Author: Liu Yaoming
Daqing Oilfield Limited Company, Construction Management Center
Summary: Over several years of research on anti-corrosion coatings for oil pipelines and tanks, technical personnel have achieved certain research results in the field of environmental protection, such as epoxy powder anti-corrosion coatings, which have been applied in practice. This article studies the specific applications of anti-corrosion coatings for oil pipelines and tanks from three aspects: solvent-free anti-corrosion coatings, water-based anti-corrosion coatings, and epoxy powder anti-corrosion coatings.
Keywords: Environmentally friendly pipe & storage tank anti-corrosion coatings
Performance and Application Strategy of Environmentally Friendly, High-Performance Coatings for Pipelines and Storage Tanks
LIU Ye-ming
(Construction Management Center of Daqing Oilfield Co., Ltd. Daqing 163000, China)
Abstract:Over many years of research on anticorrosive coatings for oil pipelines and storage tanks, technicians have achieved certain research breakthroughs in the direction of environmental protection, such as epoxy powder anticorrosive coatings, which have been applied in practice. This paper studies the application of solventless anticorrosive coatings, water-soluble anticorrosive coatings, and epoxy powder anticorrosive coatings for oil pipelines and storage tanks.
Keywords: environmentally friendly pipeline; storage tank; anticorrosive coating
1 Solvent-free anti-corrosion coating
Solvent-free anti-corrosion coatings have the characteristic of not containing volatile components. The coating's components can all form a film, thus avoiding environmental pollution or air bubble issues caused by incomplete solvent evaporation. After the coating dries, the shrinkage rate is reduced, and its density is higher, allowing coating thicknesses of 200-300μm, which also significantly improves construction efficiency by reducing cumbersome processes. based on the development of modern anti-corrosion coatings, solvent-free anti-corrosion coatings can meet the basic needs of internal and external anti-corrosion of oil pipelines and tanks. For example, EP-94, a two-component, room-temperature curing anti-corrosion coating made of low-molecular-weight epoxy resins and other additives, is a stable and durable coating with good penetration properties for water, acids, and alkalis. It can maintain stability in various media for more than 2 years. In the application of oil pipelines and tanks, EP-94 can be applied to patching and other chemical equipment, providing good anti-corrosion effects for critical areas of containers. It is suitable for warm equipment and can be used in the bottom anti-corrosion of PU foam insulation, and it is compatible with polyethylene adhesive tape.[1].
2 Water-based Anti-corrosion Coatings
As a novel coating, water-based anti-corrosion coatings are characterized by using water as the dispersing medium, which can replace conventional organic solvents, significantly reducing environmental pollution. Western countries have made notable progress in this area, achieving substantial breakthroughs and developing high-performance, weather-resistant anti-corrosion coatings. However, research in this area in China has been relatively limited, resulting in slower progress. Nevertheless, to meet anti-corrosion demands, WJ-90, a water-based lithium silicate-zinc coating with good thermal resistance (withstanding temperatures up to 400°C) and excellent protection against various organic solvents, has been developed. The coating's surface resistance is less than 105Ω, meeting the requirements for static coatings of oil pipelines and storage tanks. WJ-90 coatings can provide effective anti-corrosion performance in equipment operating under marine atmospheric and high-temperature conditions, and have been applied in locations such as the Shengzhong 263 oil product storage area of China National Offshore Oil Corporation, demonstrating significant practical value.[2].
3 Powder Anti-Corrosion Coating
Powder anti-corrosion coatings have the advantage of being environmentally friendly. This technology uses a solvent-free base, applied in a thick layer, and then the sprayed coating is recovered and reused. This makes the sprayed portion of the powder anti-corrosion coating recoverable and reusable, meeting the anti-corrosion needs of oil pipelines and tanks. Technical personnel have developed epoxy powder coatings, which have excellent adhesion and flexibility, resulting in a longer lifespan and are designated as the preferred anti-corrosion coating for oil and natural gas. In areas with harsh climate conditions, epoxy powder coatings are widely used as the best pipeline anti-corrosion coating. Single-layer epoxy coatings have excellent bending resistance. However, technical personnel have also developed double-layer molten epoxy powder coatings to improve the anti-corrosion properties of epoxy powder coatings at high temperatures. This creates a new anti-corrosion system by modifying the outer layer of the epoxy powder coating, enhancing the mechanical properties of the coating, resulting in better impact resistance and penetration resistance. Most importantly, the newly developed coating maintains the compatibility of the single-layer epoxy powder coating and does not provide a protective shield for the cathodic protection, thus preserving its advantages.
4. Conclusion
Modern oil pipelines and tanks require high-performance anti-corrosion coatings to achieve ideal corrosion protection, but reducing VOC emissions from coatings is essential for improving their environmental friendliness. The ultimate goal is to continuously reduce VOC content in coatings to the point where they contain no VOCs at all. Currently, research on anti-corrosion coatings for oil pipelines and tanks in China has entered a new stage, focusing on enhancing the environmental friendliness and durability of these coatings, enabling them to be used in more complex and harsh environments. This requires improved preparation techniques and more research data to support their application.
References:
[1] Chen Yingtao. Research on Anti-Corrosion Coating and Construction Process for Large Crude Oil Storage Tanks [J]. Comprehensive Corrosion Control, 2020, 34(09): 108-110.
[2] Zhang Xinxin, Xu Naodi, and Yu Nan. Selection and Application of Anti-Corrosion Coatings in Tank Farm Anti-Corrosion Engineering [J]. Guangdong Chemical, 2012, 39(11): 165-166+72.
Article published in "Comprehensive Corrosion Control", Vol. 36, Issue 02, February 2022