What are Anti Corrosive Coatings?
Anti Corrosive Coatings on Steel are widely used to protect the pipes from corrosion and extend the structural life of the material. These coatings act as a barrier from corrosive materials and provide chemical protection, abrasion resistance, and other advantages. They are an effective and economical option for tackling corrosion in industries such as oil and gas, chemical, petrochemical, infrastructure, marine, power generation, etc.
Purpose of Anti Corrosive Coatings
Anti Corrosive Coatings serve multiple purposes, including protecting metal surfaces from oxidation, preventing direct contact with environmental chemical hazards, acting as a barrier for corrosive materials, and prolonging the structural life of the material. These coatings are essential for protecting investments in terms of money, property, and safety of workers.
Selection of Anti Corrosive Coatings
The selection of anti-corrosion coatings is not an easy process and various parameters need to be ensured. A wide variety of anti-corrosive coatings are available in the market to suit the performance requirements of a specific application and the coating manufacturer needs to be consulted for some specific information.
Physical Corrosion in the Oil and Gas Industry
Physical corrosion in the oil and gas industry is caused by erosion, which is the gradual wearing away of materials due to physical forces, such as friction. This can be seen on the outside of metal pipes, where the metal is slowly worn away, leaving the pipe thinner and weaker than before.
Chemical Corrosion in the Piping and Pipeline Industry
Chemical corrosion in the piping and pipeline industry is an irreversible loss of material due to chemical reactions with the environment. This can occur when the materials used to construct the pipelines are not compatible with the chemicals present in the surrounding environment.
Electro-chemical Corrosion in the Oil and Gas Industry
Electro-chemical corrosion in the oil and gas industry is caused by electric microcells, which form when two dissimilar metals come into contact. This creates an electrical current which leads to corrosion of the metal.
Biological Corrosion in the Piping and Pipeline Industry
Biological corrosion in the piping and pipeline industry is caused by bio-fouling, which is the accumulation of organic material, such as bacteria and algae, on the surface of the pipe. This organic material can cause corrosion, leading to weakened pipes and reduced flow.
Types of Corrosion
Erosion:
Erosion corrosion is a form of corrosion that commonly occurs in lead-lined vessels, primarily in the area near the impeller. This type of corrosion results from the mechanical wear and tear of the metal over time.
Pitting:
Pitting corrosion is a form of corrosion that manifests as microscopic holes in the otherwise untouched surface of the metal. This type of corrosion is usually caused by the accumulation of chloride ions in the metal surface.
Selective Leaching:
Selective leaching corrosion is a form of corrosion that results in the dezincification of copper-zinc alloys. This type of corrosion occurs when zinc ions in the alloy are selectively removed from the alloy, leaving behind copper ions.
Intergranular Corrosion:
Intergranular corrosion is a form of corrosion that occurs when a metal has been improperly heat-treated or welded. This type of corrosion can lead to a weakened metal structure, which can potentially result in failure.
Stress Corrosion:
Stress corrosion is a form of corrosion that is caused by the combination of a metal’s mechanical stress and its exposure to a corrosive environment. This type of corrosion is commonly caused by welding, cold work, or other forms of mechanical stress.
Crevice Corrosion:
Crevice corrosion is a form of corrosion that occurs when an electrochemical cell forms in a crevice of the metal. This type of corrosion is caused by the accumulation of moisture or other corrosive materials in the crevice.
Preventing Corrosion:
In order to prevent corrosion, it is important to ensure that the metal surface is as clean as possible before applying any coating. Additionally, the metal surface should not have any scratches or other imperfections. Finally, the anti-corrosive coating itself should be environmentally friendly in order to avoid any further damage to the metal.
Types of Anti-Corrosive Coatings
There are various types of anti-corrosive coatings which can be used to protect metal surfaces from corrosion. Depending on the materials used, these coatings can be divided into natural paints, epoxy, polyurethane, synthetic resins, plastics, phenolic, composites, alkyd, fiber reinforced plastics, glass lining, graphite, and rubber.
Natural Paints
Natural paints are a type of anti-corrosive coating often used for new pipes, as well as for maintenance and repair work. They offer protection from corrosion by forming a barrier between the metal surface and the environment.
Epoxy
Epoxy is another type of anti-corrosive coating which is commonly used for new pipes, as well as for maintenance and repair work. It provides excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Polyurethane
Polyurethane is a type of anti-corrosive coating which is often used for maintenance and repair work. It offers excellent resistance to wear and abrasion, as well as protection from corrosion. It is available in a variety of colors and finishes.
