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NACE SP0188-2006
(formerly RP0188-99)
Item No
...
Its acceptance does not in any respect
preclude anyone, whether he or she has adopted the standard or not, from manufacturing,
marketing, purchasing, or using products, processes, or procedures not in conformance with this
standard
...
This standard represents minimum requirements and
should in no way be interpreted as a restriction on the use of better procedures or materials
...
Unpredictable
circumstances may negate the usefulness of this standard in specific instances
...

Users of this NACE International standard are responsible for reviewing appropriate health, safety,
environmental, and regulatory documents and for determining their applicability in relation to this
standard prior to its use
...
Users of this
NACE International standard are also responsible for establishing appropriate health, safety, and
environmental protection practices, in consultation with appropriate regulatory authorities if
necessary, to achieve compliance with any existing applicable regulatory requirements prior to the
use of this standard
...
NACE
International requires that action be taken to reaffirm, revise, or withdraw this standard no later than
five years from the date of initial publication
...

Purchasers of NACE International standards may receive current information on all standards and
other NACE International publications by contacting the NACE International FirstService
Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 [281] 228-6200)
...
The degree of coating continuity required is dictated by service conditions
...
This standard
practice provides a procedure for electrical detection of minute discontinuities in new coating
systems that are applied to conductive substrates
...
This standard describes procedures for determining discontinuities using two types of
test equipment: low-voltage wet sponge testers and high-voltage spark testers
...
For the purposes of this standard, the term “coating” can refer either to
atmospheric or immersion service
...
It was reaffirmed in 1990,
revised in 1999, and reaffirmed in 2006 by Specific Technology Group (STG) 03
...
It combines the input of representatives of coating manufacturers,
applicators, inspection agencies, architectural engineers, equipment manufacturers, and general
consumers
...
, Paragraph 7
...
1
...
Shall
and must are used to state mandatory requirements
...
The term may is used to state
something considered optional
...
General
...
Definitions
...
Low-Voltage Wet Sponge Testing
...
High-Voltage Spark Testing
...
Testing of Repaired Area
...
Safety
...
5
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NACE International

SP0188-2006
________________________________________________________________________
Section 1: General
1
...

1
...

The allowable number of discontinuities should be
determined prior to conducting this test, because the
acceptable number of discontinuities varies depending on
coating thickness, design, and service conditions
...
A low-voltage wet sponge tester
may be used without damaging the coating but can produce
erroneous readings
...
5 To prevent damage to a coating if a high-voltage spark
tester is being used, the total film thickness and dielectric
strength of the coating system shall be considered in
selecting the appropriate voltage for detection of
discontinuities
...
3 This standard is not intended to provide data on service
life, adhesion, or film thickness of an applied coating
system
...
0 mil])
...
6 The coating manufacturer shall be consulted to obtain
the following information, which can affect the accuracy of
the tests described in this standard to determine
discontinuities:

1
...
Inspecting a
coating previously exposed to an immersion condition could
result in damage to the coating or could produce an
erroneous detection of discontinuities due to permeation or
moisture absorption of the coating
...


(a) The length of time required to adequately dry or cure the
applied coating prior to testing
...

(b) Whether the coating contains electrically conductive
fillers or pigments that may affect the normal dielectric
properties
...


Holiday: A discontinuity in a protective coating that
exposes unprotected surface to the environment; in this
standard, a term used interchangeably with discontinuity
...
A discontinuity may or may
not affect the usefulness of the coating
...
May also
be identified as a holiday or pinhole
...

Pinhole: A minute hole through a coat or coats that
exposes an underlying coat or the substrate
...


________________________________________________________________________
Section 3: Low-Voltage Wet Sponge Testing
3
...
1
...
It is
used to locate discontinuities in a nonconductive
coating applied to a conductive substrate
...

3
...
2 The operating voltage of a low-voltage wet
sponge tester is a function of the particular electronic

1

SP0188-2006
circuit design and does not affect the sensitivity of the
device
...
1
...

The
following electronic principles describe two types of
devices generally used; others may be available but
are not described in this standard
...
1
...
1 One type of low-voltage wet sponge
tester is a lightweight, self-contained, portable
device based on the electrical principle of an
electromagnetic sensitive relay or solid-state
electronic relay circuit that energizes an audible or
visual indicator when a coating discontinuity is
detected
...

3
...
3
...
This results in a rise in oscillator
frequency as well as in the audible signal from the
device
...

3
...
2
...
The length of time
required for drying or curing shall be obtained from the
coating manufacturer
...

3
...
2 The film thickness of the coating shall be
measured with a nondestructive dry film thickness
gauge
...
A low-voltage wet sponge
tester shall not be used for determining the existence of
discontinuities in coatings having a total thickness
greater than 500 µm (20 mil), due to the relative
inaccuracy and lack of sensitivity of low-voltage wet
sponge testers
...
2
...
3
...
2
...

3
...
5 The exploring sponge lead shall be attached to
the output terminal
...
2
...

The sensitivity of the test may be increased by adding
a low-sudsing wetting agent (such as that used in
photographic film development), combined at a ratio of
30 mL (1 fl oz) wetting agent to 3
...
The
sponge shall be wetted sufficiently to barely avoid
dripping while it is moved over the coating
...
2
...

Additives can leave contaminants on the surface that
can interfere with adhesion of topcoats or repair coats
and may contaminate stored product
...
2
...

3
...
9 Sodium chloride (salt) shall not be added to the
water because it can cause erroneous indications of
discontinuities
...
It
also interferes with intercoat adhesion of additional
coats
...
2
...
This procedure shall be
repeated periodically during the test
...
2
...
3 m/s
(1 ft/s), using a double pass over each area
...
If
a discontinuity is detected, the sponge should be
turned on end to determine the exact location of the
discontinuity
...
2
...

