1、Designation: D 5162 08Standard Practice forDiscontinuity (Holiday) Testing of Nonconductive ProtectiveCoating on Metallic Substrates1This standard is issued under the fixed designation D 5162; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 procedures for determining discon-tinuities using two types of test equipme
3、nt:1.1.1 Test Method ALow Voltage Wet Sponge, and1.1.2 Test Method BHigh Voltage Spark Testers.1.2 This practice addresses metallic substrates. For concretesurfaces, refer to Practice D 4787.1.3 The values stated in SI units are to re regarded as thestandard. The values given in parentheses immediat
4、ely follow-ing the metric units are for information only.1.4 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 safety and health practices and determine the applica-bili
5、ty of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2G62 Test Methods for Holiday Detection in Pipeline Coat-ingsD 4787 Practice for Continuity Verification of Liquid orSheet Linings Applied to Concrete Substrates2.2 NACE Standard:3RP018888 Discontinuity (Holiday) Tes
6、ting of ProtectiveCoatings3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 discontinuity, as used in this standard, na flaw, void,crack, thin spot, foreign inclusion, or contamination in thecoating film that significantly lowers the dielectric strength ofthe coating film. A dis
7、continuity may also be identified as aholiday or pinhole.3.1.2 holiday, as used in this standard, na term thatidentifies a discontinuity.3.1.3 holiday detector, as used in this standard, na devicethat locates discontinuities in a nonconductive coating filmapplied to an electrically conductive surfac
8、e.3.1.4 pinhole, as used in this standard, na film defectcharacterized by small pore like flaws in the coating which,when extended entirely through the film, will appear as adiscontinuity. A pinhole in the finish coat may not appear as adiscontinuity.4. Significance and Use4.1 A coating is applied t
9、o a metallic substrate to preventcorrosion, reduce abrasion or reduce product contamination, orall three. The degree of coating continuity required is dictatedby service conditions. Discontinuities in a coating are fre-quently very minute and not readily visible. This practiceprovides a procedure fo
10、r electrical detection of minute discon-tinuities in nonconductive coating systems.4.2 Electrical testing to determine the presence and numberof discontinuities in a coating film is performed on a noncon-ductive coating applied to an electrically conductive surface.The allowable number of discontinu
11、ities should be determinedprior to conducting this test since the acceptable quantity ofdiscontinuities will vary depending on coating film thickness,design, and service conditions.4.3 The low voltage wet sponge test equipment is generallyused for determining the existence of discontinuities in coat
12、ingfilms having a total thickness of 0.5 mm (20 mil) or less. Highvoltage spark test equipment is generally used for determiningthe existences of discontinuities in coating films having a totalthickness of greater than 0.5 mm (20 mil).4.4 Coatings that are applied at a thickness of less than 0.5mm (
13、20 mil) may be susceptible to damage if tested with highvoltage spark testing equipment. Consult the coating manufac-turer for proper test equipment and inspection voltages.4.5 To prevent damage to a coating film when using highvoltage test instrumentation, total film thickness and dielectric1This p
14、ractice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved June 1, 2008. Published July 2008. Originally approvedin 1991. Last prev
15、ious edition approved in 2001 as D 5162 01.2For 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.3Available from NA
16、CE International (NACE), 1440 South Creek Dr., Houston,TX 77084-4906, http:/www.nace.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.strength in a coating system shall be considered in selecting theappropriate voltage for detecti
17、on of discontinuities. Atmo-spheric conditions shall also be considered since the voltagerequired for the spark to gap a given distance in air varies withthe conductivity of the air at the time the test is conducted.Suggested starting voltages are provided in Table 1.4.6 The coating manufacturer sha
18、ll be consulted to obtainthe following information, which would affect the accuracy ofthis test to determine discontinuities:4.6.1 Establish the length of time required to adequately dryor cure the applied coating film prior to testing. Solventsretained in an uncured coating film may form an electri
