#1
Old 04-28-2007, 08:31 AM
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Repair pvc pipe

Our hot tub develped a leak and I found a hairline crack, about 2 inches long in a section of pvc pipe. The tub is outside, so I was hoping there is an easy way to fix it, like with glue or something, rather than having to replace it, since I have never worked with pvc pipe before.
#2
Old 04-28-2007, 08:47 AM
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There are a number of ways to repair PVC. If you have the room you can cut out the ruptured piece, w/ a small saw, and replace it. They make a special coupling to insert repairs in a straight length of pipe. I'd suggest you measure the OD of the pipe and then take a couple of pix, different views, close up, etc. Then go to your local home improvement center, find an employee knowledgable about plumbing, and ask for their advice.
#3
Old 04-28-2007, 09:33 AM
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If you're talking about a drain pipe (i.e. not much pressure) you might possibly be able to repair it with PVC glue (readily available) and a thin piece of PVC (some hobby shops have this) as a patch. But this would certainly be inferior to what AR Cane recommends.
#4
Old 04-28-2007, 09:49 AM
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Cut out the piece and replace it. Glue on the outside crack is a jurry rig that will get worse.
#5
Old 04-28-2007, 09:54 AM
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Is your recent discovery of the crack related to the tub being outside during subfreezing temperatures? If so, you're likely to find other leaks. Sometimes folks don't manage to fully winterize their tub, leading to this sort of thing.
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#6
Old 04-28-2007, 10:01 AM
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Yes, unfortunately that is the case. The tub is in its seventh year, and I have never had a problem before. I am afraid that by the end of this I will become an expert in working with pvc pipe. I think it is a high pressure line since the water level diminishes slowly with the tub off, and fairly quickly with the jets running. I stopped looking when I found the hairline crack, but when I get home I will refill the tub and turn it on and see what shows up. Also, since it is outside, any repair that results in a mere trickle is OK by me, since there is nothing for the water to damage.
#7
Old 04-28-2007, 11:23 PM
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To get a tight fit on your repair job, cut out the cracked area and put an elbow piece on either side of the pipe. Glue these elbows and push them hard into the two sides of the pipe. Now measure the gap between the two ends of the pipe. Make a separate "U" shaped piece out of 2 elbows, 2 short pieces of pipe that are the same size and one piece of pipe that is the same length as the gap. Glue these pieces together. The first piece is one of the two identical pipe pieces, next an elbow, then the pipe piece that is the size of the gap, then an elbow and finally the last pipe piece. This "U" shaped piece should fit into the two elbows that you glued into either side of the pipe. Glue these together and you'll have a tight fit. Give it some time to dry before putting it under high pressure.
#8
Old 04-29-2007, 12:06 AM
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Mangosteen this is way more work than is necessary, and if the bottom of his spa is anything like mine, there may not be room to do this type of repair.
A very permanent repair is easy to do.
You can use a Union or a coupler or a repair coupler (I could not find a picture on line. Looks just like a standard pipe coupler, but does not have a shoulder inside, so it will slide along a pipe)
#9
Old 04-29-2007, 02:54 AM
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Yes, a repair coupler is the thing you want. You should be able to pick one up for ten to twenty bucks, depending on the pipe size.

Last year, my neighbor dug into a 1" PVC line and we fixed it with one of these - far simpler and faster than the alternate, which was to dig up the whole line and replace pipe, or to get enough slack in the line to wedge in a segment of pipe to glue in.

All you'll need to do is cut out a long enough segment of pipe to work in the coupler's halves and slip them over the pipe. The thing screws together by hand - no tools or glue needed.

However, the long-term better option really will be to re-plumb the whole system - this is probably just the first section of pipe to fail.
#10
Old 04-29-2007, 09:44 AM
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One more comment on the U-repair. I agree the straight repair with a suitable coupler is a FAR better technique. But IF someone insisted on doing a U-repair ...

Do NOT glue the two 90's in place on the cut ends before building the U part. It's a near-certainty that you will not get the two 90s in exactly the same plane & you'll end up with ends that can't be connected by a 2-dimensional U. Also, do not build the U separately, let it dry, and then try to fit it onto the ends of the fixed 90s for the same reason.


Instead, build the whole thing at once, assembling it dry. Once it all fits together dry, then put it together with glue. But work VERY quickly, because you're making 8 joints & you have to finish the last one while the first one is still soft enough to adjust. Ballpark two minutes divided by 8 joints is 15 seconds each.


