Plumbing – How to cut threads in plastic coated steel pipe

natural-gaspipeplumbing

I'm doing a home improvement project, and I want to bury 10' of 1/2" pipe. I've been to the city and understand the codes to do this legal. In my area, buried pipe has to be either plastic coated or buried within a protective plastic pipe (typically PVC). I've got a couple of pieces of pipe that will need to be cut and threaded.

My local big box hardware store (no names mentioned) sell the coated pipe but refuse to cut threads on their expensive Rigid pipe threading machines. They claim the coated pipe clogs up their threading machines, have a nice day.

manual pipe threader tool

I was looking at using a ratcheting pipe threader tool, but I notice from the Rigid catalog that they recommend a different die set for coated pipe? ref: dies here and ratchet handles here. That reference shows part # 51897 for 1/2 inch "high speed for plastic coated pipe".

The whole threading of plastic coated pipe sounds odd to me. I don't understand why plain 'ol pipe threading dies don't just cut right thru the stuff. Anybody know any details here?

If I'm careful with plain 'ol dies for black iron pipe work on the coated stuff?

Many thanks…

Best Answer

I spent hundreds of hours on a Rigid pipe threading machine and used the same dies for black iron, galvanized, and green coated iron gas pipe. The only issue was the green coated pipe is slightly larger on the O.D. (due only to the coating) so is a bit difficult to get the threads started. With the machine, I could grind a bit of the coating off by levering the dies open a bit, to get the thread started. With hand dies you may have to use a different method to scrape a bit of the coating off the end of the pipe, maybe just use a sharp knife or a file. Once the dies bite they will grind right through the coating, no clogging.

The official response will still be "follow the manufacturer's instructions", but I think you will be fine.