ASTM G62-2007 Standard Test Methods for Holiday Detection in Pipeline Coatings《管道涂层假期检测用标准试验方法》.pdf

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1、Designation: G 62 07Standard Test Methods forHoliday Detection in Pipeline Coatings1This standard is issued under the fixed designation G 62; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in pa

2、rentheses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the apparatus and procedurefor detecting holidays in pipeline type coatings.1.2 Method A is designed to detect holidays s

3、uch as pin-holes and voids in thin-film coatings from 0.0254 to 0.254 mm(1 to 10 mils) in thickness using ordinary tap water and anapplied voltage of less than 100 V d-c. It is effective on filmsup to 0.508 mm (20 mils) thickness if a wetting agent is usedwith the water. It should be noted, however,

4、 that this methodwill not detect thin spots in the coating, even those as thin as0.635 mm (25 mils). This may be considered to be a nonde-structive test because of the relatively low voltage.1.3 Method B is designed to detect holidays such aspinholes and voids in pipeline coatings; but because of th

5、ehigher applied voltages, it can also be used to detect thin spotsin the coating. This method can be used on any thickness ofpipeline coating and utilizes applied voltages between 900 and20 000 V d-c.2This method is considered destructive becausethe high voltages involved generally destroy the coati

6、ng at thinspots.1.4 The values stated in SI units to three significant deci-mals are to be regarded as the standard. The values given inparentheses are for information only.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibili

7、ty 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.2. Referenced Documents2.1 ASTM Standards:3A 742/A 742M Specification for Steel Sheet, MetallicCoated and Polymer Precoated for Corrugated Ste

8、el Pipe3. Terminology3.1 Definitions:3.1.1 holiday, nsmall faults or pinholes that permit cur-rent drainage through protective coatings on steel pipe orpolymeric precoated corrugated steel pipe.3.1.2 mil, n0.001 in.3.2 Definitions of Terms Specific to This Standard:3.2.1 holiday detector, na highly

9、sensitive electrical de-vice designed to locate holidays such as pinholes, voids, andthin spots in the coating, not easily seen by the naked eye.These are used on the coatings of relatively high-electricalresistance when such coatings are applied to the surface ofmaterials of low-electrical resistan

10、ce, such as steel pipe.3.2.2 pipeline type coating, ncoatings of relatively high-electrical resistance applied to surfaces of relatively low-electrical resistance, such as steel pipe.4. Summary of Test Methods4.1 Both methods rely on electrical contact being madethrough the pipeline coating because

11、of a holiday or alow-resistance path created by metal particles, or thin spots inthe coating. This electrical contact will activate an alarmalerting the operator of the incidence of a holiday.4.2 In Method A, the applied voltage is 100 V d-c or less.4.3 In Method B, the applied voltage is 900 to 20

12、000V d-c.5. Significance and Use5.1 Method AMethod A describes a quick, safe methodfor determining if pinholes, voids, or metal particles areprotruding through the coating. This method will not, however,find any thin spots in the coating. This method will determinethe existence of any gross faults i

13、n thin-film pipeline coatings.5.2 Method BMethod B describes a method for determin-ing if pinholes, voids, or metal particles are protruding throughthe coating, and thin spots in pipeline coatings. This methodcan be used to verify minimum coating thicknesses as well asvoids in quality-control applic

14、ations.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.48 on Durability of Pipeline Coating andLinings.Current edition approved July 1, 2007. Published July 2007. Origi

15、nally approvedin 1979. Last previous edition approved in 1998 as G 62 87 (1998)e 1which waswithdrawn March 2007 and reinstated in July 2007.2This was taken from the pamphlet “Operating Instructions for Tinker and RasorModel EP Holiday Detector.” Other manufacturers holiday detectors can beexpected t

16、o have similar voltage specifications.3For 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.1Copyright ASTM Interna

17、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Low-Voltage Holiday DetectorA holiday detectortester having an electrical energy source of less than 100 V d-c,such as a battery; an exploring electrode having a cellulosesponge dampened with

