However, as anyone who has ever had a wooden deck warp knows, heat causes material to expand, including composites. In the case of this particular liner, Clarkson recalls, “The installers seemed to think that the liner had to be completely restrained – but we actually had to give it room to expand.”
The installers’ plan was to put the liner in place and then pour concrete around it, with the idea that the concrete would secure the liner in place. An onsite UTComp engineer explained that level of restraint would cause the liner to rapidly fail.
“We had to show them how to build the concrete, which had to be done before they put this liner into place. It also meant they had to make a mold instead of using our product as a mold,” Clarkson says. With that onsite expertise, the team was able to install a liner that has thus far had five years of problem-free service, with a projected lifespan of 20 years more.
Finding the Right Balance
In his research at the new Ashland Corrosion Science Center, a part of the Dublin, Ohio-based resin supplier Ashland LLC, manager Kevin R. Lambrych has found in his work with unsaturated polyester and epoxy vinyl ester resins that some companies focus on the high heat distortion temperature (HDT) of the resin system but lose sight in the chase toward high-temperature performance that they need to maintain that performance over time. “The thermal and mechanical dynamic performance over time is just as critical as an initial mechanical property, like HDT,” Lambrych says.
A recent evaluation of Ashland’s Derakane™ epoxy vinyl ester resin against other similar products designed for high-temperature corrosion performance found that the initial HDT was less critical a consideration than expected. Instead, long-term success depended on taking a holistic view of how long the product can resist chemical failure while being exposed to high thermal conditions.
“As you have a resin exposed to high temperature over time, the covalent bonds will begin to break down,” Lambrych explains. “What we’ve discovered is it’s not just about things like initial temperature resistance or mechanical performance [attained]. It’s the ability for fabricated products to maintain those mechanical properties over time vs. temperature that is most critical to asset owners.”
As a result, Lambrych encourages design engineers and fabricators to ensure they’re meeting the true needs of the customer by balancing potential lifespan initial high heat performance and ultimate corrosion resistance.