30inch water pipe laying advice 1

[RogerBryenton]

Hello - new to the forum. Wanting to do some preliminary planning for laying 25,000+ feet of 30 inch .25 to .5 inch wall, carbon-steel pipe for hydro penstock. Want to keep costs modest for non-profit irrigation co-op. Considering used pipe - asking for one end to be flared to allow "spigot" connection, simpler to keep pipe on-round for welding. Hoping to find creative solutions to hauling and laying pipe, which is beside existing road. Anyone have experience with "DIY" - how do we determine "best" number of boom-style pipe layers, since we have identified good used inexpensive turbines and generators and the pipe seems to be the biggest challenge. thanks Rog

 

[BigInch]

I may be wrong, but keeping the pipe together after construction may be your biggest challenge yet. I was always under the impression that penstock lines tend to develop high surge loads, as water flows are rapidly adjusted to maintain turbine output matching load. If that is the case, seems like bell and spiggot joints are not the ideal choice. BTW, did you do a surge analysis?

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[RogerBryenton]

Thanks Big-inch - we can use a couple of big-inches! Surge can be a factor, but pelton wheels use deflectors to take water off the wheelfor shut-down, and spear valves (slow) to adjust flow to buckets for power. Pipe collapse under suction, if started too fast is also a potential problem. Handling the pipe, keeping it from creasing/buckling on low pressure (top) end (plus gettingitup a windy road) are my main conerns for DIY. Any other input? thx Rog

 

[BigInch]

Sorry, I don't mess with concrete pipes. If it was 30" steel I'd get it up there for you.

30" steel, you can stack on a truck to 3 levels. And some road building is often part of the job, but I had to use helicopters to fly up one 40' joint of 24 D up at a time when crossing some areas of the Andes. In Saudi, we had some very rough terrain going to 3000 m elev, but were able to build some often quite narrow roads to get it there. Switch backs on some slopes and on others, we stalk-joined pipe down below and winched it up a joint at a time as we added a new pipe. Won't work very well for bell-spiggot though.

I've got some pics on my web pages.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[ApC2Kp]

RogerBryenton,

You seem to have decided on carbon steel pipe, but did not mention whether the line is to be buried. Are you planning on laying the pipe on soil?

If the pipe is to be buried, then what coating or corrosion protection is planned?

An alternate material for the pipe would be HDPE. Coating is not required for buried service. Above ground service does not require painting. The pipe fusion joint machine would be significant cost / lease. There would be some cost savings from reduced weight compared to steel.

Check for pipe laying equipment on some of the projects at

http://www.isco-pipe.com

http://www.kwhpipe.com

http://www.mcelroy.com

 

[BigInch]

Maybe I'm confused. I thought the spiggot joint style indicated a RCP. What kind of pipe exactly is it?

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[RogerBryenton]

Thanks for the responses. Steel is appealing since we can get it used and it's strong, especially as we get more head, we don't lose ID with thick walls. I am looking at corrosion, and I think it will be buried. If new, we could specify a slight bell for alinging sections, but a pipe supplier suggests using a "ring" system for joining - makes alignment and welding much easier.
I am worried about moving it into a trench, with allowable bends about 50 x D, we'd need a radius of about 150ft, going from roadside into a trench, 5 to 8 feet away, including setting to grade, means about 30 to 50 feet of pipe x 2 will be "S-bending", and have to be carefully lifted since the .25 to .31 wall will want to buckle. The .5 wall will be about 200#/ft, so lifting 60 to 100 feet, means up to 20,000 lbs. I'd like to minimize the site equipment, so I wonder if two pipe-layers can effectively move the .5 wall, or if we'll need 3 (or 4)? I think we can set the .25 to .3 wall with 2 layers. And part of the fun is DIY - "community" project with "no money". - Oh - get this - I think there is an agency with several suitable pelton wheels up to 3.5 mW, willing to donate them (I've had my eye on them for years). Roger

 

[BigInch]

Can't use only two. You must be very carefull lowering that thin wall. Get 3 minimum, 4 possibly 5 sidebooms if you can. There are a number of different sizes for sidebooms and it will depend on the rated lifting capacity of the sideboom, the allowable pipe span between lift points considering the bend profile you must hold while lowering. A larger number of smaller machines are better for holding the profile.

There are pleanty of external coating to go with either or both of an inpressed current or zinc anode CP system.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[RogerBryenton]

Great - thanks - I thought 3 would be better(or 4), even if we have to do a lot more work to organize. Rog

 

[BigInch]

Ya ...takes a bit from time to time.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[stanlsimon]

It almost sounds like you are talking about one straight shot with no changes in direction. That sounds too good to be true. My concern would be your reactions at changes in direction, what is your soil load bearing capacity? What about rock removal and trench formation, do you have a source of bedding material?

 

[RogerBryenton]

Thanks Stan. We will be running downhill, some slight grades, but not much more than about 15%, through really weathered volcanics. There will be occasional bends, again if we can, they will be 150 ft radius (elastic? = 50 x D). Other local irrigation ditches remove about 1/2 the material as fine weathered sand, clay, tiny aggregate, and about 1/2 as soft but borken rock "chunks". I think we can screen the excavated material to give us 3/4 inch minus, and use it for bedding, cover, and 2 to 3 feet back fill. We can surface scrape (and may be ditching nearby), to have extra material. Yes - corner reactions will be determined once we have a clearer idea of costs and cost reduction if the state might permit right of way adjacent to the highway, since that is the logical location for about 85% of the water pipe. Again, thanks to all for your considerate responses. Roger