How to cut threads on 3/4" metal water pipe that is in a hole in the ground.

How easy/difficult is it to cut threads into 3/4 pipe that is in the ground? I've dug around the pipes and have room to work. I want to cut a section out of the pipe, thread the end, and screw a cap onto it. Is this fairly easy to do while the pipe is in a hole in the ground? Or is this way too much trouble, and maybe I need to think of some other way to do this? The pipes are old - they have probably been in the ground for decades, and are rusty, so I'm not even sure I could clean them up enough to be able to thread them. I'm also not sure I could unscrew them from the various fittings, they are so old and rusty - I'm not sure what would happen if I tried to unscrew a section of pipe from a tee, it is so old, and one mistake and I have no water until I get it fixed right.
So having said all this - is it practical to thread 3/4 water pipes (iron I'm guessing) that are in a hole in the ground?
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Yes, what you're wanting to do is possible.
With a fair amount difficulty you could use a hex pipe die (hard to start & turn) or an easier task with a ratchet threading die like ebay Item number: 330740178741.
Or clean up the pipe and use
http://www.farm-home.com/mn/v11_catalog.mvc?SAS01+selectldr+PGF+006215+JDISTRIB1591-1019~~~~~~~&SSAID=198698
along with a capped stub of 3/4" pipe.
since it appears that you're after a quick & dirty solution
cheers Bob
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I had no idea there was such a fitting - compression coupling. Good to know, though I would likely rarely use one. Thanks.
Sonny
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wrote:

It is like those sharkbites--- Hate to use them as a general rule, but sometimes they just can't be beat.
Jim
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water or natural gas?
If its galvanized water pipe what are you trying to accomplish?
messing with the pipe ill no doubt create a leak:(
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wrote:

The problem isn't that it is in the ground. The problem is that it is old and rusty. Use the compression fitting Bob linked to get things working again-- and replace the line while the weather is good. [Lowes and Home depot won't carry them-- but a good plumbing supply place ought to]
Jim
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On 5/29/2012 1:28 AM, Ook wrote:

The compression fitting shown is a possibility.
Have much old galvanized water line here on the farmstead; some dating probably back to the 30s or maybe even earlier--latest is late 50s to early 60s so have a fair amount of practice here... :)
The biggest problem is just how badly pitted it actually is--if bad enough, even the compression fitting gasket may not hold leak-free although it'll undoubtedly be able to get you by for a while so can be w/ water.
If inspection brings you to conclusion pipe is basically sound, the best "trick" I've found for breaking loose an old fitting is heat--you'll need a acetylene torch or other very good heat source; a propane hand bottle won't do it. Go back to the tee or elbow or wherever and heat the fitting and the thermal expansion will loosen the scale. _ALWAYS_ wear eye protection and cover up; the scale can pop and throw dirt fragments, etc.
Also be sure to use two wrenches to back up the fitting--do not rely on the pipe in place in the tee to restrain the joint while breaking it loose.
You'll need a hefty wrench and room to use it or you'll need to be stout yourself. The "reach to the bottom of the hole laying on the ground and try to tug at arms' length act" won't cut it... :)
--
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wrote:

Mabee not impossible, but definitely ompractical. Get back to a solid fitting - even if it means going back to the shutoff or meter, and go from there.
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wrote:

Rusty pipe doesn't take to threading well. I haven't been following this closely, but if somebody hasn't already said it, you should be thinking about putting a new line to your house, and abandoning all that buried pipe. All of it.
But if you insist on fooling with that old pipe, I'd cut it away about 4 inches from the T, then crank the 4 inch piece out of the T. The internal threads on a T hold up better than the outside of the pipe. Get a wrench sideways on the T to counter the force you use to crank out the cut piece. Take up the slack on that with one hand, and apply enough muscle so that wrench won't move as you crank. Put a capped nipple on, using plenty of teflon tape. But you need a backup plan if it goes wrong. And that's putting a new line to your house, and abandoning all that buried pipe. So maybe just use the backup plan as the primary plan, and get ahead of the game.
--
Vic



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When I need to repair a leak in threaded pipe, I have always worked back to the next fitting and installed new pipe from there. Unfortunately, if one section is bad, the rest is usually not far behind. The first leak or two I had to work back 10 to 20 feet to get to metal solid enough to work with. Eventually, I had to take out so much galvanized pipe, it was faster and easier to just replace the entire plumbing system with CPVC pipe.
My in-laws recently had their galvanized supply line break underground. It created a sink hole in the yard and a real mess in the basement. We had to have the fire department come out and shut off the water so we could work on it. Thankfully, the break was next to a fitting just a couple feet from the basement wall. I was able to remove the broken fitting, clean up the threads, and thread on a CPVC adapter. Then I ran CPVC into the house. Someday I'm sure we'll have to replace the rest of the water line out to the street, but it worked OK for an emergency fix.

That is the best approach if you have the time to do it. Copper wouldn't be a good choice in our area as our soil is very acidic. It wouldn't take long to corrode a buried copper pipe. I prefer PVC pipe for buried lines, but the black poly pipe works well too.
Anthony
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Perfect opportunity to buy another tool. I saw that a number of companies make an electric portable hand held pipe threader. It would be perfect to use in a cramped location such as a hole in the ground. Just Google, and you will find them a little pricey, but even some discounters have some cheaper ones.
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If it's just to cap the pipe, wit no future use. Why not just fill the cap with epoxy and glue it to the pipe ?
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wrote:

messing with old galvanized is just wasting your time. even if you get it to work it having been disturbed will leak again....
PEX is so cheap its a no brainer to use
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