The technique provided by the earlier poster is classically 2-dimensional thinking which can fail spectacularly when applied to a 3-dimensional world. It's funny how often humans think in 2D. I wonder why?



p.s. One final argument against a U-repair is that it creates an undrainable trap that will be a freeze hazard next year & may also become a catch point for foreign matter that will lead to clogs.
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Last edited by LSLGuy; 04-29-2007 at 09:45 AM.
#11
Old 04-29-2007, 10:35 PM
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If you make the repair as first described in this thread, you will not be able to twist the last two connections.

Quote:
Originally Posted by LSLGuy
Instead, build the whole thing at once, assembling it dry.
This is a step in the right direction, and the reason is that what you are doing is solvent welding, rather than "gluing" the pieces together. The difference is that the pipe and fittings are actually melted and become one continuous piece of plastic. To accomplish that, shear is required so that the plastic of the solvent softened pipe and the softened socket intertwine their polymers. This is the reason that all instructions (example pdf) for joining PVC specify to twist the pieces ~90 degrees as they are pushed together.

Note that PVC piping is a very forgiving system. You can do lots wrong and still end up with a leak free system. So if somebody tells you "don't need to bother" with some step, because they never had a problem, this is likely true. When done by the book, there is a safety margin in the pressure ratings. When short cuts are taken, that safety margin is eroded.

I've repaired poorly joined piping that completely came apart with only minor stress on the joints. It took a 3" line I had joined blowing apart at 100 psi to impress upon me the importance of doing it "by the book".

Dry fitting is problematic because the sockets are tapered, and an interference fit beyond about halfway. The pieces are very likely to get stuck if you try to bottom the pipes in the sockets, and if you don't bottom them, then the joints either won't fit, or will be incompletely welded when joined. With the cement applied, the plastic is softened, and extrudes out of the joint as the pipe bottoms.

Note that it is only the bottom of the U that is critical, the uprights can be any length as long as they are equal, long enough to grip between the fittings, and short enough to fit the available space. By measuring carefully, this one pipe can be designed

To do a U repair, I WOULD install the elbows on the two standing pieces (the pipe being repaired) first, buy using a flat chunk of 2x4 pressed against the faces of the fittings to make sure the second one is installed parallel to the first.

Then I would make up the bottom of the U without the uprights, using the installed elbows as a gauge to insure that the fittings are parallel and correctly spaced.

The remaining four joints I would do in one operation, twisting one upright of the U as I put it together, and spinning the other one after the fact (because I only have two hands)

Quote:
Originally Posted by LSLGuy
One final argument against a U-repair is that it creates an undrainable trap that will be a freeze hazard next year & may also become a catch point for foreign matter that will lead to clogs.
This is correct, so if possible, the plane of the U should be horizontal. An upside down U won't trap water in the repair, but can prevent the pipe as a whole from draining correctly. Another option is to replace one of the lower elbows in the U with a tee, and put a drain plug on the left over connection.

Finally, Bolted flanges with a rubber gasket are available that are an alternative to unions. Especially if the pipe will be buried, as grit gets in the threads of the union, and makes it very difficult to turn the coupling ring.

Last edited by Frank; 04-30-2007 at 01:10 AM.
#12
Old 04-29-2007, 11:21 PM
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Bloody hamsters. Trying again:

If you make the U repair as first described in this thread, you will not be able to twist the last two connections.

[QUOTE=LSLGuy]
Instead, build the whole thing at once, assembling it dry. [QUOTE=LSLGuy]

This is a step in the right direction, and the reason is that what you are doing is solvent welding, rather than "gluing" the pieces together. The difference is that the pipe and fittings are actually melted and become one continuous piece of plastic. To accomplish that, shear is required so that the plastic of the solvent softened pipe and the softened socket intertwine their polymers. This is the reason that all instructions (example pdf) for joining PVC specify to twist the pieces ~90 degrees as they are pushed together.

Note that PVC piping is a very forgiving system. You can do lots wrong and still end up with a leak free system. So if somebody tells you "don't need to bother" with some step, because they never had a problem, this is likely true. When done by the book, there is a safety margin in the pressure ratings. When short cuts are taken, that safety margin is eroded.

I've repaired poorly joined piping that completely came apart with only minor stress on the joints. It took a 3" line I had joined blowing apart at 100 psi to impress upon me the importance of doing it "by the book".

