UFC 3-570-06
JANUARY 31 2003
Existing bare piping systems. Studies should be made to determine the
extent and rate of corrosion on existing bare piping systems. When these
studies indicate that corrosion will affect the safe or economic operation of
the system, adequate corrosion control measures should be taken.
Special conditions sometimes exist where cathodic protection is ineffective or
only partially effective. Such conditions may include elevated temperatures, disbonded
coatings, thermal insulating coatings, shielding, bacterial attack, and unusual
contaminants in the electrolyte. Deviation from the recommended practice may be
warranted in specific situations provided that corrosion control personnel in responsible
charge are able to demonstrate that the objectives expressed in the recommended
practice have been achieved.
6-3
CRITERIA. The criteria described below are in accordance with the following
National Association of corrosion Engineers (NACE) standards:
RP0169, Corrosion Control of External Corrosion on Underground or
Submerged Metallic Piping Systems
RP0285, Corrosion Control of Underground Storage Tanks By Cathodic
Protection
RP0388, Impressed Current Cathodic Protection of Internal Submerged
Surfaces of Steel Water Storage Tanks
RP0193, External Cathodic Protection of On-Grade Metallic Storage Tank
Bottoms
RP0196, Galvanic Anode Cathodic Protection of Internal Submerged
Surfaces of Steel Water Storage Tanks
Personnel responsible for corrosion control are not limited to criteria in this
chapter. Criteria that have been successfully applied on existing piping systems can
continue to be used on those piping systems. Any other criteria used must achieve
corrosion control comparable to that attained with the criteria within this chapter.
6-3.1
Steel and Cast Iron Piping. Corrosion control can be achieved at various
levels of cathodic polarization depending on the environmental conditions. However, in
the absence of specific data that demonstrate that adequate cathodic protection has
been achieved, one or more of the following shall apply:
6-3.1.1
A negative (cathodic) potential of at least 850 mV with the cathodic protection
applied. This potential is measured with respect to a saturated copper/copper sulfate
reference electrode contacting the electrolyte. Voltage drops other than those across
6-2
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