Choosing and Implementing Strategies for Anticorrosive Coatings in Oil Tanks
In compliance with relevant specifications, it is imperative to apply an electrostatic conductive coating to the inner walls of crude oil tanks. Based on the nature of the conductive media, the common electrostatic conductive coatings for the inner walls of oil storage tanks can be categorized into three main types:
(1) Non-metallic Electrostatic Conductive Coatings: This category encompasses widely used coatings such as solvent-free epoxy antistatic oil pipe paint, epoxy phenolic oil tank paint, and epoxy oil-resistant antistatic anticorrosive paint.
(2) Metal Electrostatic Conductive Coatings: These coatings are influenced by the color of metal powder and offer cathodic protection with rust prevention effects on steel. When using metal powder with a lower potential as a medium, electrochemical corrosion may occur if the potential of the metal powder surpasses that of steel. Commonly employed metal electrostatic conductive coatings include epoxy zinc-rich primer and inorganic zinc-rich primer.
(3) Conductive Composite Mica Powder: Known for its enduring and effective conductivity, good paint film compactness, and the ability to produce various colors of electrostatic paint, conductive composite mica powder coatings are notable for their light color. However, they can be relatively expensive. Products in this category include light-colored solvent-free epoxy antistatic oil tank paint, light-colored epoxy phenolic oil tank paint, and light-colored epoxy oil-resistant antistatic anticorrosive paint, among others.
Anticorrosive coating for the outer wall
To ensure prolonged durability of oil tanks, the anti-corrosion coating on the outer wall is crucial. It comprises three layers: top coat, middle coat (often epoxy micaceous iron), and primer. Some tanks may have only two layers: top coat and primer. Polyurethane top coating is commonly chosen for its easy application, maintenance, and excellent properties such as unlimited coating time, compatibility, oil and solvent resistance, color retention, anti-pulverization, no yellowing, and aesthetic appeal. The middle coat provides effective shielding and impermeability against corrosive mediums. Inorganic zinc-rich and epoxy zinc-rich primers are widely used, offering benefits like excellent oil resistance, rapid drying, rust resistance, and cathodic protection. Regular evaluation of anti-corrosion coating quality is essential, ensuring the selection of high-quality coatings for oil storage tanks amid a diverse market.
Construction Strategy of Oil Tank Anticorrosive Coatings
Surface treatment
Prior to applying the anti-corrosion coating on the oil storage tank, it is imperative to sandblast, remove rust, and degrease the tank's surface. This ensures a flat, clean, and smooth surface, free from imperfections like burrs, rust spots, electric arc residues, and dust. The primer should be applied within 6 hours of completing the surface treatment.
Coating environmental conditions
Painting should occur in sunny weather, with a construction environment temperature between 5-35 degrees Celsius. Avoid painting in rainy, snowy, or foggy conditions. Choose a sheltered site with a clean environment to prevent rain, snow, or dust from settling on the wet paint surface. Ensure indoor air humidity does not exceed 80%. Before painting, ensure the oil tank is dry and clean.
Painting operation process requirements
Three commonly employed painting construction methods each possess distinct advantages and disadvantages. Selection should be based on coating performance, construction conditions, and the project area, ensuring a rational choice of construction method.
Brush coating method
Paintbrushes are utilized by workers for painting construction. During the process, pre-painting of corners, rivet heads, and welding seams precedes painting larger areas. To avoid omissions, a staggered approach is adopted, alternating between vertical and horizontal painting.
Roll coating method
Conclusion
This article provides a brief overview of choosing electrostatic conductive coating for the inner wall and anti-corrosive coating for the outer wall of oil storage tanks. It delves into the critical aspects of the construction strategy for anti-corrosive coatings, covering surface treatment, coating environmental conditions, and operational process requirements. The goal is to guarantee that the construction of anti-corrosive coatings for oil storage tanks aligns with quality standards.
(1) Non-metallic Electrostatic Conductive Coatings: This category encompasses widely used coatings such as solvent-free epoxy antistatic oil pipe paint, epoxy phenolic oil tank paint, and epoxy oil-resistant antistatic anticorrosive paint.
