ASTM_C_1147_-_14.pdf

Designation:C114714Standard 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 revision,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 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 plastics 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-cedures 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 regardedas 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 user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD4285 Test Method for 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 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 reaction 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 withpressure 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 fill 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,Sheeting,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 serviceastm.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.United States1 3.2.5 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 sheets 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 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