project to supply potable water to island 1

[allie075]

Hello:
I'm working on this project in the Caribbean to supply potable water from a main island to a smaller island about 360 meters away. The deepest point along the selected route is 12m. Locally, 4-inch PE pipe is not available. What else can I use and what problems might I encounter?

I'd appreciate your comments.

Thanks
Allie

 

[Compositepro]

A fire hose will work and is particularly easy to iship and install. It all depends on how long you want it to last.

 

[gerhardl]

Several smaller pipes?

 

[JRMacGregor]

Because the distance is only 360m, you could weld 360m of steel pipe on the larger island, and pull it across to the other island.

Obviously you need something with sufficient traction to do this (at tug at sea with suitable rigging onshore might do it), and also a fabrication "runway" on the larger island oriented in the correct direction.

The oil and gas industry fabricates steel pipeline bundles up to 7km long onshore and then pulls them offshore.

Also, long lengths of rigid steel pipe can be coiled (YES) around a reel and then laid at sea. But this is probably too much for your project.

If you use steel, put anodes on it to make it last longer.

The oil and gas industry also makes use of flexible composite pipe to transport oil, gas and water subsea. The suppliers of these pipes are Coflexip (Technip), NKT and Wellstream.

You probably don't want to try to buy one of these pipes new for your application (too small business for the suppliers). But you might be able to find a pre used water injection flexible pipe that would work.

 

[GregLamberson]

What is available on the Island as far as pipe? What is the flow rate and pressure?

Assume there are boats in the area between the Islands (anchors are the issue there) - I know, I know, sounds like a dumb question, but you never know unless you ask.



Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[waross]

If this is a fresh water pipe in salt water you may want to calculate the bouyancy. You may need weights to get it to the bottom and more weights to keep it from drifting with the tide.
respectfully.

 

[allie075]

Thanks for all your responses.

GregLamberson: Flow is about 0.27mgd and we need about 25psi. Concerning the boats, this is not a problem; we considered this in the initial route selection process.

JR McGregor: The steel pipe sounds feasible to me. If I use the anodes should I still coat the pipe in tar/bitumen? You sound like you have some experience with this so just one more question: Should I calculate for bouyancy as suggested by waross?

Waross: It is freshwater. Thanks for the heads-up. I really didn't consider that aspect.

Thanks again
Allie

 

[GregLamberson]

If you want the pipe to last more than a few years (and I'm not being smart, it may be a very short term solution??) then yes you would want to have it coated. I would suggest whoever you buy the pipe from ask them to have it FBE coated, with this amount you should be able to find it available already coated in some pipe yards stock.

Another key issue on the coating is the weld joints.

You would want to do the calcs on buyoyancy, but in the 4" pipe size, anything over about 0.190" WT will not require weight coating.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[Oceania]

The above are all good ideas, however I would also suggest ensuring additional protection where it passes over any coral as over time, tide movements and sand will start to abrade the surface. To reduce this problem if you think its going to occur is to fit some polyurethane covers over the pipe, either in the form of sheet wrapped around and secured or alternatively half shells can be molded on site with basic facilities.

Another pipe alternative is to use PVC drain pipe and overwrap with glass fibre, easily done on site or on a more suitable island.

 

[allie075]

Hey Oceania

Thanks for a new perspective. Works are to begin soon so we'll be considering what you've said.

Allie