9 Coating Systems

Coating and painting systems are the most common forms of external corrosion control used in the oil and gas industry, offering a cost-effective and feasible barrier to mitigate corrosion threats. What differentiates the terms ‘coating’ and ‘painting’ is both in relation to the thickness and purpose of the system deployed. Painting applications are generally very thin, no more than a few hundred micro-metres thick at most, limited to corrosion mitigation in atmospheric conditions and usually serve a decorative, as well as protective, use. Coating applications are generally much thicker (can be several millimetres thick) and used both for atmospheric, subsea, and underground protection. A third term, ‘lining’, is generally referred to thick coatings, or solid non-metallic materials, used for internal protection of storage tanks, separators, downhole tubular, and pipelines intended to afford a more durable corrosion barrier. Coatings applied internally for corrosion mitigation also offer improving flow dynamics, reducing inhibitor cost, and externally to offer improved appearance, minimising corrosion, and commonly to enhance implementation of cathodic protection.