Nace CP 1, Руководство по эксплуатации

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TM0101-2001
18 NACE International
11.3.2.5 Measure and record structure-to-
electrolyte potentials for structures that are to be
evaluated.
11.3.3 Evaluation of Data
11.3.3.1 Electrical discontinuity is indicated for
structures that have a potential difference greater
than 0.01 V (10 mV).
11.3.3.2 Electrical continuity is indicated for
structures that have a potential difference of 0.001
V (1 mV) or less.
11.3.3.3 The results of this test method are
inconclusive and further testing is necessary if the
measured potential difference of a structure is 0.01
to 0.001 V.
11.4 Potential Difference Technique
11.4.1 This technique is used to test for an indication of
possible electrical continuity using a voltmeter to
measure the difference in electrical potential between
two buried structures.
11.4.2 To perform this test, one test lead from a
voltmeter shall be connected to the structure to be
tested. The second test lead from the voltmeter shall
be connected to a separate structure or appurtenance
that is suspected to be electrically continuous.
11.4.3 Evaluation of Data
11.4.3.1 Data obtained by this test method should
be evaluated according to the same criteria used
for
the fixed cell/moving ground technique
(Paragraph 11.3.3).
NOTE: Structures and appurtenances found on a UST
system can misrepresent the results of this test.
Galvanized pipe or conduit and coated or uncoated
structures are some examples of different alloys or
conditions that could be detrimental to the results of
this test.
11.5 Applied Current Technique
11.5.1 This test uses either a temporary DC current
source or an existing interruptible cathodic protection
system and basic cathodic protection test equipment to
determine electrical continuity. This test can also be
used to confirm the fixed cell/moving ground and
potential difference technique test results.
11.5.2 The following procedure shall be followed when
testing using the applied current technique:
11.5.2.1 Make electrical contact between the
reference electrode and the electrolyte at a
location remote from the system to be tested.
11.5.2.1.1 The location should not be within
the potential gradient of anodes or other
structures.
Placement of the reference
electrode in a location that is shielded by
another tank or structure may result in
erroneous data concerning the continuity of
the shielded tanks or structures. Alternate
reference
electrode placements may be
necessary to determine the continuity of all
structures at the test site.
11.5.2.1.2 Once placed, the reference
electrode shall not be moved for the duration
of this test procedure.
11.5.2.1.3 Prior to testing, existing impressed
current cathodic protection systems should be
turned off. If a sacrificial anode system is
being
used, the anodes should be
disconnected from the structure, if practical.
11.5.2.2 Measure and record the tank-to-
electrolyte potential with respect to the reference
electrode.
11.5.2.3 Measure and record a structure-to-
electrolyte potential for other structures under test.
11.5.2.4 Use either of the following for the applied
current procedure:
(a) Energize the existing impressed current
cathodic protection system or sacrificial anode
system; or
(b) Energize a temporary groundbed.
The
temporary groundbed must be electrically isolated
from the structures under test.
11.5.2.5 Remeasure and record the tank-to-
electrolyte potentials with respect to the reference
electrode.
11.5.2.6 Remeasure and record the structure-to-
electrolyte
potentials for structures that are
designed to be continuous or isolated.