Why would NIBCO/CPI Durapex PEX split (lengthwise) and leak?

[celiason]

jadnashua-

Thanks for explaining the copper to pex question. Makes sense to me.
I am enjoying exploring this site and I am learning so much...
I may not be ready to tackle a major job, but at least I feel I can now understand how things work and ask coherent questions when something comes up! :^)

[Bob NH]

One possibile cause of the split would be if it was damaged when pulling it through holes or over a sharp object during installation. A very small scratch can cause high stresses if the pipe hardens with age.

If you get any more splits I suggest taking out the whole length to the extent that it is accessible. If something is weak it fails at the weakest part. When you remove that weakest part you leave other parts that are nearly as weak. If you want to avoid more breaks you should do that before you get any more breaks, which are probably inevitable.

There is an interesting aspect of strength of certain types of materials. Someone determined that the average breaking strength of a large number of samples of long pieces of string is less than the average breaking strength of the same number of short pieces of string. The reason is that there are more weak spots in the long pieces.

[Mikey]

That is interesting, and very logical. Assuming the breaking strengths of "weak points" are normally distributed, there's more opportunity for an outlier weak spot to be in a long length. Of course, there will also be outlier strong spots, but they won't fail until all the weaker ones have. With the right equipment and way too much time on your hands, you could determine the distribution of weak spots in a string by succesively testing the remnants after each break. I'm sure the Acme corporation does this.

http://en.wikipedia.org/wiki/Acme_Corporation

The next time I go mountain climbing, I'll be sure to use the shortest rope possible .

[Redwood]

In my post above I asked you to post a pic....
Seeing is believing!

[Cass]

It could be that the PEX didn't cross link right in spots in that particular batch or maybe even that roll.

[Redwood]

I would really really like to see a picture of this split PEX.

There seems to be a lot of drop a bomb on PEX and run postings. You see the plumbing industry is a bit gun shy on plastic piping. In the 1980's we went with a wrong material called Polybutylene while the rest of the world went with PEX. Who would have known chlorine eats Polybutylene? This led to a huge class action lawsuit and rest assured Shell the maker of the Polybutylene resin didn't suffer any where near as bad as the homeowners and installing plumbers. Shell at least stayed in business... Many of the plumbing companies were driven out of business. If you look back even on this forum you will see plumbers that are very negative towards PEX and frankly I'm surprised that no one has jumped in with a "The Sky is Falling" post. At the present time there are 2 companies that have had problems with their PEX systems. KITEC and ZURN are those companies and the problem was with the fittings not the tubing itself.

With the price of copper as high as it is and PEX being so inexpensive and easy to install the copper pipe industry is losing its market share and is fighting back. In California the new code is allowing the installation of PEX. The war was fought on all fronts as the California Pipe Trades Consul was fighting it because of the skill level required for its installation they even made claims of chemicals leaching out of the PEX or, Contaminents in the ground water leaching through it. Interestingly enough copper in aggressive water conditions also fail the leaching tests as copper leaches into the water. One thing for sure the Pipe Trades Consul, The Copper Development Association, and Unions have a vested interest in this. Their claims have resulted in a conditional approval in California and they will do their best to keep making claims.

What we see in these forums is someone making a post such as yours then a total lack of details...

Please indulge me! Post that picture of the split PEX!

[celiason]

Redwood,

Thank you for your interest. I will work on honoring your request for a picture. The splits are lengthwise, about 1-2" long and I will have to use a "macro" lens for the close-up. It almost looks like a a split along a "seam" in the spot. There are no apparent scratches or injury to either the inside or the outside of the PEX. If I look down the interior of the pipe, I can see light coming through the split even though it is very narrow. (The split was really visible when water was coming through it and spraying in the attic!) I have sent one of the better samples to the manufacturer for analysis but I will see what I can show you...

I did not mean in anyway to belittle the plastic piping industry or PEX products. From my research I have learned much about it and agree that in light of rising copper costs, it can be a great solution to affordable piping. I have also learned that any material can have shortcomings based on different applications. I also understand that even the best manufacturer can sometimes have a problem with quality control and have a bad "batch" slip through. I can only relate my experience with this particular brand/batch and what is occuring. (For the most part, I think PEX is OK!)

