1、Designation: G62 07 (Reapproved 2013)G62 14Standard Test Methods forHoliday Detection in Pipeline Coatings1This standard is issued under the fixed designation G62; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last re
2、vision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the apparatus and procedure for detecting holidays in pipeline type coatings.1.2 Method A is designed to
3、 detect holidays such as pinholes and voids in thin-film coatings from 0.02540.025 to 0.254 mm(1 to 10 mils) in thickness using ordinary tap water and an applied voltage of less than 100 V d-c. It is effective on films up to0.508 mm (20 mils) thickness if a wetting agent is used with the water. It s
4、hould be noted, however, that this method will not detectthin spots in the coating, even those as thin as 0.635 mm (25 mils). coating. This may be considered to be a nondestructive testbecause of the relatively low voltage.1.3 Method B is designed to detect holidays such as pinholes and voids in pip
5、eline coatings; but because of the higher appliedvoltages, it can also be used to detect thin spots in the coating. This method can be used on any thickness of pipeline coating andutilizes applied voltages between 900 and 20 000Vd-c.2 This method is considered destructive because the high voltages i
6、nvolvedgenerally destroy the coating at thin spots.1.4 The values stated in SI units to three significant decimals are to be regarded as the standard. The values given in parenthesesare for information only.1.5 This standard does not purport to address all of the safety concerns, if any, associated
7、with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3A742/A742M Specification for Steel Sheet, Metallic Coated and Polym
8、er Precoated for Corrugated Steel Pipe3. Terminology3.1 Definitions:3.1.1 holiday, nsmall faults or pinholes that permit current drainage through protective coatings on steel pipe or polymericprecoated corrugated steel pipe.3.1.2 mil, n0.001 in.3.2 Definitions of Terms Specific to This Standard:3.2.
9、1 holiday detector, na highly sensitive electrical device designed to locate holidays such as pinholes, voids, and thin spotsin the coating, not easily seen by the naked eye. These are used on the coatings of relatively high-electrical resistance when suchcoatings are applied to the surface of mater
10、ials of low-electrical resistance, such as steel pipe.3.2.2 pipeline type coating, ncoatings of relatively high-electrical resistance applied to surfaces of relatively low-electricalresistance, such as steel pipe.1 These test methods are under the jurisdiction of ASTM Committee D01 on Paint and Rela
11、ted Coatings, Materials, and Applications and are the direct responsibility ofSubcommittee D01.48 on Durability of Pipeline Coating and Linings.Current edition approved June 1, 2013July 1, 2014. Published June 2013July 2014. Originally approved in 1979. Last previous edition approved in 20072013 asG
12、62 07.G62 07 (2013). DOI: 10.1520/G0062-07R13.10.1520/G0062-14.2 This was taken from the pamphlet “Operating Instructions for Tinker and Rasor Model EP Holiday Detector.” Other manufacturers holiday detectors can be expectedto have similar voltage specifications.3 For referencedASTM standards, visit
13、 theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard
14、 an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is
15、 to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Methods4.1 Both methods rely on electrical contact being made through the pipeline coating because of a holiday or a low-resist
16、ancepath created by metal particles, or thin spots in the coating. This electrical contact will activate an alarm alerting the operator ofthe 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 20 000 V d-c.5. Significance a
17、nd Use5.1 Method AMethod A describes a quick, safe method for determining if pinholes, voids, or metal particles are protrudingthrough the coating. This method will not, however, find any thin spots in the coating. This method will determine the existenceof any gross faults in thin-film pipeline coa
18、tings.5.2 Method BMethod B describes a method for determining if pinholes, voids, or metal particles are protruding through thecoating, and thin spots in pipeline coatings. This method can be used to verify minimum coating thicknesses as well as voids inquality-control applications.6. Apparatus6.1 L
19、ow-Voltage Holiday DetectorA holiday detector tester having an electrical energy source of less than 100 V d-c, suchas a battery; an exploring electrode having a cellulose sponge dampened with an electrically conductive liquid such as tap water;and an audio indicator to signal a defect in a high-ele
20、ctrical resistance coating on a metal substrate. A ground wire connects thedetector with the low-resistance metal surface.6.2 High-Voltage Holiday DetectorA holiday detector tester having an electrical energy source of 900 to 20 000 V d-c; anexploring electrode consisting of wire brush, coil-spring,
21、 or conductive silicon electrode capable of moving along the pipelinecoating; and an audio indicator to signal a defect in a high-electrical resistance coating on a metal substrate.Aground wire connectsthe detector with the low-resistance metal surface.6.3 Peak or Crest Reading VoltmeterA kilovoltme
22、ter capable of detecting a single pulse and holding it long enough for themeter circuits to indicate.7. Reagents and Materials7.1 Tap Water, plain or with a wetting agent.NOTE 1Ordinary tap water will suffice to wet the sponge electrode when inspecting coatings up to 0.254 mm (10 mils) in thickness.
