When taking measurements between a steel pipe and copper-copper sulfate electrode, adequate CP is indicated by a value of at least ________.

The correct answer is based on the industry standard for cathodic protection (CP) measurements. A measurement of at least -0.85V indicates that the steel pipe is adequately protected from corrosion when using a copper-copper sulfate electrode. This value signifies that the potential of the steel pipe is becoming sufficiently negative, which is necessary to ensure that the pipe remains cathodic and thus protected from the corrosive environment. The requirement for a minimum potential is established to ensure that the protective measures are indeed effective in preventing corrosion.

In practice, a measurement lower than this threshold may indicate that the level of CP is insufficient, which can result in corrosion and related issues over time. Therefore, achieving a value of at least -0.85V is essential for ensuring the longevity and integrity of the pipeline infrastructure.