Dry fitting is problematic because the sockets are tapered, and an interference fit beyond about halfway. The pieces are very likely to get stuck if you try to bottom the pipes in the sockets, and if you don't bottom them, then the joints either won't fit, or will be incompletely welded when joined. With the cement applied, the plastic is softened, and extrudes out of the joint as the pipe bottoms.

Note that it is only the bottom of the U that is critical, the uprights can be any length as long as they are equal, long enough to grip between the fittings, and short enough to fit the available space. By measuring carefully, this one pipe can be designed

To do a U repair, I WOULD install the elbows on the two standing pieces (the pipe being repaired) first, buy using a flat chunk of 2x4 pressed against the faces of the fittings to make sure the second one is installed parallel to the first.

Then I would make up the bottom of the U without the uprights, using the installed elbows as a gauge to insure that the fittings are parallel and correctly spaced.

The remaining four joints I would do in one operation, twisting one upright of the U as I put it together, and spinning the other one after the fact (because I only have two hands)

[QUOTE=LSLGuy]One final argument against a U-repair is that it creates an undrainable trap that will be a freeze hazard next year & may also become a catch point for foreign matter that will lead to clogs.[QUOTE=LSLGuy]

This is correct, so if possible, the plane of the U should be horizontal. An upside down U won't trap water in the repair, but can prevent the pipe as a whole from draining correctly. Another option is to replace one of the lower elbows in the U with a tee, and put a drain plug on the left over connection.

Finally, Bolted flanges with a rubber gasket are available that are an alternative to unions. Especially if the pipe will be buried, as grit gets in the threads of the union, and makes it very difficult to turn the coupling ring.
#13
Old 04-30-2007, 12:32 AM
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It would appear that Kevbo is a man of few words on this subject.
#14
Old 04-30-2007, 12:35 AM
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Quote:
Originally Posted by dauerbach
Yes, unfortunately that is the case. The tub is in its seventh year, and I have never had a problem before. I am afraid that by the end of this I will become an expert in working with pvc pipe. I think it is a high pressure line since the water level diminishes slowly with the tub off, and fairly quickly with the jets running. I stopped looking when I found the hairline crack, but when I get home I will refill the tub and turn it on and see what shows up. Also, since it is outside, any repair that results in a mere trickle is OK by me, since there is nothing for the water to damage.
Perhaps this is your chance to move to a different technology, as in PEX. Yes, you will need transition fittings, but could potentially eliminate a number of fittings. You'll need to borrow or rent the proper tool, or employ the services of an authorized Wirsbo technician, but in the grand scheme of things, it might prove less costly.
#15
Old 04-30-2007, 12:41 AM
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Join Date: May 2005
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Quote:
Originally Posted by Rick
It would appear that Kevbo is a man of few words on this subject.
Bloody Hamsters! I thought the board SW wouldn't allow posts shorter than two characters, and the really wierd thing is when I tried editing those, my entire post shows up in MY edit window...what the heck?

ONE more try:

If you make the U repair as first described in this thread, you will not be able to twist the last two connections.

[QUOTE=LSLGuy]
Instead, build the whole thing at once, assembling it dry. [QUOTE=LSLGuy]

This is a step in the right direction, and the reason is that what you are doing is solvent welding, rather than "gluing" the pieces together. The difference is that the pipe and fittings are actually melted and become one continuous piece of plastic. To accomplish that, shear is required so that the plastic of the solvent softened pipe and the softened socket intertwine their polymers. This is the reason that all instructions (example pdf) for joining PVC specify to twist the pieces ~90 degrees as they are pushed together.

Last edited by Kevbo; 04-30-2007 at 12:46 AM.
#16
Old 04-30-2007, 12:47 AM
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Posts: 5,889
Well, it seems I have found a max post length "feature" in the board sw. Here is the rest of what I have been trying to post:

Note that PVC piping is a very forgiving system. You can do lots wrong and still end up with a leak free system. So if somebody tells you "don't need to bother" with some step, because they never had a problem, this is likely true. When done by the book, there is a safety margin in the pressure ratings. When short cuts are taken, that safety margin is eroded.

I've repaired poorly joined piping that completely came apart with only minor stress on the joints. It took a 3" line I had joined blowing apart at 100 psi to impress upon me the importance of doing it "by the book".

Dry fitting is problematic because the sockets are tapered, and an interference fit beyond about halfway. The pieces are very likely to get stuck if you try to bottom the pipes in the sockets, and if you don't bottom them, then the joints either won't fit, or will be incompletely welded when joined. With the cement applied, the plastic is softened, and extrudes out of the joint as the pipe bottoms.

