pipepvc
I made some PVC joints that will be buried, since they won't be easily accessible I would like to make sure they are perfect.
When I glued them I used primer and glue, but I had to "twist" the pipe a bit to fit the elbow (it was an "almost" 45° bend). Now, some 5 days later, it is holding well under full pressure and no water seems to be leaking anywhere, but because of the force fit on the elbow I'm still worried.
I think that if it is still holding so far it should hold for good, is it true?
Depending on how strong you want the joints, you could just push them together and leave it unglued. I've done this to create poster tubes out of 3" PVC which went through airport baggage handling just fine. PVC fittings are tapered on the inside, so the further in the pipe goes the stronger it will naturally hold.
If you want to use some glue, anything which will hold non-porous surfaces should work.
The best lubrication I've found is some good ol' Elbow Grease™.
Actually, you should measure the proper lengths and just cut. Then glue it up and install. You can mark on the PVC how far it should go into the fitting if you want to be really precise. However PVC itself expands and contracts a lot with temperature change and is fairly flexible anyway. So, in my opinion, being extremely precise doesn't mean all that much anyway. Also, The solvent melts the PVC surface to weld them together, so the fittings will likely fit differently while gluing, thus making the dry-fit method even worse than just measuring.
Another solution could be to mark how far in the fitting the piece should go and lay them next to each-other in that position, even tape them together, to check your layout. That seems pretty time-intensive, though. I still think it would be better to just measure accurately and double check your measurements.
Best Answer
I'm not sure I completely understand what you mean by "twist." You mention a 45 degree bend. Is that the bend of the elbow? Why was a "twist" required?
At any rate, if it is holding, it will probably be fine under static loads even if installation was not perfect. However, a bad joint will typically only reveal itself under more extreme dynamic loads. Pressure spikes typically occur due to air in the line or water hammer. An acceptance test generally requires applying 150% of design pressure to the line and checking for leaks (that is, hyrdostatic water pressure, not air pressure.... applying compressed air to the line could be quite dangerous if anything fails). I assume you have no way to do that.
So, the best you can hope for is that your installation was adequate and followed correct procedure. At a minimum that would involve, deburring and beveling the pipe edge, applying sufficient amounts of cement to the pipe and fitting, ensuring the pipe is seated completely and uniformly in the fitting (fusion of the pipe and fitting typically only occurs right at the tightest portion of the fitting.... elsewhere, there is simply a mechanical bond that is weaker).