1、Designation: C1147 14Standard Practice forDetermining the Short Term Tensile Weld Strength ofChemical-Resistant Thermoplastics1This standard is issued under the fixed designation C1147; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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.1. Scope*1.1 This practice covers the preparation and evaluation ofjoints between two pieces of weldable grades of
3、thermoplasticmaterials, backed and unbacked, (such as those shown in Table1) up to 2 in. (50 mm) in thickness.1.2 Since there are numerous new technologies and tech-niques constantly being developed for plastic welding, thereare no profiles and procedures that can be considered asstandard for all pl
4、astics at various thicknesses. This practice isnot intended to define profiles and procedures; however, it isintended to establish methods to evaluate minimum short termweld factors to be achieved by the welder for the respectiveplastics.1.3 Weld procedures used for test pieces shall reflect pro-ced
5、ures to be used in actual fabrication.1.4 Welding methods to be used include machine welding,extrusion welding, and hot gas welding.1.5 This practice can be utilized by relevant certificationbodies to assess welder proficiency and qualification.1.6 The values stated in inch-pound units are to be reg
6、ardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the use
7、r of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD4285 Test Method f
8、or Indicating Oil or Water in Com-pressed AirD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE4 Practices for Force Verification of Testing Machines3. Terminology3.1 Definitions For definitions of terms used in thispractice, see Terminology D883.3.2 Definitions of Terms Specific
9、 to This Standard:3.2.1 butt welding (machine)the fusing together of twopieces of plastic which are aligned in the same plane, with thesame mating thickness, by application of heat and pressure,also called hot-plate welding.3.2.2 chemical-resistantthe ability of a material to resistdegradation by re
10、action with, dissolution by, or reduction ofphysical continuity from contact with a chemical agent oragents, thereby retaining its capacity to perform as a structuralor aesthetic entity.3.2.3 extrusion weldinga process in which heated plasticis forced through a shaping orifice (or die) and applied w
11、ithpressure to suitably prepared, locally preheated plastic piecesof the same resin base, to join them.3.2.4 hot-gas weldinga technique for joining thermoplas-tics (usually sheets) in which the materials are first softened bya jet of hot gas from a welding gun. A rod of the same plasticis used to fi
12、ll the heated gap and join the sheets at the same timepressure is applied by either the rod or the tip of the gun.Sometimes referred to as string bead welding.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.19 on Film, She
13、eting, and MoldedProducts.Current edition approved May 1, 2014. Published May 2014. Originallyapproved in 1990. Last previous edition approved in 2012 as C1147 01 (2012).DOI: 10.1520/C1147-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at ser
14、viceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unit
15、ed States13.2.5 hot-plate weldingsynonymous with butt welding(machine).3.2.6 short term weld factora dimensionless number thatprovides a relative measure of the tensile strength of a weldedthermoplastic test specimen to the tensile strength of themanufactured sheet.4. Summary of Practice4.1 The shee
16、ts are prepared and welded. Tensile test speci-mens containing a section of the weld are prepared and tested.Specimens of unwelded sheet are tested and compared to thewelded specimens. The short term weld factor determined iscompared to the standard (see Table 2), or to the factor agreedupon between
17、 the supplier and the user.5. Significance and Use5.1 The mechanical performance of welded thermoplasticstructures is largely dependent on the quality of the weldingoperation. It is necessary for fabricators to determine that theproper welding procedures are being followed and that weldersmaintain t
18、heir proficiency. Results from this practice areindicative of skill in proper welding procedures for differentthermoplastic materials and the use of appropriate weldingequipment. If the welded test specimens have short term weldfactors that meet or exceed the minimums as set forth in thispractice, i
