How to block a pipe under pressure

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Old 07-01-17, 01:29 PM
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How to block a pipe under pressure

I want to block a water pipe that is under pressure.

I am working on a house in Central America with a damaged water pipe under the sink. The damaged pipe formerly had a steel pipe threades into it. The steel pipe corroded and attempts to remove it left the corroded threaded part of the steel pipe stuck inside.

After extensive attempts to remove the corroded pipe from the threads, I decided to block the pipe. (There is another line next to it, and houses here dont plumb hot water to sinks, if they have it at all, so only one line is needed.)

I tried the following to block the pipe:
1) Stuffed some plastic bags down it
2) filled a PVC cap with a cement designed to cure after 10-15 mins. Painted the concrete wall with concrete adhesive & put the cement-filled cap over the pipe. The idea was to cap the line with concrete and forget about it.

After letting the cement cure for 2 hours (adverised time 10-15 mins), I turned the water pressure back on. Looked fine for 10 mins but then started dripping.

How can I block this water line? (assume that I can use a cutting wheel or drill with appropriate bit to remove the concrete cap).
 
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Old 07-01-17, 02:59 PM
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Install a valve in the line & never open it.
 
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Old 07-01-17, 05:25 PM
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The threads are blocked by the end of the old, corroded connecting pipe. Thus, I cannot install a valve.
 
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Old 07-01-17, 06:52 PM
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Is there no way to go back further?
 
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Old 07-01-17, 11:33 PM
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Nope. Its embedded in a concrete wall. Whatever I do has to be done at the face.
 
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Old 07-02-17, 12:44 AM
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Old 07-02-17, 04:33 AM
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Both my ideas require some tools you might not have. Since the pipe is steel you could weld it shut. Or, if there is enough protruding from the wall you could cut the fitting off the end of the pipe, tap the pipe end and install a threaded cap.
 
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Old 07-02-17, 05:31 AM
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How about a nipple or short pipe the same size as you have with a cap or plug, then attaching it it the existing pipe with a Fernco or whatever band clamp is available?
 
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Old 07-02-17, 06:10 AM
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The most simple and effective solution is to follow the pipe on the other side of the wall to it's source and disconnect it there.

A picture would help.
 
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Old 07-02-17, 12:49 PM
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Doe a temporary fix, you can use a test plug. It is basically a balloon that you can fit into the pipe and inflate it. Used here in the states to test drains for leaks when building a shower. I have also seen metal tubes with rubber at the end that plumbers insert into pipes, expand the rubber to seal so that they can sweat on a valve.
 
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Old 07-03-17, 12:19 AM
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Man, this post cries out for an image. A word is worth 1/1000th of a picture.
 
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Old 07-03-17, 04:58 AM
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I can feel the OP's pain. I've spent a lot of time in Central America and things are often done quite differently down there. Piping and wiring is often buried in cement walls making repairs maddening. Sometimes they even use components as they were never intended like garden hoses for gas lines.
 
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Old 07-03-17, 06:19 AM
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garden hoses for gas lines.
What could go wrong?

To the OP: I assume it's threaded into an elbow not a T since you are trying to block the lines

I would just get the chisel out and try to very carefully unscrew the elbow from the pipe in the wall and then replace it with a threaded cap.
 
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Old 07-11-17, 03:24 PM
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Previously, I had decided to block the pipe after giving up on removing the other pipe stuck inside.

I un gave up and found a store that sells large screw extractors. That solved the problem.
 
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