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Thermal expansion due to the wether

Thermal expansion due to the wether

Thermal expansion due to the wether

(OP)
Can someone help me answering a question about thermal expansion.
When thermal expansion in a pipeline occurs due to influence of the sun,
Is this partly or total neglectable due to heating of the surroundings (the earth, pipebridge).
Thanks in advance for your contribution.

RE: Thermal expansion due to the wether

If I understand your question correctly ... it is normal to ignore thermal expansion of the ground when considering for instance piping on a rack or track.

Thermal expansion of 'the world' can be important in offshore design though. Consider a steel platform built in Spain in 25 deg C ambient, then installed in the North Sea. Initially all pipe and structure is stress free thermally. Then it's operating in winter and the pipe is hot. The structure may be at minus 20 deg C and piping at 100 deg C. Then the real thermal expansion force will be due to (45 + 100) deg C. That can be important where piping is commonly tight routed and very heavy wall.

RE: Thermal expansion due to the wether

If your supports and anchoring points move at the same expansion rate with temperture (dL/dt) and in the same direction as does the pipe, it may be so for a steel bridge, but I would think it is highly unlikely for earth connected anchors where dL/dt could not be counted on to be uniform between supports, nor the value equal to the dL/dt of the pipe.

http://virtualpipeline.spaces.msn.com

RE: Thermal expansion due to the wether

(OP)
Thanks for your replies.
I shall try to explain my question a little further:
I´m in the nasty position of working in a plant (more than 100 yrs old)where in specially the pipebridges are built according no general piping rules, the beams are made of pipe, sometimes with vertically welded bars on it and the bridge elevations are e-w and n-s the same(can you imagine the crossings?).
Most supporting is fixed over the whole lenght of the pipe,
Pipes are mostly amb. temp.
I want to know wether it is to justify to use fixed supports over the whole lenght of the pipe?

RE: Thermal expansion due to the wether

I wouldn't do that.  I doubt the pipe and the bridge change temperatures equally.  With some product in the lines, or lines at may be insulated lines, it wouldn't be reasonable to expect the temperatures of the pipes to be always the same as the bridge.  

Its also probably not necessary to use fixed supports either, unless there is a thermal growth problem and you are trying to restrict pipe growth.  And, if you use fixed supports, you will probably wind up introducing unwanted stresses into either into the pipe or into the bridge.  

http://virtualpipeline.spaces.msn.com

RE: Thermal expansion due to the wether

(OP)
B ", I agree with you about new lines with supporting.
I design my lines with approx. in the staight pieces one anchor in the middle and the rest loose and loose with guides; BUT,BUT,BUT;
When I,m turned my back, the pipingcontractors anchor everything, I give them A4 drawings with all the supports detailed out as simple as possible and they don´t even look at it.I´ve tried to explain the meaning of anchors guides and loose supports and they friendly nodd.
I´m not the man for shouting, especially not at the moment when you can hardly get a pipingcontractor.
So I hope the pipebridge expands in the same way as the pipelines.
 

RE: Thermal expansion due to the wether

If you had PE as a pipe material you would have a more pronounced difference.

If you lock everything up what about earthquake and wind? You may cause local buckling stresses that can cause the pipe to fail.

Stresses & loads occur because you try and stop something moving. If you let something move the loa is reduced.

Pipe support design was explained to me as a "junior" as being like holding a pigeon. Too loose and it will flap its wings and hurt itself. Too tight and you squash the bird to death.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng
www.waterhammer.bigblog.com.au

RE: Thermal expansion due to the wether

Good analogy.

... but with PE, the bridge wouldn't be in danger, with steel pipe, there is a possibility that the pipes are much stronger than a lot of the bridge elements.

http://virtualpipeline.spaces.msn.com

RE: Thermal expansion due to the wether

(OP)
B", I guess you are right comment about the strenght of the pipes, we are replacing many cs pipes in ss (a little more expansion).
The existing pipes are all fixed to the structures.
That is why contractors think it´s the way to do it.
I´ll careful kick some asses I think.
Geoffrey, luckely we don´t have earthquakes here and wind is incidentally max. 11 Beaufort.
Thanks all for your input.

Greetings Jaap

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