(2) Metal Electrostatic Conductive Coatings: These coatings are influenced by the color of metal powder and offer cathodic protection with rust prevention effects on steel. When using metal powder with a lower potential as a medium, electrochemical corrosion may occur if the potential of the metal powder surpasses that of steel. Commonly employed metal electrostatic conductive coatings include epoxy zinc-rich primer and inorganic zinc-rich primer.
(3) Conductive Composite Mica Powder: Known for its enduring and effective conductivity, good paint film compactness, and the ability to produce various colors of electrostatic paint, conductive composite mica powder coatings are notable for their light color. However, they can be relatively expensive. Products in this category include light-colored solvent-free epoxy antistatic oil tank paint, light-colored epoxy phenolic oil tank paint, and light-colored epoxy oil-resistant antistatic anticorrosive paint, among others.
Anticorrosive coating for the outer wall
To ensure prolonged durability of oil tanks, the anti-corrosion coating on the outer wall is crucial. It comprises three layers: top coat, middle coat (often epoxy micaceous iron), and primer. Some tanks may have only two layers: top coat and primer. Polyurethane top coating is commonly chosen for its easy application, maintenance, and excellent properties such as unlimited coating time, compatibility, oil and solvent resistance, color retention, anti-pulverization, no yellowing, and aesthetic appeal. The middle coat provides effective shielding and impermeability against corrosive mediums. Inorganic zinc-rich and epoxy zinc-rich primers are widely used, offering benefits like excellent oil resistance, rapid drying, rust resistance, and cathodic protection. Regular evaluation of anti-corrosion coating quality is essential, ensuring the selection of high-quality coatings for oil storage tanks amid a diverse market.
Construction Strategy of Oil Tank Anticorrosive Coatings
Surface treatment
Prior to applying the anti-corrosion coating on the oil storage tank, it is imperative to sandblast, remove rust, and degrease the tank's surface. This ensures a flat, clean, and smooth surface, free from imperfections like burrs, rust spots, electric arc residues, and dust. The primer should be applied within 6 hours of completing the surface treatment.
Coating environmental conditions
Painting should occur in sunny weather, with a construction environment temperature between 5-35 degrees Celsius. Avoid painting in rainy, snowy, or foggy conditions. Choose a sheltered site with a clean environment to prevent rain, snow, or dust from settling on the wet paint surface. Ensure indoor air humidity does not exceed 80%. Before painting, ensure the oil tank is dry and clean.
Painting operation process requirements
Three commonly employed painting construction methods each possess distinct advantages and disadvantages. Selection should be based on coating performance, construction conditions, and the project area, ensuring a rational choice of construction method.
Brush coating method
Paintbrushes are utilized by workers for painting construction. During the process, pre-painting of corners, rivet heads, and welding seams precedes painting larger areas. To avoid omissions, a staggered approach is adopted, alternating between vertical and horizontal painting.
Roll coating method
Workers employ rollers for quicker painting compared to the brush method. When dipping the roller in paint, it's crucial to ensure even coverage to prevent uneven application. Care should be taken to avoid a thick middle and thin sides or an uneven paint distribution. During painting, the roller should move steadily in both vertical and horizontal directions. Pre-coating is recommended for corners, rivet heads, and welds during construction
Air spraying method
The air spraying method is ideal for large-scale construction due to its high efficiency. Maintain a consistent distance and angle between the spray gun and the surface. Pre-coat corners, rivet heads, and welding seams during construction. Regularly check the wet film thickness, convert it to dry film thickness, preventing it from falling below or exceeding standards. Ensure each coating layer is fully cured and meets specifications before proceeding to the next step. Uniformly select representative measuring points during inspections, promptly coating areas with dry film thickness meeting specifications.
Conclusion
This article provides a brief overview of choosing electrostatic conductive coating for the inner wall and anti-corrosive coating for the outer wall of oil storage tanks. It delves into the critical aspects of the construction strategy for anti-corrosive coatings, covering surface treatment, coating environmental conditions, and operational process requirements. The goal is to guarantee that the construction of anti-corrosive coatings for oil storage tanks aligns with quality standards.