19、callyconductive path through the film to the substrate.4.6.2 Determine whether the coating contains electricallyconductive fillers or pigments that may affect the normaldielectric properties.4.7 This practice is intended for use with new liningsapplied to metal substrates. Its use on a coating previ
20、ouslyexposed to an immersion condition has often resulted indamage to the coating and has produced erroneous detection ofdiscontinuities due to permeation or moisture absorption of thecoating. Deposits may also be present on the surface causingtelegraphing (current traveling through a moisture path
21、to adiscontinuity, giving an erroneous indication) or current leak-age across the surface of the coating due to contamination. Theuse of a high voltage tester on previously exposed coatings hasto be carefully considered because of possible spark-through,which will damage an otherwise sound coating.A
22、lthough a lowvoltage tester can be used without damaging the coating, it mayalso produce erroneous results.5. Test MethodsTEST METHOD ALOW VOLTAGE WET SPONGETESTING5.1 Apparatus:5.1.1 Low Voltage Holiday Detectoran electronic devicepowered by a self-contained battery with voltages ranging from5 to 9
23、0 V dc, depending on the equipment manufacturerscircuit design. It is used to locate discontinuities in a noncon-ductive coating applied to a conductive substrate. Operationincludes the use of an open-cell sponge electrode wetted witha solution for exploring the coating surface, a signal returnconne
24、ction, and an audible or visual indicator, or both, forsignaling a point of coating discontinuity.5.1.2 Low Voltage Wet Sponge Testera sensitivity devicewith the operating voltage being of little importance other thanbeing part of the particular electronic circuit design.5.1.3 Wet Sponge Type Instru
25、mentsa number of commer-cially available, industry-accepted, instruments are available.The following electronic principle describes two types ofdevices generally used; others may be available but are notdescribed in this practice.5.1.3.1 Lightweight, Self-Contained, Portable Devicesbased on the elec
26、trical principle of an electromagnetic sensitiverelay or a solid-state electronic relay circuit that energizes anaudible or visual indicator when a coating discontinuity isdetected. Generally this equipment is capable of being recali-brated in the field by the user.5.1.3.2 Lightweight, Self-Containe
27、d, Portable Devicesalso based on the principle of an electronic relaxation oscillatorcircuit that reacts significantly to the abrupt drop in electricalresistance between the high dielectric value of the coating filmand the conductive substrate at the point of coating filmdiscontinuity. This results
28、in a rise in oscillator frequency aswell as in the audible signal from the device. Generally, thisequipment is incapable of being recalibrated in the field by theuser.5.2 Procedure:5.2.1 Sufficient drying or curing of the coating shall beallowed prior to conducting a test. The length of time require
29、dTABLE 1 Suggested Voltages for High Voltage Spark TestingTotal Dry Film ThicknessSuggested Inspection, Vmm mil0.5000.590 19.723.2 27000.6000.690 23.627.2 33000.7000.790 27.631.1 39000.8000.890 31.535.0 45000.9000.990 35.439.0 50001.0001.090 39.442.9 55001.1001.190 43.346.9 60001.2001.290 47.250.8 6
30、5001.3001.390 51.254.7 70001.4001.490 55.158.7 75001.5001.590 59.162.6 80001.6001.690 63.066.5 85001.7001.790 66.970.5 90001.8001.890 70.974.4 100001.9001.990 74.878.3 108002.0002.090 78.782.3 115002.1002.190 82.786.2 120002.2002.290 86.690.2 125002.3002.390 90.694.1 130002.4002.490 94.598.0 135002.
31、5002.590 98.4102.0 140002.6002.690 102.4105.9 145002.7002.790 106.3109.8 150002.8002.890 110.2113.8 155002.9002.990 114.2117.7 160003.0003.090 118.1121.7 165003.1003.190 122.0125.6 170003.2003.290 126.0129.5 175003.3003.390 129.9133.5 180003.4003.490 133.9137.4 185003.5003.590 137.8141.3 190003.6003
32、.690 141.7145.3 195003.7003.790 145.7149.2 200003.8003.890 149.6153.1 210003.9003.990 153.5157.1 218004.0004.190 157.5165.0 225004.2004.290 165.4168.9 230004.3004.390 169.3172.8 240004.4004.490 173.2176.8 250004.5004.590 177.2180.7 258004.6004.690 181.1184.6 264004.7004.790 185.0188.6 268004.8004.89
33、0 189.0192.5 274004.9004.990 192.9196.5 280005.0005.290 196.9208.3 285005.3005.500 208.7216.5 290005.6008.000 220.5307.1 30000NOTEAlternative methods for selecting a suitable test voltage aregiven in Test Methods G62and NACE RP018888.D5162082shall be obtained from the coating manufacturer. Solventsr
34、etained in the coating film could produce erroneous indicators.5.2.2 The surface shall be clean, dry, and free of oil, dirt andother contaminates. Measure the film thickness of the coatingwith a nondestructive dry film thickness gage. If the coatingfilm exceeds 0.5 mm (20 mil), use the procedures fo
