1、Designation: D2657 07 (Reapproved 2015)Standard Practice forHeat Fusion Joining of Polyolefin Pipe and Fittings1This standard is issued under the fixed designation D2657; 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This practice describes general
3、procedures for makingjoints with polyolefin pipe and fittings (excluding polyethylenepipe and fittings) by means of heat fusion joining techniques ineither a shop or field environment. These procedures aregeneral ones. Specific instructions for heat fusion joining areobtained from product manufactur
4、ers. See Practice F2620 forheat fusion joining of polyethylene pipe and fittings.1.2 The techniques covered are applicable only to joiningpolyolefin pipe and fittings of related polymer chemistry, forexample, polypropylenes to polypropylenes, or polybutylenesto polybutylenes. Material, density, and
5、flow rate shall be takeninto consideration in order to develop uniform melt viscositiesand formation of a good fusion bond when joining the samematerial to itself or to other materials of related polymerchemistry.1.3 Parts that are within the dimensional tolerances given inpresent ASTM specification
6、s are required to produce soundjoints between polyolefin pipe and fittings when using thejoining techniques described in this practice.1.4 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.5 The text of this practice re
7、ferences notes, footnotes, andappendixes which provide explanatory material. These notesand footnotes (excluding those in tables and figures) shall notbe considered as requirements of the practice.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its us
8、e. 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. See specific safetyprecautions in 3.1.1, 5.2, 8.2.3.1, Note 8 and Note 9, and A1.1.2. Referenced Documents2.1 ASTM St
9、andards:2F1056 Specification for Socket Fusion Tools for Use inSocket Fusion Joining Polyethylene Pipe or Tubing andFittingsF2620 Practice for Heat Fusion Joining of Polyethylene Pipeand Fittings3. Summary of Practice3.1 Heat-fusion joining uses a combination of heat and forceresulting in two melted
10、 surfaces flowing together to produce ajoint. Fusion bonding occurs when the joint cools below themelt temperature of the material. There is a temperature rangewithin which any particular material is satisfactorily joined.The specific temperature used requires consideration of theproperties of the s
11、pecific material, and the joining environment.With Techniques II or III (3.3.2 or 3.3.3), there is also anappropriate force to be applied which depends upon thematerial, the fusion equipment being used, and fusion tempera-ture. See Practice F2620 for heat fusion procedure for poly-ethylene pipe and
12、fittings.3.1.1 Electrically powered heat fusion tools and equipmentare usually not explosion proof. When performing heat fusionin a potentially combustible atmosphere such as in an excava-tion where gas is present, all electrically powered tools andequipment that will be used in the combustible atmo
13、sphereshall be disconnected from the electrical power source andoperated manually to prevent explosion and fire. For theheating tool, this requires bringing the heating tool up to orslightly above temperature in a safe area, then disconnecting itfrom electrical power immediately before use. This pro
14、cedureis limited to smaller sizes where heating is accomplishedbefore the heating tool drops below acceptable temperature.3.2 Adequate joint strength for testing is attained when allof the joint material cools to ambient temperature. The jointshall not be disturbed or moved until it has cooled. See
15、PracticeF2620 for heat fusion procedure for polyethylene pipe andfittings.1This practice is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.20 on Joining.Current edition approved Dec. 1, 2015. Published December 2015. Origina
16、llyapproved in 1967. Last previous edition approved in 2007 as D2657 07. DOI:10.1520/D2657-07R15.2For 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 Docum
17、ent Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 1Polybutylene undergoes a crystalline transformation forseveral days after cooling below its melt temperature. Although thisphenomenon has an eff
18、ect on the ultimate physical properties of thematerial, its effect on testing of joints has not been found to be significant.If there is any question of its effect, a comparison should be made betweenjoints that have been conditioned for different periods of time in order toestablish the conditionin
19、g-time relationship.3.3 Three fusion techniques are covered in this practice asfollows: See Practice F2620 for heat fusion procedure forpolyethylene pipe and fittings.3.3.1 Procedure 1, Socket FusionThe socket-fusion tech-nique involves simultaneously heating the outside surface of apipe end and the
