ASTM D6747-2004 Standard Guide for Selection of Techniques for Electrical Detection of Potential Leak Paths in Geomembrane《电子探测地膜中潜在漏气路径的技术选择的标准指南》.pdf
《ASTM D6747-2004 Standard Guide for Selection of Techniques for Electrical Detection of Potential Leak Paths in Geomembrane《电子探测地膜中潜在漏气路径的技术选择的标准指南》.pdf》由会员分享,可在线阅读,更多相关《ASTM D6747-2004 Standard Guide for Selection of Techniques for Electrical Detection of Potential Leak Paths in Geomembrane《电子探测地膜中潜在漏气路径的技术选择的标准指南》.pdf(9页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D 6747 04Standard Guide forSelection of Techniques for Electrical Detection of PotentialLeak Paths in Geomembranes1This standard is issued under the fixed designation D 6747; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This standard guide is intended to assist individuals orgroups in assessing different options availa
3、ble for locatingpotential leak paths in installed geomembranes through the useof electrical methods. For clarity, this document uses the termpotential leak path to mean holes, punctures, tears, knife cuts,seam defects, cracks and similar breaches over the partial orentire area of an installed geomem
4、brane.1.2 This guide does not cover systems that are restricted toseam testing only, nor does it cover systems that may detectleaks non-electrically. It does not cover systems that onlydetect the presence, but not the location of leaks.1.3 This standard does not purport to address all of thesafety c
5、oncerns, 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 requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2D 4439 Terminology for Geosynthetic
6、s3. Terminology3.1 Definitions:3.1.1 electrical leak location, nany method which useselectrical current or electrical potential to detect and locatepotential leak paths.3.1.2 geomembrane, nan essentially impermeable mem-brane used with foundation, soil, rock, earth or any othergeotechnical engineeri
7、ng related material as an integral part ofa manmade project, structure, or system.3.1.3 geosynthetic, na planar product manufactured frompolymeric material used with soil, rock, earth, or other geo-technical engineering related material as an integral part of amanmade project, structure, or system.3
8、.1.4 potential leak paths, nfor the purposes of thisdocument, a potential leak path is any unintended opening,perforation, breach, slit, tear, puncture, crack, or seam breach.Scratches, gouges, dents, or other aberrations that do notcompletely penetrate the geomembrane are not considered.Leak paths
9、detected during surveys have been grouped into fivecategories: (1) Holesround shaped voids with downward orupward protruding rims, (2) Tearslinear or areal voids withirregular edge borders, (3) Linear cutslinear voids with neatclose edges, (4) Seam defectsarea of partial or total separa-tion between
10、 sheets, and (5) Burned through zonesareaswhere the polymer has been melted during the weldingprocess.4. Significance and Use4.1 Types of potential leak paths have been related to thequality of the sub-grade material, quality of the cover material,care in the cover material installation and quality
11、of geomem-brane installation.4.2 Experience demonstrates that geomembranes can haveleaks caused during their installation and placement of mate-rial(s) on the liner.4.3 The damage to a geomembrane can be detected usingelectrical leak location systems. Such systems have been usedsuccessfully to locat
12、e leak paths in electrically-insulatinggeomembranes such as polyethylene, polypropylene, polyvinylchloride, chlorosulfonated polyethylene and bituminousgeomembranes installed in basins, ponds, tanks, ore and wastepads, and landfill cells.4.4 The principle behind these techniques is to place avoltage
13、 across a synthetic geomembrane liner and then locateareas where electrical current flows through discontinuities inthe liner (as shown schematically in Fig. 1). Insulation must besecured prior to a survey to prevent pipe penetrations, flangebolts, steel drains, and batten strips on concrete to cond
14、uctelectricity through the liner and mask potential leak paths. Theliner must act as an insulator across which an electricalpotential is applied. This electric detection method of locatingpotential leak paths in a geomembrane can be performed on1This guide is under the jurisdiction ofASTM Committee
15、D35 on Geosyntheticsand is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 2002. Last previous edition approved in 2002 as D 674702e12For referenced ASTM standards, visit the ASTM website, www.astm
16、.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.FIG. 1 Sch
17、ematic of Electrical Leak Detection MethodD6747042exposed liners, on liners covered with water, or on linerscovered by a protective soil layer, or both.5. Developed Systems5.1 Electrical leak detection systems were developed in theearly 1980s and commercial surveys have been available since1985. A s
18、hort description of these systems is presented in thissection.5.2 The Water Puddle and Water Lance SystemThe tech-nique is appropriate to survey a dry uncovered geomembraneduring its installation when placed directly on a subgrade thatis an electrically conductive layer below the geomembrane.The low
19、er conductive layer is usually the soil and the upperconductive layer being water. A cathode ground is establishedand an anode is placed in a water puddle maintained by asqueegee or to the water stream of a lance (as shownschematically in Fig. 2). Water is usually supplied by gravityfrom a tank truc
20、k parked at a higher elevation than the linedarea. For this technique to be effective, the leaking water mustcome into contact with the electrical conducting medium towhich the ground electrode of the 12 or 24 volts dc supply canbe connected. Since the geomembrane is not a perfect electricalinsulato
21、r, a steady background signal can be audible. As thewater flows through a leak path, there is an increase in thesignal. Leak paths as small as 1 mm in size are then located byan audio signal or by measuring a current of magnitude relatedto the size of the leak. It can also be used to search for leak
22、paths in geomembrane-lined concrete and steel tanks.5.2.1 FeaturesThe main advantage of this system is thepossibility to detect leak paths in geomembrane joints andsheets as work progresses during the construction phase.Larger leak paths do not mask smaller ones because thistechnique locates leak pa
23、ths independently on uncovered liner.The electrical survey rate of approximately 500 m2/h peroperator does not affect the installation work schedule andpermits a rapid construction quality control (CQC) of theinstaller work. The approximate setup time varies from 1 to 3h.5.2.2 LimitationsThis techni
24、que cannot be used with aprotective layer covering the liner. The presence of wrinklesand waves, steep slopes and lack of contact between the linerand the conductive soil at bottom of slopes inhibits the surveyspeed. This technique cannot be used during stormy weatherwhen the membrane is installed o
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