Water weight of elbow 3

[rmw]

Imagine a piece of pipe of a couple of meters length on a set of rollers free to rotate. This piece of pipe has one 90 degree LR elbow on it and the elbow and pipe end are full of water and capped with a flat plate at each end. (No, this is not homework.)

I need to determine the water weight as well as the metal weight for the overhung portion of the elbow that would cause the pipe to rotate. Forget the seal plate weight, it is imaginary and just to set up the problem. The real world problem has more pipe attached to the elbow and I already have what I need with respect to that pipe.

I have looked all over the Internet as well as Crane and Navco, etc for a method to determine water weight and pipe weight for this type of situation but can't find anything. Is there something there or does someone have a trick? And, Pennpiper, I even looked on your site and didn't find anything.

rmw

 

[Montemayor]

rmw:

Are you still living in my neck of the woods? The reason I ask is that I have the information (at least the water weight portion) for long-radius and short radius elbows, from 1/2" through and including 48". You don't tell us what size of L-R elbow you are dealing with; is it a secret? --- just kidding.

I have all this information in volume capacity of fittings - which includes 180 degree Returns, 45 degree elbows, Tees, caps, crosses, and stub ends. I took all this information from my 1971 Tube-Turns Catalog that was falling apart at the seams and put it into an Excel workbook together with a lot of other information that I didn't want to throw away. I guess since there is not Tube-Turns Catalog available anymore, this stuff has really appreciated, right? --- just kidding.

I am attaching the information for your use in your secret squirrel experiment (I really think it's homework, but what the heck...). Enjoy.

 

[MikeHalloran]

With 3D CAD, you can build a solid with the shape of the elbow's interior, and find its volume and centroid, from which you can compute the water weight and moment.

Similarly, you can model the elbow itself and do the same thing.

Or, using, e.g. Excel, you can compute the elbow's interior volume as 1/4 of a torus, and the elbow itself as the difference between two torii.

Or is it harder than that, and I am reading the question wrong?



Mike Halloran
Pembroke Pines, FL, USA

 

[rmw]

Art,

That is one fantastic spreadsheet. Thank you for that. Yes, I am still in your neck of the woods. Are you in these woods or off somewhere else grand-fathering.

I will phone you with the size if you are in town (but not tonight.) I have been meaning to call for some time now.

Mike,

Thanks for your reply too.

It isn't the volume or the metal weight of the complete elbow I need, it is that portion that is contributing to the creation of the moment that wants to rotate the pipe only. Will 3D CAD give me that? I am not a CADDer but I am surrounded by those who are.

rmw

 

[MikeHalloran]

Logically, you can slice off the ell at the plane transverse to the pipe where the cross section just starts to diverge from symmetry about the pipe axis, i.e. at the transition between the elbow proper and the tangent section connected to the pipe. That's what's contributing to the moment.

It's pretty simple to do the exact same thing in CAD.
A good CAD driver can probably do it in less time than it will take you to explain the problem.





Mike Halloran
Pembroke Pines, FL, USA

 

[grandnobi]

guys,

do we really need fancy computer programs to determine the volume of a quarter donut?

http://en.wikipedia.org/wiki/Torus

... o tempora, o mores... ;-)

 

[pennpiper]

rmw,
You just did not look in the right place.

Look here under "Calculators" there is both metric and imperial piping weight programs.

http://www.pipingdesigners.com/Tools.htm

 

[rmw]

Pennpiper,

You are right, eventhough I had checked your site, I hadn't looked at that particular calculator and it is helpful. It gives the weight of the whole elbow and that is a help. But that doesn't solve my problem. Mike had given me a good path forward, but to do it I will have to get in line to get some very busy CADD operators time to do it. I was hoping to move forward in the meantime.

The problem is to calculate the moment created by the cantilevered weight of the portion of the elbow and its water from the plane created by the OD of the pipe on the elbow outlet side as it slices through the 'torus' of the elbow while also accounting for the absence of a counterbalancing weight (of metal and water) where the elbow falls away from the plane of the pipe wall on the opposite side. The 'triangle' so to speak created by the sweep of the elbow.

Surely I'm not the first engineer to have to figure the moment due to a cantilevered piece of pipe full of water at an elbow am I? I do have other pipe and fittings further out on the cantilevered leg and those are pretty straightforward.

The pipe is big enough for a very large racoon to crawl up into so we are talking some real weight.

rmw

 

[pennpiper]

rmw,
First:
That web site is NOT mine. I just have the honor of helping the "Owner" when ever I can.

Second"
You have not told us what the practical application we you are working on here.

Third:
Are you trying to over engineer a common issue?

 

[BigInch]

Download this xls before I red flag this thread.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[LSThill]

BigInch (Petroleum)

Link to is not working:

http://files.engineering.com/getfile.aspx?folder=6895ac9d-636c-4096-be1f-d5

is not working

Leonard S. Thill

 

[BigInch]

Thanks for letting me know. You're right
I'll put it on rapidshare.

http://rapidshare.com/files/211982257/water_filled_ell___pipe_moment.xls.html

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[rmw]

BigInch,

That is a real nice spread sheet, but it doesn't give me anything that I could not have already calculated. Thanks anyway. What I need is the moment at the centerline of the outlet of the elbow looking straight down into the page as you drew it. Or, that is to say rotate your view 90 degrees towards you or away from you as you wish and give me the moment where you have the arrow. The pipe and elbow are oriented in the horizontal plane and the elbow and piping that is attached to the elbow are trying to rotate the long pipe about its axis. Was there a way with this spread sheet to rotate the pipe 90 degrees that I didn't see?

Pennpiper, the pipe that this elbow is attached to is not anchored and the cantilevered weight of the elbow and the piping and everything else downstream are imposing too much load on what supports the pipe run on the other end downstream of the elbow. I have to accurately quantify what this load is so I can justify that the proposed new support will work.

I have already done it on the basis of a just using a mitered rectangular elbow but I wanted to get a more sophisticated than that. I may be trying to over engineer it and it is beginning to look like no one else has a solution either (other than Mike's suggestion re; 3D CADD).

It is a real world problem but I regret that I can't reveal many more details due to the client's desire for anonymity. Otherwise I wouldn't be spending valuable time on my weekend pursuing this.

I thought surely someone in this forum would have already encountered this situation.

rmw

 

[BigInch]

So the elbow is in the horizontal plane?
I identify the coordinate system as,
Horizontal plane is X-Y.
Axis of the pipe is X-X.
Axis of the ell's outlet (end with cover) is Y-Y
Vertical is Z-Z.

The centroid of the ell is at 0.7171 * R
(The spreadsheet has 2/3 R, which is wrong)

The moments at the joint of the ell to the pipe,
yes, there are two moments, and they are
Bending moment
My at the joint of the ell to the pipe, which is,
My = Ell weight * 0.7171 * R (bending moment)
And a torsional moment about X-X,
Mx = Ell weight * 0.7171 * R (torsional moment)






**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/