super rigid erw 1" metal pipe. concrete filled? 1

[brian sansone]

Hi
I am trying to make a 12' long, 1" diameter schedule 40 pipe that will not sag when hung horizontal. I am shooting for supports every 12'.

My first idea is to somehow fill the pipe with cement or concrete. Another idea is epoxy.
I need to figure out a process to get the cement/epoxy in the pipe, and determine if it will actually work

Any takers?
Thanks
Brian

 

[BAretired]

I suggest calculating the deflection without concrete fill first. The pipe will sag, it's just a question of how much.

BA

 

[EdStainless]

1" OD or 1"NPT? Two very different sizes.
Filling it will not make it stiffer.
The OD is the controlling factor, If you need it stiffer overwrap it with graphite/epoxy.


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[JStephen]

If it's just supporting its own weight, it won't much matter.
If it's supporting some other load, simplest solutions are to increase the pipe size or increase the wall thickness, with pipe size having the most effect.
I expect grout or concrete inside would either do nothing or increase the sag.
You could camber it so when it sagged, it was theoretically straight.

 

[cvg]

I'm looking at a 1 inch fire sprinkler line hung from the ceiling, supported at about 10 - 12 feet OC. I assume it is pressurized and I can see no visual sag.

 

[oldestguy]

Find the size steel rod that will fit inside. Besides adding some strength, you are less likely to get buckling and thus a little more strength until failure. How about next thickness wall for the pipe?

 

[miningman]

What size aggregrate do you intend using in the concrete mix and how do you intend preventing voids in the concrete??

 

[BAretired]

How can the sprinkler line deliver water if it's filled with concrete, epoxy or steel rods? The best remedy for excessive sag would be a shorter spacing of hangers. If that is not possible, use a thicker or larger pipe.

BA

 

[oldestguy]

BA retired. I make the same mistake with quick reading.
My first idea is to somehow fill the pipe with cement or concrete. Another idea is epoxy.
I need to figure out a process to get the cement/epoxy in the pipe, and determine if it will actually workain't for water.

 

[BUGGAR]

How 'bout a carbon fiber prestress strand located inside the pipe toward the bottom and stressed between pipe caps at the ends?
(ps: I tried it and it won't calc out)

 

[bones206]

Assuming the only constraints are diameter and support spacing, use a material with a high strength-to-weight ratio. Carbon fiber pipe, titanium pipe, aluminum pipe, etc. All commercially available.

 

[BridgeSmith]

Some of those options would work, bones, but be very expensive. Aluminum is not terribly expensive, but the deflection could be as bad or worse than steel. While it is lighter than steel and has nearly the same strength, the modulus of elasticity is much less than steel, so the deformation under load is much larger.

 

[bones206]

That's a really good point. I guess what you actually want in this case is a high stiffness-to-weight or modulus-to-weight ratio. Not sure what the budget or the context of this pipe is.

 

[BridgeSmith]

Nothing is going to have zero deflection, because nothing is infinitely stiff. If it has to be absolutely straight in the final condition, it will have to be cambered to compensate for the deflection. Aside from that, it's a question of how much deflection is acceptable and how much is someone willing to spend keep the deflection within that limit.

 

[TLHS]

You could try to camber it... but you'd need to connect it in such a way that it wouldn't roll.

You'd get better suggestions if you explained what you were trying to do.

 

[PEinc]

Brian_Sansone has posted this question in two different threads (here and in the Concrete Engineering general discussion thread) against ET guidelines. In almost 3 weeks, he hasn't responded or provided any more information in either of the two threads. We are wasting our time guessing what he needs and responding without sufficient information.

http://www.PeirceEngineering.com

 

[Ron]

@PEinc....yep!


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