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HDPE surface installation questions 2

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irrigationguy

Agricultural
Oct 27, 2023
1
Looking at installing a 24 or 30" Hdpe dr9 4710 line on top of ground. 4200 linear feet, 500' elevation. This will replace a buried steel pipe that has failed to due landslides that has z kinked a 20" steel pipe. Any advice how to anchor or hold the pipe from sliding/snaking too much? Will be pushing water up a hill, open discharge at the top. Also any advice on longevity of line on top of ground? Need this to last 50+ years. Ideas to hold pipe if that ground under it slides? Thanks in advance​
 
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Here is the same book from the original source and it appears to be a better pdf:

PPI
 
If you have a large (especially daily) temperature variation, generally you should not lay HDPE on the surface.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
 
Even UV stabilised PE will be lucky to make 50 years.

The issue also si one of solar gain / temperature derating above 20C.

Even if this line runs continuously, which is not possible to guarantee for 5 years neve mind 50, you could still get solar gain as the pipe is black.

Anything above 20C and you start to de-rate. not sure what SDR9 is good for, but you don't have much spare if you're lifting water up 500 ft / 151m / 15 bar at the base.

PE also expands and contracts like no ones business ( 10 times that of steel) so surface lay needs to allow for that and is often laid as a snaky lay. but you need to avoid it turning into a Z shape.

Best lay it at 90 degrees to the slope.

Landslides are a bitch to deal with so I would avoid trying to fix things which are unfixable and just go out and fix it when it moves / breaks, but it is alit more flexible than steel and will withstand a lot of movement.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
Attached is photo of above ground HDPE installation at Richmond Power Plant in St. Croix Virgin Islands. I did not design but I had to do a firewater system modification which affected the piping. The pipe was about 300 - 400 feet long, straight, and was supported with clamp type supports as shown and had a rubber expansion joint on each end to absorb thermal expansion. Each end also went into the ground after the expansion joint so it was basically anchored at each end.
 
 https://files.engineering.com/getfile.aspx?folder=be4a20af-73a8-41dd-8024-e5e2e67e6712&file=1st_From_Guard_House_#2_Facing_Guard_House_#2.JPG
Here is the above ground piping design guide of the Plastic Pipe Institue (PPI). This can be obtained on their website along with other good reference material.

 
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