If you are talking about white plastic PVC piping then you cannot make it predator safe for anything larger than a rat. If you completely enclosed it with all the hardware cloth on the outside, top, bottom and sides it could be rat proofed and slow a coon down but anything bigger would be able to bend the pipes. The pipes are so light that if you don't enclose the bottom you'll have to stake it down and put a 2 ft apron of hardware cloth to keep predators from just going under it.
Still too flexible. Maybe if you use 1 1/2 or bigger rigid PVC with glue and the molded joints it will hold but columbiacritter's concern nailed the problem with the light stuff, and don't forget snow load too. The rigid stuff can easily support roof steel and handle hardware cloth fastened to it with self tapping screws and fender washers and probably achieve what your after as well as being a quick build. Remember to steer clear of chicken wire, a critter will go right thru it and don't forget to skirt it.
Are you attaching a coop for winter and nights or are these summer birds only?
I agree with everyone. The plastic piping is just too light-weight.
And if you're gonna spend the extra $$$ to make it predator proof, you might as well have purchased wood posts.
If you are just thinking about making a temporary run for chicks, then it's a great idea.
I made a temporary run for mine when they were smaller.
Now I use it to pen up unruly roosters or as a tractor to place chickens in certain areas for bug maintenance.
Attached is a picture of a short (36" high) attachment run we made using electrical conduit pipe and attaching 36" hardware cloth to sides and top. The conduit pipe, while less expensive than PVC is thicker and thus adds rigidity. The entire run was attached to a base of 2 by 6 pressure treated lumber for added stability.
Again, while this run is 10 feet long, it is only 3 feet high and 3 feet wide, although others who have posted on this forum have made larger runs out of PVC and wire and perhaps they will post of their success/problems with this.
In our case, the chickens have this available to them during the daylight hours but are locked in their coop each evening.
We made one to use for an extra pen that can be moved about.It's 8x10x6 with 2x4 wire around and poultry cloth on top.It's not meant to be predator proof,just excercise and space for teens...lol.I have seen some very nice runs put together with 1' pvc.5ft high and pitched canvas roof. I have also seen the lightweight plastic corrugated on top.