When you’re laying or burying pipelines, it’s important to explore the options for coating. There are many types of coating, and each has the potential to reduce corrosion. By understanding the pros and cons of the different pipeline coating types, you can choose the one that’s best for you based on usage and environment.
You’ll want to have some kind of coating on the steel pipes. Otherwise, pipes will corrode – and that can lead to leaks and several other problems. Essentially, the coating will add durability and increase the lifespan so that it is resistant to the various elements it comes up against outside or within your operations.
A professional pipeline coating company can help to direct you toward the best coating type for your operation. At Element Coatings, for example, experienced technicians can discuss the pros and cons after learning more about what your pipes are regularly exposed to.
Coal Tar Epoxy
Coal tar epoxy/enamel offers one of the most affordable coatings on the market. It was popular decades ago as a solution to the naked pipeline. However, it has grown to be a less dominant coating because it is so toxic. As such, it is only used in a limited number of situations.
Pros:
- Low cost
Cons:
- Highly flammable
- Highly toxic
Asphalt Enamel
Asphalt Enamel has a limited life, which means that the coating will likely have to be reapplied at some point. However, it does offer a fast cure – and is considered to be a better solution than coal tar epoxy as it is not as toxic.
Pros:
- Low cost
- Fast cure
Cons:
- Limited temperature range
- Poor chemical resistance
Liquid Epoxy
Liquid epoxy is commonly used in applications where the pipes will be working with water or electricity. If the liquid traveling through the pipe is hot, other solutions will work better as the epoxy begins to decompose at temperatures above 250 degrees.
Pros:
- Excellent water penetration
- Good bendability
- Excellent electrical resistance
Cons:
- Limited field applications
- Limited heat resistance
Fusion-Bonded Epoxy
Fusion-Bonded Epoxy (FPE) can go on as either a liquid or as a powder. It adheres well to steel, which is why it’s a common solution when working with oil pipelines and various industrial pipes. The polymer coatings vary from traditional paint coatings because they offer a harder component – and can hold up in more extreme conditions.
Pros:
- Premium chemical resistance
- High dimensional stability
Cons:
- Expensive
- High labor requirement
Liquid Polyurethane
Liquid polyurethane is one of the more flexible options for pipeline coating. It is commonly used in mill and field applications due to its good bendability and impact resistance. It offers a lower heat resistance than coal tar epoxy and lower solvent resistance than liquid epoxy, so it’s not a common choice for most applications.
Pros:
- Excellent water penetration
- Excellent electric resistance
Cons:
- Limited heat resistance
- Decent impact resistance
High-Density Polypropylene
High-density propylene is highly resistant in several categories. It allows the pipes to bend and resist a significant amount of impact. Depending on what is going through the pipe, however, it is only fairly resistant to such things as sulfur and amines.
Pros:
- Low material cost
- Low application cost
- Excellent water penetration
Cons:
- Limited heat resistance
- Lacks dimensional stability
In many instances, it is actually a three-layer polypropylene (3LPP) that is used to offer an external anti-corrosion coating.
Multi-Layer Epoxy Systems
Multi-layer epoxy systems may use many products to help with chemical resistance and adhesion. While the cost is initially higher, it can offer a higher level of protection against the elements as well as whatever fluid travels through the pipes.
Pros:
- Excellent adhesion
- Resistant to hydrocarbons
- High resistance to abrasion
Cons:
- Stringent application parameters
- High initial cost
Metallic Spray Coatings
Aluminum, zinc, and other metallic spray coatings offer thermal protection. Depending on the length of the pipe, the spray can provide an easy method of installation. If you’re going to submerge the piping system, this is a low-cost solution.
Pros:
- Low cost
- High corrosion protection
Cons:
- Limited temperature protection
Prepping the Pipeline
Often, it’s helpful to have a coating inspection done on the pipelines before you begin the installation process. There are several reasons for this.
First, you’ll be able to look at the integrity of the pipeline. If there are already signs of wear, corrosion, or other issues, you’ll need to replace or prep the pipe.
Second, you’ll be able to make sure that the selected coating is capable of meeting industry standards.
Finally, with the help of a pipeline coating inspector, you can ensure that you get the most appropriate coating. Otherwise, you may end up putting your operations at risk or get a subpar product that will need to be replaced sooner than you had originally anticipated.
Choose the Pipeline Coating that Works for You
The pipeline coating you choose should be long-lasting and be applied where you need it – either in the field or be coated before you begin laying the pipeline.
Ultimately, before you choose any type of pipeline coating, you’ll want to review the factors that will impact the pipes:
- Climate and location of the pipeline
- The physical state of fluid transported in the pipeline
- Flammability of fluid
- Viscosity of fluid
It is also important to remember that there are both internal and external coatings available for your pipeline. As you choose internal coatings, they must be able to withstand the high impact that moving particulates create as they travel. As you explore external coatings, they have to withstand environmental conditions that range from soil stress to saltwater to contaminants in the air.
Talk to a pipeline coating company to find out what their qualifications are. Once you have weighed the pros and cons of a coating, you can move forward with confidence knowing that you are making a solid investment.
