1、Designation: F2550 13 (Reapproved 2018)Standard Practice forLocating Leaks in Sewer Pipes By Measuring the Variationof Electric Current Flow Through the Pipe Wall1This standard is issued under the fixed designation F2550; the number immediately following the designation indicates the year oforiginal
2、 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.INTRODUCTIONInfiltration of groundwater into a sewer through defects in the pip
3、e can considerably increase theoperation and capital costs of a sewer system. Exfiltration of sewage out of a sewer pipe may causedegradation of aquifers and shoreline waters. Accurate location, measurement, and characterization ofall potential pipe leak defects are essential inputs for cost-effecti
4、ve design, testing, and certification ofpipe repairs, renewal, and new construction. While commonly used sewer leak assessment methods,such as air and water pressure testing, represent cost effective methods to provide overall Pass/Failpipe assessments, their inability to provide accurate location a
5、nd size of leaks, particularly atindividual joints and service connection, limit their use in remediation and rehabilitation decisionsupport.1. Scope1.1 This practice covers procedures for measuring the varia-tion of electric current flow to detect and locate potential pipeleaks in pipes fabricated
6、from electrically nonconductivematerials such as brick, clay, concrete, and plastic pipes (thatis, reinforced and non-reinforced). The method uses the varia-tion of electric current flow through the pipe wall to locatedefects that are potential water leakage paths either into or outof the pipe.1.2 T
7、his practice applies to mainline and lateral gravity flowstorm sewers, sanitary sewers, and combined sewers withdiameters between 3 and 60 in. (75 and 1500 mm). The pipesmust be free of obstructions that prevent the probe passingthrough the pipe.1.3 The scanning process requires access to sewers, fi
8、llingsewers, and operations along roadways that are safety hazards.This standard does not describe the hazards likely to beencountered or the safety procedures that must be carried outwhen operating in these hazardous environments. (7.1.3) Thereare no safety hazards specifically associated with the
9、use of anelectro-scan apparatus that complies with the specificationsprovided in this standard. (6.7 and 6.10.)1.4 The measurement of the variation of electric currentrequires the insertion of various items into a sewer. There isalways a risk that due to unknown structural conditions in thesewer suc
10、h items may become lodged in the pipe or may causethe state of a sewer in poor structural condition to furtherdeteriorate. This standard does not describe methods to assessthe structural risk of a sewer.1.5 The values stated in inch-pound units are to be regardedas standard. The values given in pare
11、ntheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.6 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-pria
12、te safety, health, and environmental practices and todetermine the applicability of regulatory limitations prior touse.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopm
13、ent of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 lateral, nsewer pipe connecting the common sewercollection system to the user.2.1.2 mai
14、nline, npipe that is part of the common sewercollection system.1This practice is under the jurisdiction of ASTM Committee F36 on Technologyand Underground Utilities and is the direct responsibility of Subcommittee F36.20on Inspection and Renewal of Water and Wastewater Infrastructure.Current edition
15、 approved Aug. 1, 2018. Published August 2018. Originallyapproved in 2006. Last previous edition approved in 2013 as F255013. DOI:10.1520/F2550-13R18.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was devel
16、oped in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.12.1.3 maintenance h
17、ole, n(MH) vertical shafts intersect-ing a sewer that allows entry to the sewer for cleaning,inspection and maintenance.2.1.4 owner, nentity holding legal rights to, and respon-sible for the operation and maintenance of the sewer pipe.2.1.5 probe, nscan electrode placed in a pipe.2.1.6 sliding pipe
18、plug, ndevice that blocks the flowthrough a pipe and at the same time can be pulled through thepipe.3. Significance and Use3.1 The testing of sewers for leaks is a regular practicenecessary for the maintenance and optimal performance ofsewer collection systems so remedial action can be prioritized,d
19、esigned, and carried out to reduce infiltration and exfiltration.3.2 This practice serves as a means to detect and locate alltypes of pipe defects that are potential sources of water leakseither into or out of electrically non-conducting pipes. Leakingjoints and defective service connections are det