Note that it is only the bottom of the U that is critical, the uprights can be any length as long as they are equal, long enough to grip between the fittings, and short enough to fit the available space. By measuring carefully, this one pipe can be designed

To do a U repair, I WOULD install the elbows on the two standing pieces (the pipe being repaired) first, buy using a flat chunk of 2x4 pressed against the faces of the fittings to make sure the second one is installed parallel to the first.

Then I would make up the bottom of the U without the uprights, using the installed elbows as a gauge to insure that the fittings are parallel and correctly spaced.

The remaining four joints I would do in one operation, twisting one upright of the U as I put it together, and spinning the other one after the fact (because I only have two hands)

Quote:
Originally Posted by LSLGuy
One final argument against a U-repair is that it creates an undrainable trap that will be a freeze hazard next year & may also become a catch point for foreign matter that will lead to clogs.

This is correct, so if possible, the plane of the U should be horizontal. An upside down U won't trap water in the repair, but can prevent the pipe as a whole from draining correctly. Another option is to replace one of the lower elbows in the U with a tee, and put a drain plug on the left over connection.

Finally, Bolted flanges with a rubber gasket are available that are an alternative to unions. Especially if the pipe will be buried, as grit gets in the threads of the union, and makes it very difficult to turn the coupling ring.

Last edited by Kevbo; 04-30-2007 at 12:48 AM.
#17
Old 04-30-2007, 11:12 AM
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Kevbo's post #11 is (with corrected coding)
Quote:
Originally Posted by Kevbo
Bloody hamsters. Trying again:

If you make the U repair as first described in this thread, you will not be able to twist the last two connections.

Quote:
Originally Posted by LSLGuy
Instead, build the whole thing at once, assembling it dry.
This is a step in the right direction, and the reason is that what you are doing is solvent welding, rather than "gluing" the pieces together. The difference is that the pipe and fittings are actually melted and become one continuous piece of plastic. To accomplish that, shear is required so that the plastic of the solvent softened pipe and the softened socket intertwine their polymers. This is the reason that all instructions (example pdf) for joining PVC specify to twist the pieces ~90 degrees as they are pushed together.

Note that PVC piping is a very forgiving system. You can do lots wrong and still end up with a leak free system. So if somebody tells you "don't need to bother" with some step, because they never had a problem, this is likely true. When done by the book, there is a safety margin in the pressure ratings. When short cuts are taken, that safety margin is eroded.

I've repaired poorly joined piping that completely came apart with only minor stress on the joints. It took a 3" line I had joined blowing apart at 100 psi to impress upon me the importance of doing it "by the book".

Dry fitting is problematic because the sockets are tapered, and an interference fit beyond about halfway. The pieces are very likely to get stuck if you try to bottom the pipes in the sockets, and if you don't bottom them, then the joints either won't fit, or will be incompletely welded when joined. With the cement applied, the plastic is softened, and extrudes out of the joint as the pipe bottoms.

Note that it is only the bottom of the U that is critical, the uprights can be any length as long as they are equal, long enough to grip between the fittings, and short enough to fit the available space. By measuring carefully, this one pipe can be designed

To do a U repair, I WOULD install the elbows on the two standing pieces (the pipe being repaired) first, buy using a flat chunk of 2x4 pressed against the faces of the fittings to make sure the second one is installed parallel to the first.

Then I would make up the bottom of the U without the uprights, using the installed elbows as a gauge to insure that the fittings are parallel and correctly spaced.

The remaining four joints I would do in one operation, twisting one upright of the U as I put it together, and spinning the other one after the fact (because I only have two hands)

Quote:
Originally Posted by LSLGuy
One final argument against a U-repair is that it creates an undrainable trap that will be a freeze hazard next year & may also become a catch point for foreign matter that will lead to clogs.
This is correct, so if possible, the plane of the U should be horizontal. An upside down U won't trap water in the repair, but can prevent the pipe as a whole from draining correctly. Another option is to replace one of the lower elbows in the U with a tee, and put a drain plug on the left over connection.

Finally, Bolted flanges with a rubber gasket are available that are an alternative to unions. Especially if the pipe will be buried, as grit gets in the threads of the union, and makes it very difficult to turn the coupling ring.
(That is, almost the same as his previous post, which has been fixed for coding by a mod).
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