23、 On films between0.254 and 0.508 mm (10 and 20 mils), a nonsudsing type wetting agent added to the water is recommended to allow for faster penetration of the liquidinto pinhole defects.8. Test Specimen8.1 The test specimen shall be a representative length of production-coated pipe or polymeric prec
24、oated corrugated steel pipe.9. Standardization of Instruments9.1 The instruments shall be standardized with respect to voltage output in accordance with the manufacturers instructions,using a peak or crest reading voltmeter. This is used more commonly with Method B where voltage may vary from test t
25、o test butcan also be used for verification of the voltage on a Method A test.9.2 The low-voltage holiday detector shall be standardized with respect to sensitivity by having the alarm activated when aselected resistance, having a 12 W rating, is placed across its terminals. A common factory setting
26、 for sensitivity is 100 000 .Most units can be reset to any predetermined sensitivity value in this manner.10. Procedure for Method A10.1 Use the low-voltage holiday detector described in 6.1.10.2 Assemble the wand and electrode according to the manufacturers instructions and attach the ground wire
27、to the metalsurface.10.3 Attach the electrode clamps to the end of the wand, dampen the sponge electrode with tap water, and place it between theclamps. Then tighten the clamps with the screw until they are well down into the sponge electrode. Attach the ground wire (leadwith battery clamp) and the
28、wand to the terminals. Clip the ground wire to some point where the metal surface is bare. Now touchthe electrode to a second point where the surface is bare and note that the audible signal will be activated. The detector is nowready to operate by passing the damp sponge over the coated surface. Wh
29、en a holiday is picked up by the audible alarm, theelectrode can be turned on end and the exact spot of failure can be noted by searching with the tip of the electrode.G62 14210.4 The voltage between the electrode (sponge) and the metal surface upon which the coating lies shall not exceed 100 V d-c,
30、measured between the electrode sponge and the coated metal when the detector is in its normal operating position.10.5 Prior to making the inspection, ensure that the coated surface is dry. This is particularly important if formed surfaces areto be inspected. If the surface is in an environment where
31、 electrolytes might form on the surface, such as salt spray, wash the coatedsurface with fresh water and allow to dry before testing. Take care to keep the electrolyte at least 12.7 mm (12 in.) from any baresheared or slit edge.10.6 A low-voltage holiday detector is not satisfactory for the inspecti
32、on of pipeline coatings over 0.508 mm (20 mils) inthickness. This type of holiday detector will not detect thin spots in pipeline coatings.11. Procedure for Method B11.1 Use the high-voltage holiday detector.11.2 Determine the test voltage desired by multiplying the dielectric breakdown voltage per
33、millimetre (mil) of the coating(Note 2) times the minimum allowable thickness of the coating in millimetres (mils).NOTE 2The dielectric breakdown voltage per millimetre (mil) can be determined for each coating experimentally as follows: Increase the holidaydetector voltage over a known coating thick
34、ness and measure the voltage at the point where the detector will just begin to ring. Divide this voltage bythe known coating thickness to obtain the amount of volts per millimetre (mil). This can also be obtained from most coating manufacturers literature.FIG. 1 Suggested Form for Use in Presenting
35、 Data for Method A and Method BG62 14311.2.1 An alternative method of determining test voltage is by use of one of the following equations depending on coatingthickness.11.2.2 If the coating thickness is less than 1.016 mm (40 mils):V5M=Tc (1)where:V = test voltageTc = coating thicknessM = 3294 if T
36、c is in millimetresM = 525 if Tc is in mils.11.2.3 If the coating thickness is greater than 1.041 mm (41 mils):V5K =Tc (2)where:V = test voltageTc = coating thicknessK = 7843 if Tc is in millimetresK = 1250 if Tc is in mils11.2.4 These equations are predicated on the amount of voltage needed to jump
37、 an air gap of the same length as the coatingthickness. Therefore, they are useful for testing voids, pinholes and thin spots in the coating, but would not be useful as a coatingthickness quality control tool.11.3 Ground the test specimen by attaching the ground wire to a bare metal spot on the pipe
38、 surface. Plug the ground wire intothe holiday detector. Then make up the searching electrode in accordance with the manufacturers recommendations, using a brushwire or conductive silicon electrode. Plug the searching electrode into the holiday detector. Turn on the holiday detector.11.3.1 CAUTION:
39、Because of the high voltages involved, do not touch the ground wire and the metal part of the electrode atthe same time if the instrument is on.11.4 The detector is now ready to operate by passing the electrode over the test specimen. The detector will ring if it passesany void, pinhole, or area of
40、the coating thinner than the minimum allowable thickness. When a holiday is detected by the audiblealarm, the electrode can be repositioned to determine the exact holiday area by observing the origin of the spark jump.11.5 Prior to making the inspection, ensure that the coated surface is dry. Drynes
41、s is critical in a high voltage test. Take careto keep the electrode at least 12.7 mm (12 in.) from any bare sheared or slit edge.12. Report12.1 The report shall include the following (see Fig. 1):12.2 Complete identification of the specimen including names and code number of the coating, pipe diame
42、ter, source,production data, and production run number. For polymeric precoated corrugated steel pipe, the reporting requirements ofSpecification A742/A742M shall be used for identification,12.3 Name and type of instrument used, method of standardization, and whether Method A or Method B was used, a
43、nd12.4 If Method B was used, state the test voltage, the method used to calculate the voltage, and the minimum allowablethickness in millimetres (mils) of the test sample.13. Precision and Bias13.1 Precision data are limited to adjacent specimens taken from the production-coated pipe as for the poly
44、meric corrugatedsteel pipe assuming that the production process was uniform with respect to pipe surface condition and coating material. Specimensthat were not adjacent in the as-produced condition, or were taken from different lengths of pipe, may represent differing processconditions.13.2 Repeatab
45、ilityWhen the same instrument is used by the same operator, duplicate measurements on the same specimenshall agree within 65 %.13.3 ReproducibilityDifferent operators using different instruments, set at the same voltage, inspecting the same specimenshall obtain average results agreeing with each oth
46、er within 610 %.13.4 BiasThis test detects the presence of a conductive path through the coating and is therefore not a measurement. No valuefor bias can be determined.G62 14414. Keywords14.1 holiday detector; holidays; piping; pinhole; wet sponge detectorASTM International takes no position respect
47、ing the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This stan
48、dard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Internation
49、al Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you 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
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