ASTM G9-2007 Standard Test Method for Water Penetration into Pipeline Coatings《管道涂层渗水性的标准试验方法》.pdf
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1、Designation:G907Standard Test Method forWater Penetration into Pipeline Coatings1This standard is issued under the fixed designation G 9; 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 parent
2、heses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method covers the determination of the apparentrate of depth of water penetration into insulating coatingsapplied to pipe.1.2 The values stated i
3、n SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 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 he
4、alth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2G12 Test Method for Nondestructive Measurement of FilmThickness of Pipeline Coatings on Steel3. Summary of Test Method3.1 The method consists of an immersion-type test wh
5、erepipe specimens are suspended in an aqueous electrolyte for theduration of the test period. Electrical measurements of coatingcapacitance and dissipation factor are used to follow the waterabsorption rate of the test materials.4. Significance and Use4.1 The deterioration of an insulating coating f
6、ilm is inti-mately related to its moisture content. The water penetrationtest provides a means for monitoring the passage of moisturethrough a coating material by means of changes in its dielectricconstant. When expressed in relation to time, the test data willreflect a rate of deterioration which i
7、s a characteristic of thecoating material and will bear a relation to its expected usefullife as an insulating coating. The test for water penetration willalso provide information that is useful in establishing theoptimum coating thickness for a given material.5. Apparatus5.1 Immersion CellAny suita
8、ble nonmetallic vessel tocontain the test specimens. Dimensions of the vessel shallpermit the following requirements:5.1.1 Test specimens shall be suspended vertically with atleast 25 mm (1.0 in.) clearance from the sides and bottom.5.1.2 Test specimens shall be separated by not less than 25to 40 mm
9、 (1 to 1.5 in.) and a vertically suspended anode shallbe placed at an equal distance from each specimen not less thanthe separation of distance.5.1.3 The test vessel shall be deep enough to allow forimmersion of the samples in the electrolyte to the levelspecified in 8.1.NOTE 1Commercially available
10、, glass battery jars in 2-dm3(0.55-gal)and 10-dm3(2.7-gal) sizes can be conveniently used with 19-mm(0.75-in.) and 51-mm (2.0-in. nominal) diameter specimens, respectively.5.1.4 A suitable sample support plate fabricated from amaterial having a low dielectric constant shall be used tosuspend the sam
11、ples and anode above the immersion cell. Thesupport plate shall contain an access hole for the referenceelectrode. A typical test cell is illustrated in Fig. 1.5.2 Electrolyte, consisting of tap water with the addition of1 weight % of each of the following technical-grade anhydroussalts: sodium chlo
12、ride, sodium sulfate, and sodium carbonate.NOTE 2Add 30 g (1.05 oz) of sodium chloride for each dm3(0.26 gal)of water.5.2.1 The electrolyte in the immersion cell shall be main-tained at the proper level by regular additions of tap water. Theelectrolyte shall not be reused after completion of the tes
13、t.5.3 Voltage SourceA direct current power supply, capableof supplying low ripple voltage shall be used to maintain apotential difference of 6.0 6 0.1 V dc between each of the testspecimens and a common electrode.5.4 ConnectorsWiring connections from the anode to thespecimen shall be of No. 18 AWG i
14、nsulated copper. Attach-ment to the anode shall be sealed and kept above the level ofthe electrolyte. Attachment to the specimen shall be made by a1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibil
15、ity ofSubcommittee D01.48 on Durability of Pipeline Coating and Linings.Current edition approved July 1, 2007. Published July 2007. Originally approvedin 1969. Last previous edition approved in 1998 as G987(1998) which waswithdrawn March 2007 and reinstated in July 2007.2For referenced ASTM standard
16、s, 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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
17、9428-2959, United States.method that will allow disconnection from the anode when themeasuring bridge is in use. A convenient means for accom-plishing this is through the use of insulated pin-type jacks.5.5 Capacitance Bridge3,4Measurements of equivalentspecimen capacitance and coating dissipation f
18、actor shall bemade with a low-voltage a-c, resistive-ratio-arm type measur-ing bridge having the following characteristics:5.5.1 Oscillator frequency, 1 kHz 6 2%,5.5.2 Series capacitance range, 1 to 1100 pF 6 1%,5.5.3 Series capacitance sensitivity, 0.5 pF,5.5.4 Dissipation factor range, 0.001 to 1.
19、0 at 1 kHz, and5.5.5 Dissipation factor sensitivity, 0.001 at 1 kHz.5.6 Measuring CircuitMeasurements of specimen capaci-tance and coating dissipation factor shall be made using acircuit that places the sample unknown in series with thecomparison circuit of the measuring bridge. Connection of theunk
20、nown to the measuring bridge shall be made in such amanner as to eliminate the introduction of stray capacitanceinto the measuring circuit. A diagram for connecting the testcell to the bridge is shown in Fig. 2. In this arrangement, boththe test leads are shielded and the chassis of the bridge isgro
21、unded. The immersion cell shall also be shielded to avoidcapacitance effects from surrounding objects.NOTE 3A shield for the test cell can conveniently be fabricated frommost commercially-available tin or aluminum foils of approximately0.0382-mm (0.0015-in.) thickness and formed around the container
22、.5.7 Thickness GageMeasurements of coating thicknesswill be required for this test. Any instrument suitable for usewith Test Method G12can be used.5.8 Anode, fabricated from 4.76-mm (0.1875-in.) diameterAISI Type 303 stainless-steel rod, and shall be 178 mm (7.00in.) long, with the upper 50 mm (2.00
23、 in.) threaded to accept alocking nut.6. Test Specimen6.1 The test specimen shall be a representative piece ofproduction-coated pipe and shall be free of obvious coatingflaws or defects (see Fig. 3). Any suitable diameter andspecimen length can be used. Physical limitations of theimmersion cells sug
24、gested in 5.1.3, Note 1, make it necessaryto restrict the overall sample length to approximately 300 mm(12.0 in.) for both the 26.7-mm (0.75-in. nominal) and60.3-mm (2.0-in. nominal) diameter coated pipe specimens.6.2 The upper and lower ends of the test specimen shall beplugged and sealed with nonc
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