ASTM_D_6365_-_99_2011.pdf

Designation:D636599(Reapproved 2011)Standard Practice forthe Nondestructive Testing of Geomembrane Seams usingthe Spark Test1This standard is issued under the fixed designation D6365;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.Scope1.1 This practice covers the nondestructive testing of fieldseams in geomembranes using the spark test.A suspect area isindicated by the generation of a spark.The test is applicable toseams made by the extrusion method,seams made by usingwelding tape(a strip of the same type of material as thegeomembrane,that is welded over adjacent sections ofgeomembrane to create a seam),or seams where it is practicalto insert a conductive material in the seam just prior to orduring fabrication.1.2 The spark test may produce an electrical spark andtherefore can only be used where an electrical spark would notcreate a hazard.1.3 Unless the voltages and distances prescribed are care-fully adhered to,a“false positive”indication may result.Thisfalse positive occurs when the arc distance is too large for thevoltage applied at the time and conditions of testing.1.4 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.5 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 health and safety practices and to determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D4439 Terminology for GeosyntheticsD4491 Test Methods for Water Permeability of Geotextilesby Permittivity3.Terminology3.1 Definitions:3.1.1 geomembrane,nan essentially impermeable geosyn-thetic composed of one or more synthetic sheets.3.1.1.1 DiscussionIn geotechnical engineering,essen-tially impermeable means that no measurable liquid flowsthrough a geosynthetic when tested in accordance with TestMethods D4491.3.1.2 seam,na permanent joining of two or more materi-als.3.2 For definition of other terms,see Terminology D4439.4.Summary of Practice4.1 To use this practice a conductive material is inserted intothe field seam just prior to or during fabrication.The conduc-tive material in the seam is connected to the negative terminalof the test apparatus,and a positive voltage is applied acrossthe seam edge.A suspect area in the seam is indicated by aspark from the voltage source to the conductive material.5.Significance and Use5.1 Spark testing of geomembrane field seams is particu-larly useful in locations where other nondestructive test meth-ods are not practical,for example in tight corners or acircumferential seam around a pipe.6.Apparatus6.1 The test apparatus consists of a highvoltage,lowcur-rent source with a negative terminal for ground and a positiveterminal for a voltage applicator.A voltage applicator mayconsist of a handle and wire brush,conductive neoprenesqueegee,or other suitable applicator.6.2 The range of the high voltage source is typically 20 000to 35 000 V.6.2.1 The voltage required to cause a discharge(spark)between the positive electrode and the negative electrode wireis expressed by the formula.V 5 K=D(1)where:V=test voltage,1This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-thetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved June 1,2011.Published July 2011.Originally approvedin 1999.Last previous edition approved in 2006 as D6365 99(2006).DOI:10.1520/D6365-99R11.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 K=a constant(V/(mm)1/2),andD=the distance from the edge of the extrusion bead on thelower panel to the conductive material in mm.6.2.2 If the voltage is not adequate due to underestimatingD,a false positive test(a seam with a suspect area resulting inno spark and testing as a good seam)may result.6.2.3 Good results have been obtained using the test volt-ages and distances given in Table 1.6.2.4 The conductive material should be located 8 to 15 mmfrom the edge of the extrusion bead on the bottom geomem-brane to be a successful test.7.Procedure7.1 Before or as the seam is fabricated a continuous elec-trically conductive material is inserted in the lapped area of thepanels 2 to 5 mm(0.1 to 0.2 in.)from the edge of the top panelof membrane.See Fig.1.7.2 Prior to testing,it is necessary to connect the conductivematerial installed in the field seam to the negative terminal ofth