Synthetic Resins
Synthetic resins are a type of anti-corrosive coating which is often used for new pipes, as well as for maintenance and repair work. They offer excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Plastics
Plastics are a type of anti-corrosive coating which is often used for new pipes, as well as for maintenance and repair work. They offer excellent protection from corrosion and can be applied in a wide variety of thicknesses.
Phenolic
Phenolic is a type of anti-corrosive coating which is often used for new pipes, as well as for maintenance and repair work. It provides excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Composites
Composites are a type of anti-corrosive coating which is often used for new pipes, as well as for maintenance and repair work. They offer excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Alkyd
Alkyd is a type of anti-corrosive coating which is often used for new pipes, as well as for maintenance and repair work. It provides excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Lining:
Fiber Reinforced Plastics
Fiber reinforced plastics are a type of anti-corrosive lining which is often used for new pipes, as well as for maintenance and repair work. They offer excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Glass Lining
Glass lining is a type of anti-corrosive lining which is often used for new pipes, as well as for maintenance and repair work. It offers excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Graphite
Graphite is a type of anti-corrosive coating which is often used for new pipes, as well as for maintenance and repair work. It provides excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Rubber
Rubber is a type of anti-corrosive coating which is often used for new pipes, as well as for maintenance and repair work. It provides excellent protection against corrosion and can be applied in a wide variety of thicknesses.
Rubber Lining as an Anti-corrosive agent
Natural Rubber Lining
Natural rubber is one of the most commonly used rubber materials for lining applications as it has excellent abrasion resistance and is relatively chemically inert. It is well suited for applications such as storage tanks, pipelines and other vessels that contain corrosive liquids.
SBR Rubber Lining
SBR (Styrene-Butadiene Rubber) is a synthetic rubber that is commonly used for rubber lining applications. It offers superior abrasion, tear and impact resistance compared to natural rubber and is also resistant to most oils and chemicals.
Neoprene (Polychloroprene) Rubber Lining
Neoprene is a synthetic rubber that is commonly used for rubber lining applications. It offers superior abrasion, tear and impact resistance compared to natural rubber and is also resistant to most oils and chemicals. It is especially well-suited for applications that require exposure to higher temperatures.
Butyl (Isobutylene) Rubber Lining
Butyl rubber is a synthetic rubber that is commonly used for rubber lining applications. It has excellent resistance to weathering, ozone, and oxidation, and is also resistant to most chemicals and oils. It is ideal for applications that require exposure to higher temperatures and has superior abrasion and tear resistance compared to natural rubber.
Halogenated Butyl Rubber Lining
Halogenated Butyl rubber is a synthetic rubber that is commonly used for rubber lining applications. It is a halogenated version of butyl rubber that offers superior chemical and oil resistance, along with superior abrasion and tear resistance compared to natural rubber.
Bromobutyl Rubber Lining
Bromobutyl rubber is a synthetic rubber that is commonly used for rubber lining applications. It is a brominated version of butyl rubber that offers superior oil and chemical resistance, along with superior abrasion and tear resistance compared to natural rubber.
Applications of Rubber Lining:
Neoprene Rubber Lining:
Neoprene rubber lining is highly resistant to acid, abrasion, oil, and seawater, making it an ideal choice for high temperature and corrosive service applications, where natural rubber fails. Neoprene rubber lining is especially useful in chlor-alkali plants, phosphoric acid plants, and DI water plants.
Butyl Rubber Lining:
Butyl rubber lining is an ideal choice for high-temperature corrosive service applications, such as reaction vessels, as well as hot and abrasive services. Butyl rubber lining provides superior protection against extreme heat and corrosive fluids and is commonly used in chlor-alkali plants, phosphoric acid plants, and DI water plants.
Fluoropolymer Coatings and Linings
Corrosion can be a major issue for industrial and commercial applications, leading to costly repairs and downtime. To combat this, fluoropolymer coatings and linings offer a comprehensive solution to protect surfaces from the effects of corrosion. These coatings consist of high-performance resins and fluoropolymer lubricants that form a smooth, hard and slick final coating. This provides excellent protection against corrosion and chemical damage, while also creating a lubricated surface for improved performance.
