ASTM G55-07(2019)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: G55 − 07 (Reapproved 2019)
Standard Test Method for
Evaluating Pipeline Coating Patch Materials
ThisstandardisissuedunderthefixeddesignationG55;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Significance and Use
1.1 This test method provides an accelerated means of 3.1 Holidays in pipeline coatings may be repaired by
circumferential wrapping with a suitable pipe wrap tape.
determining the relative sealing abilities of pipeline patching
materials that are used to seal holidays in pipeline coatings on However,thistechniqueisnotalwayspracticableandpatching
mayberequired.Theeffectivenessofapatchmaterialdepends
steel pipe. This test method is intended for utilization of
specimens of pipeline coatings on small-diameter pipe, for upon its adhesion to the original pipeline coating to effect
representing coatings used for buried or submerged service, sealing.
and where the purpose of the coating is to provide an electrical
3.2 The results of this accelerated test have been found to
barrier between the steel pipe and its environment.
yield comparative data useful for the selection of patching
1.2 This test method is not intended for evaluating patch materials. The user is cautioned against the use of this method
for absolute material properties characterization.
materials that are overlapped upon themselves.
3.3 This procedure provides an accelerated method by
1.3 The values stated in SI units are to be regarded as the
exposing the patch to a severe radius of curvature on small-
standard. The values given in parentheses are for information
diameterpipe.Thespecimenisalsoexposedtoastressvoltage
only.
in the presence of a highly conductive electrolyte.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Apparatus
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4.1 Test Vessel—A cylindrical glass battery jar (or
mine the applicability of regulatory limitations prior to use. equivalent), approximately 300 mm (12 in.) in diameter and
1.5 This international standard was developed in accor- 300mminheight.Onemagnesiumanodeshallbecontainedin
each battery jar, with a maximum of eight pipe specimens, and
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the witheachspecimenmeasuringabout25mm(1in.)indiameter
by approximately 300 mm in length of coated pipe. (See 4.3
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical and Fig. 1 and Fig. 2.)
Barriers to Trade (TBT) Committee.
4.2 Suspension—The suspension ring for supporting the
pipe specimens shall be an electrically nonconductive circular
2. Summary of Test Method
disk, measuring approximately 300 mm (12 in.) in diameter
and approximately 5 mm ( ⁄16 in.) in thickness. (See 6.4.) Drill
2.1 Patched pipeline coating specimens are suspended in an
a 15-mm ( ⁄2-in.) diameter hole through the center of the ring
aqueous, alkaline, low-resistivity electrolyte. The specimens
for external extension of the anode lead wire. Drill eight
areindividuallyconnectedtoamagnesiumanodeorrectifierat
apointexternaltotheelectrolyte.Thecoated,patchedpipeline suspension holes, about 45 mm (1 ⁄4 in.) in diameter, through
thesuspensionringforthepipespecimens;theseholesshallbe
specimens are sealed at the base and at all other areas except
centered 110 mm (4 ⁄2 in.) from the center of the suspension
the patch boundaries, such that the only paths for current flow
ring and evenly spaced around the ring at 45° increments as
areattheboundariesofthepatches.Currentflowineachpatch
measured from the center of the suspension ring.
area is averaged from monthly readings taken for one year.
4.3 Potential—A high-purity magnesium anode shall be
used, weighing approximately 2.3 kg (5 lb), and having an
open-circuit potential of approximately 1.7 d-c V relative to a
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
copper-copper sulfate electrode, and complete with a factory-
Subcommittee D01.48 on Durability of Pipeline Coating and Linings.
sealed lead wire. The magnesium anode may be replaced by a
Current edition approved Oct. 1, 2019. Published October 2019. Originally
controlledd-cvoltagefromarectifier,andthenmaintainingthe
approved in 1977. Last previous edition approved in 2013 as G55– 07(2013). DOI:
10.1520/G0055-07R19. potential between the specimen having the least current flow
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G55 − 07 (2019)
4.5.4 Microammeters, d-c, 0 to 100-µA and 0 to 500-µA.
4.5.5 Voltmeter, for direct current, having an internal resis-
tance of not less than 10 MΩ and having a range from 0.01 to
5.0 V.
4.5.6 Full-Wave Rectifier, optional, 0 to 0.05% ripple,
capable of maintaining 1.50 6 0.05 d-c V relative to a
copper-coppersulfatecell,andhavingacapacityforatleast10
A of direct current.
