ASTM_G_19_-_88_1996e1.pdf

Designation:G 19 88(Reapproved 1996)e1Standard 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 revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon(e)indicates an editorial change since the last revision or reapproval.e1NOTEKeywords were added editorially in June 1996.1.Scope1.1 This test method describes the determination of therelative disbonding characteristics of damaged coatings onsteel pipe by cathodic 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 the 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 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 use.1.5 The values stated in SI units to three significant deci-mals are to be regarded as the standard.The values given inparentheses are for information only.2.Referenced Documents2.1 ASTM Standards:G 12 Test Method for Nondestructive Measurement of FilmThickness of Pipeline Coatings on Steel2G 62 Test Methods for Holiday Detection in Pipeline Coat-ings23.Summary of Test Method3.1 Apparatus and materials are described 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 comparisons 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 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 magnesium anode,mini-mum 4.082 kg(9 lb),with a factory-sealed,4107-cmil(14-gage Awg)minimum,insulated copper wire shall be used.Asolution potential of not less than 1.45 V with respect to acopper-copper sulfate reference electrode is required.Usesufficient anodes to maintain required potential.5.2 ConnectorsThe 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 insulating 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 and 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 sameinstrument shall be used for measuring current between speci-men and anode.Alligator clips on the leads are permissible.5.3.2 Volt-Ohm-Meter for measuring resistance of the cir-cuit.1This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.48 on Durability of Pipeline Coatings and Linings.Current edition approved May 27,1988.Published July 1988.Originallypublished as G 19 71 T.Last previous edition G 19 83.2Annual Book of ASTM Standards,Vol 06.02.3A pipe-to-soil Voltmeter-Ammeter,Agra Engineering Co.,Tulsa,Okla.,hasbeen found suitable for this test.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTM5.3.3 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 diameter,having a potential of 0.316 V with respect toa standard hydrogen electrode.A calomel electrode may