20、 inside of a fitting socket, which is sized to besmaller than the smallest outside diameter of the pipe.After theproper melt has been generated at each face to be mated, thetwo components are joined by inserting one component into theother. See Fig. 1. The fusion bond is formed at the interfaceresul
21、ting from the interference fit. The melts from the twocomponents flow together and fuse as the joint cools. Optionalalignment devices are used to hold the pipe and socket fittingin Logitudinal alignment during the joining process; especiallywith pipe sizes 3 in. IPS (89 mm) and larger.3.3.2 Procedur
22、e 2, Butt FusionThe butt-fusion techniquein its simplest form consists of heating the squared ends of twopipes, a pipe and a fitting, or two fittings, by holding themagainst a heated plate, removing the plate when the proper meltis obtained, promptly bringing the ends together, and allowingthe joint
23、 to cool while maintaining the appropriate appliedforce. See Fig. 2. An alignment jig shall be used to obtain andmaintain suitable alignment of the ends during the fusionoperation.3.3.3 Procedure 3, Saddle FusionThe saddle-fusion tech-nique involves melting the concave surface of the base of asaddle
24、 fitting, while simultaneously melting a matching patternon the surface of the pipe, bringing the two melted surfacestogether and allowing the joint to cool while maintaining theappropriate applied force. See Fig. 3.4. Significance and Use4.1 The procedures described in Sections 7, 8, and 9, whenimp
25、lemented using suitable equipment and procedures in eithera shop or field environment, produce strong pressure-tightjoints equal to the strength of the piping material. Somematerials are more adaptable to one technique than another.Melt characteristics, average molecular weight and molecularweight d
26、istribution are influential factors in establishing suit-able fusion parameters; therefore, consider the manufacturersinstructions in the use or development of a specific fusionprocedure.5. Operator Experience5.1 Skill and knowledge on the part of the operator arerequired to obtain a good quality jo
27、int. This skill and knowl-edge is obtained by making joints in accordance with provenprocedures under the guidance of skilled operators. Evaluateoperator proficiency by testing sample joints.5.2 The party responsible for the joining of polyolefin pipeand fittings shall ensure that detailed procedure
28、s developed inconjunction with applicable codes and regulations and themanufacturers of the pipe, fittings, and joining equipmentinvolved, including the safety precautions to be followed, areissued before actual joining operations begin.6. Apparatus: General Recommendations6.1 Heating ToolThe tool m
29、ay be heated by gas orelectricity. Gas-fired heaters for 2in. IPS and smaller socketand butt fusion joints only, shall have heat sinks of sufficientcapacity to prevent excessive draw down of the toolFIG. 1 Socket FusionD2657 07 (2015)2temperature, and are used only in above-freezing conditions.Elect
30、ric heating plates maintain consistent fusion temperatureswhen provided with an adequate power source. Electric heatingplates for general fusion use shall be controlled thermostati-cally and most are adjustable for a set point temperatureranging from 300 to 575F (150 to 300C). Some tools mayhave a f
31、ixed set point for a particular application.6.2 Heating Tool FacesHeating tools may be made frommaterials such as aluminum, stainless steel, copper, or copperalloys. Copper or copper-alloy heating faces are not suitable,unless chromium-plated or clad with another suitable metal,because some polyolef
32、ins react with copper. Plastic materialsmay stick to hot metal heating surfaces. This sticking may beminimized by applying a non-stick coating to the heatingsurfaces or by fitting a high-temperature, non-stick fabric overthe heating surfaces. The heating plate surfaces, coated oruncoated, shall be k
33、ept clean and free of contaminants such asdirt, grease and plastic build-up, which may cause excessiveFIG. 2 Typical Butt Fusion OperationFIG. 3 Saddle FusionD2657 07 (2015)3sticking and create unsatisfactory joints. Most of these con-taminants are removed from the hot tool surfaces using a clean,dr
34、y, oil-free lint-free cloth. Do not use synthetic fabrics whichmay char and stick to the fusion surface. Some pigments, suchas carbon black, may stain a heating surface and probablycannot be removed; such stains will not contaminate the jointinterface.6.2.1 After a period of time in service, non-sti
