Running Ductile iron water pipes under highways
Running Ductile iron water pipes under highways
(OP)
Good Afternoon,
We are making several crossings under a few highways.
The highways are dual carriageway so quite wide.
The pipelines are carrying potable water in ductile iron cement-lined material from 800mm to 1600mm.
Is it normal to change the pipe material to HDPE and use a steel casing?
As the ductile iron is buried, up to the crossing area we are using the push-fit spigot socket joints. So could the DI pipe be flanged under the roads?
Any advice appreciated and whether there are any preferred methods of doing this in accordance with AWWA etc.
Best Regards
John
We are making several crossings under a few highways.
The highways are dual carriageway so quite wide.
The pipelines are carrying potable water in ductile iron cement-lined material from 800mm to 1600mm.
Is it normal to change the pipe material to HDPE and use a steel casing?
As the ductile iron is buried, up to the crossing area we are using the push-fit spigot socket joints. So could the DI pipe be flanged under the roads?
Any advice appreciated and whether there are any preferred methods of doing this in accordance with AWWA etc.
Best Regards
John





RE: Running Ductile iron water pipes under highways
in most city and county arterial roadways, DIP or steel pipe is commonly used, with or without joint restraint as necessary.
under state or federal highways, usually in a steel casing.
AWWA does not have any requirements for highway crossings that I am aware of, this is a highway department requirement
RE: Running Ductile iron water pipes under highways
While I think it is more common for many ductile iron piping installations of substantial highways such as USA Interstates to be of the casing carrier pipe-type, I have seen some in fairly recent years installed uncased. Some guidance for USA ductile iron casing/carrier pipe installations (I think as referred to by cvg) is mentioned in ANSI/AWWA C600 Installation of Ductile-Iron Water Mains and their Appurtenances as well as AWWA Manual M41. In the international field, a good bit of concrete-sheathed ductile iron pipe has even been used particularly in Japan and the Middle East for uncased jacked/trenchless crossings of substantial carriageways, and such makes for a quite formidable composite pipe.
RE: Running Ductile iron water pipes under highways
This pipe will be installed in Kurdistan region and not the more common oil field type sand areas.
I am puzzled why the drawings show PE100 pipe just for the road crossings hence my post!!
Especially as in some of the cases we are up to 17 bar and that's without surge possibilities.
Regards
John
RE: Running Ductile iron water pipes under highways
PE100 SDR 11 is good for 16 bar as I'm sure you know which seems high for push fit spigot joints to me.
I can only guess in Kurdistan in the past that the road has sunk and pulled the pipe with it or earthquakes have also resulted in sprung pipe where the road has been a more solid item than the pipe. Also open ct road crossings tend to suffer from collapse, compression and shock loading as the trench is never put back right so PE is a much more forgiving material than DI.
In the main though if you're auguring or other trenchless types of crossing I would have thought you need a casing of some sort but that size of pipe is huge to go under a road - what are transporting? the entire water supply of Kurdistan? - it's not that big a place
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Running Ductile iron water pipes under highways
ductile iron with push on joints can be designed for 350 psi working pressure (plus 100 psi surge) for a total of 450, see Table 7 in ANSI/AWWA C151/A21.51 “Ductile-Iron Pipe, Centrifugally Cast, for Water” Higher pressure design is also available. Push on joints allow a significant amount of flexibility, so some settlement can be tolerated. However, for a pipe this size and cost, I would make sure the "trench gets put back right"
https://www.dipra.org/ductile-iron-pipe-resources/...
RE: Running Ductile iron water pipes under highways
We are pumping 630 MLD in two parallel pipelines each 1600mm diameter.
In the U.K. We use Saint Gobain 'natural' for drinking water supply pipelines. It has from 4mm to 9mm cement mortar lining depending on diameter.
Difficult to understand why the material change under the road unless the chief engineer is perhaps worried about making the spigot joints over approx 40m.
Does this have to be an open-cut installation?
It is normal for the top of the casing pipe to be 1.7m (5.5 ft)from the road/rail. So that's a deep trench.
But as I'm not an installer I don't know if 1.7m plus trench depth under pipe is considered 'deep' or it's common installation detail for pipe crews.
Grateful for your help and have a great weekend.
Regards
John
RE: Running Ductile iron water pipes under highways
your trench is 1700 plus 1600 = 3300 total to the bottom. that sounds reasonable within a highway right of way. The government or other right of way owner should be dictating whether it goes in a casing or if it needs to be jacked and bored, or not.
RE: Running Ductile iron water pipes under highways