NACE RP 0391 is a Recommended Practice published by NACE International (now AMPP) that gives guidance on evaluating, selecting, applying, and testing coatings for the internal protection of metallic pipelines and piping systems handling various fluids. It focuses on corrosion control inside pipelines (e.g., water, oil, gas, produced water) where internal coatings, linings, and auxiliary measures (pigging, corrosion inhibitors) are used to extend service life and reduce maintenance.