19、t can be concluded that, with the same degree of skilland diligence by the welder, acceptable welds can be obtainedin fabricated structures.6. Apparatus6.1 The apparatus for welding shall consist of the following:6.1.1 Welding Device, suitable for joining thermoplastics.6.1.2 Air Supply, when needed
20、, conforming to Test MethodD4285.6.1.3 Temperature Measuring Device , capable of measur-ing the welding temperature to within 61 % for the specificplastic as set forth in Table 1.6.1.4 Clamps, suitable for holding the specimen whilewelding.6.1.5 Saw, suitable for cutting thermoplastic sheet.6.1.6 Sa
21、nder, Router, Joiner, or Saw, suitable for bevelingedges of sheet.6.2 The apparatus for testing tension specimens shall consistof the following:6.2.1 Tensile Machine A testing machine capable of pull-ing the specimens at a rate of 2 6 0.1 in./min (50 6 2.5mm/min) of crosshead movement (speed of move
22、ment whenthe machine is running without a load).6.2.1.1 The rate of movement between heads of the testingmachine shall remain essentially constant under changing loads(see Note 2).NOTE 2It is difficult to meet this requirement when loads aremeasured with a spring type or pendulum type weighing devic
23、e.6.2.1.2 The testing machine shall measure the load to within1 %. The testing range shall be so selected that the maximumload on the specimen falls between 15 and 85 % of the fullscale capacity.6.2.1.3 The use of autographic equipment to record the loadversus head movement is recommended.6.2.1.4 Ve
24、rification of the testing machine shall be made inaccordance with the recommendations of Practices E4.6.2.2 Micrometer or Vernier Caliper , suitable for measur-ing width and thickness of the test specimen to the nearest0.001 in. (0.025 mm).7. Test Specimens7.1 Test Pieces For Hot Gas and Extrusion W
25、eldingStartwith a 10 by 42 in. (250 by 1050 mm) piece of plastic sheet ofthe type and thickness to be tested. Cut the sheet as shown inFig. 1 to yield five pieces, four measuring 5 by 18 in. (125 by450 mm) and one measuring 6 by 10 in. (150 by 250 mm). Two5 by 18 in. (125 by 450 mm) pieces will be u
26、sed for horizontalwelding and two 5 by 18 in. (125 by 450 mm) pieces forvertical welding.7.1.1 The 6 by 10 in. (150 by 250 mm) sample shall be cutinto control specimens as described in Section 7.2.2. Labeleach piece as to type of plastic, method of welding, orientationof welding and welder identific
27、ation.7.1.2 Edge Preparation Bevel one 18 in. (450 mm) edgeof each 5 by 18 in. (125 by 450 mm) piece in preparation forwelding. Beveling shall be done using suitable apparatus suchas routers, sanders, joiners, or saws, that accurately reflectmethods utilized in the field. Typical bevel profiles for
28、thevarious sheet thicknesses are illustrated in Fig. 2 and Fig. 3.These profiles are optional and do not have to be used by thefabricator to meet the weld test standard, however, experienceTABLE 1 Typical Guide for Hot Gas Welding TemperaturesNOTE 1For other welding techniques, consult material and
29、equipmentsupplier for recommendations.F (C)ARecommended GasTypeBHDPE 500600 (260316) Nitrogen or AirPP 550600 (288316) Nitrogen or AirPVC 500550 (260288) AirCPVC 550660 (288349) AirPVDF 650680 (343360) Nitrogen or AirECTFE 665695 (352368) NitrogenETFE 675710 (357377) AirFEP 650725 (343385) AirPFA 67
30、5750 (357399) AirMFA 536554 (280290) AirAMeasured14 in. (6 mm) inside weld tip, directly in gas stream.BInert gas may be used in place of air.TABLE 2 Minimum Short Term Weld FactorsThermoplastic Hot Gas Extrusion Hot PlateHDPE 0.8 0.8 0.9PP 0.8 0.8 0.9PVC 0.8A0.9CPVC 0.6A0.8PVDF 0.8 0.8 0.9ECTFE 0.9
31、 0.9 0.9ETFE 0.9 0.9 0.9FEP 0.9 0.9 0.9TFE (PFA Filler) 0.9 0.9APFA 0.9 0.9 0.9ANot applicable.C1147 142has shown that the use of beveled edges is advantageous toweld quality in sheet greater than 60 mils (1.5 mm) in thicknessin hot gas and extrusion welding processes. Do not use solventsor other ch
32、emicals for cleaning the beveled surfaces that in anyway will adversely affect the properties of the plastic. Thecleaning operation should not in any way alter the profile orbevel of the edge. Details of bevels and test procedures usedshould accompany test specimens and the report of test results.7.
