I made some PVC frames for around a window and some garage doors to hang Christmas lights on. Unfortunately, I was working out in the cold, and the PVC was brittle. When I attempted to cut a piece, it broke instead of cutting cleanly. This resulted in not having enough long pieces to finish the project. I also didn't have any straight couplings, so in order to save myself a 30 minute trip back to the store, I came up with a way to splice two smaller pieces together.

NOTE: This is only suitable for decorative projects. This splice is not suitable for anything that needs to hold pressure or support any critical weight.

If you want a quick explanation, click above to watch the video, otherwise read on.

Supplies

3-4" long piece of PVC pipe
Handsaw/hacksaw
Bench Vice or Gloves

Step 1: Cut Splice to Length

Get a scrap piece of the same diameter pipe you need to join together and cut it 3 - 4" long.

Step 2: Mark Your Pipe

On the end of the pipe, make two marks that are ~ 1/2" apart. Transfer these marks down the length of the pipe to mark your cut lines.

***I came to this measurement by trial and error, but if you wanted, you could probably determine the exact distance to mark by calculating the circumference of the inner diameter of the pipe and subtracting it from the outer circumference. It was quicker to make a couple cuts than to grab a calculator and measuring tools.

Step 3: Slice It Up

If you have a bench vice, gently clamp your pipe into the vice (don't want to snap the plastic). I was outside, so I just held the pipe in my hand, but I'd recommend using gloves just in case.

Using a handsaw/hacksaw (something with a fine tooth will be easier to use), cut along the lines you marked through one wall of the pipe. Remove your saw and cut along the second line. You should now have a piece that looks similar to the image above.

Step 4: Squeeze and Shove

With the slice of pipe removed, squeeze the two cut ends together and force them into one end of the PVC pipe you want to join together. Push the coupling half way into the pipe. Twisting the coupling into the pipe will make it easier to move. Repeat the process with the other end of the coupling.

Step 5: Final Thoughts

Now you have an inner coupling that maintains the same outer diameter of the pipe.

You could add some superglue to the coupling to make sure it didn't come out if necessary.
I'd recommend adding the coupling and butting the two joined ends together before you cut them to their desired length.
And...just to say it again, this splice should NOT be used for any pressure applications. It WON'T hold up.

Questions or comments, leave them on my youtube video (I'm much more active over there).