I just read this article.

[www.flowguardgold.com]

Of particular concern is the following paragraph:

Quote

A New Failure Mode

In early 2021, Lubrizol Advanced Materials performed a failure analysis of a ¾” section of PEX-b tubing that experienced multiple through-wall cracks on the hot water side after approximately 10 years in residential service in California. These cracks were unique because they formed around the pipe rather than parallel to the direction of water flow.

The analysis found a chlorine degraded layer less than 0.1% of the thickness of the pipe. Based on the age of the pipe in service, this amount of degradation could be considered normal, and the pipe should have remained in service without failure for many years. Yet, pinhole leaks formed and the pipe had to be replaced.

The analysis indicated that the crack began in the thin embrittled layer that had been degraded by chlorinated water, and then expanded under mechanical stress caused by flexing of the pipe. This type of failure is classified as a “stage 2” failure in chlorine resistance testing.

To understand why the stress that created the initial cracks is occurring, it’s helpful to know a little about how PEX is manufactured. PEX-a and PEX-c are manufactured in a way that locks the cross-linked polymers in a straight-line configuration while PEX-b manufacturing can lock the cross-linked polymers in a coiled position.

When any piping, including PEX, is bent out of its natural state, it places the pipe under mechanical stress. If the pipe’s natural state is coiled, straightening the pipe or bending it in the opposite direction of its initial coil will induce stress; if the pipe’s natural state is straight, bending it will induce stress. When an already stressed PEX pipe is degraded by chlorine, the risk of stress corrosion cracking may be lower because the stress would be considered static. However, when a PEX pipe that has experienced even minimal chlorine degradation is subjected to new bending stress from expansion and contraction or manipulation, the risk of cracking is significantly higher. The stress can force the tiny cracks that occur in the degraded layer to expand to the point where the pipe fails.

So basically it says if your PEX is staright and you bend it, or if it came in a coil and you straighten it, then the pipes will eventually fail if chlorinated water passes through it day after day.

How concerned should I be? I just replaced a bunch of polybutylene tubing with PEX because polybutylene is no longer used and not even insurable by insurance carriers. Now I see PEX lawsuits all over and being referred to as the "next polybutylene".

Interesting that this article is published by FlowGuard Gold, the CPVC people.



Edited 2 times.

I would say that there's good ol' copper, but even that's not foolproof. When we lived in Louisville, my neighbor's house was built around the same time as mine, we were both on city water, and both had 100% copper supply piping. He battled an endless number of pinhole leaks that formed in his pipes and could never figure out why, while my piping had zero leaks or issues.

Sum,

I fully understand your concern. I've been there with polybutylene. Unlike polybutylene however, which was produced only by one company (Shell), as you know pex can and is bein produced by A, B or C methods. Also by many different strongly competing companies. With so much competition I can imagine lowest price pressures might be a factor (in order to compete in our capitalistic society quality might come second for some of them).

I admit that initially I used to be a big proponent of polybutylene. Before the internet I have sold polybutylene pipe on numerous occassions to one of the largest rv manufacturer in the US however I refused to sell them acetal insert fittings nor aluminum rings as my gut had told me they were going to be a problem.

When pex became the next promised "perfect" pipe I refused to sell any pex because of my fear of some mfrs possibly not using virgin resins as well as that I learned by my polybutylene experience to become a strong skeptic of any new pipe.

Side comment:
speaking from experience (having been on a commercial repiping crew for a few months, including repiping copper due to electrical issues .. having to help repipe some 2" copper type K on a 3 year old court house building) copper is also far from perfect for every situation.

Is there any piping material that I believe is "perfect?"

No.

Are all or most pex mfrs equal?

Absolutely not.

I'm sorry that I really haven't answered your specific question. I really don't know which brand is "best" or if in the future we all find out that as with polybutylene that we were over-promised how long pex would last, being a perfect pipe and if besides UV there are other possible issues.

well said


IMO: the perfect piping material is Monel Stainless Steel, unaffordable, but perfect

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Good assessment Vic. Competition applies price pressure but it also forces innovation as companies try to escape price pressure, and we may see one or more of the Pex A,B, or C types emerge as a strong and dependable leader. We could also see all 3 types go down the drain like polybutylene. To quote Mark Twain, "You pays your money and you takes your choices."

Interested to know what the electrical issue was with the 3 year old 2" copper in the court house?

? used as a ground and improperly bonded to main ground rods resulting in current flow ?

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Vic, I think I was just frustrated and went on a rant.

I know there is no perfect pipe material, and many times, a failure can be not due to the material itself, but due to poor connection methods, inferior installation, or water quality. I know the original polybutylene is more likely to fail with plastic fittings but not so much copper fittings, and more so with hot side then cold side. For this reason I did a lot of homework before making my decision on the replacement piping materials and methods.

I end up running PEX with no intermediate joints with a cold and hot manifold system and thus many more tubing to minimize joints (and thus potential failure) and make it easier to isolate individual lines for repair and diagnosis. But I never imagined by doing so I would be stressing the tubing out by unbending the PEX out of a coil (since I ordered 100' coils for both 1/2 and 3/4 sizes), and the unbending can result in premature failures, if that report is to be believed. PEX is probably more complicated because of PEX A, B and C, and there are so many connection methods cold expansion, crimped, cinched and others.

It is just concerning to jump from bad bad polybutylene to now some are calling the next polybutylene.

Sum, thanks again for your thoughts and experiences. I know and have seen you grow so much in your plumbing practices since you started becoming a "regular" here many years ago. I want to add that I am grateful for your generous sharing of time with so many of your plumbing projects and experiences. I hereby declare, by the power given to me (by myself) as well as I'm sure agreed upon by many of our fellow regulars .... that you have passed your unofficial plbg apprenticeship and are now an official plbg "expert" for so many reasons. I have observed so many times that you study your upcoming plumbing projects beforehand and reflect on the results and then share them with us. Thank you so much. My hat is off to you.

Don411, bernabeu perfectly hit the nail on head. In the middle of our work an electricians from Los Angeles County Mechanical Department told me I was lucky to still be alive after I cut the 2" copper main.

Wow, good to know, thanks Vic

vic, thank you for the compliments, I am far from an expert but I do try to do a good job on all my projects.

Yes I can see how s copper pipe that's used for grounding can be an issue. Not only old copper pipes but old electrical conduits like rigid or EMT conduits. I have seen some DIY work where a section of original EMT was cut away, only to be replaced by two plastic boxes and a Romex cable in between where the ground conductor was not properly connected to provide ground continuity back to the electrical panel, and the installer wasn't aware that the metal conduit was acting as the EGC. I have seen it quite a few times it's quite scary.

re: electrical dangers / see new thread titled "ALMOST AN OOPS"

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638