33、1.3 Welding ProcedureSecurely clamp the test sheets tobe welded to a suitable fixture and adjust welding devicetemperature as specified in Table 1. Weld two specimens, onevertically to simulate tank walls, and one horizontally tosimulate tank floors. If a machine such as a hot plate welder orother e
34、quipment that is in a fixed position is being used, thetwo test specimens, cut and configured as in 7.1, are welded inthe machines normal welding plane. The two samples shallnot be welded in the same cycle of the machine. Weldingprocedures must be identified and adequately described as partof the re
35、port. The completed weld may be projecting above orbe flush with adjacent surfaces.7.2 Preparation of Test Specimens :7.2.1 Weld Test SpecimensCut and discard a 1 in. (25 mm)strip off each end of an 18 by 10 in. (460 by 250 mm) weldedspecimen resulting in a piece 16 by 10 in. (400 by 250 mm).Cut rem
36、aining piece across the weld into 1 6 0.01 in. (25 60.25 mm wide) by 10 in. (250 mm) long strips. The width ofthe test specimens can be varied depending on the capacity ofthe tensile machine and the type and thickness of plastic beingtested. Set aside at least 10 of these specimens from theverticall
37、y welded sample and the same number from thehorizontal for weld test evaluation and condition a minimum of16hat736 4F (23 6 2C).7.2.2 Control SpecimensCut 5 pieces off the 6 by 10 in.(150 by 250 mm) control specimen to the same dimensions aswelded test specimens. Condition at least 5 specimens forev
38、aluation for 16 h at 73 6 4F (23 6 2C).8. Test Procedure8.1 Tensile Strengths:8.1.1 Control SpecimensMeasure width and thickness ofthe test pieces in accordance with D5947 to the nearest 0.001in. (0.025 mm) at the one-third intervals of that length not heldby the grips. Record the respective measure
39、ments, calculate therespective cross-sectional areas, and calculate the averagecross-sectional area of test pieces.8.1.1.1 Conduct the tensile test using a suitable test machinepulling at a cross-head speed of 2 6 0.1 in. (50 6 2.54mm)/min.8.1.2 Welded SpecimensMeasure width and thickness ofthe test
40、 pieces in accordance with D5947 to the nearest 0.001in. (0.025 mm) at the one-third intervals of that length not heldby the grips. Do not measure thickness within14 in. (6 mm) ofthe weld bead area. Record the respective measurements,calculate the respective cross-sectional areas and calculate theav
41、erage cross-sectional area of test pieces.8.1.2.1 Conduct the tensile test using a suitable test machineat a cross-head speed of 2 6 0.1 in. (50 6 2.54 mm)/min.9. Calculation9.1 Calculate the tensile strengths of each specimen asfollows:S 5 P/A (1)FIG. 1 Test PiecesFIG. 2 Typical Bevel Profile (Shee
42、t 0.090 to 0.5 in. (2.3 mm to 13mm) in Thickness)FIG. 3 Typical Bevel Profile (Sheet 0.5 in. (13 mm) Thick)C1147 143where:S = tensile strength, psi (MPa),P = peak load lbf (or N), andA = average cross-sectional area, in.2(or mm2).9.1.1 Average cross-sectional area is the product of theaverage width
43、and average thickness for each individualspecimen as measured in 8.1.1 and 8.1.2.9.1.2 When fabric backed sheet is tested, the overallthickness, including the fabric, shall be used in determining thethickness measurements in 8.1.1 and 8.1.2.9.2 Control StrengthCalculate the average tensile strengtho
44、f the five control specimens.9.3 Short Term Weld FactorCalculate the short term weldfactors for each vertically and horizontally welded specimen asfollows:Short Term Weld Factor 5Specimen Weld Strength, psi MPa!Average Control Strength, psi MPa!(2)9.4 All weld factors of the test specimens shall mee
45、t orexceed the values for the type of thermoplastic material listedin Table 2 or as agreed to between the supplier and user. If anyspecimens fail to meet or exceed the specified values, thewelder is not considered certified and shall resubmit newlyprepared specimens for retesting. Subsequent failure
46、s shouldcall for investigation of the technique and equipment.10. Report10.1 Report the following information:10.1.1 At the time the test specimens are provided fortesting, welder shall provide details of weld joint techniques asrequired in Section 7, which should include profile, type ofweld equipm
47、ent, type of gas and flow rate, temperatures used,type and nominal thickness of plastic sheet and rod, andmethod of bevel preparation, if any.10.1.2 Identification of the welder and the date of testspecimen fabrication shall be recorded.10.1.3 Weld strengths of all of the welded specimens, thefive c
48、ontrol specimens, and the calculated short term weldfactors shall be reported.11. Welder Proficiency11.1 All welders engaged in the fabrication of structuresintended to hold, contain, or convey corrosive chemicals can beevaluated in accordance with the mandates of this practice.11.2 To maintain qual
49、ification, welders shall prepare andhave tested, according to this practice, test specimens of eachcombination of plastics and welding equipment for which theywish qualification. Results achieved shall be in accordancewith the requirements given in 9.4.11.2.1 The frequency of qualification testing shall be estab-lished by the appropriate certification body.11.2.2 If required by the appropriate certification body, thetest results shall be maintained in the personnel file of thewelder for future reference.12. Keywords12.1 chemical r
