Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
(OP)
Hey Engineers,
I have a pump at the bottom of an Open Pit Mine (similar to sketch attached) that's going to discharge water up the pit wall to the nearest pond. Based on the Pump Size I can calculate the required thickness for the HDPE Pipe. However, I'm concerned with the fact that currently the client is only anchoring the HDPE Pipe on the Top and Bottom of the Pit Wall. Since the elevation is so great I would of thought that some intermediate support would be required due to the weight of the pipe and/or fluid hanging off the top support.
My thoughts are to check the Pipe based on the Hoop Stress (from the pumping) and Tensile Stress (from the hanging HDPE Pipe) but I would also think that the environmental issues should be considered (like wind, temperature growth and shrinkage, etc.).
Does anyone have references I could review to help in determining an appropriate Pipe Size and Thickness?
Also, any experience/knowledge to share is greatly appreciated!
Thanks!
I have a pump at the bottom of an Open Pit Mine (similar to sketch attached) that's going to discharge water up the pit wall to the nearest pond. Based on the Pump Size I can calculate the required thickness for the HDPE Pipe. However, I'm concerned with the fact that currently the client is only anchoring the HDPE Pipe on the Top and Bottom of the Pit Wall. Since the elevation is so great I would of thought that some intermediate support would be required due to the weight of the pipe and/or fluid hanging off the top support.
My thoughts are to check the Pipe based on the Hoop Stress (from the pumping) and Tensile Stress (from the hanging HDPE Pipe) but I would also think that the environmental issues should be considered (like wind, temperature growth and shrinkage, etc.).
Does anyone have references I could review to help in determining an appropriate Pipe Size and Thickness?
Also, any experience/knowledge to share is greatly appreciated!
Thanks!





RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
Download the handbook:
http://plasticpipe.org/publications/pe_handbook.ht...
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
One thing that should be considered (but often isn't) is the requirement for a maric valve or similar on the scour point to prevent unexpectedly high flow rates.
EDIT
If the risk is considered too great, the pipe can be installed on the pit ramp instead.
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
It comes in different sizes and doesn't act in the same manner – you don't get 12 3/4" pe pipe. For one thing it creeps under constant force and has a thermal expansion rate about 10 times that of steel. Long term strength starts to go down over 20C.
If this is on the surface in a hot place it will snake and also creep if it gets hot in the sun.
The links by bimr are a great start point.
Also you seem to thinking about SDR 5 pipe. Think about that for a minute, the Id will be 3/5 of the OD. That's crazy. There must be something else you can use.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
CVG is correct in that Constructablility is a concern. So in my opinion Aluminum is not the answer.
I'm in agreement with CVG that intermediate supports and/or pumping is a more likely better option.
For Miningman,
Currently the client (location in Northern Ontario, Canada) is already hanging DR7 HDPE down the pit wall similar to what is shown on the sketch but only approximately 180-190m down... flow rate at about 125m3/hr. A Pre-Feas was completed for a Pumping Station at a deeper elevation using DR 5 HDPE Pipe (quotation from a manufacturer - they will make it custom for the client). My task is to verify the "sales pitch" from the manufacturer is ok.
On a side note, the Pre-Feas. Looked into the option of using a PEXGOL pipe system but was not considered fully because of the high capital cost. I'll be bring this item back up with the client as a possible option again. Check out "http://www.pexgol.com/mine-dewatering"
Have you seen this before Miningman?
Bimr,
I actually have a previous edition of this document... thanks for the link.
My main goal of this post is to trying to get feedback on people who have dealt with this similar issue and/or have references to help. Through my experiences I have seen what cvg described... intermediate supports and/or intermediate pumping typically NOT one straight shot up the pit wall.
Cheers!
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
Once again cvg is correct, the ease of installation of the PE is the main reasoning of using this material.
However, since the pit is getting deeper the mix of both steel and HDPE might have to be used.
Does anyone have technical reports/references based on hanging HDPE Pipe over the pit wall?
Cheers,
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
Generally electrofusion joints are quite strong and I assume they are nearly as strong as the pipe itself (don't have the technical docs infront of me but that's my belief without checking).
If the pipe must hang off the pit wall just anchor it at the top based on weight of pipe and friction due to water running down the pipe (if the pipe is scoured) because the friction can be quite high depending upon your pipe size (i think it's maximum when the pipe is running half full?). The pipe manufacturer might be able to tell you the axial stress capacity of the pipe if you want this as well.
As said intermediate supports are desirable but not always practical.
This is nothing new, even though some would be surprised when they first see it because it is dangerous, but lots of other things in mining is dangerous too which is why you can never get out of the car when you are on site :)
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall
More concerned about the high stresses on joints and possible failure on due to axial stresses. I'm thinking at some point the length will be so large that the pipe will stretch out like a piece of bubblegum and snap. However, I can estimate that using the material data available.
No problems if there are no references. Sometimes I luck out and I find some technical reports on mining companies completing trial and errors on their systems. As an example, I found one on Pumpboxes vs. Frothing. Part of me was hoping maybe something would be out there.
I'll talk with different pipe manufacturers and this PEXGOL company to see what they have to say. After which I can discuss different options with the client.
I appreciate the discussion though!
Cheers,
Keith
RE: Looking for References to Help Calculate the Thickness of a HDPE Pipe Hanging Down a Open Pit Wall