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Underground Corrosion Control 3:32
CP 1 – Cathodic Protection Tester Course Manual
©
NACE International, 2000
02/01/05
Steel Reinforced Concrete
RP0290 Cathodic Protection of Reinforcing Steel in Atmospherically
Exposed Structures
The standard specifies the 100 mV polarization criterion plus two other, more
complex criteria. These are 1) a potential at least as negative as that at the
base of the Tafel slope on an E-Log I curve and 2) a polarized potential more
negative than the statistical standard deviation of the native potentials.
Discussion of these two latter criteria is beyond the scope of this course.
International Standard ISO 15589-1
Petroleum and Natural Gas Industries–Cathodic Protection of
Pipeline Transportation Systems
Part 1 On-land pipelines
•
Metal-to-electrolyte potential chosen for a corrosion rate less than 0.01
mm/yr (0.39 mils/yr)
•
Polarized potential more negative than –850 mV
CSE
•
Limiting critical potential not more negative than –1,200 mV
CSE
•
Anaerobic soils or sulfate-reducing bacteria (SRB) more negative than
–950 mV
CSE
•
High soil resistivity
ƒ –750 mV
CSE
for 100 < ρ < 1,000 Ω -m
ƒ –650 mV
CSE
for ρ > 1,000 Ω -m
•
Cathodic polarization of 100 mV
Precautions:
Avoid using 100 mV under conditions of high temperatures, SRB,
interference current, equalizing current, telluric current, mixed metals or
SCC conditions more positive than –850 mV
CSE
.
Canada
Canadian Standards Association Standard, Z662, Oil and Gas Pipeline
Systems references CGA Recommended Practice OCC-1, For the Control
of Corrosion on Buried or Submerged Metallic Piping Systems. The criteria
are the same as in RP0169.
CSA Standard Z169 covers cathodic protection of aluminum.