Connecting ductile iron pipe to plastic pipe

[DerbyRunner]

One of our employees wants to extend a ductile iron pipe to move some water to another part of our facility.

The existing pipe is ductile iron, running under a driveway. I think it is 10". We have some existing 8" plastic pipe (green color) that is left over from another job. Can the two different pipe types be joined, and if so, how do you do it?

 

[rgr33]

In general, green pipe color is sewer pipe, which is not meant to be pressurized.

Better check that out before committing to it.

 

[/pine]

One of our employees wants to extend a ductile iron pipe to move some water to another part of our facility.

The existing pipe is ductile iron, running under a driveway. I think it is 10". We have some existing 8" plastic pipe (green color) that is left over from another job. Can the two different pipe types be joined, and if so, how do you do it?

For gravity systems
Try an Internet search for "fernco pipe couplings 10 x 8"

 

[DerbyRunner]

For gravity systems Try an Internet search for "fernco pipe couplings 10 x 8"

I did that, thank you. It is for gravity/ditch water so it is not under pressure.

One thing I am confounded by is that the end of the ductile that needs to be connected to is the bell end. Those rubber couplings, I presume, are for the non-bell end?

 

[gary49]

Yes, Fernco bands are for the spigot, or straight end of the pipe not the hub end.

 

[jfh28]

cut the bell off leaving a straight end......keep in mind that you are reducing the size of the piping down stream.....what might fit in a 10" won't fit in an 8".......put some kind of a grid at the 10" entrance to filter out the big debris......your other option would be a small concrete distribution box like you would use in a septic field with the 10 going in one side and the 8 attaching on the other side......this would also give you a clean out port if you think clogging could be an issue.......Jack

 

[quicksandfarmer]

You can get a rubber donut by Fernco that goes in the bell end and fits over the plastic pipe. You glue it in with a special glue, Rector Seal is a brand.

 

[Tractor Seabee]

You can get a rubber donut by Fernco that goes in the bell end and fits over the plastic pipe. You glue it in with a special glue, Rector Seal is a brand.

I have used those donuts many times, never had to glue them. Soap heavily to get them in using a 2X board and a large hammer. Not sure they make on in 10" though. Ductile iron is not easy to saw when cutting off a bell. I would go the vendor that sells underground utility products. I would wager there is a simple solution. Ferguson and Fowler come to mind.

Ron

 

[gary49]

cut the bell off leaving a straight end......keep in mind that you are reducing the size of the piping down stream.....what might fit in a 10" won't fit in an 8".......put some kind of a grid at the 10" entrance to filter out the big debris......your other option would be a small concrete distribution box like you would use in a septic field with the 10 going in one side and the 8 attaching on the other side......this would also give you a clean out port if you think clogging could be an issue.......Jack

I like the idea of a box with a cover, maybe even a grate considering that it's a piping no-no to decrease pipe size going downstream. I'd be tempted to use the 10" pipe as a chase and run the 8" pipe thru it if you have enough pipe, then you wouldn't have to worry about joining the different sized pipes.

 

[DerbyRunner]

I like the idea of a box with a cover, maybe even a grate considering that it's a piping no-no to decrease pipe size going downstream. I'd be tempted to use the 10" pipe as a chase and run the 8" pipe thru it if you have enough pipe, then you wouldn't have to worry about joining the different sized pipes.

I am told an 8" pipe will handle the anticipated flow, and that it does upstream before the 10" ductile which is through a driveway. Ductile was put there due to heavy equipment that traverses through.

I will see if there is sufficient access and clearance to use the ductile as a chase for 8" pipe. Interesting idea. Thanks!

 

[EddieWalker]

I've never met a drain pipe that was big enough. Eventually, Mother Nature will outdo herself to prove her point. The idea of reducing the size of a drain pipe goes against everything that I hold sacred in plumbing. How many sections of smaller pipe are you using to make this tempting? How clean is the runoff and how positive are you that nothing other then water will ever flow through it? How much would it cost to buy a 10 inch pipe and slide it into the bell, then use a rubber coupling to hold it together? Is there any cost savings in going to the smaller pipe?

 

[DerbyRunner]

I got a little more information. The source water is ditch water that is delivered to our property through a 1,000 foot 8" green pvc pipe system, then dumping into an open ditch that comes to our property. About 110 gals/minute.

The open bell end of the ductile iron pipe is near the ditch, and about 3' lower than the ditch. My employee envisions adding a concrete box in the ditch with a slide gate on one side (in line with the flow) and an 8" pvc pipe in a side wall. If the slide gate is open, water would flow (as it does now) through the ditch. With the slide gate closed, water would instead go in the 8" pipe.

This way, the 8" pipe could "tap into" the ditch water and get it routed over to the ductile pipe. It would require two 90 degree fittings as the only location to tap into the ditch is about 6-8 feet "downstream" from where the ductile iron is located.

After considering the impact of debris, I am wondering if this should be piped as a "closed system" or not. There is also an issue of silt, which needs to be periodically shoveled.

I've seen other implementations where an open concrete box is used to "tap into" the ditch water, then pipe it to another open concrete box where the ductile iron is located. The piping would connect the two concrete boxes, and each concrete box could be cleaned and shoveled out as necessary. Maybe also some filter screens.

Does this make more sense as an approach compared to a closed piping system? If it does then there would be no need to join the two types of pipe together.

 

[3Ts]

I would never ever reduce the size of a drain pipe. Since there is a potential for silt and possibly debris, I would use a box with a grate on the top to facilitate clean-out. There needs to be an inch or so of space under the pipe to allow for silt build-up. The box needs to be larger than the 10" pipe so the flow slows down and drops the silt in the box.

I vote for a concrete box with the pipes thru the sides and a grate on top. This way the smaller pipe can be used and easy access to it WHEN it gets clogged (not if). I had a drain pipe that an excavator put a kink in it so the pipe was now about 1/2" narrower at one spot and that is where debri built up, even with a screen at the inlet.

 

[DerbyRunner]

The 10" ductile was used because it was available. Everything else associated with this water flow is handled using 8" pipe (or open ditch.)

If open concrete boxes are to be used, I wonder how you size those to allow the best settling of silt and debris before entering the pipe. And for best sizing for cleaning out when necessary. There is moderate silt that comes with the water. But the majority of that (I think) is caught right as the water enters our property.

 

[chim]

About 6 years ago we did something sort of similar at our shop. There is a paved driveway that has a pipe under it so storm water doesn't get trapped on the one side. It was just a pipe with the ends exposed in a depression on each side. The downstream side is about 2' below the driveway and there was a narrow trench that ran from the driveway to some wasteland on the side of the property.

The inlet end of the pipe was always getting clogged with debris and there was a large puddle much of the time. We had a small precast catch basin (something like 24"x24"x30" deep) out in the one storage yard. We made a bar grate for it, poked a hole in the side, and slid it over the end of the pipe for the inlet side.

On the other side of the driveway we poured a larger concrete box in place, built a bar grate for it and extended a large PVC pipe from this box to "no man's land". The open trench had separated a good piece of our laydown yard for years, so burying the pipe made life easier for storing materials.

We did have the pipe openings far enough off the floor of the box to create a sump to catch debris. Although the plan was to periodically clean the sump, we never have. The water flowing through cleans enough of a path for itself.