Nace CP 1 - Above Ground Storage Tanks; Interiors of Steel Water Storage Tanks; Oil Heater-Treaters

Underground Corrosion Control 3:31
CP 1 – Cathodic Protection Tester Course Manual
© NACE International, 2000
02/01/05
Interiors of Steel Water Storage Tanks
RP0388 Impressed Current Cathodic Protection of Internal Submerged
Surfaces of Steel Water Storage Tanks
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 the structure-to-electrolyte boundary
must be considered for valid interpretation of this voltage measurement.
American Water Works Association Standard D104 Automatically
Controlled Cathodic Protection of Internal Submerged Surfaces of Steel
Water Storage Tanks” specifies –0850 to –1050 mV polarized to CSE.
Oil Heater-Treaters
RP0575 Internal Cathodic Protection Systems in Oil Treating Vessels
A minimum of –850 mV vs CSE (–800 mV vs a silver-silver chloride
electrode (Ag-AgCl)). If, however, the fluid contains sulfides or hydrogen
sulfide, a minimum potential of –950 mV (–900 vs Ag-AgCl) can be
required.
Above Ground Storage Tanks
RP0193 External Cathodic Protection of On-Grade Metallic Storage Tank
Bottoms
• 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 the structure-to-electrolyte
boundary must be considered for valid interpretation of this voltage
measurement.
• A negative polarized potential of a least 850 mV relative to a saturated
copper-copper sulfate reference electrode.
• A minimum of 100 mV of polarization.