HDPE Direction Drill

[cr1973]

Hello all,

I need to drill some HDPE under a small river with some fairly steep banks.

Just wondering if there is a ball park figure on how much I can deflect the pipe joints. I am looking to install about 100 feet, have not yet determined by total vertical drop as of yet.

 

[Zambo]

What is the diameter of the HDPE pipe?

 

[coloeng]

I don't remember the exact website, but Chevron has a pretty good set of technical bulletins on HDPE pipe which should provide good information. Do a Net search on HDPE pipe and you should be able to find it.

Their recommendation is to not exceed 100 x D(pipe)and that any raduis smaller than 150 x D(pipe) will reduce the safe pulling strength of the pipe.

Hope this helps.

 

[cr1973]

It will be a 24" diameter pipe.

 

[cvg]

are you installing jointed pipe? I would think you would use welded pipe with no joints, no deflection of joints necessary.

 

[cr1973]

Yes, it'd be fused joint pipe. I know there is a max bending radius allowable. I am looking to bored about 120 feet and achieve an elevation change of 20 feet or so.

 

[bimr]

HDD river crossings incorporate radii-of-curvature, which allow the PE pipe to cold bend within its elastic limit. These bends are so long in radius as to be well within the flexural bending capability of SDR 11 PE pipe which can be cold bent to 25 times its nominal OD (example: for a 12” SDR 11 PE pipe, the radius of curvature could be from infinity down to the minimum of 25 feet, i.e., a 50-foot diameter circle). Because the drill stem and reaming rod are less flexible, normally PE can bend easily to whatever radius the borehole steel drilling and reaming shafts can bend because these radii are many times the pipe OD. However, in order to minimize the effect of ovaling some manufacturers limit the radius of curvature to a minimum of 40 to 50 times the pipe diameter. As in a previous section, the tensile stress due to bending is included in the calculations.

http://www.plasticpipe.org/publications/pe_handbook.html