1.1 Accelerated testing of catalyzed titanium for use as CP anodes in soils or natural waters is intended to provide an indication of the anode’s ability to perform satisfactorily for a specific number of years. Because such anodes can fail
with little or no weight loss, lifetime expectation cannot be extrapolated from operation at normal operating current density. Testing must instead be conducted at high current density until an acceptable amount of charge has been accumulated. This test is considered appropriate for
catalyzed anodes based on film-forming metals, such as tantalum, niobium, and zirconium, when used for
applications in soils or natural waters. Catalysts may be mixed-metal oxides (MMO) or precious metal/metal oxide cermets.
1.2 The anode shall survive the accelerated total charge density that is equivalent to the total charge density for the anode design service requirements. The relationship between life and current density is not linear for these
anodes, but rather a log-log relationship, as shown in Figure 1. The total charge density for the accelerated test is numerically smaller than the total charge density calculated for the design service requirement.
1.3 Total charge density is simply the anode life multiplied
by the current density. For the accelerated total charge
density, it is the current density of the test multiplied by the
minimum test duration. For the total design service charge
density, it is the current density for the anode in the
intended service times the desired service life for the anode.
1.3.1 For example, for an anode intending to be put in
service for 20 years at 100 A/m2 (9.3 A/ft2), the design
service charge density would be 2,000 A-y/m2 (190 Ay/
ft2) or 17,500,000 A-h/m2 (1,630,000 A-h/ft2). The
accelerated total charge density may be determined
from the manufacturer’s information.
1.4 The electrolyte used for this test shall be an aqueous
solution of 1.0 M sodium sulfate. Because this electrolyte is
aggressive toward these types of anodes, the results of this
test may be considered to be conservative.
1.5 Testing shall be conducted using a full-wave, singlephase,
unfiltered power supply with a minimum of 40%
ripple. This condition will simulate the power supplies
commonly used for CP in the field.
1.6 An anode specimen with an active surface area of ~50
mm2 (~0.078 in2) should be used for this test, and shall be
operated at a test current density so as to verify that the
specimen meets the manufacturer’s life versus current
density curve. If this size or shape of anode specimen is
impossible or inappropriate, a different specimen size may
be used and current adjusted to provide the current density
required.
NACE TM0108-2008 history
2012NACE TM0108-2012 Testing of Catalyzed Titanium Anodes for Use in Soils or Natural Waters (Item No. 21252)
2008NACE TM0108-2008 Testing of Catalyzed Titanium Anodes for Use in Soils or Natural Waters Item No. 21252