Polymer and polymer-lined equipment has become more common in the chemical process industries (CPI) due to its cost-effective corrosion resistance in severe chemical service. Fluoropolymer-lined steel, high-density polyethylene (HDPE)-lined steel, and polyvinyl chloride (PVC) are examples of materials used for tanks, vessels, and other CPI equipment. Economic considerations demand that the life of this equipment be extended as long as is safely possible.