View Full Version : How fragile is PEX?

05-15-2011, 12:15 PM
I'm re-doing parts of the 60 year old plumbing in my house, and decided to go with Uponor/Wirsbo Pex A. But after working with it for a while, it seems nearly impossible to install it without making scratches in it. Even the specially made suspension clips made for PEX can make deep scratches if you slide tubing through them at anything other than a perfectly straight angle.

But supposedly scratches, over time, can become leaks.

I know lots of installations and refits are using PEX now, and I suspect many installers aren't being as careful as I am, so maybe the scratches are considered acceptable?

Any thoughts on this?

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Tom Sawyer
05-15-2011, 12:31 PM
Here, maybe this will help.



master plumber mark
05-15-2011, 01:07 PM
the stuff is pretty tuff, they install it in concrete without
putting any sheilding on it against the concrete grinding against it
for the next 50 years...

I have seen it frozen solid.... and bounce back....

except for UV light and the issues concerning the cloride in the water breaking it down over time.....

I dont think anything will damage it......

05-15-2011, 01:23 PM
Before I decided on Pex, I looked into the causes of Pex failures, and by far the reason was thought to be improper installation, either with crimping the fittings, or damaging the tubing during install. And some leaks in the tubing away from the fittings were thought to be from scratches made at some point. Over 3, 5, or 10 years, they could turn from scratches into leaks.

I believe what you're saying, but I'm still confused. Where would folks draw the line in terms of not using a piece of Pex, based on scratches and scrapes and gouges?

BTW--the youtube vid was very interesting, but he didn't in the end see if it would still hold 80 psi, without leaking.

Tom Sawyer
05-15-2011, 01:47 PM
It will and actually held 165lbs which is as much pressure as I get out of the compressor.

05-15-2011, 03:49 PM
That's a good demonstration of its re-formability and resilience. But if it were damaged while being pulled through joists or studs, you either wouldn't know, or wouldn't be able to re-form it without pulling it all out again. And according to Uponor's manual, you cannot fix a gouge or a tear that way, only a kink.

What bothers me are the reports that deep scratches or small gouges lead to premature failure of the wall of the pex, over years. Was hoping someone could speak to that. Has anyone actually ever seen that happen?

Tom Sawyer
05-15-2011, 04:08 PM
Unlike copper it does not take a whole lot of skill to install pex however one must still be careful not to drag it across sharp objects and such. Common sense handling procedures apply just as in any product. If you are all that concerned then stick with copper.

Derek S
05-15-2011, 07:04 PM
A contractor told me "PEX is great! It will last 25 years!"

I am ready to put in PEX but I am concerned. 25 years ago is only 1986. If I built a house in 1986, I do not want to be changing water lines in 2011 (or if I build in 2011, 2036 is too soon). I see houses from 1950 in the neighborhood a lot.

Should I stick with copper? Or does PEX last longer than 25 years?

05-16-2011, 07:21 AM
Pex has been in use much longer in Europe, and the longevity has not proven to be a problem. Note, when it first came out, there was only one manufacturing method, called -A pex tubing. Now, there are two other methods, called -B, and -C. Uphonor was in there at the beginning, and still used -A method, which creates the most consistent cross-linking. The others can, but they are more susceptable to any hiccup in the manufacturing process. Poor cross-linking means less strength and flexibility. Type -A manufactured products are the most flexible and have the highest cross-linking. If I remember, I think the first commercial use was in around 1956.

05-16-2011, 04:25 PM
PEX Failure issues to date...
CPI DuraPex: Tubing failures splitting on hot side CPI DuraPex is an orphaned product CPI went out of business and sold manufacturing rights to NIBCO there is a thread on this forum with details. Nibco is not accepting liability.
Nibco DuraPex: Tubing failure splitting hot side 1 documented case on another forum.
Kitec: Fitting failure dezincification
Zurn: Fitting failure dezincification
Wirsbo/Uponor: Fitting failure dezincificaion

With the tubing pretty much any brand is fine except DuraPex...

As far as fitting failures from dezinification the manufacturers have switched to Dezincification Resistant Brass, Bronze, and plastics eliminating the problem. Dezincfication only was a problem in some areas where the water supply was agressive towards brass.

Tom Sawyer
05-16-2011, 05:57 PM
The " many years in Europe" line is true but.....They handle lawsuits a bit different over there and a lot of stuff goes un-reported. Uponor, the oldest maker of PEX has had many many documented failures and ensuing settlements. They just don't get advertised

05-17-2011, 10:01 AM
The " many years in Europe" line is true but.....They handle lawsuits a bit different over there and a lot of stuff goes un-reported. Uponor, the oldest maker of PEX has had many many documented failures and ensuing settlements. They just don't get advertised

So do cars and trucks and we still drive them everyday.