18、an electrically conductive liquid suchas tap water; and an audio indicator to signal a defect in ahigh-electrical resistance coating on a metal substrate. Aground wire connects the detector with the low-resistancemetal surface.6.2 High-Voltage Holiday DetectorA holiday detectortester having an elect

19、rical energy source of 900 to 20 000 Vd-c; an exploring electrode consisting of wire brush, coil-spring, or conductive silicon electrode capable of movingalong the pipeline coating; and an audio indicator to signal adefect in a high-electrical resistance coating on a metalsubstrate. A ground wire co

20、nnects the detector with thelow-resistance metal surface.6.3 Peak or Crest Reading VoltmeterA kilovoltmetercapable of detecting a single pulse and holding it long enoughfor the meter circuits to indicate.47. Reagents and Materials7.1 Tap Water, plain or with a wetting agent.NOTE 1Ordinary tap water

21、will suffice to wet the sponge electrodewhen inspecting coatings up to 0.254 mm (10 mils) in thickness. On filmsbetween 0.254 and 0.508 mm (10 and 20 mils), a nonsudsing type wettingagent added to the water is recommended to allow for faster penetrationof the liquid into pinhole defects.8. Test Spec

22、imen8.1 The test specimen shall be a representative length ofproduction-coated pipe or polymeric precoated corrugated steelpipe.9. Standardization of Instruments9.1 The instruments shall be standardized with respect tovoltage output in accordance with the manufacturers instruc-tions, using a peak or

23、 crest reading voltmeter. This is used morecommonly with Method B where voltage may vary from test totest but can also be used for verification of the voltage on aMethod A test.9.2 The low-voltage holiday detector shall be standardizedwith respect to sensitivity by having the alarm activated whena s

24、elected resistance, having a12 W rating, is placed across itsterminals. A common factory setting for sensitivity is 100 000V. Most units can be reset to any predetermined sensitivityvalue in this manner.10. Procedure for Method A10.1 Use the low-voltage holiday detector described in 6.1.10.2 Assembl

25、e the wand and electrode according to themanufacturers instructions and attach the ground wire to themetal surface.10.3 Attach the electrode clamps to the end of the wand,dampen the sponge electrode with tap water, and place itbetween the clamps. Then tighten the clamps with the screwuntil they are

26、well down into the sponge electrode. Attach theground wire (lead with battery clamp) and the wand to theterminals. Clip the ground wire to some point where the metalsurface is bare. Now touch the electrode to a second pointwhere the surface is bare and note that the audible signal willbe activated.

27、The detector is now ready to operate by passingthe damp sponge over the coated surface. When a holiday ispicked up by the audible alarm, the electrode can be turned onend and the exact spot of failure can be noted by searching withthe tip of the electrode.10.4 The voltage between the electrode (spon

28、ge) and themetal surface upon which the coating lies shall not exceed 100V d-c, measured between the electrode sponge and the coatedmetal when the detector is in its normal operating position.10.5 Prior to making the inspection, ensure that the coatedsurface is dry. This is particularly important if

29、 formed surfacesare to be inspected. If the surface is in an environment whereelectrolytes might form on the surface, such as salt spray, washthe coated surface with fresh water and allow to dry beforetesting. Take care to keep the electrolyte at least 12.7 mm (12in.) from any bare sheared or slit e

30、dge.10.6 A low-voltage holiday detector is not satisfactory forthe inspection of pipeline coatings over 0.508 mm (20 mils) inthickness. This type of holiday detector will not detect thinspots in pipeline coatings.11. Procedure for Method B11.1 Use the high-voltage holiday detector.11.2 Determine the

31、 test voltage desired by multiplying thedielectric breakdown voltage per millimetre (mil) of thecoating (Note 2) times the minimum allowable thickness of thecoating in millimetres (mils).NOTE 2The dielectric breakdown voltage per millimetre (mil) can bedetermined for each coating experimentally as f

