ASTM G18-07

Standard Test Method for Joints, Fittings, and Patches in Coated Pipelines

SIGNIFICANCE AND USE
The exposed metal surfaces at joints, fittings, and damaged areas in an otherwise coated pipeline will be subjected to corrosion if allowed to come in contact with the soil environment. The performance of joint and patching materials designed to function as protective coverings will depend upon such factors as the ability of the material to bond to both the pipe coating and exposed metal surfaces, the integrity of the moisture seal at lapped joints, and the water absorption characteristics of the joint material.
The existence of substantial leakage current through the coating joint, patch, or fitting is reliable evidence that the 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 they are related to the water absorption rate of the joint material. Water permeating an insulating barrier increases its capacitance and its progress can be measured through the use of a suitable impedance bridge.
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 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 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. The values given in parentheses are for information only.

General Information

• Status: Historical
• Publication Date: 30-Jun-2007
• ICS: 23.040.01 - Pipeline components and pipelines in general
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.48 - Durability of Pipeline Coating and Linings

Relations

• Replaces: ASTM G18-88(1998) - Standard Test Method for Joints, Fittings, and Patches in Coated Pipelines (Withdrawn 2007)
• Effective Date: 01-Jul-2007
• Replaced By: ASTM G18-07(2013) - Standard Test Method for Joints, Fittings, and Patches in Coated Pipelines
• Effective Date: 01-Jun-2013

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G18 − 07
StandardTest Method for
1
Joints, Fittings, and Patches in Coated Pipelines
ThisstandardisissuedunderthefixeddesignationG18;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope negative (−) terminal of a 6-V d-c power supply (see Fig. 1).
An anode, also immersed in the electrolyte and connected to
1.1 This test method describes determination of the com-
the positive (+) terminal of the power supply, completes the
parative corrosion preventative characteristics of materials
test circuit. Joint or patch performance is followed through
used for applications to joints, couplings, irregular fittings, and
periodicdeterminationsofleakagecurrentmeasuredasvoltage
patchedareasincoatedpipelines.Thetestmethodisapplicable
drops across a calibrated resistor in the anode-to-cathode
to materials whose principal function is to act as barriers
circuit.
between the pipe surface and surrounding soil environment.
3.2 Capacitance and dissipation factor measurements are
1.2 The test method described employs measurements of
used to supplement the periodic leakage current determina-
leakage current, capacitance, and dissipation factor to indicate
tions.
changes in the insulating effectiveness of joint and patching
materials.
4. Significance and Use
1.3 The values stated in SI units are to be regarded as the
4.1 The exposed metal surfaces at joints, fittings, and
standard. The values given in parentheses are for information
only. damaged areas in an otherwise coated pipeline will be sub-
jected to corrosion if allowed to come in contact with the soil
1.4 This standard does not purport to address all of the
environment. The performance of joint and patching materials
safety concerns, if any, associated with its use. It is the
designed to function as protective coverings will depend upon
responsibility of the user of this standard to establish appro-
such factors as the ability of the material to bond to both the
priate safety and health practices and determine the applica-
pipe coating and exposed metal surfaces, the integrity of the
bility of regulatory limitations prior to use.
moisture seal at lapped joints, and the water absorption
1.5 The values stated in SI units to three significant deci-
characteristics of the joint material.
mals are to be regarded as the standard. The values given in
parentheses are for information only.
4.2 The existence of substantial leakage current through the
coating joint, patch, or fitting is reliable evidence that the
2. Referenced Documents
material has suffered a significant decrease in its performance
2
2.1 ASTM Standards:
as a protective barrier. In a similar manner, measured changes
G12Test Method for Nondestructive Measurement of Film in joint capacitance and dissipation factor are useful because
Thickness of Pipeline Coatings on Steel
they are related to the water absorption rate of the joint
material. Water permeating an insulating barrier increases its
3. Summary of Test Method
capacitance and its progress can be measured through the use
of a suitable impedance bridge.
3.1 The test method consists of an immersion test where
coated pipe specimens, each containing a simulated joint, tee,
5. Apparatus
or patched area, are suspended in an electrolyte and placed
under cathodic protection by connecting the specimens to the
5.1 Test Vessel, nonconducting, shall be used to contain the
test specimens. Dimensions of the vessel shall permit the
following requirements:
1
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
5.1.1 The test vessel shall be large enough to allow for
Subcommittee D01.48 on Durability of Pipeline Coating and Linings.
suspension of the specimens in a vertical position and equidis-
CurrenteditionapprovedJuly1,2007.PublishedJuly2007.Originallyapproved
tant from a centrally located anode. The specimens shall not
in 1971. Last previous edition approved in 1998 as G18–88(1998) which was
withdrawn March 2007 and reinstated in July 2007. DOI: 10.1520/G0018-07. touch either each other, the walls, or bottom of the test vessel.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.1.2 The test vessel shall be deep enough to allow for
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
immersionofthespecimensintheelectrolytetotheloweredge
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. of the upper moisture shield (see Fig. 2).
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