Nace CP 1, Course Manual

Page: 316 / 535

RP0285-2002
12 NACE International
7.3.2 All construction work performed on CP systems
shall be done in accordance with construction drawings
and specifications.
All deviations from construction
specifications shall be approved prior to installation and
shall be noted on as-built drawings.
7.3.3 The installation of CP systems shall be under the
supervision of trained and qualified personnel to
ensure that the installation is done in accordance with
the drawings and specifications.
7.3.4 Galvanic Anodes
7.3.4.1 Packaged anodes should be kept dry
during
storage. Electrical continuity between
anode and lead wire shall be tested without
compromising the integrity of the package. Any
waterproof covering must be removed before
installation.
7.3.4.2 Anodes shall be installed according to the
system specifications. Packaged galvanic anodes
shall be surrounded with select fill and compacted.
Paragraph 6.2.4.5 describes the select fill. Also
see Paragraph 3.6.1.
7.3.4.3 Care should be exercised so that lead
wires and connections are not damaged during
backfill operations.
Lead wires should have
enough slack to prevent strain. Anodes should not
be carried or lowered into the excavation by the
lead wire.
7.3.5 Impressed Current Anodes
7.3.5.1 Impressed current anodes shall be
inspected for defects and for conformance to
specified material.
Care shall be exercised to
avoid damaging the anodes during handling and
installation.
7.3.5.2 Impressed current anodes shall be buried
as indicated in construction specifications. Backfill
material shall be placed to ensure that there are
no voids around anodes.
Backfilling operations
shall not damage the anode or its lead wire.
7.3.5.3 Anode lead wires shall be carefully
inspected for insulation defects. Extreme care
shall be taken to avoid damaging the wire
insulation.
Anodes with damaged lead wire
insulation shall not be installed.
7.3.6 Wire and Cable
7.3.6.1 Care shall be exercised when installing
direct burial cable to the anodes to avoid damage
to insulation. Sufficient slack shall be left to avoid
strain. Backfill material around the cable shall be
free of rocks and foreign matter that might damage
the wire insulation when the wire is installed in a
trench.
7.3.6.2 Underground splices of header cable to
the groundbed should be avoided. Connections
between header cable and conductors from
anodes
shall be mechanically secure and
electrically conductive. If buried or submerged, all
splices and connections must be sealed to prevent
moisture penetration so that electrical isolation
from the environment is ensured.
7.3.7 Rectifier Units
7.3.7.1 The rectifier unit shall be inspected to
ensure that internal connections are mechanically
secure and that no damage is present. Rating of
the
DC power source shall comply with
construction specifications.
7.3.7.2 Cable connections to the rectifier shall be
mechanically secure and electrically conductive.
Before the power source is energized, it shall be
verified that the negative cable is connected to the
structure to be protected and that the positive
cable is connected to the anodes. After the DC
power source has been energized, measurements
shall be made to verify that these connections are
correct.
7.3.7.3 Alternating current (AC) wiring to rectifiers
shall comply with local and national electrical
codes and requirements of the utility supplying
power. A disconnect switch external to the rectifier
should be provided on a dedicated AC circuit. The
rectifier case shall be properly grounded.
7.3.8 Wire Connections
7.3.8.1 The structure and all wires shall be clean,
dry, and free of foreign materials when the
connections are made. Connections of wires to
the structure shall be installed so that they will
remain secure and electrically conductive.
7.3.8.2 All wire attachments should be coated
with an electrical isolating material. If the structure
is
coated, the isolating material shall be
compatible with the coating and wire insulation.
7.3.8.3 Wire shall be installed with slack.
Damage to insulation shall be avoided.
7.3.9 Isolating Devices
7.3.9.1 Inspection and electrical measurements
shall be made to ensure that electrical isolation
devices are effective.
7.4 System Commissioning
7.4.1 The energizing of CP systems for storage tanks
shall be based on the initial design parameters. Major
items that should be known are: