1、Designation:G 80 07Standard Test Method forSpecific Cathodic Disbonding of Pipeline Coatings1This standard is issued under the fixed designation G 80;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber i
2、n 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 covers an accelerated procedure forsimultaneously determining comparative characteristics of in-sulating coating systems applied t
3、o steel pipe exterior for thepurpose of preventing or mitigating corrosion that may occur inunderground service where the pipe will be in contact withnatural soils and may or may not receive cathodic protection.Itis intended for use with samples of coated pipe taken fromcommercial production and is
4、applicable to such samples whenthe coating is characterized by function as an electrical barrier.1.2 This test method is specific with no options.Foralternative methods of test see Test Methods G 8.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses ar
5、e for informationonly.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-bility of regulatory limitations prior to
6、use.2.Referenced Documents2.1 ASTM Standards:2G 8 Test Methods for Cathodic Disbonding of PipelineCoatingsG 12 Test Method for Nondestructive Measurement of FilmThickness of Pipeline Coatings on Steel3G 16 Guide forApplying Statistics toAnalysis of CorrosionData3.Summary of Test Method3.1 The coatin
7、g on the test specimen is subjected to electri-cal stress in a highly conductive,alkaline electrolyte.Electricalstress is obtained by means of a sacrificial magnesium anode.The coating is perforated before starting the test.3.2 After the test period is concluded,results are determinedby physical exa
8、mination and comparing the loosened ordisbonding coating at the perforations in the immersed areawith loosened or disbonded coating at a new test hole in thecoating made in an area that was not immersed.4.Significance and Use4.1 Breaks or holidays in pipe coatings may expose the pipeto possible corr
9、osion,since after a pipe has been installedunderground,the surrounding earth will be more or lessmoisture-bearing and constitutes an effective electrolyte.Dam-age to pipe coating is almost unavoidable during transportationand construction.Normal soil potentials as well as appliedcathodic protection
10、potentials may cause loosening of thecoating,beginning at holiday edges,in some cases increasingthe apparent size of the holiday.Holidays may also be causedby such potentials.While apparently loosened coating andcathodic holidays may not result in corrosion,this test providesaccelerated conditions f
11、or loosening to occur and thereforegives a measure of resistance of coatings to this type of action.4.2 The effects of the test are evaluated by physical exami-nation assessing the effective contact of the coating with themetal surface in terms of observed differences in the relativeadhesive bond.It
12、 is usually found that the electrically stressedarea propagates from the holiday to a boundary where theloosened coating leaves off for the more effective contact orbond attributed to an original condition throughout the speci-men before electrical stressing was applied.Assumptionsassociated with te
13、st results include:4.2.1 That attempting to loosen or disbond the coating at anew test hole made in the coating in an area that was notimmersed represents maximum adhesion or bond as measuredby the lifting technique used,and that the same liftingtechnique can be used at a test hole that was immersed
14、,therebyproviding a means of comparing relative resistance to lifting.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.48 on Durability of Pipeline Coating and Linings.Current
15、 edition approved July 1,2007.Published July 2007.Originally approvedin 1983.Last previous edition approved in 1998 as G 80 88(1998)which waswithdrawn March 2007 and reinstated in July 2007.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at servicea
16、stm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.Copyright ASTM International Provided by IHS under license with ASTM Licensee=University of Texas Revised Sub Account/5620001114 Not for Resale,12/04/2007 07:01:10 MSTNo reproduction or networking permitted without license from IHS-,-,-4.2.2 That any rela
