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#39621 - 12/17/10 04:15 AM Small Bore Vs. Large Bore Pipe
dsiingh Offline
Member

Registered: 12/03/09
Posts: 19
Loc: India
Dear All,

How can we justify small bore pipes are much more flexible than Large bore pipes.

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#39623 - 12/17/10 05:24 AM Re: Small Bore Vs. Large Bore Pipe [Re: dsiingh]
Jop Offline
Member

Registered: 12/12/05
Posts: 191
Loc: Florida, USA
Logic!

1) Go out to the field.
2) Place two low supports (1 meter high) on the ground and 8 meters apart.
3) Now place two pieces of pipe, one 24" (DN600) and one 2" (DN 50) spanning across the two supports.
4) Now get up on top and walk across the 24" pipe and then walk back across to 2".
5) Did you notice any difference between the flexibility of the two pipes?
_________________________
Jop

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#39626 - 12/17/10 06:40 AM Re: Small Bore Vs. Large Bore Pipe [Re: Jop]
danb Offline
Member

Registered: 04/22/05
Posts: 1320
Loc: ...
Jop,

The only problem is to determine is if as per Project specification 2" pipe is to be considered small bore or large bore smile

Regards,
_________________________
Dan

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#39631 - 12/17/10 09:28 AM Re: Small Bore Vs. Large Bore Pipe [Re: danb]
Jop Offline
Member

Registered: 12/12/05
Posts: 191
Loc: Florida, USA
DanB:
That was not the question.
The question was:
"How can we justify small bore pipes are much more flexible than Large bore pipes?"

Or restated:
How can we prove small bore pipes are much more flexible than large bore pipes?
_________________________
Jop

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#39632 - 12/17/10 09:36 AM Re: Small Bore Vs. Large Bore Pipe [Re: Jop]
danb Offline
Member

Registered: 04/22/05
Posts: 1320
Loc: ...
Yes Jop, sorry. It was only a small joke based on the fact that on some jobs 2" is considered large bore also.

In any case there are the charts that shows the required length to absorbe an amount of displacements. "dsiingh" can show them to the client and the client can see that a small bore is more flexible. It will be happy. (assuming that "dsiingh" wanted this kind of answer)

Best regards,
_________________________
Dan

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#39781 - 12/28/10 11:22 AM Re: Small Bore Vs. Large Bore Pipe [Re: dsiingh]
AnirbanDatta Offline
Member

Registered: 04/08/10
Posts: 5
Loc: India
What danb and Jop are saying are very correct.

Dear dsiingh,

Pls use the following formula for claculating the delection for same span of small and large bore pipes (of your requirement) continuously supported:

D = 5wL^4/384EI

where
D = defelction
w = weigth of pipe (filled or empty) per unit length
L = distance between two adjacent supports, i.e. span
E = elastic modulus of pipe mateial
I = moment of inertia of pipe

From the above you will easily find that for same value of L, D would be higher for smaller dia. pipe.

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