35、r highvoltage spark testing described in Test Method B, High VoltageSpark Testing.5.2.3 Test the instrument for sensitivity in accordance with5.3.5.2.4 Attach the signal return wire from the instrumentterminal to the metallic substrate and ensure a good electricalcontact.5.2.5 Attach the exploring s
36、ponge lead to the other terminal.5.2.6 Wet the sponge with a solution consisting of tap waterand a low sudsing wetting agent, combined at a ratio of notmore than12 fluid oz of wetting agent to 1 gal water. Anexample of a low sudsing wetting agent is one used inphotographic development. The sponge sh
37、all be wetted suffi-ciently to barely avoid dripping of the solution while thesponge is moved over the coating. The wetting agent residuemust be removed prior to executing repairs to the coating.5.2.7 Sodium chloride (salt) shall not be added to thewetting solution because of the potential erroneous
38、 indicationsof discontinuities. The salt, after drying on the coated surface,may form a continuous path of conductivity across the surface.It will also interfere with intercoat adhesion of additional coats.5.2.8 Contact a bare spot on the conductive substrate withthe wetted sponge to verify that the
39、 instrument is properlyconnected. This procedure shall be repeated periodically dur-ing the test.5.2.9 Move the sponge over the surface of the coating at amoderate rate approximately 0.3 m/s (1 ft/s), using a doublepass over each area.Apply sufficient pressure to maintain a wetsurface. If a disconti
40、nuity is detected, turn the sponge on end todetermine the exact location of the discontinuity. Improvedaccuracy of location can be achieved using a corner of thesponge if practical.5.2.10 Discontinuities that require repair shall be identifiedwith a marker that is compatible with the repair coating
41、or onethat is easily removed.5.2.11 To prevent telegraphing take care to ensure that thesolution is wiped dry from a previously detected discontinuitybefore continuing the test.5.2.12 The wetting agent must be completely removed byrinsing the holiday area prior to repair.5.2.13 Wet sponge holiday de
42、tection is not recommendedbetween coats of a multicoat system. However, when a test isconducted between coats of a multicoat system, a wetting agentshall not be used and all residue left by the test water must becompletely removed prior to applying additional coats.5.3 Verifying Operation of Equipme
43、nt:5.3.1 The instrument shall be tested for sensitivity prior toinitial use and periodically thereafter, in accordance with theequipment manufacturers instructions.5.3.2 Test the battery for proper voltage output. Refer to themanufacturers instructions.5.3.3 Switch the instrument to the “on position
44、,” if appli-cable.5.3.4 Wet the sponge with a wetting solution consisting oftap water and a wetting agent (see 5.2.6).5.3.5 Connect the signal return wire to the instrumentground output terminal.5.3.6 Touch the signal return wire alligator clip to the wettedsponge. The instrument signal should signa
45、l in accordance withthe instrument manufacturers instructions.5.3.7 If the instrument should fail to signal, it shall beconsidered defective.5.4 Verifying Instrument Calibration:5.4.1 Verify instrument calibration in accordance with themanufacturers latest published instructions. If out of calibra-t
46、ion, the instrument shall be calibrated in accordance with theinstrument manufacturers latest published instructions, orreturned for calibration. A certificate of calibration, renewedannually, may be required if the quality management systemthat controls the testing dictates.TEST METHOD BHIGH VOLTAG
47、E SPARKTESTING5.5 Apparatus:5.5.1 High Voltage Detector (in excess of 500 V)Anelectronic device used to locate discontinuities in a noncon-ductive protective coating applied to a conductive substrate. Itconsists of an electrical voltage source, an exploring electrode,and a signal return wire connect
48、ion from the indicator, signal-ing current flow through a coating film discontinuity, to thesubstrate. The detector shall be equipped with a visual oraudible indicator, or both.5.5.2 Exploring Electrode, shall be of the type capable ofmaintaining continuous contact with the surface being in-spected,
49、 such as bolts, raised areas, etc. It shall be kept cleanand free of coating material.5.5.3 High Voltage Electrical Detector, can be identified aseither a pulse or direct current type. A pulse type detectordischarges a cycling, high voltage pulse, while a direct currenttype discharges continuous voltage.5.6 Procedure:5.6.1 Sufficient drying or curing of the coating shall beallowed prior to conducting a holiday test. The length of timerequired shall be obtained from t
