Is CP worthless ?

摘要

What kind of question is this? Most in the pipeline industry agree that cathodic protection (CP) is the smart way to provide backup corrosion protection on underground pipelines. But consider: If you use solid film backed corrosion coatings, you may be wasting money by adding CP to the pipeline. There is a common sense reason for this statement. CP systems protect pipelines by delivering electrical current to the steel surface. Solid film back corrosion coatings have the property of resistivity, which means they block electrical current. This blocking effect is called cathodic shielding. The phenomenon of cathodic shielding, or blocking of protective CP current, has been the subject of dozens of technical papers since the mid 1980's. You can review a cross section of these papers on Polyguard's website. You can also view a 10 minute explanation of the cathodic shielding process.