The metals we use in the construction of the structures, when exposed to environmental conditions, can quickly deteriorate and lead to structural failure. One of the major issues that affect metals is corrosion. And the cost of corrosion is often very high. According to the National Association of Corrosion Engineers (NACE), half of all corrosion costs could have been prevented, and one of the most effective ways is through the use of protective coatings. In fact, 85% of the various ways to prevent corrosion involves the use of some sort of protective coating.
But what are protective coatings? How do these formidable corrosion resistors work? What protective coating types do we have? And how would you ship them in bulk?
What are Protective Coatings?
Protective coatings, such as paints, are layers of solid materials that we apply to substrates to protect the substrates from corroding. A protective coating could be liquid, mastic composition, or liquefiable before use. But as soon as they are applied, they dry up and solidify to form a film that protects or decorates the application surface. Application options for protective coatings include spray, welding on, applying through hand tools, or plating on.
With the use of protective coatings on metals, we can significantly reduce the slow, but catastrophic, effects of corrosion. A common example of a protective coating is paint. Other examples include bitumen, tar, plastics, and pitch. And each of these coatings is used in various applications, such as infrastructure, water treatment, commercial architecture, power generation, marine, industrial maintenance, and oil and gas exploration.
Although corrosion is one of the major reasons we use protective coatings, protective coatings help to resist:
- Chemical attack
- Fire damage
- Physical damage, and
- Thermal degradation
Usually, we apply a protective coating after we are done with construction. And the number of layers of coatings to use depends on the constructor and the environmental demand on the coating. However, some metal pieces have to be primed by the manufacturer from the factory before they ship them to their final destinations to be used. There, the constructor installs the metals and gives them a final layer of coat.
The use of protective coating is non-negotiable because of the importance of the structures they protect. For instance, you wouldn’t want to risk using a metal pillar without a protective coating. And this is why protective coatings are generally valuable and expensive.
How do Protective Coatings Work?
The ways protective coatings protect the surfaces they are applied on are quite intuitive. They either prevent the corroding process from happening, inhibit the coming together of corrosion prerequisites, or redirect the process of corrosion so that it has no adverse effect on the material they are applied on. These three methods of operation help us to classify the protective coatings into inhibiting coatings, barrier coatings, and sacrificial coatings.
Inhibitive coatings, often found among primers, are the ones that stop corrosion from happening at all. By interfering with the electrolytes that the corrosion process needs before it begins, inhibitive coatings ensure that corrosion is not even a problem in the first place.
For a long time, red lead was the perfect example of an inhibitive coating. However, when the harmful effects of lead came to light, its use has been regulated and reduced to a minimum.
As the name suggests, barrier coatings form a wall that prevents corrosion requirements from coming in contact with the application surface. Although we can’t completely stop water and other corrosion ingredients from touching the substrate with barrier coating alone, the barrier coating still makes sure to rid the water of a significant amount of ions. So that even if corrosion was to happen, there aren’t enough ions to initiate a significant corrosive effect.
A lot of protective coatings fall into this category to some extent, if not completely. Thermal barrier coatings are a good example of barrier coatings. And they are often used to prevent corrosion on metals that are exposed to high temperatures during their lifespans.
Sacrificial coatings are protective coatings that often contain metal, such as zinc, that corrodes faster than steel. When you apply a sacrificial coating to the surface of a metal, the coating does the corroding instead of the metal. And by doing so, protects the metal beneath it by forming a barrier of corroded zinc between the environment and the underlying metal. You could liken sacrificial coatings to the heroes who save the day in the movies but die in the process.
The Types of Protective Coatings
As you might expect, protective coatings are not all the same. Their areas of application are so wide that it is impossible to have just one protective coating for all purposes. Also, there are many materials we can use to make protective coatings, and each has its strengths and weaknesses. Consequently, we have various types of protective coatings for different purposes.
1. Two-Part Epoxy Coatings
The best thing about the two-part epoxy coating is that it contains a resin and a hardener. And with this combination, we can derive various coating properties, depending on how we manipulate the components. For instance, using bisphenol A as a resin for the two-part epoxy would yield different chemical and physical properties than using phenolic novolac. As a result of their property flexibility, epoxy coatings are used in heavy-duty industrial applications on iron and steel.
What might be a downside to epoxy coatings is that they are limited in their aesthetics properties. For instance, you shouldn’t rely solely on epoxy coatings to have excellent gloss retention or look striking. Fortunately, you can layer epoxy coatings on other types of protective coatings to get the best of everything. However, their functional effects are irresistible. Their chemical, water, and abrasion resistance properties are remarkable.
Advantages of two-part epoxy coatings
- Excellent corrosion resistance properties
- Resistant to friction
- Resistant to corrosive fluids
- Effective in extreme temperature applications
- Retains its properties when submerged
- Can be manipulated to derive various coating properties
Disadvantages of epoxy coatings
- Poor aesthetics properties
- Exposure to UV light chalks it
Applications of epoxy coatings
- Excellent for interior tank linings
- Marine conditions, such as bridges, hydroelectric facilities, offshore oil platforms
- Oil and gas pipelines
- Automotive applications (because of their resistance to heat)
The strengths of the polyurethane coatings lie in their durability and their high abrasion resistance. Another remarkable property of polyurethane coatings is their excellent aesthetic property, which is more pronounced in the aliphatic polyurethanes, a category of polyurethane coatings. The aliphatic polyurethanes also manage to pull off an impressive performance under sunlight, which makes them suitable for coating exterior surfaces.