3
...
13 To prevent telegraphing, care should be taken
to ensure that the solution (tap water) is wiped dry from
a previously detected discontinuity before continuing
the test
...
3 Verifying Sensitivity of Equipment
3
...
1 The tester shall be tested for sensitivity prior to
initial use on each project and periodically thereafter
during the project, in accordance with the
manufacturer’s instructions
...
3
...

3
...
3 The ground cable shall be connected to the
tester ground output terminal
...
3
...


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NACE International

SP0188-2006
3
...
5 The sponge shall be saturated with a wetting
solution consisting of tap water and a wetting agent
(see Paragraph 3
...
6)
...
3
...
The tester signal should actuate
in accordance with the manufacturer’s instructions
...
3
...

3
...
4
...
4
...
4 Connect a 100,000-ohm resistor with an
accuracy tolerance of ±5% across the output
terminals
...

3
...
1
...
4
...
3 and 3
...
1
...

3
...
2 The following procedures shall be used to verify
sensitivity of testers having an electronic relaxation
oscillator circuit:
3
...
2
...

Refer to the manufacturer’s instructions
...
4
...
2 Switch the tester to “on
...
4
...
1 Test the battery for proper voltage output
...

3
...
1
...

3
...
1
...
The alarm should actuate
...
4
...
3 At different intervals, a 10-megohm, 1megohm, 100,000-ohm, and 10,000-ohm resistor
should be connected across the output terminals
...
4
...
4 A discernible increase in frequency should
be detected as the resistance is decreased
...
4
...
5 If the tester fails to indicate a frequency
change, it shall be considered inoperative
...
1 High-voltage spark testers are suitable for determining
the existence of discontinuities in coatings of all
thicknesses
...

Suggested starting voltages are provided in Table 1
...

4
...
The conductivity of concrete varies depending
on moisture content, type, density, and location of rebars
...
If the metallic ground is not visible, the ground
wire shall be placed directly against the bare concrete
surface and weighted with a damp cloth or wet-sand-filled
paper bag
...


Table 1
Suggested Voltages for High-Voltage Spark
Testing
Total Dry Film Thickness
(µm)
200 to 300
300 to 400
400 to 500
500 to 1,000
1,000 to 1,400
1,400 to 2,000
2,000 to 3,200
3,200 to 4,700

(mil)
8 to 11
12 to 15
16 to 20
21 to 40
41 to 55
56 to 80
81 to 125
126 to 185

Suggested
Voltage
(V)
1,500
2,000
2,500
3,000
4,000
6,000
10,000
15,000

4
...
3
...
It consists of an
electrical energy source, an exploring electrode, and a
ground connection from the indicator signaling current
flow through a coating discontinuity to the substrate
...
3
...
It shall be kept clean and free of coating material
...
3
...
A
pulse type tester discharges a cycling, high-voltage
pulse
...

4
...
4
...
The length
of time required for drying or curing shall be obtained
from the coating manufacturer
...

4
...
2 The thickness of the coating shall be measured
with a nondestructive dry film thickness gauge
...
Although the high-voltage spark tester is suitable
for determining discontinuities in coatings less than 500
µm (20 mil), the coating manufacturer should be
consulted before using this test
...

4
...
3 The high-voltage spark tester shall be calibrated
in accordance with Paragraph 4
...

4
...
4 The high-voltage spark tester shall be adjusted
to the proper voltage for the coating thickness being
tested
...
This air gap varies depending on
the total applied film thickness
...
The maximum
voltage for the applied coating shall be obtained from
the coating manufacturer
...

4
...
5 The ground wire from the high-voltage spark
tester ground output terminal shall be attached to the
conductive substrate, and positive electrical contact
shall be ensured
...
If the
rebars are not visible, the ground wire shall be placed
directly against the bare concrete surface and weighted
with a damp cloth or wet-sand-filled paper bag
...
4
...

This test shall be
conducted periodically during the testing of the coating
...
4
...
3
m/s (1 ft/s) using a single pass
...
If
moisture exists, it shall be removed or allowed to dry
before the test is conducted
...
4
...

4
...
5
...
5
...
1 Test the energy source (battery) for proper
voltage output according to the manufacturer’s
instructions
...
5
...
2 Connect the exploring electrode and
grounding cable to the terminals of the tester
...
5
...
3 Switch the tester to the “on” position
...
5
...
4 Touch the exploring electrode to the
ground cable alligator clip
...

4
...
1
...

4
...
6
...
The tester shall be recalibrated
periodically thereafter
...
6
...
1 Connect a high-voltage voltmeter between
the probe and the ground lead
...
6
...
2 Switch the tester to the “on” position
...
6
...
3 Compare the voltage of the voltmeter with
the output voltage of the tester
...

4
...
1
...

4
...
1
...


NACE International

SP0188-2006
________________________________________________________________________
Section 5: Testing of Repaired Area
5
...
The length of time required for
drying or curing shall be obtained from the coating
manufacturer
...
2 The test shall be conducted following the procedures
previously outlined in this standard for the type of tester
selected
...
3 Only those areas that have been repaired shall be
retested, unless otherwise specified
...
1 Precautions shall be taken to prevent electrical shock
...
The manufacturer’s safety instructions shall be
followed to prevent electrical shock
...
2 Prior to conducting high-voltage tests in an enclosure,
an inspection shall be conducted to indicate whether the
enclosure is safe for entry, including testing for flammable or

explosive gas
...

6
...


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References
1
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2
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3
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