How to Choose the Right Resin for Your CIPP Job

Heat deflection temperature is one factor to consider when making the determination

How to Choose the Right Resin for Your CIPP Job

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“I installed a liner. It melted, sagged and plugged the sewer pipe I’d lined. 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 that your supplier made for you. Let’s explore the differences in resin formulations and why some have high heat deflection temperatures (HDT) and others don’t.

Let’s start with “neat” resins or resins that are pure resins that contain no additives that change or modify what you are installing. These resins when cured by themselves with hardeners or catalysts will demonstrate a certain flexural modulus, tensile strength and flexural strength value as tested by ASTM D790 and ASTM D638. With those values in mind, the ASTMs 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.

When we add tube to the resin, we know that it reduces the three properties cited in ASTM D790 and ASTM D638. If the tube and resin combination remains above the standard, then the suppliers may find that adding one of the fillers reduces their costs while still meeting 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. While still meeting the ASTM standards for CIPP, it may leave the completed liner less able to resist higher temperatures. These components may also reduce resistance to certain chemicals found in some industrial applications as well.

It’s very important to review the documentation provided to you by your supplier and not apply a product to a liner job that won’t end well. At Pipe Lining Supply, we publish HDT values, as well as chemical resistance charts for each of the resin formulations we provide.

About the Author: John Heisler is the owner of Pipe Lining Supply and Quik-Lining Systems Inc. He has more than 20 years of experience in the CIPP lining industry and over 40 years in the underground construction industry.


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