Why do CPVC Pipes Fail?

CPVC pipe failOne of the services we offer here at Först Consulting Group is Forensic Investigation. That means we go into a construction site or building to figure out what the problem is and how and why it was caused. Sometimes we do it to help the owner fix the problem. Other times, there are damages that need to be collected and the owner needs proof. In either case, we can help remediate the situation by providing detailed proof and acting as a credible third-party, neutral witness.

Let’s look at the problem of why CPVC pipes fail.

What is a CPVC Pipe?

First of all, what is a CPVC pipe? The acronym CPVC stands for chlorinated polyvinyl chloride, a thermoplastic that makes the pipe more flexible and able to withstand hotter temperatures than a standard PVC pipe—up to 200 degrees Fahrenheit over the standard 40 degrees Fahrenheit. This is the main difference between the two types of pipes. CPVC pipe also is available in both nominal pipe sizes as well as copper tube sizes, while PVC pipe is only available in nominal pipe sizes.

For more than 30 years, CPVC pipes have been used in fire sprinkler systems due to their ease of installation, corrosion resistance and relatively low failure rate. This has changed however, as the failure rate of both the pipes and their fittings has increased. What is the main cause? Contamination by incompatible chemicals (80%), followed by poor installation practices and only a small number of manufacturing defects.

The way we are able to detect these defects is best explored through forensic contaminant identification techniques. These tests indicate that contamination can cause everything from hairline cracks to total disintegration. This stress on the pipes, along with the chemicals that are trapped inside during the original pressurization, leads to environmental stress cracking (ESC).

Related: National Fire Safety Association guidelines.

Common Causes of CPVC Pipe Failures

Some of the most common failures caused by improper installation include: excessive or insufficient glue, the wrong antifreeze, pipe misalignment, or clamping issues. The wrong filler content can also cause a failure.


CPVC pipe failureWith the glues, their organic solvents soften the pipe and fitting surfaces to allow the polymer molecules to intertwine to form a permanent bond. These solvents are volatile and meant to quickly evaporate. The problem arises when the installer uses too much glue that runs down inside the vertical runs of the pipe. It there serves as a place where contaminants can be absorbed and trapped underneath because the glue cannot dry as quickly on the inside of the pipe. The hairline cracks are often found when the excess glue is scraped away.

On the other end of the spectrum, if insufficient glue is applied, a void may form between the pipe and the fitting, resulting in a weaker fitting that lowers the burst pressure of the fitting.


When CPVC pipes contact other non-metallic materials, like fire caulk, failure may happen. It may also occur when CPVC pipe is used by hydrocarbons when it is design for use with water. Commonly, these contaminants come from  metal pipe thread cutting oils, pipe thread sealants and coatings applied to the inside surfaces of metal was supply pipes that are connected to the plastic pipes. Because CPVC sprinkler systems are pressurized and held under fairly constant static pressure over long periods of time, they are especially vulnerable.

For Forensic Investigations of Construction Defects, Contact Först Consulting Group

As experts in Forensics involved with the Construction Industry, Först Consulting Group can help to analyze pipe failures in your establishment. With state-of-the-art technology and equipment, along with our extensive knowledge of building practices, we can determine the cause of your CPVC pipe failure and provide you with an extensive and detailed report.

With this knowledge, you will know how to take action. Whether you need to have the installer repair the issue or need take the installer or manufacturer to court, you will have the documentation to back up your claim. If you are called into litigation and need an expert witness to testify, we can help there also.

With Först Consulting Group, you have an expert on your side. Contact us today to discuss any construction defect issues you might have. We can help you find a remedy.


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