20、ected that oftenmay not show as a defect when viewed from inside the pipe.The scan data may be processed and analyzed to provide someinformation on the size and type of pipe defect. (8.4.1)3.3 This practice applies to mainline and lateral gravity flowstorm sewers, sanitary sewers, and combined sewer
21、s fabricatedfrom electrically non-conducting material with diameters be-tween 3 and 60 in. (75 and 1500 mm). The pipes must be freeof obstructions that prevent the probe passing through the pipe.4. Contract Responsibilities4.1 Apart from the provisions generally included in a testingservices contrac
22、t, testing contracts for measuring the variationin electric flow through a pipe wall should define or affixresponsibility for or make provisions for the following items:4.1.1 Access to the site of work is to be provided to theextent that the owner is legally able to so provide or, if not soable, a w
23、ritten release from responsibility for the performanceof work at sites where access cannot be made available;4.1.2 Clearances of blockages or obstructions in the sewersystem;4.1.3 Location and exposure of all maintenance holes (MH);4.1.4 MH numbering system for all areas of the project andMH invert
24、elevations and depths;4.1.5 Shutdown or manual operation of certain pump sta-tions if such becomes necessary for performance of the work;4.1.6 Permission to use water from fire hydrants at the worksite, or other suitable designated sources within a reasonabledistance from the work areas, which is ne
25、cessary for contractedwork performance;4.1.7 Authorization to perform work that must be performedduring nighttime hours, weekends, or holidays; and4.1.8 Traffic control by uniformed officers or contract per-sonnel when the safety of workers or the public requires suchprotection.5. Principle of Opera
26、tion5.1 Most sewer pipe materials such as clay, plastic,concrete, reinforced concrete, and brick are poor conductors ofelectrical current.Adefect in the pipe wall that leaks water willalso leak electrical current, whether or not water infiltration orexfiltration is occurring at the time of the test.
27、5.2 The test is carried out by applying an electrical potentialof 9 to 11 Volts rms with a frequency of 500 Hz to 30 kHzbetween an electrode in the electrically nonconductive pipe andan electrode on the surface, which is usually a metal stakepushed into the ground. A simplified electrical circuit fo
28、r thisprocedure is shown in Fig. 1. The water in the pipe is at a levelthat ensures that the pipe is full at the electrode location.Provided electrical current is prevented from flowing along theinside of the pipe, the electrical resistance of the current pathbetween the electrode in the pipe and th
29、e surface electrode isvery low except through the electrically nonconductive pipewall. The high electrical resistance of the pipe wall allows onlya very small electrical current to flow between the twoelectrodes unless there is a defect in the pipe such as a crack,defective joint, or faulty service
30、connection. The greater theelectric current flow through the pipe opening, the larger thesize of the leak.FIG. 1 Schematic of a Simplified Electrical Scanning Circuit in a Non-Conductive PipeF2550 13 (2018)26. Apparatus6.1 The method for measuring the variation in electric flowthrough a pipe wall re
31、quires a means of preventing the electriccurrent from the electrode in the electrically nonconductivepipe from traveling along the inside of the pipe before reachingthe ground electrode. Such a means is a three-electrode array,known as a probe. The probe is constructed in such a way thatwhen equal v
32、oltages are applied to all three electrodes, theelectric fields of the outer electrodes prevent electrical currentfrom the center electrode flowing along the pipe. This alsocauses the electric field of the center electrode to be focusedinto a disk about 1 in. (25 mm) wide. This electric field projec
33、tsonto the pipe wall as a circumferential band with a width ofabout 10 % of the pipe diameter. The center of the band islocated at the center of the probe. As a result, the electricalcurrent flow through the center electrode of the probe, calledthe focused current, is dependant on the electrical res
34、istivity ofthe pipe wall within the area of the band around the circum-ference of the pipe.6.2 The essential components of the scanning apparatus are:a controlled voltage source; the probe; an insulated cable toconnect the probe to the voltage source and move the probethrough the pipe; a system to m
