The basic function of any paint or coating is to protect the substrate underneath from degradation and corrosion. Corrosion control is especially important when dealing with high-value assets, such as offshore oil rigs and other industrial structures, which must withstand harsh environmental conditions such as salt water and intense temperatures.

According to NACE International, a global leader in developing corrosion prevention and control standards, certification and education, the total annual U.S. cost for organic and metallic protective coatings is $108.6 billion. The organization stated that fifty percent of all corrosion costs are preventable, and approximately 85 percent of these are in the area of coatings.

Protecting a substrate from corrosion is one of the most important functions of coatings. Much care must be put into selecting the proper coating to meet the individual performance goals of the customer.  

“Each application presents different challenges and the choice of technology will depend greatly on the operational environment,” said  Bas Hesselink, technical manager – Protective Coatings at AkzoNobel.

AkzoNobel offers a full range of anticorrosive technologies, including polyurea-based direct-to-metal systems for general exterior use, zinc-based epoxy systems for more corrosive environements, epoxy high-build barrier coatings for aggressive environments such as offshore structures, and highly specialized coatings such as temperature-resistant silicone based systems for the most extreme challenges.”

Axalta Coating Systems provides a full range of both liquid and powder coatings. Its liquid portfolio includes both waterborne and solventborne products that vary by resin chemistry and inhibitive and barrier pigmentation packages to meet corrosion protection goals.  Both zinc-based and zinc-free primers are available.

“A number of Axalta’s powder products are specifically designed for corrosion protection applications,” said Doug Cinoman, research manager for Axalta Research and Development. “Nap-Gard fusion-bonded epoxy (FBE) powder coatings are widely used to help protect pipeline structures from corrosion. They are formulated to offer enhanced physical and chemical stability, resistance to soil stress, adhesion to metal, and resistance to abrasion and excellent corrosion resistance.   Alesta ZeroZinc powder coatings are also designed to protect against corrosion.  The ZeroZinc primer line offers outstanding corrosion resistance and is zinc-free – while still meeting the ISO 12944, C5 I standard. Ganicin undercoats, recently introduced, also provide corrosion protection in a liquid product. ‘

Bill Sante, director of marketing and business development for Axalta’s powder coating business said there is opportunity for durable polyester coatings, such as Abcite powder coatings, for architectural steel and aluminum that are exposed to salt-water environments on oil rigs and elsewhere.  “FBE coatings for pipe and rebar, such as Axalta’s Nap-Gard powder coatings, are designed to withstand high operating temperatures and exposure to aggressive chemicals, which is key to the oil and gas sector.” 

When choosing the right corrosion protection product there are many elements to consider. Factors related to substrate preparation, customer’s budget and performance goals, are all key considerations.

“First, factors related to the substrate itself must be considered,” said Cinoman. “These include the type of metallic substrate and its inherent susceptibility to corrosion, shape complexity (curved surfaces, edges, corners, crevices), surface preparation (roughness), and cleanliness (dirt, oil, grease, rust). Next, environmental and operating conditions must be taken into account.  Regulatory and emission requirements can vary by jurisdiction requiring the selection of compliant systems.  In use, exposure to harsh conditions (temperature, corrosive liquids and gases, mechanical wear) and their duration will guide the coating choice.”

“Finally, customer specific attributes and end-use specifications play a critical role,” Cinoman added.  “These can include cost, color, hiding power and ease of application.  The related durability requirements/warranties with respect to structural integrity and color/gloss retention are also a factor.”  

“The most important factor is the end-use environment, particularly in aggressive offshore locations, to ensure that the system meets the customer’s performance expectations,” said Hesselink. “In addition, coatings also have to meet local standards and certification requirements which can vary significantly. Application conditions and surface preparation area also highly important to ensure that the system meets the customer’s lifetime expectations.”

A properly prepared substrate is an important first step in ensuring good adhesion and performance of any coating.  “However, in some cases, a customer’s processes may not result in optimal substrate cleanliness and profile,” said Marko Strukelj, product director for Axalta’s liquid coatings business. “In these instances, appropriate coating system selection can help to offset the non-ideal conditions as much as possible.

