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I'm looking to replace some copper pipe with PEX. The online debate seems heated, although local plumbers I've talked to seem indifferent about the particulars, just praising PEX in general vs. copper.

Some of the online debate around cinch clamps involves anecdotes about them failing a small percentage of the time. For example, it was mentioned in this question. Given the low cost of cinch clamps and ease of application, would it be a good idea to double up on clamps on each fitting? Any reason this wouldn't be cheap insurance?

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aaron
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3 Answers3

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I do not think it would be a good idea to double up on the clamps. When you are clamping PEX onto a fitting, you want to try to get the clamp near the middle of the fitting, ideally between two ribs. With two clamps, it wouldn't be possible to do this.

To ease your trepidation about the staying power of the clamps, do a test clamp on a fitting. Let it stay overnight, and then try to get it off. You should find that it's very strong. If you ask me, the PEX + clamps is tougher than copper and solder.

Edwin
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    certainly more idiot proof..not that you're an idiot...you know what i mean. –  Aug 07 '14 at 01:12
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After having one or two leaks using single SSC clamps, I always use two clamps on each connection. Offset where the crimps are to make the best connection. I've had no failures since!

Richard
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  • This seems very contrary to the other answer and to the installation instructions. Do you have some sort of manufacturer or industry documentation indicating that this is effective _and_ warranted by the mfgrs? How many single-clamp failures have you had over what time period, and how many double-clamp connections have you installed and monitored over what time period. 2 failures in 10 years vs 0 failures in 6 months isn't quite a fair fight, so that info is helpful for others. – FreeMan Aug 23 '22 at 12:26
  • I don't know what the manufacturers recommend and have no documentation from anyone. When I first used these clamps 12 years ago, it seemed like they were slightly wider (not certain though) than they are today and I only used one at first and didn't have any problems. Take the fitting and match up the clamp over the fitting and note how exact you need to have the clamp placed to get it precisely over two barbs. After I had one failure 10+ years ago, I changed to two clamps and have had zero failures since. Just my experience..I don't feel I'm lucky enough to get those clamps placed just so. – Richard Aug 26 '22 at 02:29
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The idea of crimps are flawed and leakage around the two crimp bumps are likely. In order to pull a crimp tight, you need to bunch up material at the crimper's closure point. This means there is a noncontact area around the two raised bumps. My joint failures show this clearly, there are no embossed ridges at the bump areas and water stains show leakage at the point where the crimps are raised away from the pipe at the crimp bumps

Secondly why is pipe compound not recommended?

Screwed-tight pipe clamps stretch out, why do we believe cinch clamps will not?

owlpic
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    If you have questions, ask a question, don't put them in an "answer" - SE is not a "forum" it's a question and answer site, where what you put in the "answer" space should be responsive to the question in the question space; which this barely is - it's not even clear that you are talking about the same sort of clamp. – Ecnerwal Jun 02 '15 at 01:31