe sections withjoints.7.3 Thrust RestraintWhen installing piping systems withjoints that cannot transmit the anticipated maximum longitu-dinal thrust, thrust restraint shall be required at changes indirection, or terminal ends, to prevent joint disengagement.7.3.1 Where the piping system em
41、ploys non-self restrainingjoints (for example, elastomeric seal bell and spigot type joints)at points where line shift or joint separation at system operatingpressure can be anticipated, that is, pump discharge, directionalchanges, reducers and dead ends, thrust restraint shall berequired to prevent
42、 joint disengagement and ensure the properperformance of the pressure piping system.7.3.2 Where the piping system employs self-restrainingjoints (for example flanges, heat fusion, mechanical jointrestraint or solvent cement joints) at these points in the system,thrust blocking shall not be required
43、for thrust restraint.7.4 Thrust Restraint MethodsThrust restraint shall beachieved by use of mechanical thrust restraint devices or by useof concrete thrust blocking.7.4.1 Mechanical Thrust Restraint Devices:7.4.1.1 Devices used for thrust restraint of PVC pipe shallconform to Standard F1674.7.4.1.2
44、 Consult device manufacturer for design assistance.TABLE 1 Soil ClassesAClass I crushed rockB,C100% passing 1-12-in sieveD, # 15% passing#4 sieve,# 25% passing38-in sieve, # 12% passing#200 sieveClass II clean, coarse grained soilsEGW, GP, SW, SPor any soil beginning with one of these symbols(can co
45、ntain fines up to 12%)uniform fine sands (SP) with more than 50%passinga #100 sieve should be treated as Class IIImaterialClass III coarse grained soils with fines GM, GC, SM, SCor any soil beginning with one of these symbolssandy or gravelly fine grained soils ML, CLor any soil beginning with one o
46、f these symbolswith $ 30% retained on #200 sieveClass IV fine-grained soils or any soil beginning with oneof these symbolswith # 30% retained on #200 sieveML, CLClass V fine-grained soils, organic soils highcompressibility silts and clays, organic soilMH, CH, OL, OH, PtASoil classification descripti
47、ons and symbols are in accordance with Practice D2487 and D2488.BFor Class I, all particle faces shall be fractured.CSee section 9.6 for additional restrictions on Class 1 material maximum particle size.DSieves and sieve cloths shall be in accordance with Specification E11.EMaterials such as broken
48、coral, shells, slag, and recycled concrete (with less than 12% passing a No 200 sieve) should be treated as Class II soils.D2774 1237.4.2 Cast In Place Concrete Thrust Block Construction:7.4.2.1 The thrust block shall be constructed of cast in placeconcrete having a compression strength of 2000 psi
49、(14 MPa)or more. Precast concrete blocking, wood blocking, or stoneblocking with wood wedges, are not acceptable.7.4.2.2 The thrust block acts as an anchor between pipe orfitting and the solid trench wall. The size of the thrust blockshall be adequate to prevent pipe movement at the point ofthrust. Consult the system designer.7.4.2.3 The thrust block cavity shall be hand dug intoundisturbed soil and framed, with soil or wood to hold freshlypoured concrete. The earth bearing surfaces shall be undis-turbed.7.4.2.4 Before pressurizing the line, adequate time shall
