One of the trade mags a couple of months back had an in depth article on cutting and threading this stuff.
You can't just use regular threading tools. The hole in the die head has to be enlarged to accommodate the extra diameter of the pipe due to the PVC coating. There are also padded vice jaws so you don't damage the coating.
I have worked with this stuff before. It can be a real pain if you let it. We have no problem threading it, we bought some steel plates that go between the conduit and the jaws on the threader to prevent damage to the coating. The only problem we seem to be running into is the seals in our benders are starting blow. I think it is more of a benders age problem then a pvc coated rigid problem. But any ideas are more then welcome. Thanks
We did a sewage plant and used pvc coated rigid. The company that sold us the conduit provided a threader for upto 4" coated and some special dies for smaller pipe (3/4 & 1")for our pony threader. Depending on how big your job is, maybe you could do the same.