Abstract
The criteria and methods given by AMPP/NACE SP0169 and TM0497 rely heavily on the use of Instant-Off potential measurements to assess cathodic protection levels on pipelines. Despite wide acceptance of these standards, there is little or no data to demonstrate that an Instant-Off potential accurately represents the polarized potential that exists across the metal/electrolyte interface of a pipeline under normal operating conditions. This paper summarizes laboratory testing that was conducted to demonstrate the accuracy of Instant-Off potentials. Test results show that Instant-Off potentials significantly underestimate pipeline polarized potentials. Examples are given where the reliance on Instant-Off potentials can lead to pipeline damage.
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2023
Association for Materials Protection and Performance (AMPP)
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