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In know that PVC should be chamfered and even lightly sanded before gluing for better insertion on the fitting (and probably some other reason).

What about CPVC, a manual told me to just cut, apply glue and insert the pipe into the fitting keeping pressure. No sanding, no chamfering and no wiping with primer. Another article told me to chamfer the edges before gluing. So what is the correct procedure?

  • I've never heard you should chamfer or sand PVC, so interested in seeing answers. – JPhi1618 Jan 12 '16 at 14:55
  • From what I understand, with PVC you should: cut, chamfer, sand, prime and then glue. BTW, without chamfering PVC I have a hard time inserting the pipe into the fitting. – Luiz Borges Jan 12 '16 at 14:57
  • Where are you in the world? I wonder if PVC fittings are a little different where you are. I've only used it for irrigation in the US, and the inside edge of the fittings is relieved a little so the pipe slides right in. Also, I'm not saying your wrong about chamfering - I've just never done it, so I'm interested in when its needed. Maybe I've been doing it the hard way the whole time! – JPhi1618 Jan 12 '16 at 15:04
  • Brazil, I've used PVC for cold water and waste. Now I will do some for hot water. – Luiz Borges Jan 12 '16 at 15:16
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About the only reason I could see to chamfer the end is that it would seat a mm or 2 deeper in the fitting. In that the glue is solvent welding the plastic, I doubt it makes a lot of difference in the strength of the joint. That said, I don't see that it would be a problem if it helps in joining unless you overdo it (like sharpen the end).

As far as I know, primer and sanding serve the same purpose - primer softens the surface and sanding gives more surface area. Both of these improve the performance of the solvent. Whether you need primer or not depends on the glue - there are single step glues that combine the primer and cement and there are two step glues that require priming then gluing.

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  • If I recall correctly, you sand to remove the shine (I guess to make the primer act better). Also the primer doesn't really soften the pipe (unless I really wet it), I think it just cleans the surface – Luiz Borges Jan 13 '16 at 0:23
  • @LuizBorges - At least here in the states, there are cleaners (which just clean the surface) and primers (which soften the surface). "Soften" may perhaps be too strong a word to describe the result - it mainly gets a little tackier. I usually use both: cleaner, then primer, then cement. – Comintern Jan 13 '16 at 0:31
  • The one here I guess is a primer, it seems to make the surface smoother. It is called something like "prep solution". – Luiz Borges Jan 13 '16 at 1:38
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I have owned one for years, it aids insertion and helps remove tailings that otherwise would flow down the line necessitating more thorough flushing (or maybe plugging something up). It's a good practice but no requirement. As for CPVC cleaner or primer, follow the directions on your can of cement.

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I can't see any advantage to chamfering the ends of PVC pipe, before applying glue and inserting it into the fitting (elbow, tee, coupling, valve, etc.) Where the pipe "dead-ends" into the fitting, the fitting's "stop-shoulder" is cut at a right-angle (not chamfered), and the end of pipe after cutting (without chamfering) would also be at a right-angle.

So all you would be doing by chamfering the pipe, is reducing (very slightly) the PVC-to-PVC contact (a small 45 degree angle "gap"), once seated.

Admittedly, after having said all this, the effect is probably insignificant, as the "lip" of the "stop" inside the fitting, is a fraction of the wall thickness of the pipe, providing little in the way of PVC to PVC contact. The system is obviously designed to satisfy the requirement via thorough application of glue between the external circumference of the pipe, and internal circumference of the fitting.

Most important is to ensure a right-angle cut on the pipe. I use a mitre-box and saw when possible. Then, even with clean new pipe, with a fine grit sandpaper, sand lightly the pipe-end circumference to a length equal to the depth of the fitting "stop".

Also, "scrub" lightly the cut end with sandpaper on a hard flat surface, or with sandpaper glued to a block of wood (without taking the end "out-of-square"), to ensure cleanliness and maximum contact. Then, wipe where sanded with a clean rage, and make-up the fitting with the glue per instruction, ensuring dead-end contact with the stop-lip in the fitting.

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