Should CIPP Liners Melt when Temperatures Rise Over 150F?
“I installed a competitor’s liner and it ‘melted’ and sagged and plugged the sewer pipe I’d lined. My question is why? I thought the resin used in these systems was stronger than other materials.”
All plastics aren’t the same. For example, if you are plumbing a high efficiency gas furnace or water heater, many manufacturers require you to use CPVC pipe to prevent the ‘melting’ of regular schedule 40 PVC pipe. The CPVC material is formulated with a resin that can handle higher temperatures. The same is true for the resin systems used in CIPP lining processes. The answer to your question is in the resin selection you made or your supplier made for you. Let’s explore the differences in resin formulations and why some have a high heat deflection temperatures (HDT) and others don’t.
First let’s start with “neat” resins or resins that are pure resins that contain no additives that change the or modify the resin you are installing. These resins when cured by themselves with the hardeners or catalysts will demonstrate a flexural modulus, tensile strength, and flexural strength value as tested by ASTM D790 and ASTM D638. With those values in mind, the ASTM’s for CIPP lining set a minimum value of a completed composite of resin and tube to be no less than 250,000 psi. At this point manufacturers and suppliers can modify their formulations to meet the standard by adding components to the resins. The additives used are usually less expensive than the “neat” resin material and used for the purpose of getting a resin that is competitively less expensive but still meets the spec. The additives range from silica, talc and cab-o-sil among others that are used as a filler.
When we add tube to the resin we know that it reduces the three properties cited in the D-790 & D-638 tests above. If the tube and resin combination remains above the standard, then the suppliers may find that adding one of the fillers may reduce their costs and still meet the 250,000 psi flexural modulus, 4,500 psi flexural strength and 3,000 psi tensile strength standards. Many of the additives reduce the HDT (heat deflection temperature) while reducing the other components and while still meeting the ASTM standards for CIPP may leave the completed liner less able to resist higher temperatures. These components may also reduce chemical resistance to certain chemicals found in some industrial applications as well.
It’s very important for you as an installer to review the documentation provided to you by your supplier for the materials you are using and not apply a product to a liner job that doesn’t end well. We publish HTD temperatures as well as chemical resistance charts for each of the resin formulations we provide. We sell a large amount of our 60 minute Quik-Pox resin that carries a high HDT and a high chemical resistance as it contains no fillers and is a “neat” resin formulation. Our 60 minute Quik Pox, for example has a HDT of 250F and is the resin of choice for steam exhaust piping discharge. If you job is out of the ordinary home installation and you’re unsure of which resin system to you, call our staff at Pipe Lining Supply and we’ll help you through the right selection for you. You can reach us at +1-888-354-6464 or Email to info@pipeliningsupply.com.
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