ASTM D4787-08
(Practice)Standard Practice for Continuity Verification of Liquid or Sheet Linings Applied to Concrete Substrates
Standard Practice for Continuity Verification of Liquid or Sheet Linings Applied to Concrete Substrates
SIGNIFICANCE AND USE
The electrical conductivity of concrete is primarily influenced by the presence of moisture. Other factors, which affect the electrical continuity of concrete structures, include the following:
Presence of metal rebars,
Cement content and type,
Aggregate types,
Admixtures,
Porosity within the concrete,
Above or below grade elevation,
Indoor or outdoor location,
Temperature and humidity, and
Age of concrete.
The electrical conductivity of concrete itself may be successfully used for high-voltage continuity testing of linings applied directly with no specific conductive underlayment installed. However, the voltage required to find a discontinuity may vary greatly from point to point on the structure. This variance may reduce the test reliability.
Although the most common conductive underlayments are liquid primers applied by trowel, roller, or spray, and which contain carbon or graphite fillers, others may take the form of the following:
Sheet-applied graphite veils,
Conductive polymers,
Conductive graphite fibers,
Conductive metallic fibers, and
Conductive metallic screening.
Liquid-applied conductive underlayments may be desirable as they can serve to address imperfections in the concrete surface and provide a better base for which to apply the lining.
This practice is intended for use only with new linings applied to concrete substrates. Inspecting a lining previously exposed to an immersion condition could result in damaging the lining or produce an erroneous detection of discontinuities due to permeation or moisture absorption of the lining. Deposits may also be present on the surface causing telegraphing. The use of a high voltage tester on a previously exposed lining is not recommended because of possible spark through which will damage an otherwise sound lining. A low voltage tester can be used but could produce erroneous readings.
The user may consider this practice when performance requirements of the lining in a specifi...
SCOPE
1.1 This practice covers procedures that may be used to allow the detection of discontinuities in nonconductive linings or other non-conductive coatings applied to concrete substrates.
1.2 Discontinuities may include pinholes, internal voids, holidays, cracks, and conductive inclusions.
1.3 This practice describes detection of discontinuities utilizing a high voltage spark tester using either pulsed or continuous dc voltage.
Note 1—For further information on discontinuity testing refer to NACE Standard RP0188-88 or Practice D 5162.
1.4 This practice describes procedures both with and without the use of a conductive underlayment.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.6 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. For a specific hazard statement, see Section 7.
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Designation:D4787 −08
StandardPractice for
Continuity Verification of Liquid or Sheet Linings Applied to
1
Concrete Substrates
This standard is issued under the fixed designation D4787; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
3
1. Scope 2.2 NACE Standards:
RP0188-88 Discontinuity (Holiday) Testing of Protective
1.1 This practice covers procedures that may be used to
Coatings
allow the detection of discontinuities in nonconductive linings
or other non-conductive coatings applied to concrete sub-
3. Terminology
strates.
3.1 Definitions of Terms Specific to This Standard:
1.2 Discontinuities may include pinholes, internal voids,
3.1.1 conductive underlayment, n—a continuous layer ap-
holidays, cracks, and conductive inclusions.
pliedtothepreparedconcretesurfacepriortotheapplicationof
1.3 This practice describes detection of discontinuities uti-
a nonconductive lining layer(s) that will allow high voltage
lizing a high voltage spark tester using either pulsed or
spark testing for discontinuities in the lining, as it will conduct
continuous dc voltage.
the current present when the spark is generated.
NOTE 1—For further information on discontinuity testing refer to 3.1.2 current sensitivity, n—some high voltage testers have
NACE Standard RP0188-88 or Practice D5162.
adjustable current sensitivity that can be used to prevent low
levels of current flow activating the audible alarm. The alarm
1.4 This practice describes procedures both with and with-
sensitivity control sets the threshold current at which the
out the use of a conductive underlayment.
audible alarm sounds. If the high voltage can charge the lining,
1.5 The values stated in SI units are to be regarded as
a small amount of current will flow while this charge is
standard. The values given in parentheses are for information
established. If the lining contains a pigment that allows a
only.
low-level leakage current to flow from the probe while testing
1.6 This standard does not purport to address all of the
the threshold current can be set so that the alarm does not
safety concerns, if any, associated with its use. It is the
sound until this current is exceeded, that is, when a holiday or
responsibility of the user of this standard to establish appro-
flaw is detected. Increasing the current threshold setting makes
priate safety and health practices and determine the applica-
the instrument less sensitive to this low level current flow,
bility of regulatory limitations prior to use. For a specific
decreasing the current threshold setting makes the instrument
hazard statement, see Section 7.
more sensitive to current flow.
