Support for piping across long spans 1

[pianoman1]

I have a paper mill client that wants to replace about 750 feet of underground 3" steam piping with above-ground piping. One problem is that the structures he has available to hang pipe from are mostly 50 to 60 feet apart. I've been looking for either light pre-fab pipe bridges or some guidance on how to design a two-cable truss for under the piping, but can't find anything useful online. Anyone have any thoughts or references? I hate to add a bunch of posts in the client's woodyard.

Thanks in advance for any feedback.

 

[RVAmeche]

How high are you trying to route the pipe aboveground? I assume adding little stanchions or something close to grade isn't suitable?

 

[pianoman1]

Average height above ground would be 16 to 20 feet.

 

[KevinNZ]

You can look increasing the pipe size so it will span more. Then get a gun piping designer to push the limits and what can be done. You can span very gaps if you really have to.

https://www.eng-tips.com/viewthread.cfm?qid=218151

 

[pianoman1]

That's wild, Kevin. Unfortunately this is for steam, so arched spans aren't practical from a condensate management point of view, and pipe deflection versus pitch need to be managed as well. We have chip blowlines that are up to 36" diameter, thin wall but have stays and guy-wires so they span up to 100 feet, but I can't find any guidance for how to design them. Might have to just do it from scratch....

 

[Gator]

Can you use Open Web Steel Joists?

 

[LittleInch]

Well it's basically beam theory.

15 to 18m for a 3~" pipe is a long stretch.

you may though find that the pipe is actually OK providing you can avoid a hard point support where it might buckle, but the droop in the middle would look very strange to most people.

If you can maintain a high degree of axial force this would actually help to maintain the level and reduce the chance to sag too much.

Or you're into a lightweight truss design or some sort of cable stayed design.

What doe your vertical profile look like?
How much space do you have?

This is something like I was thinking of. Can't see the max spans, but give them a call?

https://www.cabproducts.com/cable-rings-electrical/

https://www.dpbuildingsystems.co.uk/index.php?route=blog/article&article_id=37

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

Are you aware of the Pioneering Engineering work done by the COADE company and their "SKYHOOK" concept ???

This may be suitable for you as long as the windspeed is low .....

MJCronin
Sr. Process Engineer

 

[pianoman1]

Interesting, I might be able to make that work with the right cable and a ring every ten feet or so. I have to run about 400 feet through mostly open space, in that 400 feet there are structures for old chip lines about 50 feet apart. Trying to run almost horizontal, 1/4" per foot slope just to keep condensate moving downhill. Here in Maine I need to add in wind, snow and ice to the pipe and insulation load.

 

[pianoman1]

MJCronin - I think the mill has some OSHA concerns with the quantity of Helium required onsite...

 

[LittleInch]

Design for overhead traffic light systems looks the best bet to me. Lots of them are >20 span.

To keep your pipe straight you will need variable length hangers to cope with the supporting cable sag.

But you never said this was outside. I guess if it's steam then you won't need to worry about ice, but wind will be interesting.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pianoman1]

Littleinch - you're right, the snow and ice don't stay around long on insulated steam piping, but any components I add will need to consider them. I have browsed the pipe bridge websites, I'll pursue that with a couple providers and see what light units cost.

 

[pennpiper]

pianoman1,
Unfortunately, this appears to be a time when all the advice you get, is not good advice at all!

Sometimes its possible to do all the right things and still get bad results