1、Designation:G 19 04Standard Test Method forDisbonding Characteristics of Pipeline Coatings by DirectSoil Burial1This standard is issued under the fixed designation G 19;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last
2、 revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method describes the determination of therelative disbonding characteristics of damaged coatings onsteel pipe by catho
3、dic protection potentials in direct soil burial.This test method is intended to apply to the testing of all typesof nonmetallic pipeline coatings and tapes including thermo-plastics,thermoset,and bituminous materials.1.2 Results may vary widely when test sites are in differentgeographical areas of t
4、he country,and even in differentlocalities.1.3 This test method is limited to nonconducting,or non-metallic pipe coatings and is not applicable to conductingmaterials such as zinc coatings on steel pipe.1.4 The values stated in SI units to three significant deci-mals are to be regarded as the standa
5、rd.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 theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bilit
6、y of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2G 12 Test Method for Nondestructive Measurement of FilmThickness of Pipeline Coatings on SteelG 62 Test Methods for Holiday Detection in Pipeline Coat-ings3.Summary of Test Method3.1 Apparatus and materials are descri
7、bed whereby protec-tive coatings on steel pipe are subjected to disbonding by anelectrical stress.Specimens with intentionally damaged areasare buried in soil at an outdoor site and electrically connectedto a magnesium anode.After test,the disbonded coating isremoved,the exposed area measured,and co
8、mparisons aremade to other specimens similarly exposed.4.Significance and Use4.1 Coated pipe is seldom,if ever,buried without somedamage to the coating.Hence,an actual soil-burial test cancontribute significant data,provided the method of testing iscontrolled and the test specimen monitored and the
9、relationshipbetween the area disbonded,the current demand,and the modeof failure is fully understood.4.2 Means are provided for measuring and following theelectrical potential and current flow and relating these data tothe final measurement of disbonded area.5.Apparatus5.1 AnodeA standard packaged m
10、agnesium anode,mini-mum 4.082 kg(9 lb),with a factory-sealed,4107 cmil(14 gageAwg)minimum,insulated copper wire shall be used.Asolutionpotential of not less than 1.45 V with respect to a copper-copper sulfate reference electrode is required.Use sufficientanodes to maintain required potential.5.2 Con
11、nectorsThe wiring circuit from anode to testspecimen and from specimen to reference electrode should be4107 cmil(14 gage Awg)minimum insulated copper wire.Attach the wires to the test specimen as shown in Fig.1 bysoldering or brazing at the air-exposed end,and coat the placeof attachment with insula
12、ting material.A junction box isoptional for connecting the resistor in series between the anodeand the test specimen.5.3 The instruments used shall include the following:5.3.1 Voltmeter,a suitable instrument such as a high imped-ance(10mV)analog multimeter having a sensitivity of50 000V/V minimum an
13、d a multiple range from 0.01 to 2 Vfor direct current is used for measuring the potential betweenspecimen and the reference electrode,3current between speci-men and anode,and the resistance of the circuit.The same1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related C
14、oatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.48 on Durability of Pipeline Coating and Linings.Current edition approved Nov.1,2004.Published November 2004.Originallyapproved in 1971.Last previous edition approved in 1996 as G 19 88(1996)e1.2For referenced AST
15、M 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.3A pipe-to-soil Voltmeter-Ammeter,Agra Engineering Co.,Tulsa,Okla.,hasbeen found suit
16、able for this test.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.instrument shall be used for measuring current between speci-men and anode.Alligator clips on the leads are permissible.5.3.2 Volt-Ohm-Meterfor measuring resistance of the cir-cuit.5.3.3 Reference Electrode,consisting of a copper-coppersulfate half cell in a conventional glass or plastic tube withporous plug construction,but preferably not over 19.05 mm(34in.)in diamet
