Nace CP 1, Руководство по эксплуатации

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RP0290-2000
NACE International 5
3.4.3.3 The anode material selected should be
resistant to the electrochemical reactions that
occur at the anode-concrete interface.
3.4.3.4 Concrete drying effects can limit the ability
of the anode to deliver adequate current at
specified circuit voltage.
3.4.4 Structural considerations
3.4.4.1 The physical space available, access,
maintenance of right-of-way, safety, and other
construction and maintenance aspects should be
considered. Overhead clearance and dead load
constraints may preclude the use of overlay
systems in some areas of concrete structures.
3.4.4.2 Future repairs to the concrete structure
and future extensions to the cathodic protection
system should be considered.
3.4.4.3 The physical properties of anode material
selected must be compatible with the concrete
structure.
3.4.4.4 Durability, shrinkage, ease of repair and, if
relevant, skid resistance of wearing surfaces
should be considered in the selection of anode
systems.
3.4.4.5 The effect of construction and repair
techniques that utilize insulating materials (e.g.,
epoxy injection), high temperature (e.g., asphaltic
overlays), or impact loads should be considered in
the selection of anode systems, instrument design,
and wiring methods.
3.5 In the design of an impressed current cathodic protect-
ion system, the following items should be considered.
3.5.1 Materials and installation practices that conform
to applicable codes and standards such as the National
Electrical Code
10
issued by the NFPA,
(4)
those issued
by OSHA,
(5)
NEMA,
(6)
NACE, ACI,
(7)
ASTM, and any
other applicable codes or standards should be
specified.
3.5.2 Detailed specifications should be given for all
materials and installation practices to include
transportation, storage, handling, and disposal that are
to be incorporated in construction of the impressed
current cathodic protection system. When performance
specifications or requirements are used, specific
evaluation procedures should be outlined or citations
published, and recognized industry standards should
be listed. Terminology should be clearly defined.
3.5.3 Voltage and current attenuation along the anode
and its connecting wire in distributed anode impressed
current systems should be evaluated. The design
should optimize anode system length, anode spacing
and size, and conductor size in order to achieve the
criteria set forth in Section 2.
3.5.4 The proximity of anodes to other metallic
embedments such as form ties, chairs, tie wire,
embedment plates, and electrical conduit shall be
determined. Minimum depth of cover over the
reinforcement must be maintained in accordance with
the manufacturer’s recommendations. If the minimum
cover cannot be maintained, insulating methods should
be used to prevent deadshorts or near shorts in
specific areas.
3.5.5 Rectifiers should be selected to provide
adequate allowance for anticipated changes in current
requirements and circuit resistance with time. Circuit
resistance is related to the type of concrete used,
internal moisture content, temperature, and chloride
content with their respective fluctuations.
3.5.6 Components should be located where the
possibility of damage is minimal.
3.5.7 System design shall provide safe step-and-touch
potentials.
3.5.8 Suitable design drawings that clearly delineate
the overall layout of the concrete structure to be
protected should be prepared. The location of
significant items of system hardware, corrosion control
test stations, electrical bonds, electrical insulators, and
adjacent metallic embedments should be shown.
3.5.9 Design or shop drawings, details, and schedules
for each impressed current cathodic protection
installation should be prepared to show quantities,
detailed anode layout, relevant typical cross-sections,
and location of the components within the protected
concrete structure(s). Tolerances should be stated.
3.5.10 In areas where stray currents are suspected,
appropriate tests should be conducted. Special
considerations may be required to achieve the criteria
set forth in Section 2 when stray currents are
encountered.
3.5.11 Cathodic protection may not be appropriate to
protect certain metal items mounted on, in, or adjacent
to the protected concrete structure. Electrical isolation
and avoiding stray current corrosion of such items
should be addressed during the cathodic protection
system design.
____________________________
(4)
National Fire Protection Association (NFPA), 1 Battermarch Park, Quincy, MA 02269-9101.
(5)
Occupational Saftey and Health Administration (OSHA), 200 Constitution Ave NW, Washington, DC 20210.
(6)
National Electrical Manufacturers Association (NEMA), 1300 N. 17th St. Ste. 1847, Rosslyn, VA 22209.
(7)
American Concrete Institute (ACI), P.O. Box 9094, Farmington Hills, MI 48333.