An Overview of Intumescent Coatings

By Aggie Lotz

Industrial maintenance and protective coatings are formulated to provide protection for exterior and interior substrates against corro­sion, abrasion, thermal, and chemical and ultraviolet (UV) degrada­tion in both industrial and critical service environments. These coat­ing systems, as the name indicates, are used primarily in industrial segments where aggressive corrosive or chemical environments exist, in addition to commercial applications where long-term protection and aesthetics are required. While such coatings are primarily con­sidered functional, appearance and retention of these coating systems have also become important performance requirements. Industrial maintenance and protective coatings are combinations of products designed to perform and protect under specific condi­tions. Such coatings systems are usually applied by specially trained, professional applicators in a fabrication facility or in the field. They can be applied as part of new construction, or during routine main­tenance to provide continued asset protection from various forms of structural deterioration.

Dominating the industrial maintenance coatings segment is sol­ventborne coatings-including both conventional and high-solids products-accounting for approximately 65% of 2015 total volume. The majority of industrial maintenance solventborne coatings are high-solids products, as the industry strives to meet ever-tightening environmental regulations without sacrificing product performance. Included in the high-solids category is 100% solids technology that plays a key role in severe service applications. It is used extensively in tank linings, deck coatings, and secondary containment. They are mostly epoxy, novolac, and even aromatic polyurethane when impact resistance is required to improve wear. The trend toward high-solids coatings is expected to continue.

One example of an end market pushing the performance envelope for conventional coatings is the oil and gas industry. A current trend is toward higher pipeline operating temperatures to increase transpor­tation volumes. Therefore, a common characteristic is the elevated temperature of the oil (up to 150°C and potentially even higher). This directly impacts pipeline coating performance that can degrade at elevated temperatures, resulting in internal and external corrosion problems affecting such flowline systems. In the past 10 years, one solution to mitigate external pipeline corrosion has been the use of epoxy/phenolic resin-based coatings; these perform reliably up to 120°C. High-temperature, epoxy/novolac matrices can handle constant or repeated temperatures up to 177°C in dry conditions and 149°C in the wet, but they require a thermal cure-not practical for many field applications. Nanotechnology refers to materials with dimensions in the 1-100 nanometer range, where quantum mechanics yield interesting proper­ties. Nanostructured materials yield extraordinary differences in rates and control of chemical reactions, electrical conductivity, magnetic properties, thermal conductivity, strength, and fire-retardant properties.