ASTM G18-88(1998)
(Test Method)Standard Test Method for Joints, Fittings, and Patches in Coated Pipelines (Withdrawn 2007)
Standard Test Method for Joints, Fittings, and Patches in Coated Pipelines (Withdrawn 2007)
SCOPE
1.1 This test method describes determination of the comparative corrosion preventative characteristics of materials used for applications to joints, couplings, irregular fittings, and patched areas in coated pipelines. The test method is applicable to materials whose principal function is to act as barriers between the pipe surface and surrounding soil environment.
1.2 The test method described employs measurements of leakage current, capacitance, and dissipation factor to indicate changes in the insulating effectiveness of joint and patching materials.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 The values stated in SI units to three significant decimals are to be regarded as the standard.
WITHDRAWN RATIONALE
This test method describes determination of the comparative corrosion preventative characteristics of materials used for applications to joints, couplings, irregular fittings, and patched areas in coated pipelines. The test method is applicable to materials whose principal function is to act as barriers between the pipe surface and surrounding soil environment.
Formerly under the jurisdiction of Committee D01 on Paint and Related Coatings, Materials, and Applications, this test method was withdrawn in March 2007 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:G18–88(Reapproved1998)
Standard Test Method for
Joints, Fittings, and Patches in Coated Pipelines
ThisstandardisissuedunderthefixeddesignationG18;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method describes determination of the com-
parative corrosion preventative characteristics of materials
used for applications to joints, couplings, irregular fittings, and
patchedareasincoatedpipelines.Thetestmethodisapplicable
to materials whose principal function is to act as barriers
between the pipe surface and surrounding soil environment.
1.2 The test method described employs measurements of
leakage current, capacitance, and dissipation factor to indicate
changes in the insulating effectiveness of joint and patching
materials.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility 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.
1.4 The values stated in SI units to three significant deci-
mals are to be regarded as the standard. The values given in
parentheses are for information only.
FIG. 1 Test Circuits
2. Referenced Documents
3.2 Capacitance and dissipation factor measurements are
2.1 ASTM Standards:
used to supplement the periodic leakage current determina-
G12 TestMethodforNondestructiveMeasurementofFilm
Thickness of Pipeline Coatings on Steel tions.
4. Significance and Use
3. Summary of Test Method
3.1 The test method consists of an immersion test where 4.1 The exposed metal surfaces at joints, fittings, and
damaged areas in an otherwise coated pipeline will be sub-
coated pipe specimens, each containing a simulated joint, tee,
or patched area, are suspended in an electrolyte and placed jected to corrosion if allowed to come in contact with the soil
environment. The performance of joint and patching materials
under cathodic protection by connecting the specimens to the
designed to function as protective coverings will depend upon
negative (−) terminal of a 6-V d-c power supply (see Fig. 1).
such factors as the ability of the material to bond to both the
An anode, also immersed in the electrolyte and connected to
pipe coating and exposed metal surfaces, the integrity of the
the positive (+) terminal of the power supply, completes the
moisture seal at lapped joints, and the water absorption
test circuit. Joint or patch performance is followed through
characteristics of the joint material.
periodicdeterminationsofleakagecurrentmeasuredasvoltage
4.2 The existence of substantial leakage current through the
drops across a calibrated resistor in the anode-to-cathode
coating joint, patch, or fitting is reliable evidence that the
circuit.
material has suffered a significant decrease in its performance
as a protective barrier. In a similar manner, measured changes
in joint capacitance and dissipation factor are useful because
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
they are related to the water absorption rate of the joint
Subcommittee D01.48 on Durability of Pipeline Coatings and Linings.
material. Water permeating an insulating barrier increases its
Current edition approved Sept. 30, 1988. Published November 1988. Originally
capacitance and its progress can be measured through the use
published as G18–71T. Last previous edition G18–83.
Annual Book of ASTM Standards, Vol 06.02. of a suitable impedance bridge.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G18
5. Apparatus
5.1 Test Vessel, nonconducting, shall be used to contain the
test specimens. Dimensions of the vessel shall permit the
following requirements:
5.1.1 The test vessel shall be large enough to allow for
suspension of the specimens in a vertical position and equidis-
tant from a centrally located anode. The specimens shall not
touch either each other, the walls, or bottom of the test vessel.
5.1.2 The test vessel shall be deep enough to allow for
immersionofthespecimensintheelectrolytetotheloweredge
of the upper moisture shield (see Fig. 2).
NOTE 1—A commercially available, 42 L (11-gal) waste container of
high-density polyethylene can be conveniently used as a test vessel and
will accommodate up to six test specimens of a size indicated in 7.2.
5.2 Support Plate, fabricated from a nonconductive mate-
rial, to suspend the specimens in the test vessel. The support
plateshallcontainanaccessholeforthereferenceelectrode.A
typical test cell is illustrated in Fig. 3.
5.3 Anode, fabricated from 9.525 mm (0.375-in.) diameter
300 series stainless steel rod, 609.6 mm (24.00 in.) long. Other
FIG. 3 Joint Test Cell
inert anodes such as carbon or platinum may be used.
