# SWL of 20-21' span of 1.5" Schedule 40 pipe



## rphilip (Sep 10, 2014)

Is there any permissible safe working load (Uniformly distributed) for a 20 to 21' span of 1.5" schedule 40 pipe?

I've looked online and in a few print resources I have but havn't found anything that even list's a safe working load for shorter spans.

In the application I'm wanting to use it there's no practical way to get a third support point.

Thanks

Philip


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## Robert (Sep 10, 2014)

This is all I could find. http://www.alvinindustrial.com/info/info_02.htm
I would say that at the length you are looking at nobody will have a limit. If you can do math you can figure it our yourself, but good luck on that too much engineering for me. Look at Speed-rail and Hollander web sites for some info.


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## Footer (Sep 11, 2014)

Back the truck up.... a 21 FT span of 1 1/2" schedule 40???

That is a freakishly long span for pipe. I would go to truss if I could. Pipe at that length will develop a bend just under its own weight....

With that though, you have to first define a deflection criteria before you can decided how much you can load something down. In this case being no one is walking on the piece, L/180 is your go to. Punching it into Rigcalc, your looking at a 7#/FT UDL and a 74# center point load.


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## rphilip (Sep 11, 2014)

Footer said:


> Back the truck up.... a 21 FT span of 1 1/2" schedule 40???
> 
> That is a freakishly long span for pipe. I would go to truss if I could. Pipe at that length will develop a bend just under its own weight....
> 
> With that though, you have to first define a deflection criteria before you can decided how much you can load something down. In this case being no one is walking on the piece, L/180 is your go to. Punching it into Rigcalc, your looking at a 7#/FT UDL and a 74# center point load.



Yes it's a freakishly long span, truss is the long term goal but pipe is cheaper to use to demonstrate what's possible. We plan to hang it and use with a very few lights for a few months, then replace with truss when budget allows. It's hard enough to access that there won't be any temptation to add extra lights.

Thanks

Philip


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## porkchop (Sep 11, 2014)

rphilip said:


> Yes it's a freakishly long span, truss is the long term goal but pipe is cheaper to use to demonstrate what's possible. We plan to hang it and use with a very few lights for a few months, then replace with truss when budget allows. It's hard enough to access that there won't be any temptation to add extra lights.
> 
> Thanks
> 
> Philip



How are you hanging this span? There's a big difference between a 20' span only supported only on either end and a 20 foot span hung from points every 4'.


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## gafftapegreenia (Sep 11, 2014)

rphilip said:


> Yes it's a freakishly long span, truss is the long term goal but pipe is cheaper to use to demonstrate what's possible. We plan to hang it and use with a very few lights for a few months, then replace with truss when budget allows. It's hard enough to access that there won't be any temptation to add extra lights.
> 
> Thanks
> 
> Philip



I am of the mind that if I had to do a span like that with pipe I wouldn't do it at all. I would fear that once Id done it with pipe, the argument would be made that "well if it works with pipe why do you need truss?", thus making the battle to get truss all the harder. As always, IMHO, and YMMV. 


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## Footer (Sep 11, 2014)

If you have a good welding shop nearby the could truss two pipes rather easily. I have done this with both box tube and heavy flat stock and it works. You need to design it properly but it can be done.


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## danTt (Sep 11, 2014)

You also might think about cheeseboroughing two lengths of pipe next to each other. It will stiffen it and give you a cheap (less rated) alternative to truss. You might also be better off with Schedule 80 or something thicker, instead of schedule 40, for the same reason.


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## Footer (Sep 11, 2014)

danTt said:


> You might also be better off with Schedule 80 or something thicker, instead of schedule 40, for the same reason.



True. It only bumps you up to a 9# UDL and 91# center point load.

Also, with this being a 7# UDL and ever fixture I know of weighing more then that, EVERY fixture you put on this pipe needs to be figured as a point load an NOT a UDL. If you don't know how to do that, DON"T do this. The pipe should also be marked with its loading criteria... whenever doing anything like this always assume that you will be fired or hit by a bus on the way home.


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## rphilip (Sep 11, 2014)

rphilip said:


> Is there any permissible safe working load (Uniformly distributed) for a 20 to 21' span of 1.5" schedule 40 pipe?
> 
> I've looked online and in a few print resources I have but havn't found anything that even list's a safe working load for shorter spans.
> 
> ...


So, ....

I did a more precise measurement and my intended support points are 21' 11.5" apart, ....

Don't work so well with 21' pipe sections so I'll solve this problem a different way.

It was also a last minute thing which always makes life more interesting (intended show is tomorrow night).

Philip


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