ASTM G62-87(1998)

Designation: G 62 – 87 (Reapproved 1998)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Methods for
Holiday Detection in Pipeline Coatings
This standard is issued under the fixed designation G 62; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope drainage through protective coatings on steel pipe or polymeric
precoated corrugated steel pipe.
1.1 These test methods cover the apparatus and procedure
3.1.2 mil—0.001 in.
for detecting holidays in pipeline type coatings.
3.2 Definitions of Terms Specific to This Standard:
1.2 Method A is designed to detect holidays such as pin-
3.2.1 holiday detector—A highly sensitive electrical device
holes and voids in thin-film coatings from 0.0254 to 0.254 mm
designed to locate holidays such as pinholes, voids, and thin
(1 to 10 mils) in thickness using ordinary tap water and an
spots in the coating, not easily seen by the naked eye. These are
applied voltage of less than 100 V d-c. It is effective on films
used on the coatings of relatively high-electrical resistance
up to 0.508 mm (20 mils) thickness if a wetting agent is used
when such coatings are applied to the surface of materials of
with the water. It should be noted, however, that this method
low-electrical resistance, such as steel pipe.
will not detect thin spots in the coating, even those as thin as
3.2.2 pipeline type coating—Coatings of relatively high-
0.635 mm (0.025 mils). This may be considered to be a
electrical resistance applied to surfaces of relatively low-
nondestructive test because of the relatively low voltage.
electrical resistance, such as steel pipe.
1.3 Method B is designed to detect holidays such as
pinholes and voids in pipeline coatings; but because of the
4. Summary of Test Methods
higher applied voltages, it can also be used to detect thin spots
4.1 Both methods rely on electrical contact being made
in the coating. This method can be used on any thickness of
through the pipeline coating because of a holiday or a
pipeline coating and utilizes applied voltages between 900 and
2 low-resistance path created by metal particles, or thin spots in
20 000 V d-c. This method is considered destructive because
the coating. This electrical contact will activate an alarm
the high voltages involved generally destroy the coating at thin
alerting the operator of the incidence of a holiday.
spots.
4.2 In Method A, the applied voltage is 100 V d-c or less.
1.4 The values stated in SI units to three significant deci-
4.3 In Method B, the applied voltage is 900 to 20 000
mals are to be regarded as the standard. The values given in
V d-c.
parentheses are for information only.
1.5 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 Method A—Method A describes a quick, safe method
responsibility of the user of this standard to establish appro-
for determining if pinholes, voids, or metal particles are
priate safety and health practices and determine the applica-
protruding through the coating. This method will not, however,
bility of regulatory limitations prior to use.
find any thin spots in the coating. This method will determine
2. Referenced Documents the existence of any gross faults in thin-film pipeline coatings.
5.2 Method B—Method B describes a method for determin-
2.1 ASTM Standards:
ing if pinholes, voids, or metal particles are protruding through
A 742/A 742M Specification for Steel Sheet, Metallic
3 the coating, and thin spots in pipeline coatings. This method
Coated and Polymer Precoated for Corrugated Steel Pipe
can be used to verify minimum coating thicknesses as well as
3. Terminology voids in quality-control applications.
3.1 Definitions:
6. Apparatus
3.1.1 holiday—small faults or pinholes that permit current
6.1 Low-Voltage Holiday Detector—A holiday detector
tester having an electrical energy source of less than 100 V d-c,
These test methods are under the jurisdiction of ASTM Committee D-1 on Paint
such as a battery; an exploring electrode having a cellulose
and Related Coatings, Materials, and Applications and are the direct responsibility
sponge dampened with an electrically conductive liquid such
of Subcommittee D01.48 on Deterioration of Pipeline Coatings and Linings.
as tap water; and an audio indicator to signal a defect in a
Current edition approved Sept. 25, 1987. Published November 1987. Originally
published as G 62 – 79. Last previous edition G 62 – 85.
high-electrical resistance coating on a metal substrate. A
This was taken from the pamphlet “Operating Instructions for Tinker and Rasor
ground wire connects the detector with the low-resistance
Model EP Holiday Detector.” Other manufacturers’ holiday detectors can be
metal surface.
expected to have similar voltage specifications.
Annual Book of ASTM Standards, Vol 01.06. 6.2 High-Voltage Holiday Detector—A holiday detector
G62
tester having an electrical energy source of 900 to 20 000 V picked up by the audible alarm, the electrode can be turned on
d-c; an exploring electrode consisting of wire brush, coil- end and the exact spot of failure can be noted by searching with
spring, or conductive silicon electrode capable of moving the tip of the electrode.
along the pipeline coating; and an audio indicator to signal a 10.4 The voltage between the electrode (sponge) and the
defect in a high-electrical resistance coating on a metal metal surface upon which the coating lies shall not exceed 100
substrate. A ground wire connects the detector with the V d-c, measured between the electrode sponge and the coated
low-resistance metal surface. metal when the detector is in its normal operating position.
6.3 Peak or Crest Reading Voltmeter—A kilovoltmeter 10.5 Prior to making the inspection, ensure that the coated
capable of detecting a single pulse and holding it long enough surface is dry. This is particularly important if formed surfaces
for the meter circuits to indicate. are to be inspected. If the surface is in an environment where
electrolytes might form on the surface, such as salt spray, wash
7. Reagents and Materials
the coated surface with fresh water and allow to dry before
7.1 Tap Water, plain or with a wetting agent. testing. Take care to keep the electrolyte at least 12.7 mm ( ⁄2
in.) from any bare sheared or slit edge.
NOTE 1—Ordinary tap water will suffice to wet the sponge electrode
10.6 A low-voltage holiday detector is not satisfactory for
when inspecting coatings up to 0.254 mm (10 mils) in thickness. On films
the inspection of pipeline coatings over 0.508 mm (20 mils) in
between 0.254 and 0.508 mm (10 and 20 mils), a nonsudsing type wetting
thickness. This type of holiday detector will not detect thin
agent added to the water is recommended to allow for faster penetration
of the liquid into pinhole defects.
spots in pipeline coatings.
8. Test Specimen
11. Procedure for Method B
8.1 Th
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