Commercial Boiler Corrosion Solved with Pelseal Viton™ Caulk

Extreme Performance in Extreme Environments

Following the installation of a boiler and venting system for an insurance company headquarters, representatives from Butters Fetting Co., a Wisconsin-based safety, building information modeling, and preconstruction project services provider, learned of a gasket failure. 

The problem originated in a venting joint, which was sealed at the time of installation with a high-temperature, silicone-molded gasket. Soon after the installation, the gasket in question had become brittle and was breaking down, compromising the joint and allowing water to leak from the boiler venting onto the floor. The water—which was acidic due to the products of combustion coming from the boiler—was staining the concrete floor below.

When the gasket failed, Butters Fetting technicians returned to apply RTV, a customary sealant type in venting applications.

Butters Fetting HVAC Systems Specialist, Paul Coburn, says the RTV sealant is actually recommended in most installation manuals to join similar ducts.

The RTV did offer resistance to temperatures up to 600° F, but it, too, was unable to stand up to the corrosive chemicals. Just a few weeks later, the customer called to say that it was leaking again.

“A coworker and I were discussing how to address the issue,” Coburn says. “I was worried we would have to rip out all the venting, but he said we needed a Viton caulk.”

Coburn had heard of Viton but was not familiar with it. “I searched for it and found Pelseal. I saw that the Viton product had an emphasis on solvent- and acid resistance. I said ‘I think this is what we need.’” His only remaining concern was the temperature rating.

Boiler venting can be exposed to temperatures as high as 350~370° F, and during a conversation with Bill Ross, Pelseal’s President, Coburn learned that Viton is able to handle temperatures as high as 450° F.

Ross offered a sample of Pelseal 2690, a Viton caulk, which Coburn used to reseal the venting. When it leaked again after a few weeks, he returned to investigate.

“The only problem was that we needed more Pelseal,” Coburn says. “The gaps on the venting were very large, and we hadn’t applied enough. We did notice, though, that the bead we had applied looked the same as when it had been installed. There was no wear or degradation whatsoever, even after a few weeks of exposure to the acid.”

In addition, one advantage of Pelseal is that the original application did not need to be removed. “With RTV we would have had to remove the sealant before reapplying,” Coburn says. “In this case, we just added more 2690 to the existing bead. It was an easy fix.”

At the time of this writing, six months after the reinstallation, Coburn says there have been no leaks or other issues. “That tells me that it’s holding up very well,” he says.

He adds that this is a common problem; Coburn says that most (if not all) of his 200 field technicians face the same issue and typically replace the silicone gaskets as they fail. “This is huge for us,” he says. “The Pelseal Viton caulk represents a significant improvement in our ability to provide durable seals for our customers, even in the harshest environments.”
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