Advantages of Fluoropolymer Anti-Corrosion Coatings and Linings
Fluoropolymer anti-corrosion coatings offer a wide range of benefits for both industrial and residential applications. These coatings provide excellent resistance to corrosion, abrasion, and impacts, as well as electrical and chemical resistance. They also have a broad temperature range and are weather-resistant, making them an ideal choice for many industrial and residential uses. Here are some of the key advantages of fluoropolymer anti-corrosion coatings:
- Resistance to Galling
Fluoropolymer anti-corrosion coatings provide excellent resistance to galling, which is the process of metal surfaces being worn away by friction. This makes them ideal for high-friction applications such as automotive components. - Non-Wetting Surface
Fluoropolymer coatings provide a non-wetting surface, meaning that it will prevent any liquids from sticking to the surface. This makes them very easy to clean and helps to reduce the risk of corrosion caused by standing water. - Reduced Friction
Fluoropolymer coatings also provide a reduced friction surface, making them ideal for applications that require a low-friction surface. This can also help to reduce wear and tear on components, making them last longer. - Non-Stick Surface
Fluoropolymer coatings provide a non-stick surface, meaning that they will not attract dust and dirt particles. This makes them ideal for applications in high-traffic areas, as they will be easy to clean. - Electrical Resistance
Fluoropolymer coatings provide electrical resistance, which is important for applications such as electrical wiring. This ensures that electrical components are protected from corrosion and other damage. - Abrasion Resistance
Fluoropolymer coatings provide excellent abrasion resistance, meaning that they will not easily be scratched or damaged. This makes them ideal for applications where the surface may be exposed to wear and tear. - Chemical Inertness
Fluoropolymer coatings are chemically inert, meaning that they will not react with most substances. This makes them ideal for use in a wide range of applications, including food and drug service.
Conclusion
Fluoropolymer anti-corrosion coatings provide excellent protection against corrosion, abrasion, impacts, and electrical and chemical resistance. They also have a broad temperature range and are weather-resistant, making them an ideal choice for many industrial and residential uses.
Advantages of High-Build Coatings
Lowers Metal Content:
High-build coatings reduce permeation through the coating and possible corrosion of the metal substrate, leading to a lower metal content in the fluid being handled.
Extends Life:
The thick coatings offered by high-build coatings are more durable when exposed to abrasive media, making them more resistant to wear and tear and extending their life.
Repairable:
High-build coatings can be easily repaired by welding if they become mechanically damaged. Thin coatings (<20mil) must be stripped and recoated if repairs are not possible.
Pressure-Vacuum Cycling:
Thick coatings are also better able to withstand pressure-vacuum cycling than thin coatings.
Cost-Effective:
The cost of a thick coating is not directly proportional to its thickness. Longer online performance is achieved at only a small additional cost with high-build coatings.
No Welds:
No welds exist with a high-build coated vessel in comparison to one that is sheet-lined. Welds in sheet-lined vessels are a known point of failure.
Uses:
High-build coatings are used in all chemical processes with hazardous, corrosive, abrasive and-or toxic media. They are also well-established in the chemical, pharmaceutical, and petrochemical industry.
Resistance:
High-build coatings are ideal in any plant because of their good chemical and physical resistance and long lifetime in service. They are also insensitive to mechanical impact, alternating pressure, vibration, temperature shock, and aging.
Application of High-Build Coatings
High-build coatings are widely used for anti-corrosion applications. These coatings provide a protective layer on surfaces to protect them from corrosion and other environmental damage. They come in a variety of forms, from high-solids to low-solids coatings, to suit a variety of application needs.
Mixed Beds
Mixed beds are a common application for high-build coatings. These beds consist of a mixture of different materials, such as sand and gravel, that are used to filter impurities from water or air. High-build coatings are applied to these beds to protect the materials from corrosion and other environmental damage.
Water Storage Tanks
High-build coatings are also often used to protect water storage tanks from corrosion. These coatings provide a layer of protection from rust and other forms of corrosion, ensuring that the tank remains in good condition for many years.
Pumps
Pumps are another application for high-build coatings. These coatings protect the pump from wear and tear caused by frequent use, as well as corrosion caused by exposure to water and other liquids.
Piping
High-build coatings are also used on piping systems to protect them from corrosion and other environmental damage. These coatings provide a layer of protection from rust, ensuring that the system remains in good condition for many years.
Chemical Storage Tanks
Chemical storage tanks are another common application for high-build coatings. These coatings provide a layer of protection from corrosion caused by exposure to chemicals, ensuring that the tank remains in good condition for many years.
Valves
Valves are another common application for high-build coatings. These coatings provide a layer of protection from corrosion, ensuring that the valve remains in good condition for many years.
Chemical Day Tanks
Chemical day tanks are another common application for high-build coatings. These coatings provide a layer of protection from corrosion, ensuring that the tank remains in good condition for many years.
Filter Housings
Filter housings are another common application for high-build coatings. These coatings provide a layer of protection from corrosion, ensuring that the housing remains in good condition for many years.
Wet Bench Components
Wet bench components are another common application for high-build coatings. These coatings provide a layer of protection from corrosion, ensuring that the components remain in good condition for many years.
Vacuum De-gasifiers
Vacuum de-gasifiers are another common application for high-build coatings. These coatings provide a layer of protection from corrosion, ensuring that the de-gasifier remains in good condition for many years.