32、ollows: Increase theholiday detector voltage over a known coating thickness and measure thevoltage at the point where the detector will just begin to ring. Divide thisvoltage by the known coating thickness to obtain the amount of volts permillimetre (mil). This can also be obtained from most coating

33、 manufac-turers literature.11.2.1 An alternative method of determining test voltage isby use of one of the following equations depending on coatingthickness.11.2.2 If the coating thickness is less than 1.016 mm (40mils):V 5 M=Tc (1)where:V = test voltageTc = coating thicknessM = 3294 if Tc is in mil

34、limetresM = 525 if Tc is in mils.11.2.3 If the coating thickness is greater than 1.041 mm (41mils):V 5 K =Tc (2)4The sole source of supply of a suitable peak or crest reading voltmeter knownto the committee at this time is Itt-Jennings, 970 McLaughlin Ave., San Jose, Calif.95116. If you are aware of

35、 alternative suppliers, please provide this information toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.G62072where:V = test voltageTc = coating thicknessK = 7843 if Tc is in millimetresK =

36、 1250 if Tc is in mils11.2.4 These equations are predicated on the amount ofvoltage needed to jump an air gap of the same length as thecoating thickness. Therefore, they are useful for testing voids,pinholes and thin spots in the coating, but would not be usefulas a coating thickness quality control

37、 tool.11.3 Ground the test specimen by attaching the ground wireto a bare metal spot on the pipe surface. Plug the ground wireinto the holiday detector. Then make up the searching electrodein accordance with the manufacturers recommendations, usinga brush wire or conductive silicon electrode. Plug t

38、he searchingelectrode into the holiday detector. Turn on the holidaydetector.11.3.1 CAUTION: Because of the high voltages involved,do not touch the ground wire and the metal part of the electrodeat the same time if the instrument is on.11.4 The detector is now ready to operate by passing theelectrod

39、e over the test specimen. The detector will ring if itpasses any void, pinhole, or area of the coating thinner than theminimum allowable thickness. When a holiday is detected bythe audible alarm, the electrode can be repositioned to deter-mine the exact holiday area by observing the origin of the sp

40、arkjump.11.5 Prior to making the inspection, ensure that the coatedsurface is dry. Dryness is critical in a high voltage test. Takecare to keep the electrode at least 12.7 mm (12 in.) from anybare sheared or slit edge.12. Report12.1 The report shall include the following (see Fig. 1):12.2 Complete i

41、dentification of the specimen includingnames and code number of the coating, pipe diameter, source,production data, and production run number. For polymericprecoated corrugated steel pipe, the reporting requirements ofSpecification A 742/A 742M shall be used for identification,12.3 Name and type of

42、instrument used, method of stan-dardization, and whether MethodAor Method B was used, and12.4 If Method B was used, state the test voltage, themethod used to calculate the voltage, and the minimumallowable thickness in millimetres (mils) of the test sample.13. Precision and Bias13.1 Precision data a

43、re limited to adjacent specimens takenfrom the production-coated pipe as for the polymeric corru-gated steel pipe assuming that the production process wasuniform with respect to pipe surface condition and coatingmaterial. Specimens that were not adjacent in the as-producedcondition, or were taken fr

44、om different lengths of pipe, mayrepresent differing process conditions.13.2 RepeatabilityWhen the same instrument is used bythe same operator, duplicate measurements on the same speci-men shall agree within 65%.13.3 ReproducibilityDifferent operators using differentinstruments, set at the same volt

45、age, inspecting the samespecimen shall obtain average results agreeing with each otherwithin 610 %.13.4 BiasThis test detects the presence of a conductivepath through the coating and is therefore not a measurement.No value for bias can be determined.14. Keywords14.1 holiday detector; holidays; pipin

46、g; pinhole; wet spongedetectorFIG. 1 Suggested Form for Use in Presenting Data for Method A and Method BG62073ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised

47、 that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either rea

48、pproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If yo

49、u feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).G62074