The cost of the entire coating system and the expected durability can be negatively affected by substrate surface preparation.  Strukelj noted that there are other options to be considered that may help improve performance, like applying thicker layers of coating and/or using high quality paint products such as Corlar and Ganicin undercoats and Imron topcoat.  

“Poor substrate preparation is a key cause of premature coating failure,” said Hesselink. “We are continuing to develop our coatings that are more resistant to reduce the effects of poor substrate preparation; however, the fact remains that corrosion develops from the substrate and as this degrades over time the coating performance will suffer as a result.”

Customers expect productive and user-friendly coating systems.  “Many are sensitive to the environmental impact of their operations and prefer reduced volatiles, minimal waste from the products, and require profitable cycle time from the products that they use, noted Strukelj.  “Finally, they look for superior long-term corrosion protection from various environmental factors, e.g., chemical, ultraviolet radiation, abrasion, and scratch and mar performance, and seek robust film properties such as excellent adhesion and chip resistance to various properly prepared substrates, e.g., blasted, chemical, solvent, and solvent-sand-solvent treatments.  Overall, they want a brand name that they can depend on and a durable coating they can rely on.”

Performance requirements are dependent on the in-service demands of the asset and the expectations of the customer.  “Performance can include many attributes as well as corrosion resistance, including color retention, chemical resistance and even fire protection,” said Hesselink. “The ultimate choice will depend on the type of asset, the regulatory and operational environment, as well as customer preference for a particular aesthetic finish or color scheme.”  

AkzoNobel has a strategic focus on corrosion protection research and technology both internally and in external partnerships with major customers, universities and other institutions. “That work includes the fundamental understanding of corrosion, surface preparation influence and lifetime prediction methods,” said Hesselink. “A great example is the partnership with Manchester University in which a multimillion-pound investment has been made into research into coating breakdown mechanisms in corrosive environments, New technologies for corrosion control and protection are being actively screened and introduced in our product range.”

AkzoNobel’s major focus is on the oil and gas, power generation and mining markets. Hesselink stressed that despite the external pressures upon all of these market segments, such as lower commodity prices, there are still opportunities to grow in these segments. “For example, as oil and gas capital expenditure is reduced, we are helping our customers further extend asset life via proactive maintenance programs such as our Interplan tool,” he added.  “Using Interplan, we can develop focused plans to repair and maintain coating systems on assets that could otherwise fail.”

Axalta’s Cinoman noted that the company continues to conduct and sponsor research to expand the understanding of mechanism, detection, and control of corrosion. “We also focus on developing accelerated methods that offer improved correlation to field performance. Axalta is also focusing on enhanced product service life through improved barrier coatings as well as next generation anti-corrosion pigment packages. We are excited about the new developments now underway in the protective coatings industry that offer novel chemical, electrical, mechanical, and thermal properties to reduce corrosion.  Examples of these include polymeric and nano-scale corrosion inhibitors.” 

NACE International Launches First Corrosion Design Competition for University Students

The University Student Design and Applied Solutions Competition, the first ever student design competition focused on corrosion, will engage university and military academy students in designing an applied solution to a real world problem caused by corrosion that is currently affecting military weapons systems and facilities as well as civilian and industrial structures.

The competition is being managed by NACE International, the Worldwide Corrosion Authority, through funding US Department of Defense Corrosion Policy and Oversight Office.

“Corrosion is an expensive, destructive problem for many government and industry sectors,” said Bob Chalker, CEO of NACE International. “Working with the DOD to introduce a unique, new competition is an exciting first for our organization. We hope it will bring fresh perspective, new solutions, and inspire the next generation of corrosion engineers.”

In this inaugural event, undergraduate and graduate students, under the supervision of faculty advisors, will be challenged to design and create prototypes to inspect corrosion in difficult-to-access areas. The competition was designed to replicate real-world conditions and exemplify how corrosion impacts military and industrial structures, vehicles, and infrastructure.

The final competition will take place from April 18-19, 2016 in Houston, Texas. More information can be found at www.usdasc.com.