3.1.3 discontinuity, n—a localized lining site that has a
2. Referenced Documents
dielectric strength less than a determined test voltage.
2
2.1 ASTM Standards:
3.1.4 high voltage spark tester, n—an electrical device
D5162 Practice for Discontinuity (Holiday) Testing of Non-
(producing a voltage in excess of 500 V) used to locate
conductive Protective Coating on Metallic Substrates
discontinuitiesinanonconductiveprotectivecoatingappliedto
G62 Test Methods for Holiday Detection in Pipeline Coat-
a conductive substrate. The high voltage is applied to the
ings
coating or lining using an exploring electrode and any current
resulting from the high voltage passing through a discontinuity
in the coating or lining is passed to the device via a signal
1
This practice is under the jurisdiction of ASTM Committee D01 on Paint and
return cable (also known as a ground or earth wire).
Related Coatings, Materials, and Applications and is the direct responsibility of
3.1.5 holiday, n—smallfaultsorpinholesthatpermitcurrent
Subcommittee D01.46 on Industrial Protective Coatings.
CurrenteditionapprovedJune1,2008.PublishedJuly2008.Originallyapproved
to flow through the conductive substrate, also known as a
in 1988. Last previous edition approved in 1999 as D4787 – 93 (1999). DOI:
discontinuity.
10.1520/D4787-08.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on Available from NACE International (NACE), 1440 South Creek Dr., Houston,
the ASTM website. TX 77084-4906, http://www.nace.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4787−08
3.1.6 spark-over, n—the distance a spark, from a high where:
voltage tester, will jump across a space from a gr
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D4787–93(Reapproved1999) Designation: D 4787 – 08
Standard Practice for
Continuity Verification of Liquid or Sheet Linings Applied to
1
Concrete Substrates
This standard is issued under the fixed designation D 4787; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers procedures that may be used to allow the detection of discontinuities in nonconductive linings or other
non-conductive coatings applied to concrete substrates.
1.2 Discontinuities may include pinholes, internal voids, holidays, cracks, and conductive inclusions.
1.3This practice describes detection of discontinuities utilizing a low voltage wet sponge holiday detector and a high voltage
pulsating or continuous dc spark tester. Linings with thickness in excess of 20 mils must be tested utilizing high voltage spark
testing equipment.
1.3 This practice describes detection of discontinuities utilizing a high voltage spark tester using either pulsed or continuous dc
voltage.
NOTE 1—For further information on discontinuity testing refer to NACE Standard RP0188-88 or Practice D 5162.
1.4 This practice describes procedures both with and without the use of a conductive underlayment.
1.5 The values stated in the inch-pound SI units are to be regarded as the standard. The values given in parentheses are for
information only.
1.6 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. For a specific hazard statement, see Section 7.
2. Referenced Documents
2.1 ASTM Standards:
D149Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
2
Commercial Power Frequencies ASTM Standards:
D 5162Practice for Discontinuity (Holiday) Testing of Nonconductive Protective Coating on Metallic Substrates Practice for
Discontinuity (Holiday) Testing of Nonconductive Protective Coating on Metallic Substrates
G 62 Test Methods for Holiday Detection in Pipeline Coatings
3
2.2 NACE Standards:
RP0188-88 Discontinuity (Holiday) Testing of Protective Coatings
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 discontinuity—a localized lining site that has a dielectric strength less than a determined test voltage.
3.1.2conductive underlayment—a continuous layer applied to the prepared concrete surface prior to the application of a
nonconductive lining layer(s) that will allow high voltage spark testing for discontinuities in the lining. conductive underlayment,
n—a continuous layer applied to the prepared concrete surface prior to the application of a nonconductive lining layer(s) that will
allow high voltage spark testing for discontinuities in the lining, as it will conduct the current present when the spark is generated.
3.1.2 current sensitivity, n—some high voltage testers have adjustable current sensitivity that can be used to prevent low levels
of current flow activating the audible alarm. The alarm sensitivity control sets the threshold current at which the audible alarm
1
This practice is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.46 on Industrial Protective Coatings.
Current edition approved Jan. 10, 1999. Published September 1999. Originally published as D4787–88. Last previous edition D4787–88.
Current edition approved June 1, 2008. Published July 2008. Originally approved in 1988. Last previous edition approved in 1999 as D 4787 – 93 (1999).
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from National Association of Corrosion Engineers, P.O. Box 218340, Houston, TX 77218.
3
Available from NACE International (NACE), 1440 South Creek Dr., Houston, TX 77084-4906, http://www.nace.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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