5.4 D-C Voltmeter, to serve the dual purpose of (1)
measuringleakagecurrentasapotentialdropacrossa1,000-V
5.6 Ohmmeter—Measurements for end-cap integrity shall
shunt in the measuring circuit and (2) measuring the potential
be made with a suitable ohmmeter capable of reading resis-
of the test specimen with reference to a Cu-CuSO half cell.
tance to an upper limit of 1000 MV65%.
The instrument characteristics for these functions shall be:
5.7 Reference Electrode—ACu-CuSO half cell of conven-
5.4.1 Voltage Range—50 µV full scale to 10 V full scale in
tional glass or plastic tube with porous plug construction, but
overlapping 13 and 33 ranges.
preferably not over 19.05 mm ( ⁄4 in.) in diameter, having a
5.4.2 Accuracy—63 percent of full scale on all ranges.
potential of−0.316 V with respect to the standard hydrogen
5.4.3 Input Resistance—Greater than 10 MV on all ranges.
electrode.
5.5 Thickness Gage—Measurements of coating thickness
will be required for this test. Any instrument suitable for use NOTE 2—Asaturated calomel half cell may be used, but measurements
made with it shall be converted to the Cu-CuSO reference for reporting
with Test Method G12 can be used. However, the choice of
by adding−0.072 V to the observed reading.
measuring gage shall be compatible with the joint coating
thickness that will be encountered in the test.
5.8 Voltage Source—A battery or rectifier-type power sup-
plyshallbeusedtomaintainapotentialdifferenceof6.0 60.1
V dc between each of the test specimens and the Cu-CuSO
half cell. Where multiple specimens are tested, a suitable
voltage-dividing circuit will be required for individual control
of the voltage applied to each specimen.
5.9 Circuit Wiring from the anode to specimen shall be of
No. 18Awg insulated copper.Aswitch for disconnecting each
specimen from its voltage source shall be included in the
circuit. A1000 V6 1 percent, 1-W (minimum) precision
resistor shall be placed in the anode-to-cathode circuit as a
shunt for current. A diagram illustrating the test cell wiring
appears as Fig. 1.
5.10 Capacitance Bridge—Measurements of specimen ca-
pacitance and dissipation factor shall be made with a low-
voltage a-c, resistive ratio arm-type bridge having the follow-
ing characteristics:
5.10.1 Oscillator Frequency, 1 kHz 6 2% tolerance.
5.10.2 Series Capacitance Range, 100 pF to 1100 pF
accuracy 61% 6 1 pF, whichever is larger.
5.10.3 Dissipation Factor Range, 0.002 to 1.0 at 1 kHz
accuracy 65%or 6 0.001 dissipation, whichever is larger.
5.11 Connectors—Miniature, pin-type, insulated jacks shall
NOTE 1—All dimensions are in millimetres with inches in parentheses.
FIG. 2 Joint Test Specimen be used at the point of connection to each test specimen. The
G18
NOTE 3—Materials that are intended for use as a field-applied patch
jacks serve two important functions: (1) they permit the
over damaged areas on coated pipelines can be tested using the same
disconnection of the specimen from the voltage source when
procedures, with the patching compound applied, instead, to the bared
the impedance bridge is in use, and (2) disconnection of the
area of the simulated joint.
specimen from the test circuit also removes the effect of stray
7.8 The upper 76.2 mm (3.0 in.) of the completed joint test
capacitance due to excessive lead length that may introduce
specimen shall be coated with the material used for the lower
error into impedance bridge measurements.
end cap.This moisture shield can be conveniently made, in the
5.12 Foil Shield—As an additional safeguard against stray
caseofsomewaxesandepoxies,withseveralsuccessivebrush
capacitance effects, wrap the entire test vessel in heavy-gage
or dip-applied applications. The thickness of the moisture
aluminum foil as shown in Fig. 3 and ground the shield.
shield should be approximately 3.175 mm (0.125 in.).
6. Materials
8. Testing Temperature
6.1 Electrolyte—The electrolyte shall consist of potable tap
8.1 Perform all tests at a room temperature of 21 to 25°C
water with the addition of 3 weight percent of technical-grade
(70 to 77°F).
sodium chloride.
6.2 Materials for sealing the ends of the specimens may
9. Preliminary Test Measurements
consist of waxes, epoxies, or other suitable materials. How-
ever, they should have a dielectric constant in the range from 2 9.1 Coating and Joint Thickness—Measure and record the
thicknessofthebasecoatingwhichliesexposedateachendof
to 6, and exhibit a low water-absorption rate. It is also
importantthattheend-capmaterialmaintainsgoodadhesionto the test joint. Measurements shall be made in accordance with
Test Method G12. In a like manner, measure and record the
any coated pipe surfaces throughout the test period.
average thickness of the joint covering.
7. Test Specimen
10. Procedure for Leakage Current Measurements
7.1 The joint specimen shall be prepared from a represen-
tative piece of 60.325 mm (2.375 in.) outside diameter, 10.1 Suspend the joint tes
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