Pipe line design 1

[Weldinspect]

Hello, for an ASTM A53-B, 600 mtrs, 10 inch above ground pipe design with 60-80 C water stream, do I need to consider thermal expansion and model it with special software or is it enoutgh to make a static design?

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[Weldinspect]

Another question, can I design all supports to be anchors? or what´s the criteria to design the supports, anchors in the midle of straight lines?

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[zdas04]

Your question really depends on pressures as well as temperature, materials of construction, topography, and how long you expect it to last. A 10-inch HDPE line that short that is only going to be in service a couple of months certainly does not need to be anchored. A steel line that short may need expansion loops in addition to anchors.

There was a 4-inch steel line run 25 miles across my county a few years back (they crossed highways at culverts) without any anchors at all. The topography undulated enough that where the pipe overtopped bumps in the terrain it could rise several feet in the air and when it when through minimums it could shrink so that it was a couple of feet off the bottom. That kept expansion/contraction stresses under control. The pipe tended to wander from its lay-location though. Sometimes the pipe that rose up during the day would fall over and when it cooled off would move the pipe to the side. For the 6-months it was in service this wasn't a big deal, but much longer and it would have been.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[pennpiper]

Weldinspect,
Wise people who build cross country pipelines tend to not use Expansion Joints, however they do use Anchors and pipe Guides to control the movement of the pipe during temperature changes.
The primary reason for NOT using Expansion Joints is because they present a weak point in a Pipeline.

Look here for examples of above ground Pipelines.

http://www.canstockphoto.com/images-photos/above-ground-pipeline.html

and

https://www.shutterstock.com/search/gas+pipeline

and

http://www.alamy.com/stock-photo/pipeline-above-ground.html

Sometimes its possible to do all the right things and still get bad results

 

[mk3223]

The hot water pipe is to be thermally expanded. The thermal expansion of the pipe may be manually calculated without any pipe stress software, such as Caesar II.
The piping design of the anchor vs lateral guides, search the forums for reference, such asthread378-255151.

 

[KevinNZ]

You can manually calculate suitable expansion loops and how much the pipe moves at each support and the loads at the anchors. but so much easier to do with a programme line Autopipe or Caesar. If the lay of the land is not flat the manual calculations are much harder.

While 80C is not all that hot and stresses in the pipe may not be high. Thermal loads pushing on anchors could be very large.

 

[LittleInch]

?So the original questions were:
Do you need to consider thermal expansion - Yes
do you model it or use some hand calculations - for me it depends on the complexity of the route
Can all supports be anchors - Yes, but then the strength of the anchors needs to be much higher than a simple support of guide and hence costs more.

A lot will depend on the route and the end conditions and any required horizontal or vertical bends. Also what temperature is the pipe installed at? Is it insulated? Trace heated?

80C is a temperature where things can start to happen and forces can become significant.

In theory 600m for a 60 C temp rise (80 - assumed install of 20) is approx. 430mm. now that assumes no stress in the pipe and frictionless supports, but gives an idea of what you're looking at.

your issues will be end load on whatever this pipe is connecting to, possibility of lateral buckling and falling off the supports and stress at any bends where the movement tends to go towards as the bend is not a strong as the pipe. Add in what ever pressure this pipe is operating at.

A dead straight line might be able to just have a number of anchors so long as the intervening pipe can't buckle, but anything else....



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Weldinspect]

More information, thank you all for your imputs:

Ambient temperature: 15 - 31 degrees C
Maximun pressure: 4 bar
Life expectancy: 30 years
Material: ASTM A53-B
Expansion joint: only at the pump
Maximun expansion at a 77.1 section: 79 mm
No insulation yet specified
No trace heating, this is sewage water going to the treatment plant

I have installed many pipelines and remember that usually fixed supports are in the midle of every pipe section and reading a paper they say they advise to use them every 150 to 200 meters, could we design this way and then calculate the resultant expansions and pipe stress?

It is a shame my laptop was stolen a few years ago including the CAD drawings I had

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[pennpiper]

Weldinspect,

Ambient temperature: 15 - 31 degrees C (59degree F - 86degree F)
Location of this Pipeline: ?
Operating Temp: 60C - 80C (140F -176F)
Maximun pressure: 4 bar (58 PSI)
Life expectancy: 30 years
Material: 600 Meters10" ASTM A53-B
Expansion joint: only at the pump (Suction or Discharge? and Why?)
Maximun expansion at a 77.1 section: 79 mm
No insulation yet specified
No Heat Tracing, this is sewage water going to the treatment plant



Sometimes its possible to do all the right things and still get bad results

 

[mk3223]

usually fixed supports are in the middle of every pipe section

Ensure that the both ends of the pipe section to have adequate flexibility for the thermal expansion as a fixed support was installed in the middle of the pipe section

they advise to use them every 150 to 200 meters

It sounds the design is for an expansion loop to be added on a straight pipe run of 150 to 200 meters long.

For the personal safety, a personal protection insulation may be considered as the op temp of 80 deg-C.

 

[Weldinspect]

Thank you again E-T team, and sorry to say that our client changed the pipe specifications to a PE that could be installed on top of the floor. So now we have to study this new specifications to change the design.

@pennpiper Location: El Salvador

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[racookpe1978]

NO Heat Tracing???

If in Miami, maybe.
Even north-FL gets 1-5 days of freezing weather each winter, and unless an outdoor pipe can be assued of drainage every freezing day-night-day-night of below 0 C air temperatures is subject potential damage if the line is static. West TX lost several steam and gas turbine power plants because their control and air lines froze up after one 2-day freezing period.

 

[Weldinspect]

This is for Central America racookpe. Thanks

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