35、easure the position of the probein the pipe; a system to measure the focused current; a systemto measure the electrical current flowing through all threeelectrodes in the probe, called the total current; and a surfaceelectrode. When a sliding pipe plug (7.1.6.2) is used, a systemto measure the water
36、 pressure in the pipe at the location of theprobe, called the water head, is required.6.3 The geometric dimensions of the probe shall be suchthat the change of focused current as a result of a hole in thepipe with a diameter of 0.5 % of the pipe diameter will bedetected and potential leaks separated
37、 by more than 25 % ofthe pipe diameter will be resolved. That is for a 10 in. (250mm) diameter pipe a hole with a diameter of 0.05 in. (1.3 mm)will be detected and openings more than 2.5 in. (62 mm) apartwill be shown as two separate leaks.6.4 The focused current and the total current flowing be-twe
38、en the surface electrode and the probe and the water headshall be measured and recorded at not less than 0.40 in. (10.0mm) intervals along the pipe while the probe is pulled througha pipe at a speed of 32.8 ft/min (10.0 m/min).6.5 The accuracy of the probe position measurement systemshall be within
39、60.5 % with a resolution 0.05 %. That is for apipe test section that is 100.00 ft long the length of pipemeasured by the system shall be 100.00 6 0.5 ft and thesmallest distance readout unit will be 0.05 ft or less6.6 The resolution of the current measurements shall beequal to or less than 0.1 % of
40、the maximum current. That is ifthe maximum current is 40 mA then the smallest currentreadout unit will be 0.04 mA6.7 The applied voltage between the probe and the surfaceelectrode shall have a frequency between 500 and 30 000 Hzand a voltage range of 9 to 11 volt rms. The maximum currentbetween the
41、probe and the surface electrode shall be 0.04 Arms. These parameters prevent the occurrence of sparks orelectric shock to humans during normal operation or in theevent of a short circuit.6.8 The measurement of the probe location, total current,focused current, and water head shall be stored in real
42、time asdigital data in an electronic device.6.9 The probe position, total current, focused electrodecurrent, and the water head shall be displayed in real time onan electronic device on the surface when the system isactivated.6.10 The design of the electrical circuits shall prevent theoccurrence of
43、sparks or electrical shock to humans if faults ordamage occur such as a severed cable.6.11 Power cable winches shall have an automatic slipclutch to prevent overstrain of the probe cable that may occurif the probe becomes stuck in the pipe.7. Procedure7.1 Sewer Preparation:7.1.1 The test is usually
44、carried out by moving the probethrough the sewer at approximately 30 ft/min (10 m/min). Forthe average MH interval of 300 ft (100 m), this takes about 10min. The time to set up and dismantle the test equipment andfill the sewer in the region of the probe usually takes up mostof the field time.Approp
45、riate selection of the sewer section testsequence, establishment of a setup routine, and ready avail-ability of suitable equipment can considerably reduce the testpreparation time.7.1.2 Generally, testing does not require any pipe prepara-tion. However, the sewer must be clear of obstructions thatpr
46、event the probe passing through the pipe such as severe rootintrusion or protruding service connections. Inability to passthe haul line (7.1.5) through the pipe will indicate the presenceof such obstructions and should be reported (7.2.4).7.1.3 Person-Entry into Sewer MHsField operationsshould not r
47、equire person-entry of MHs. Person-entry ishazardous and requires additional time to carry out the safetychecks and set up safety equipment. However, unforeseensituations may occur that require person-entry of a MH.Suitably trained personnel and safety equipment should be onhand just in case person
48、entry is required. Prior to a personentering a MH the atmosphere in the MH must be evaluated fortoxic or flammable gases and oxygen depletion in accordancewith local, state or federal safety regulations and must becarried out in accordance with the owners person-entry of MHprocedures.7.1.4 Sewer Flo
49、wTesting can be carried out in all condi-tions of sewer flow, from dry to surcharged.7.1.5 Haul Line:7.1.5.1 A line is required to pull the probe between theMHs of the pipe section to be tested. The haul line is flushedbetween the MHs at each end of the pipe section to be scannedusing either water or air.7.1.5.2 An effective haul line is a jet cleaner hose.7.1.6 Filling the Sewer at the Probe LocationWater in thepipe provides the electrical connection between the probe andthe pipe wall (Fig. 1). To scan the complete circumference ofa electrically nonconductive pipe, it mu