35、ck coatings orfabrics will deteriorate and become less effective. Deterioratedfabrics should be replaced, and worn, scratched, or gougednon-stick coatings should be re-coated when they lose effec-tiveness. Heat fusion quality may be adversely affected bydeteriorated non-stick surfaces. Spray-on chem
36、icals, such asnon-stick lubricants or oils shall not be applied to heating ironsurfaces as they will contaminate the joint.6.3 Temperature IndicatorHeating tools shall be equippedwith a thermometer or other built-in temperature indicatingdevice. This device indicates the internal temperature of theh
37、eating iron which is usually higher than temperature of thefusion surfaces. Use a pyrometer periodically to verify thetemperature of the tool surfaces within the pipe or fittingcontact area. Select multiple checkpoints to ensure uniformsurface temperature.NOTE 2A significant temperature variation, t
38、hat is, cold spots, on thefusion surfaces may indicate a faulty heating iron which may need to beserviced before it can be used.7. Procedure 1Socket Fusion7.1 ApparatusSocket fusion tools manufactured in accor-dance with Specification F1056 are used for joining polyolefinpipe, tubing, and fittings.7
39、.1.1 Heating ToolIn order to obtain a proper melt, it isnecessary for a uniform temperature to be maintained acrossthe heating surface. Therefore, gas-fired tools are generallyrestricted to use with pipe sizes of 2 in. IPS (63 mm) or less.7.1.2 Heating Tool FacesConsisting of two parts, a maleend fo
40、r the interior socket surface and a female end for theexterior pipe surface. Both parts shall be made to suchtolerances as to cause an interference fit.7.1.3 Alignment JigThe alignment jig is an optional toolwhich consists of two sets of devices holding the componentsin alignment to each other. One
41、set of holding devices is fixed,and the other allows longitudinal movement for making thejoint.7.1.4 Rounding Clamps, (cold ring) to maintain roundnessof the pipe and control the depth of pipe insertion into thesocket during the joining operation.7.1.5 Depth Gage, for proper positioning of the round
42、ingclamp.7.1.6 Chamfering Tool, to bevel the end of the pipe.NOTE 3The depth gage and chamfering tool may be combined into asingle tool.7.1.7 Tubing Cutter, to obtain a square end cut on the pipe.7.1.8 Fitting Puller, an optional tool to assist in the removalof the fitting from the heating tool and
43、to hold the fitting duringassembly.7.2 Procedure:7.2.1 Attach the proper size heater faces to the heating tool,and heat the tool to the fusion temperature for the material.7.2.2 Cut the pipe end squarely, and clean the pipe end andfitting, both inside and outside, by wiping with a clean, dry,oil-fre
44、e, lint-free cloth.7.2.3 Chamfer the outside edge of the pipe end slightly andfix the rounding clamp about the pipe as determined from thedepth gage.NOTE 4Chamfering may not be required by some procedures or somefusion tools. Pipe sizes 1 in. (25.4 mm) and smaller are not usuallychamfered, regardles
45、s of tooling design.NOTE 5Some recommend using a 50 to 60-grit emery or garnet clothto roughen the outside of the pipe and inside of the fitting as a means ofminimizing any possible skin interface when making the fusion. Sandpa-per is not recommended for this purpose, as it might disintegrate andcon
46、taminate the joint interface. If roughening is performed, first clean thesurfaces before roughening. Clean dust and particles from the roughenedsurfaces afterwards by wiping with a clean, dry, oil-free, lint-free cloth.7.2.4 Bring the preheated tool faces into contact with theoutside surface of the
47、end of the pipe and the inside surface ofthe socket.7.2.5 Heat the pipe end and the fitting socket for the timerequired to obtain a proper melt. Proper melt is a function ofmaterial, time, tool temperature, and the size of the parts. Pipeand fittings of larger diameters require more time to reach th
48、eproper melt consistency than those of smaller diameters.Underheated or overheated materials will not form a goodbond.7.2.6 At the end of the heating time, simultaneously removethe pipe and fitting straight out from the tool, using a snapaction. Immediately insert the pipe straight into the socket o
49、fthe fitting so the rounding clamp is flush against the end of thefitting socket. Hold or block the joint in place until the melts ofthe mating surfaces have solidified. The exact cooling timedepends on the size of the pipe and the material being fused.7.2.7 Remove the rounding clamp, and inspect the meltpattern at the end of the socket for a complete impression of therounding clamp in the melt surface. There shall no gaps, voids,or unbonded areas. Clean the heating tool of any residualmaterial using a wood stick or a clean, dry, oil-free, lint-free,non-syntheti