I have tried to provide as many details as possible and address all questions and I check back daily to this board and continue to search for answers. Until I hear from the manufacturer, I myself have no idea what is going on.

I am not running, just trying to wait patiently until I have an answer...
Believe me, I am very frustrated and waiting and searching for answers is difficult...until I know something, I don't know how to proceed...

Please bear with me while I get the photo up...(I have three children who are out of school now and they are requiring the majority of my time, an addition to my work...):cool:

[Redwood]

Thanks I appreciate that!

[celiason]

Redwood,

Here are some pictures I took of the second portion of pex removed...each picture is from the same piece of pipe at the same split location... They are the best I could do and I hope they come through OK...please let me know if they don't ( I am a little behind the curve when it comes to this technology stuff, but the children are helping me...)

If you can see, the split happens in what looks like a "seam" along the length (note the outside) and appears to start on the interior of the pex, and on the outside you can see where the water actually came through (the sidewall of the pipe split through to the outside)...what could cause this? There are no scratches on the outside...and this is nowhere near a fitting, just in the pipe itself! I am hoping that the engineers and technicians at NIBCO/CPI can find an answer for me. I have receipt confirmation for the sample I sent them from 6-13-08 (Friday the 13th!) and have been instructed to wait 30 days before calling them for results...It is hard to be patient, but this board helps alot! For the most part, it appears that pex is usually pretty reliable (as well as any other material it seems, based on where you use it), and cost effective...

Anybody else have a similar experience? What should I expect from the manufacturer? Any advice or suggestions are welcome...

...hopeful and optimistic...

[Redwood]

Wow! The sky is falling!

That is the first tubing related failure I have ever seen or, heard of!
It looks from the end view that the damaged section extends past that point I do hope that it was cut back until any evidence of the cut inside was no longer showing when the repair was made.

I am very interested in what they find was the problem. I know that any manufacturer would be very interested in finding the root cause of failure and I'm sure they will come up with answers.

[celiason]

Redwood,

I am glad the pictures came through OK! Now you can understand my puzzlement and frustration about what to do...the split on the interior doesn't appear to run the the whole length of the pipe ( it is hard to tell). When I try to feel down inside the pipe (either end), I can fell a little "ridge" or seam inside. I don't know if we removed all the "bad stuff" or not...

We have replaced as much of this run of pex that is accessible. The rest is behind drywall...I keep looking on the internet for answers, but i haven't found anything and the company website isn't very helpful. When I asked a question through the tech support on the website, I never received a response (in January 2008). I don't know what method NIBCO/CPI used to manufacture this Durapex in 1998. Silane,Engels or radiation? is this Pex-a? Pex b? Is it extruded?

I will let you know as soon as I get an answer from NIBCO/CPI!

Again, thanks for your interest!

...still waitin'...fightin' the urge to pick up the phone...

[celiason]

...not to keep beating a dead horse...

...here is a picture that shows light coming through the split in the same piece of pex (tricky shot in full sunlight)...

(It looks like the pipe started splitting from the inside out and eventually the water pressure was too much.)

To repeat, residential application, county/city treated water, PRV, expansion tank, gas water heater, all professionally installed to code (no DIY) and manufacturer specs/clearances, no UV exposure...

...sigh...

...any ideas?...

I'll keep checking the board, but I probably won't post for awhile until I hear something from the manufacturer. Thanks again to everyone and their 2 cents. I appreciate it!

-c

[Redwood]

Yea I know it appears to have started inside, Thats why I was asking if it had been cut back far enough when the repairs were made...

Well I'll definitely be watching for when you post what they say...

[Mikey]

I've never even seen a piece of PEX up close and personal, but I'm surprised there's any seam at all -- If I were making plastic tubing, I'd use a seamless extrusion process. It definitely was a weak point in this sample.

[Redwood]

Thats just it Mikey, There is no seam in PEX it is polyethylene extruded as a tube then molecules are cross linked by one of several methods. Its pretty tough stuff!

http://en.wikipedia.org/wiki/Cross-linked_polyethylene