Broken Pvc Water Pipe

[Somtham]

Yesterday a worker dug into our main water pipe that feeds the house, garden, and fish ponds. It's a 4" diameter PVC pipe buried about 50cm. How the phuq he did this after many cautions about the pipe being below where he was digging, I don't know. Anyway, it's cracked and I need to replace it.

Normally for replacing sections of small diameter buried pipe I just cut out a few meters of length, put a coupler on each end of the buried pipe, then raise the pipe (bend it) as high as I can and then place the new section into the couplers and lower the pipe allowing the new section to slide into the couplers as it's lowered. Well, with 4" pipe this method doesn't look like it will work to well as I can't raise (bend) the pipe high enough. So, I need a better way to make this repair. Anybody have a suggestion?

Thanks and rgds

[jayenram]

4" pipe is one helluva big supply pipe for one dwelling. However, it will bend. You just have to expose a sufficient length to allow this to be practicable. The other way is to use a ring joint compression fitting (assuming the opposing ends are anchored). I've not seen a 4" diameter compression fitting available local to me, but this is a 1".

There is obviously a pressure limitation on this type of fitting but you don't say what pressure is in the main.

[Somtham]

Thanks for the reply Jayenram. We'll dig out as much as possible along the length. The limitation will be where there are T's coming off the 4" main. Do you suggest replacing as short a section as possible thereby bending the old pipe or replace a 4m section and try bending the stubs of the old pipe along with the new pipe?

FYI we have a 4" bore hole with a 9hp kubota hooked up with a 4" output pipe that feeds about 2,500 cubic meters of pond water and also our sand filter which in turn supply's the house and garden water.

Thanks again.

rgds

[Boksida]

You have a couple of other options:

1. Get a 4" dresser coupling and put it in line as this will give you longitudinal adjustment

2. Use two elbows and put in a flexible hose section and bury the lot.

3. Use four elbows and put in a small bypass type section past the broken area.

4. Find somebody with a hot air PVC welding kit and replace the broken section.

Varying degrees of cost and difficulty and some increased line pressure which will depend on how much you are pumping.

[Somtham]

You have a couple of other options:

1. Get a 4" dresser coupling and put it in line as this will give you longitudinal adjustment

2. Use two elbows and put in a flexible hose section and bury the lot.

3. Use four elbows and put in a small bypass type section past the broken area.

4. Find somebody with a hot air PVC welding kit and replace the broken section.

Varying degrees of cost and difficulty and some increased line pressure which will depend on how much you are pumping.

Thanks for those added suggestions Boksida. I've never heard of a "dresser" coupling but if it is a straight coupler without the middle pipe stop that sounds great. Do they sell them in Thailand or do you make your own by grinding down the stop in the mid section of a normal coupler? The L's would work but will cost me some added friction loss that we really don't need.

rgds

[Boksida]

I have seen metal dresser couplings sold in Bangkok. These would work with the PVC pipe as the OD of the pipe that fits into the seal will be the same. Hope the little picture is good enough for you to get the idea how they work.

Just google it and you will get heaps of pictures.

Edited March 25, 2008 by Boksida

[Iolare]

You could cut out the broken portion and install a new section with a couple on one end and a union on the other.

[Somtham]

You could cut out the broken portion and install a new section with a couple on one end and a union on the other.

Thanks everyone for your suggestions. I ended up digging to expose about 8m of length and then cut out a 4m section and replaced it with a new length of pipe bent to get it to slide into the couplings on each end. No leaks and we're back in business.

Thanks again for your suggestions

rgds

[pab]

Have a look at www.coolthaihouse.com. Great site and full of very practical ideas and suggestions, including your queries. good luck mate

You could cut out the broken portion and install a new section with a couple on one end and a union on the other.

Thanks everyone for your suggestions. I ended up digging to expose about 8m of length and then cut out a 4m section and replaced it with a new length of pipe bent to get it to slide into the couplings on each end. No leaks and we're back in business.

Thanks again for your suggestions

rgds

[Screws]

Have a look at www.coolthaihouse.com. Great site and full of very practical ideas and suggestions, including your queries. good luck mate

You could cut out the broken portion and install a new section with a couple on one end and a union on the other.

Thanks everyone for your suggestions. I ended up digging to expose about 8m of length and then cut out a 4m section and replaced it with a new length of pipe bent to get it to slide into the couplings on each end. No leaks and we're back in business.

Thanks again for your suggestions

rgds

While we're on pipes, what pipes are o.k. for hot water? Any kind of plastic pipe?