# HDPE3408 SDR11 suitable for 480' deep borehole ?

Discussion in 'Vertical and Horizontal Loops' started by Davidren, Jun 8, 2011.

1. ### DavidrenNew Member

I will have couple 480 feet boreholes drilled, can I use HDPE3408 SDR11 pipes ?

Thanks.

Yes
Eric

3. ### DavidrenNew Member

Not understand.

Eric,

For HDPE3407 SDR11, the Hydrostatic Pressure is 160 PSI. Hydrostatic pressure is also the maximum operating pressure for that type of pipe.

1 foot head = 0.433 PSI, so 160 PSI = 370 foot head. The pipe is always full of water, so the HDPE3407 SDR11 can not be sized vertically over 370 foot.

4. ### Sound GeothermalNew Member

480' BH

Yes, but you need to be careful that if it is an air hole and dry - you probably don't want to fill up the loop all the way – gets too heavy. Check the differential pressures of the fluid(s) inside the pipe and outside the pipe to insure that you don’t reach collapse pressure with the outside fluid (ex: enhanced grout at 15+ #/gallon).

If it is a mud hole, the fluid on the outside of the pipe equalizes the pressure with the fluid inside the pipe. If you are using enhanced grout, you may need to add some pressure to the pipe while you grout and then release it after the grout has set.

The equation to calculate the hydrostatic head (pressure) of a column of fluid is .052 x fluid weight in pounds/gallon x depth in feet. Check collapse pressure of the pipe and be sure not to exceed that “differential pressure” outside to inside.
Cary Smith CGD

5. ### DavidrenNew Member

Thanks.

Can you refer more detailed info ?
And, not understand this "enhanced grout at 15+ #/gallon"

Thanks again.

Last edited: Jun 10, 2011
6. ### urthbuoyWell-Known MemberIndustry ProfessionalForum Leader

He is referencing the weight of the grout. You can calculate the compression on the unpressurzed pipe if you don't pressurize it.

Sounds like you're DIY with the queries?