Aromatic polyurethanes, on the other hand, can’t boast of this sunlight-resistant performance. In fact, sunlight chalks them. However, use aromatic polyurethanes in marine applications and you’ll get the best from them. Generally, polyurethane coatings are preferred as topcoats over other layers of coatings.
Advantages of polyurethane coatings
- Excellent abrasion resistance
- Remarkable aesthetic properties
- The aliphatic polyurethanes are suitable for use on surfaces exposed to sunlight
- The aromatic polyurethanes are suitable for submerged surfaces
Disadvantages of polyurethane coatings
- Polyurethanes are more expensive than epoxies
- The presence of isocyanate (-NCO) makes it a harmful carcinogenic
- Requires skilled workers wearing protective gear to apply
Applications of Polyurethane coatings
Polyurethane coatings are mostly used as topcoats in
- Marine applications
- Nuclear power plant coatings
Polysiloxanes have the excellent abrasion resistance of the other protective coating types. They also exhibit excellent weather resistance and aesthetics. But where polysiloxane coatings beat the others is when they’re combined with epoxies to form epoxy polysiloxanes coatings.
Epoxy polysiloxane coatings offer the best of epoxies and polysiloxanes. As a result, the combination provides unbeatable weather, abrasion, UV, corrosion, and chemical resistance. This combination makes up the master combination for various coating needs and applications. In addition to their versatility, epoxy polysiloxanes are easy to apply and more durable.
The only critical disadvantage of epoxy polysiloxane is that they are very expensive when compared to other protective coating types.
Advantages of Polysiloxane coatings
- Excellent abrasion and weather resistance
- Great aesthetics
- They make two-coat applications possible (polysiloxane and a zinc primer), as opposed to the more popular three-coat application involving zinc, epoxy, and polyurethane. The result is a reduction in labor costs
- Excellent performance under UV light
- More resistant to high temperatures than the other coating types
Disadvantages of polysiloxane coatings
- They are expensive
Applications of polysiloxane coatings
- The versatility of epoxy polysiloxane makes them suitable for most applications.
Zinc-rich protective coatings are often sacrificial coatings. That is, they corrode in the place of the substrate they are applied on. This galvanic protection of substrates has proven to be very effective for various applications. Zinc-rich coatings also double as barrier protective coatings, as they form a wall between the environment and the substrate as they corrode.
The two types of zinc-rich coatings are organic and inorganic coatings. While the organic zinc-rich coatings contain polyurethane or epoxy binders, their inorganic counterpart contains silicate binders. And though the latter offers more effective abrasion resistance and galvanic protection, the former does not require extreme surface preparation before application.
The strong galvanic protection property of zinc-rich coatings makes them most suitable for applications where corrosion is the main villain.
Advantages of zinc-rich coatings
- Excellent abrasion resistance
- Very durable
- Suitable for steel coating, as it offers both barrier and galvanic protection.
- Zinc-rich coatings have high UV resistance
- They are easy to apply, as long as the substrate surface is clean
Disadvantages of zinc-rich coatings
- Zinc-rich coatings need to be top coated
- The surface of the substrate needs to be well cleaned before applying inorganic zinc-rich coatings
Applications of zinc-rich coatings
Zinc-rich coatings are well suited for highly corrosive environments, such as:
- Marine applications
- Water treatment plants
- Architectural applications
- Pumps and compressors
How to Ship Protective Coatings in Bulk
Protective coatings are best shipped in trailers. These trailers must have had their interior linings covered with protective coatings themselves to prevent their chemical content from damaging their walls.
Another important factor to put into consideration is the hazardous nature of some chemicals that are present in some protective coatings. When wrongly handled during transport, these chemicals could spill out and cause bodily harm to anyone closeby. In addition to that, this could lead to penalties from regulatory bodies, such as the United States Department of Transportation (USDOT), which are in charge of the transport of hazardous chemicals.
These same regulatory bodies have laid down an eternally long and ever-increasing list of regulations as regards the bulk transport of hazardous materials. And some protective coatings fall under this category. Failure to comply with every single one of these regulations is risking the ire of the unforgiving regulatory bodies.
How Total Connection Eases Your Bulk Protective Coatings Shipping
You could try to ship your bulk protective coatings all on your own, making sure to avoid breaking any of the regulations while still keeping up with updates on these regulations. Of course, that’s assuming that you have the right trailers to ship them and enough well-trained labor to handle the shipping and paperwork. Or you could leverage the expertise and experience of Total Connection logistics company in shipping bulk protective coatings. And you would be saving your company a lot of stress, expense, and unnecessary labor.
Total Connection is a third-party logistics company that prides itself in helping you tighten up your supply chain by offering affordable, efficient, and flexible services. Let us know what you would like us to ship for you by filling out the quote form below and watch us take it over from there.