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PVC vs. CPVC

PVC vs. CPVC

PVC vs. CPVC

(OP)
I have to make some repairs to a roping dummy. It is made out of PVC pipe and fittings.
I have a new can of CPVC cement on hand.
It's 30 miles to town to get PVC cement.
Is CPVC cement acceptable for PVC?
There are no codes concerning the construction of roping dummies but I do need strength.
The dummy had a close encounter with a horse. The horse won!

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: PVC vs. CPVC

Quote (http://weldon.com/technical-support/faq/)

Q: Will CPVC solvent cement work on a PVC piping installation?


A: Yes. CPVC solvent cement technically will work on PVC piping. However, we recommend that the correct Weld-On primer and PVC solvent cement for the particular application should be used. Please note that PVC solvent cement, because of temperature limitations, is not recommended for CPVC piping.

TTFN (ta ta for now)
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RE: PVC vs. CPVC

CPVC is a little bit stronger than PVC at ordinary temperatures, and should bond just fine to the PVC.

I'm surprised you didn't make the dummy out of EMT? :)

Actually, it makes sense, you want the dummy to give way not the horse.

RE: PVC vs. CPVC

For such a specialized mechanical application, my experience suggests that silicone RTV will be a sufficient adhesive. If the joints are anywhere near clean before assembly, disassembly by force will be difficult once the RTV has cured.

Consider also that you might wish for the joints to separate more easily during, uh, an encounter, in which case whatever non-silicone caulking you have lying around would suffice.

Mike Halloran
Pembroke Pines, FL, USA

RE: PVC vs. CPVC

Valid point on disassembly Mike (I'd say difficult to separate, but less impossible than CPVC cement, and much more likely to give way in an impact event). I don't like silicone in general, but in that instance it might make sense.

RE: PVC vs. CPVC

(OP)
Thanks for the reassurance friends.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: PVC vs. CPVC

(OP)
Hi Mike.
I posted a link in the plastics forum.
Pud responded with this link:

Quote (https://www.polymersolutions.com/blog/whats-the-di...)

However, CPVC has a big vulnerability, one that it shares with PVC — it is susceptible to environmental stress cracking (ESC) by phthalates, such as diisononyl phthalate (DINP). DINP is a plasticizer commonly used to make PVC more flexible, and its use allows us to have vinyl car seats (Oh yay!), super-thin electrical cable insulation, and rust-resistant car bumpers. It’s also commonly used in sealants — and therein can lie a problem.

Recently, a client asked us to help them understand why a CPVC pipe had failed. We suspected a caulk containing DINP had been in contact with the pipe.
The video of the test is interesting.
You can see the cracks starting and growing under a drop of DINP on a section of CPVC pipe..
Rather than take a chance that the RTV contains DINP I will stick with CPVC cement.
Thank you for your participation.
Bill


Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: PVC vs. CPVC

Thank you Bill, and thank you Pud, for the education.

Mike Halloran
Pembroke Pines, FL, USA

RE: PVC vs. CPVC

The more you know...

RE: PVC vs. CPVC

If you place a piece of PVC pipe in acetone it will swell to twice its original diameter and become rubbery. The cracking is caused by stresses between the swelled and not yet swelled plastic. Both plastics can be bonded with pure solvent but cements have polymer predissolved in the solvent to give more viscosity, slow evaporation of the solvent, and for gap filling. The cement sets quickly when the pipe fittings absorb the solvent from the cement. The solvent must then slowly diffuse through the pipe wall to dry-out.

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