April 2024
Special Focus: Maintenance and Reliability
Hot or not: The future of thermal management
Effective and efficient insulation solutions remain paramount for the chemical process, oil and gas, and petrochemical sectors.
Effective and efficient insulation solutions remain paramount for the chemical process, oil and gas, and petrochemical sectors. Traditional mechanical insulation systems have long been the go-to solution for insulating heated tanks and pipes. These systems primarily safeguard personnel and enhance energy efficiency; however, they contain imperfections. Insulation systems’ tendency to absorb moisture significantly draws back thermal insulation materials, which decreases their effectiveness and increases the risk of corrosion under insulation (CUI).
As a result, these industries have shifted toward spray-on insulation coatings. While these coatings offer some advantages, they also have limitations, such as restricted film thickness and temperature resistance, not to mention the prerequisite of a primer.
However, paint and coatings researchers are introducing an enhanced silicone-based spray-on insulation coating engineered to transcend the limitations of existing insulation products. The insulation coating boasts improved features, including hydrophobicity, greater film thickness and superior temperature resistance. It provides direct-to-metal corrosion protection, eliminating the need for a primer and reducing material usage. This new coating sets a new benchmark in insulation technology, offering a faster, hotter and drier solution to the persistent insulation challenges in critical industries.
Today's insulation practices.
Downstream industry assets often operate at temperatures ranging from below ambient to an intense > 1,200°F (> 650°C). Effective insulation remains necessary for asset and worker protection, energy efficiency and condensation control. Today, several industries rely heavily on various mechanical insulation systems, such as mineral wool, calcium silicate, perlite and aerogel. The process typically begins with applying a primer coat to the asset, followed by the insulation fitting and culminating with the installation of a protective jacket (often made of metal) to shield the insulation from physical damage and water ingress.
However, these traditional insulation methods remain challenging. Installation can be cumbersome and labor-intensive, especially for large-scale applications, requiring significant scaffolding on large applications, cutting to fit complex geometries and running the risk of being improperly sealed. The inevitable seepage and saturation of water from rain, wash-downs or other sources under the jacketing are just some of the concerns regarding insulation. CUI “will occur" rather than “might occur."
Once water saturates the insulation, its thermal performance plummets, creating an ideal environment for CUI. In cases of heavy saturation, the added water weight can cause the insulation to shift or even collapse on vertical surfaces or bulge out of its metal jacket, severely diminishing its insulative capability. These scenarios underscore a pressing issue in the industry: the need for more resilient and efficient insulation solutions that can withstand these challenging environments. So, what does the future hold?
Faster application.
The commonly used waterborne acrylic or epoxy spray-applied coatings present limitations, particularly in coating thickness and temperature resistance. The application process for these coatings is often lengthy and laborious, especially for large-scale structures like petrochemical storage tanks. It is not unusual for 5–10 layers to be applied, each ranging from 20 mils−65 mils (0.51 mm–1.65 mm), cumulatively reaching up to 200 mils (5.1 mm) in total dry film thickness. The application of each layer, along with the necessary primer and potential topcoat, can span several days, extending the completion time to weeks. For example, each coating layer for petrochemical storage tanks can take multiple days to apply.
The author’s company’s researchers and asset owners conducted application testing of a next-generation silicone-based spray-applied insulation coatinga in the lab and the field. The results showed a substantial reduction in the need for multiple coats. The coatings can be applied in thicknesses of up to 250 mils (6.35 mm) per coat. Depending on the specific application requirements, only one or two coats are needed, substantially cutting down the time and cost of the insulation process. Despite the reduced number of layers, it can achieve a higher total coating thickness of 500 mils (12.7 mm).
Application test results also indicated that the silicone coating can be applied and reach dry-to-touch in a few hours or less at 77°F (25°C). The coating was also hard enough to walk on the next day, allowing for easy application of a second coat, if needed. Finally, application to hot substrates was also possible, preventing the asset, in many circumstances, from being taken out of service during application.
Moreover, the application process eliminates the time-consuming and resource-intensive need for extensive scaffolding on large tanks. Instead, a coating applicator can efficiently cover the asset using a lift or similar equipment, further streamlining the insulation process and reducing any downtime for downstream operations.
