Abstract
Criteria for determining effective cathodic protection are listed as: 1) Current density. Useful when current density required for protection is known and the design of the structure lends itself to reasonably accurate determination of current pickup. 2) Potential change. The author believes a potential change of 0.3 volt is adequate but suspects it results in over-protection. Polarization effects may obscure significance of measurements. 3) Current-potential curves. Elaborate equipment is required and the method is time consuming. 4) Copper-Sulfate Potential. The accepted criterion of 0.85 volt loses some of its validity in highly aerated soils.
Methods, instruments, techniques and examples of potential measurements are given. Multiple-rectifier systems, pipe lines in salt water, steel structures in salt water, and oil and gas well casings are considered.
