Corrosion under insulation (CUI) is a hot-button issue for the industrial industry, and rightfully so. Studies have shown that CUI is the cause of 40-60% of the money spent on piping maintenance in the oil and gas industry1. That’s no small sum, and that’s why many minds throughout the industry are working to find new solutions to help prevent or inhibit corrosion.
This has often been done through finding methods to prevent water from contacting the surface of the pipe, like pipe coatings or water-resistant insulations. Water is frequently an integral component to pipe corrosion, thus inhibiting water contact can be an important step to take when designing to avoid corrosion. For this reason, many strategies to tackle CUI utilize water-resistant insulations to prevent water ingress. The industry’s focus on water-resistant insulations stems largely from the fact that it is one of the more obvious variables to address. As a result, water-resistant insulations are gaining a strong foothold in the engineering community as a method for protecting pipes from CUI.
Notably, with the exception of closed cell foam insulations, like cellular glass, no industrial insulation is inherently water-resistant. The materials you see advertised with words likehydrophobic,water-repellent, orwater-resistant, are made that way via ingredients in the manufacturing process or coatings that are applied after the insulation has been manufactured. Given this growing trend toward specifying water-resistant insulations, Johns Manville has developed a robust portfolio of insulations which resist water absorption through hydrophobic treatments.
With our most recent release of water-repellent mineral wool, MinWool-1200® Pipe insulation, we now offer four different insulations that feature water-resistance properties: MinWool-1200; Sproule-1200™; Thermo-1200™, and InsulThin® HT. Through these offerings, system designers can now match the insulating option with the performance characteristics that best suit the needs of their application without sacrificing the water-resistant component.
MinWool-1200 Pipe insulation is tested using BS EN 13472 Thermal Insulating Products for Building Equipment and Industrial Installations – Determination of Short-Term Water Absorption by Partial Immersion of Preformed Pipe Insulation. This is a British Standard test method used in Europe that is gaining popularity in American specifications. It is used to measure water absorption over a 24-hour time-period. The test partially submerges pipe insulation in water for 24 hours to determine how much water it absorbs within that time-period. MinWool-1200 Pipe insulation absorbs <1kg/m2 of water during the BS EN 13472 test.
If the application calls for an insulation with higher compressive strength, hydrophobic Sproule-1200™ expanded perlite or water-resistant Thermo-1200™ calcium silicate may be a better alternative than MinWool-1200 Pipe as they offer substantially higher compressive strength (80 psi and 100 psi, respectively). These two materials offer varying levels of water-resistance, with Sproule-1200™ demonstrating more resistance to water ingress than Thermo-1200™.
While Sproule-1200™ was designed to be highly impervious to water, Thermo-1200™ was designed to offer water-resistance during a light to moderate rainstorm (up to 1.25”/hour) during installation. At JM, we calibrated the amount of water-resistance needed to prevent our Thermo-1200™ calcium silicate from absorbing more than 15% of its weight by water over the course of a 20-minute rainstorm falling at 1.25 inches of rain per hour. This water-resistance enables installers to either work through the rainstorm or seek shelter (if necessary) without scrambling to tarp the pipes immediately to prevent water from contacting the insulation during a rainstorm.
Sproule-1200™ and Thermo-1200™ are unique from other water-resistant materials on the market because they have the XOX Corrosion Inhibitor®. This can be a key differentiator for specifiers looking for an insulation that will still offer protection against corrosion at higher temperatures (above 600°F), when the hydrophobic treatment burns off.
If you have questions about the types of water-resistant insulations that are available, click here to ask a question or to speak with one of our technical experts. We’ll be diving further into the details of how water-resistant insulations influence CUI in our upcoming webinar on March 13th, 2019 at 2:00 PM ET. Our hosts will discuss how you can utilize water-resistance and corrosion inhibitors to protect your system from CUI. Click here to learn more and sign up.