Nace CP 1, Руководство по эксплуатации

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RP0169-2002
NACE International 25
of proper functioning may be current output, normal
power
consumption, a signal indicating normal
operation, or satisfactory cathodic protection levels on
the pipe.
10.4.2 All impressed current protective facilities
should be inspected annually as part of a preventive
maintenance program to minimize in-service failure.
Longer or shorter intervals for monitoring may be
appropriate.
Inspections may include a check for
electrical malfunctions, safety ground connections,
meter accuracy, efficiency, and circuit resistance.
10.4.3 Reverse-current switches, diodes, inter-
ference bonds, and other protective devices, whose
failures would jeopardize structure protection, should
be inspected for proper functioning at intervals of two
months. Longer or shorter intervals for monitoring may
be appropriate.
10.4.4 The effectiveness of isolating fittings,
continuity bonds, and casing isolation should be
evaluated during the periodic surveys.
This may be
accomplished by electrical measurements.
10.5 When pipe has been uncovered, it should be
examined for evidence of external corrosion and, if
externally coated, for condition of the external coating.
10.6 The test equipment used for obtaining each electrical
value should be of an appropriate type. Instruments and
related equipment should be maintained in good operating
condition and checked for accuracy.
10.7 Remedial measures should be taken when periodic
tests and inspections indicate that cathodic protection is no
longer adequate.
These measures may include the
following:
10.7.1 Repair, replace, or adjust components of
cathodic protection systems;
10.7.2 Provide supplementary facilities where
additional cathodic protection is necessary;
10.7.3 Thoroughly clean and properly coat bare
structures if required to attain cathodic protection;
10.7.4 Repair, replace, or adjust continuity and
interference bonds;
10.7.5 Remove accidental metallic contacts; and
10.7.6 Repair defective isolating devices.
10.8 An electrical short circuit between a casing and
carrier pipe can result in inadequate cathodic protection of
the pipeline outside the casing due to reduction of
protective current to the pipeline.
10.8.1 When a short results in inadequate cathodic
protection of the pipeline outside the casing, steps
must be taken to restore cathodic protection to a level
required to meet the cathodic protection criterion.
These steps may include eliminating the short between
the casing and carrier pipe, supplementing cathodic
protection, or improving the quality of the external
coating on the pipeline outside the casing. None of
these steps will ensure that external corrosion will not
occur on the carrier pipe inside the casing; however, a
shorted casing does not necessarily result in external
corrosion of the carrier pipe inside the casing.
10.9 When the effects of electrical shielding of cathodic
protection current are detected, the situation should be
evaluated and appropriate action taken.
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Section 11: External Corrosion Control Records
11.1 Introduction
11.1.1 This section describes external corrosion
control records that will document in a clear, concise,
workable manner, data that are pertinent to the design,
installation, operation, maintenance, and effectiveness
of external corrosion control measures.
11.2 Relative to the determination of the need for external
corrosion control, the following should be recorded:
11.2.1 Corrosion leaks, breaks, and pipe
replacements; and
11.2.2 Pipe and external coating condition observed
when a buried structure is exposed.
11.3 Relative to structure design, the following should be
recorded:
11.3.1 External coating material and application
specifications; and
11.3.2 Design and location of isolating devices, test
leads and other test facilities, and details of other
special external corrosion control measures taken.
11.4 Relative to the design of external corrosion control
facilities, the following should be recorded:
11.4.1 Results of current requirement tests;
11.4.2 Results of soil resistivity surveys;
11.4.3 Location of foreign structures; and