Improved CUI mitigation.
CUI remains a pervasive issue that poses significant risks, including expensive maintenance, operational shutdowns and incidents leading to injuries or fatalities. Globally, corrosion accounts for an estimated expenditure of $2.2 T/yr, with nearly half of this figure attributed to the oil and gas sector, according to the World Corrosion Organization. A notable incident underscoring the severity of CUI occurred in 2001 in the UK, where a pipe transporting flammable gas ruptured, causing an explosion and subsequent fire. This incident resulted in at least three injuries and the release of 180 metric t of flammable substances into the environment, highlighting the consequences of insufficient corrosion protection.
The enhanced silicone-based spray-on insulation coatingsa offer superior direct-to-metal corrosion protection, making a primer optional instead of required. For example, one of the tests involved assessing the material's resistance to corrosion under harsh conditions. It included two main evaluations: first, exposing the material to 1,440 hr of salt spray, per the International Organization for Standardization (ISO) 9227 standard, to simulate a marine environment; and secondly, the material was subjected to 720 hr of water condensation testing following the ISO 6270-2 standard, mimicking high-humidity conditions. This was done on panels maintained at normal room temperature and heated to 500°F (260°C) for 100 hr to understand how heat affects their corrosion resistance. The aim was to ensure the material meets the ISO 12944-6 C5H high corrosion performance category.
The tests revealed minimal scribe creep and no blistering, flaking, cracking or rusting on the surface of the panels using the new coating direct-to-metal or as a system in various corrosion tests.
Greater durability and safety.
While conventional waterborne acrylic or epoxy-based spray-on insulation coatings adequately protect oil and gas storage tanks within common temperature ranges, they fail to serve a substantial segment of the pipe market operating above 350°F (177°C). The newer silicone-based spray-on insulation coating bridges this gap, extending its applicability to a broader portion of the pipe market thanks to its temperature resistance. Thermal testing shows that pipes endure continuous and cyclic temperatures reaching as high as 500°F (260°C), surpassing the 350°F limit typically associated with other coatings.
Tests reveal that after being exposed to dry heat at 500°F (260°C) for 100 hr, the coating showed less than 5% mass loss, proving its durability. Furthermore, when researchers heated a coated pipe with a ceramic blanket, it tolerated cyclic temperatures of > 500°F (> 260°C) without visible damage such as cracking or flaking. The tests demonstrate that the coating can cope with the expansion and contraction of steel during temperature changes. Additionally, the coating has been tested at extremely low temperatures and shown resilience against conditions as cold as –196°C without significant damage.
Apart from withstanding temperature extremes, field applications and lab tests also confirm the silicone-based coating's low thermal conductivity. Because it is hydrophobic, the new coating resists water absorption better than many fibrous insulation materials. It absorbs < 3% water when submerged after 72 hr, compared to much higher absorption rates in mineral wool. Lower moisture means increased insulation performance for greater operational efficiency.
The coating's ability to significantly reduce surface temperatures, even at high temperatures, and its low thermal conductivity allow it to provide safe-to-touch surfaces with a single coat per American Society for Testing and Materials (ASTM) standards. For example, the author’s company’s coatinga helps protect against accidental burns and injuries by reducing heat transfer to the skin.
The new silicone-based coating maintains manageable surface temperatures, even under high-heat conditions. Simultaneously, its low thermal conductivity ensures compliance with ASTM safe-to-touch standards using one coat. This feature streamlines the insulation process, allowing equipment to remain operational during application and repair, bypassing the typical downtime associated with mechanical insulation methods. Moreover, the coating remains a strong defense against CUI, saving time and money for the asset owner and applicator. HP
NOTES
a PPG PITT-THERM® 909
The Author
Nicole Rakers is a Product Development Supervisor for the PPG Protective and Marine Coatings business, focused on product development for atmospheric protection and thermal management. She has more than 10 yr of experience developing innovative solutions for customers, taking projects from conception through the stage-gate process to launch and post-launch support.
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