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repairing PVC pipe that's underground  RSS feed

 
Posts: 55
Location: Charlotte, Tennessee
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I'm so PO'd. I was digging in a sword fern, and cracked through a PVC pipe. I looked up repair on Youtube, and I think the method they recommend of using a compression coupling could work. Any experience with this kind of thing? The break is about 18" underground (it waters the urban decorative garden of the house we're leaving).



 
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Dig it up, no getting around it. By the time you get down there, you probably have a hole big enough to expose a couple feet of pipe. MUCH better repair to cut out the damaged part and glue in new pipe; and the only way if the pipe is cracked longitudinally. The main issue is to dry out the pipe at the repair and for that the shut-off valve needs to work properly. Try rags, air pressure, hydraulics (force a cylinder down a pipe that insists on holding water; cylinder about 2/3 the diameter of the inside of the pipe will force standing water out); push the end of the (cut) pipe down to encourage draining. If one side keeps dribbling fast, the valve may not be good or the pipe may be mostly horizontal and slow to drain. If you can start the plumbing (as opposed to the digging) in the morning and leave the cut pipe to drain for an hour or so you can wait it out. other wise there is the old WonderBread trick. Wad up a gob of dough, shove it back into the offending pipe and it stops the water. You have about 20 minutes before your dam leaks; the bread dissolves, though it would be better to have a drain cock in the line open when you first turn the water back on.

PVC cuts like butter with any usual saw. Cut the replacement piece 1/4-1/2" shorter than the gap; try to keep the cuts square or your measurements will be weird because one side of the pipe is longer than the other. Use two couplings. One needs to be a "slip" coupling so that you can slide it fully onto one side of the joint and allow the new pipe to lay into place. You can make a slip coupling using a 1/2-round wood file and a normal coupling - just file down the ridge inside; lots easier to buy one if they're available.

Sand the pipe where the glue goes, sand the inside of the fittings (couplings); and/or use PVC primer (nasty stuff, way worse than the glue). Glue up one end of the repair, wetting both the pipes and the inside of the fitting; you have about 30 seconds of easy working time and after that the glue starts to set. Hold the joint together for 60 seconds because under certain circumstances it will try to separate. Make sure your slip coupling really slips fully and easily. Start by holding the coupling up to the end of the pipe you're NOT going to initially slide the coupling onto. Use an ink pen to mark the location where the end of the coupling needs to be when 1/2 it's length has slid onto that pipe. Then sand the fitting and the pipes and glue inside and outside like before and slide the coupling fully onto the unmarked side of the repair. Align the two pipes, the repair and the existing one, and slide the coupling over the pipe with the mark - up to the mark. Two channel lock pliers large enough to easily hold the fitting and the pipe be a big help. IIRC the blue nitrile gloves survive the glue for a few minutes - the primer, not so long.

All done. Give it 30 minutes before stressing it.

You have one hell of a swing if you nailed a pipe 18" down from the surface... <g>


Luck,
Rufus
 
Erica Colmenares
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Thanks so much for this response, Rufus!

The main issue is to dry out the pipe at the repair and for that the shut-off valve needs to work properly.



At least there I'm lucky. We blew out the system earlier this month, so there's no water running through it.


Sand the pipe where the glue goes, sand the inside of the fittings (couplings); and/or use PVC primer (nasty stuff, way worse than the glue).


Oh, good, I'm glad sanding's an option. I prefer that to buying another nasty-smelling product that I may only use once.

I'm not sure I understand each step of your description but I'll read it through more slowly and try to visualize.

You have one hell of a swing if you nailed a pipe 18" down from the surface... <g>


I thought I'd hit a root! I didn't install the system and I forgot it ran right there. Not my favorite moment, as you can imagine.
 
pollinator
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Here is how to repair pipe in a straight run. Glue an elbow to both sides, then use 2 elbows to make the repair piece. I hope the pic makes sense of it
20181127_202053-480x640.jpg
[Thumbnail for 20181127_202053-480x640.jpg]
 
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Interesting idea, but I'm wondering if those right angles might restrict the flow?  Seems like a straight run should be best?
 
Erica Colmenares
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wayne fajkus wrote:Here is how to repair pipe in a straight run. Glue an elbow to both sides, then use 2 elbows to make the repair piece. I hope the pic makes sense of it



I saw a video of this approach, and it makes sense. I think for our application, too, it would work fine. Luckily, we have a fantastic hardware store nearby, with plenty of help troubleshooting. It's great to go with a couple ideas for solutions that will work. Thanks!
 
wayne fajkus
pollinator
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I wouldn't trust the original link you posted.  That type fitting has a rubber bushing. If it was above ground and had a drip you could tighten it some more. Not so much underground.

Using regular straight couplers can be done but requires more digging because you would have to bend the old pipe up to get the repair pipe in place. Its tricky and you might get a good glue joint on one side and very little pipe inserted into the other side.  The elbow alleviates that problem.

As far as water flow, 2 elbows in the system is of no concern to me. Having a joint that is not sealed or fails in time is the bigger concern. The install probably has several elbows in it already.

OP didnt specify if this is gravity fed or a pressurized pipe. That may change my thoughts about it.

 
Erica Colmenares
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wayne fajkus wrote:

OP didnt specify if this is gravity fed or a pressurized pipe. That may change my thoughts about it.


It's pressurized.
 
Erica Colmenares
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We had a day without rain, and I fixed the pipe. I ended up using a telescoping pipe because it's the one that meant I had to dig the least. As much of a pain as it was, all to transplant a sword fern, I'm glad I had the learning experience. We'll see it if holds, when we turn on the irrigation in the spring.

Before

After

 
Phil Gardener
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Looks like a nice job!
 
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