5. Test Specimens
5.1 Dimensions—The specimen shall be steel pipe approxi-
mately 25 mm (1 in.) in diameter, approximately 300 mm (12
in.) in length, and previously coated with the desired original
pipeline coating.
5.2 Circuit Tap—A 5-mm ( ⁄16-in.) diameter hole shall be
drilled or tapped (or a self-tapping screw may be used) at a
point 13 mm ( ⁄2 in.) below the top of each specimen. This tap
is for a machine screw anode lead wire connection.
5.3 Pipe Suspension Support Holes—A6-mm( ⁄4-in.)diam-
eter hole shall be drilled completely through both walls of the
coatedpipespecimenatapoint20mm( ⁄4in.)fromthetopend
of the specimen and located vertically beneath the circuit tap
hole.Ashort length of wooden dowel pin about 5 mm ( ⁄16 in.)
indiametershallbeusedasaninsertionthroughthesuspension
holes to support and level the pipe specimen on the circular
suspension ring when the suspension ring is mounted on the
battery jar.
5.4 Intentional Holidays—A 4-fluted 13-mm ( ⁄2-in.) diam-
FIG. 1 Test Assembly for Evaluating Pipeline Coating Patch Ma-
terials eterfacingbitshallbeusedtodrillintentionalholidaysthrough
the original pipeline coating to the metal. Drilling such
holidays shall be practiced on scrap pieces of small-diameter
and a copper-copper sulfate reference cell (with the cell being
coatedpipe,priortodrillingtheholidaysinthetestspecimens.
properly immersed in the electrolyte) at 1.50 6 0.05 d-c V.
Drilling shall not be any deeper than necessary into the metal
(See Note 1.) The anode should be composed of a suitable
2 ofthepipe.Threeholidaysshallbepreparedoneachspecimen
nonconsumable material. This option will avoid the precipi-
in a vertical line directly underneath the circuit tap to corre-
tation of magnesium salts on the specimens.
spond to electrolyte immersions of 38 mm (1 ⁄2 in.), 114 mm
NOTE 1—The potential of the magnesium anode will approximate this 1 1
(4 ⁄2in.),and190mm(7 ⁄2in.),asmeasuredfromthetopofthe
range over the life of the test. If a calomel electrode is used for the
holiday to the surface of the electrolyte. The thickness of the
reference cell, the potential should be−1.43 6 0.05 d-c V.
suspension ring shall be considered for its effect in elevating
4.4 Electrolyte—Use 1% each by weight of anhydrous pure
the pipe specimens in the electrolyte.
grades of sodium chloride, sodium sulfate, and sodium
5.5 Patches—Asquare patch configuration of 25 by 25 mm
carbonate, dissolved in either distilled water or demineralized
(1 by 1 in.), evenly centered about the holiday, shall be lightly
water. This electrolyte shall never be less alkaline than
marked. This will provide a minimum patch overlap of 6 mm
pH=10.0 and should be within a resistivity range from 20 to
( ⁄4 in.) as measured perpendicular to the center of each patch
35Ω · cm.
edge to the circumference of the holiday. The top and bottom
4.5 Instruments:
edges of each patch shall be in the horizontal plane. Each
4.5.1 Resistivity Meter, capable of measuring 20 to 40Ω ·
marked patch area shall be lightly buffed with 120-grit sand-
cm in an aqueous solution.
paper. A primer shall be
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