Battling corrosion is a costly but critical requirement for the oil and gas industry. Billions of dollars are spent each year to protect and repair high-value infrastructure from corrosion. When it comes to pipelines, fusion-bonded epoxy (FBE) powder coatings play a central role.

FBE coatings have become a staple in pipeline protection, dominating as the primary coating solution for buried and subsea applications. These pipelines, often stretching thousands of miles, face continuous exposure to aggressive environmental conditions. FBE coatings form a durable barrier against moisture, soil electrolytes and corrosive chemicals, extending asset life while minimizing leaks and costly downtime.

Corrosion Prevention Strategies

Two key strategies, which are often used synergistically, can combat corrosion in pipeline applications: cathodic protection systems and anticorrosive coatings.

Cathodic protection systems work by converting the pipeline into the cathode of a galvanic cell. This is achieved by coupling it with a less noble metal, which serves as the anode and corrodes in place of the steel. When used in this manner, this less noble metal is commonly referred to as a “sacrificial anode,” thus offering “cathodic protection” to the pipeline. While more sophisticated cathodic protection systems exist, such as impressed current systems, the fundamental principle remains the same.

Complementing the cathodic protection systems are anticorrosive coatings, which form a physical barrier between the steel and the environment. These coatings may be solvent-based or powder coatings, and they can range from single to multilayer depending on pipeline location, environmental exposure and mechanical stress requirements. The main principle being employed here is to inhibit moisture and electrolytes from reaching the surface of the metal, thus preventing the initiation of corrosion.

Fundamentals of FBE Powder Coatings

FBE coatings are thermosetting powder coatings designed specifically to perform in the highly aggressive environments that pipelines are subjected to. The main binder consists of epoxy resin and curing agents that are formulated to form a tough, chemically resistant layer that bonds tightly to the substrate. These coatings typically utilize specialty materials and functional fillers, such as wollastonite, to improve mechanical strength, thermal stability and corrosion resistance to ensure optimal protection.

The application process is highly controlled. First, the surface of the pipeline undergoes abrasive blasting to remove contaminants and provide a roughened surface profile to maximize mechanical adhesion. The pipe is then preheated to 180–250 °C prior to coating application, a technique that ensures maximum bonding once the powder is applied.

Next, the FBE coating is electrostatically applied onto the hot surface, where it immediately flows and begins to cure, eventually forming a highly crosslinked film with a typical dry film thickness of 250–500 µm (10–20 mils). In some cases, the pipe may undergo a post-curing process to ensure the coating is fully crosslinked. Once sufficiently cooled via air or water jets, the coating is inspected for dry film thickness, continuity (holiday detection) and other parameters that are critical to performance in the field.

A Cornerstone in Pipeline Protection

FBE powder coatings owe their popularity to a variety of factors when compared to solvent-based coatings. The application process of FBE coatings is more efficient, as they only require one layer as opposed to the two or even three layers that are often required to adequately protect the pipeline with solvent-based coatings.

Durability is another key advantage. FBE coatings resist damage from abrasion and mechanical stresses that can be encountered during pipeline handling and installation. Their strong adhesion to steel (achieved during the fusion process) minimizes the risk of delamination, even under thermal cycling conditions. The strong bond also provides excellent resistance to cathodic disbondment, which is one of the more difficult requirements for pipeline applications.

Environmentally, FBE coatings have a significant advantage. They are 100% solids systems and thus emit virtually zero volatile organic compounds (VOCs) during the application and curing processes. Their high level of durability offers long service life, reducing the need for frequent maintenance or recoating, which lowers both the environmental impact and lifecycle costs of pipeline operations. Altogether, FBE coatings offer an attractive balance of cost, performance and sustainability profile for pipeline applications.

Challenges and Limitations of FBE Coatings

Despite their advantages, FBE coatings are not without challenges. The application process demands precision, as inadequate surface preparation or curing can compromise performance and lead to premature field failure. FBE coatings also lack flexibility at higher film builds and can be susceptible to cracking if the coated pipes are bent too aggressively. Additionally, because the system relies on high temperatures for application and curing, field repairs and coating of weld joints typically require the use of liquid coatings or other specialized repair materials.

Optimal Balance of Properties

Fusion-bonded epoxy powder coatings continue to play a central role in pipeline protection strategies. Their unmatched combination of corrosion resistance, mechanical durability and environmental performance makes them an ideal solution for buried and subsea pipelines. While they require careful application and have limitations in flexibility and repairability, their long-term benefit to service life makes FBE coatings a trusted choice in safeguarding critical pipeline infrastructure.

For more information, contact the author at ecasebolt@chemquest.com or visit https://chemquest.com.