Agitators
Agitators are another common application for high-build coatings. These coatings provide a layer of protection from corrosion, ensuring that the agitator remains in good condition for many years.
CMP Components
CMP components are another common application for high-build coatings. These coatings provide a layer of protection from corrosion, ensuring that the components remain in good condition for many years.
Anti Corrosive Coating Selection Criteria
Chemical Exposure
When selecting a suitable anti-corrosive coating, it is important to take into consideration the potential chemical exposure that the coating may be subject to. This includes the type and concentration of the chemicals and their potential to damage the coating.
Permeability of Coatings
The permeability of the coatings to the materials they are intended to protect must also be taken into consideration when selecting an anti-corrosive coating. The coating must be able to provide a barrier that effectively prevents corrosion.
Pressure Considerations
When handling gaseous materials, the pressure that the coating must be able to withstand should be taken into account when selecting a suitable anti-corrosive coating.
Purity and Regulatory Requirements
When selecting an anti-corrosive coating, the purity requirements of the coating should be taken into consideration, as well as any FDA and USDA requirements that may apply.
Maximum Operating Temperature
The maximum operating temperature of the coating should also be taken into consideration when selecting an anti-corrosive coating. This is important to ensure that the coating is able to withstand the high temperatures that may be encountered in some applications.
Abrasives
When selecting an anti-corrosive coating, any abrasives that may be present should be taken into consideration. These abrasives may damage the coating if not properly controlled.
Cost
The cost of the coating should also be taken into consideration when selecting an anti-corrosive coating. The cost of the coating will depend on a variety of factors, such as the type of coating, the thickness of the coating, and the complexity of the vessel configuration.
Vessel Configuration
The dimensions and complexity of the vessel configuration should also be taken into consideration when selecting an anti-corrosive coating. This will help to ensure that the coating is able to provide the necessary protection for the vessel.
Desired Fluoropolymer
The desired fluoropolymer should also be taken into consideration when selecting an anti-corrosive coating. This will help to ensure that the coating is able to provide the necessary protection against corrosion.
Thickness of Lining
The thickness of the lining should also be taken into account when selecting an anti-corrosive coating. The thickness of the coating will determine the level of protection that the coating is able to provide.
Reparability
The reparability of the coating should also be taken into consideration when selecting an anti-corrosive coating. This will help to ensure that any damage to the coating can be easily repaired.
Track Record
The track record of the coating should also be taken into consideration when selecting an anti-corrosive coating. This will help to ensure that the coating is able to provide the necessary protection and performance over time.
Coatings and Linings Thickness Selection Criteria
When it comes to selecting the thickness of protective coatings and linings, the key factor to consider is the corrosion rate of the underlying carbon steel. If the corrosion rate is greater than 10 mpy (mills per year), then thick linings are recommended. Thick linings are defined as having a thickness greater than 25 mils (0.635mm). Conversely, if the corrosion rate is less than 10 mpy (mills per year), then thin linings should be applied. Thin linings are defined as having a thickness less than 25 mils (0.635mm).
Thin Lining for Product Purity and Nonstick:
Thin lining is an ideal choice for products that require purity, such as food-grade materials, as well as nonstick surfaces. It helps prevent localized corrosion and keep the product free from contamination.
Thick Lining for Corrosion Prevention and Permeation Resistance:
Thick lining is an effective option for corrosion prevention and permeation resistance. It is much more durable and can provide a long-term solution for protecting surfaces from corrosion. It also prevents the permeation of liquids, gases, and other materials, which can be hazardous.
Coatings vs Linings: A Comparison
When it comes to thickness, coatings range from 10 to 1500 microns (0.01 to 1.5mm) whereas linings range from 3000 to 5000 microns (3 to 5 mm). Not only this, coatings can be done from both inside and outside, however, lining is only done from the inside of the pipe. Additionally, lining involves placing a pipe inside a pipe, whereas pipe coatings are different from this.
Why Coatings are better than linings with respect to the following:
Adhesive Forces
Coatings provide a stronger adhesive force than linings, making them a better choice for applications that require a strong bond. This is especially true for vacuum applications, as coatings create a stronger seal than linings and better prevent air from escaping.
Vacuum Application
Coatings offer a superior seal to linings when used in a vacuum application. This is due to the increased adhesive force of the coating, which creates a tighter seal and prevents air from leaking out.
Heat Transfer
Coatings provide better heat transfer than linings due to their higher thermal conductivity. This makes them ideal for applications where thermal shock is a concern, as coatings can quickly and evenly dissipate heat.
Thermal Shock
Coatings are better at withstanding thermal shock than linings due to their higher thermal conductivity. This allows coatings to dissipate heat quickly and evenly, reducing the risk of thermal shock.