Constant pipe support to combat thermal expansion 3

[tdt108]

I am working on a project to support a large pipe during thermal expansion. Most of the weight will be supported from the top, but a constant portion of the weight needs to be supported from the bottom to minimize permanent thermal expansion without causing a buckle at the top. I originally thought about using a constant spring and that still is likely the best option, but they are expensive and bulky. My next thought is to use hydraulic/pneumatic cylinders with some type of valve. I am still a student so I am pretty new to engineering design and have not worked with hydraulic and pneumatic cylinders much so I am wondering if this would be a possible solution or if these cylinders are commonly used for this purpose. If anyone has any other recommendations, please share if you'd like to.

Thanks,
T

 

[LittleInch]

A sketch always helps.

How does supporting a pipe from the top cause a buckle?

Springs are easy, simple reliable and work well.

Air / pneumatics can fail and are more difficult to control due to temperature changes, leaks etc and probably cost the same or more. You don't see them for a reason.

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

 

[tdt108]

I think this setup is simple enough to do by hand and without CAD since I am looking for somewhat general concept advice rather than something specific to my project. I have attached both PDF and PNG files just in case. Let me know if there are any viewing issues.


[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1655299774/tips/Pipe_const_sup_a1vzw2.pdf[/url]

 

[tdt108]

The pipe would buckle from too much bottom support, not top support, sorry.

 

[LittleInch]

Ah, that's what a sketch is vital.

So this is a vertical pipe of how long?
The thermal expansion, even for a long pipe of say 20m is very small.

What you seem to want to do is reduce the effective force / weight on the top. So at some point the pipe turns from having a compressive stress / reduction in length to an tensile stress resulting in increase in length.

A spring looks good.

An airbag would do a similar job, but the pressure you need might be quite large unless you add a big plate to the bottom of the pipe.

All pretty simple equations and calculations.

But what you seem to be trying to do is quite strange and hence not many other examples. Most people would either support the pipe from the bottom for its weight and add some sort of bellows or maybe just make it thick enough or hang it form the top and stiffen up the top hanger.

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

 

[tdt108]

The pipe will provide an initial expansion of .15m which is elastic and then a maximum plastic elongation of about .35m that occurs throughout the life of the pipe. The top support of the pipe holds around 3/4 of the pipe weight, while the bottom holds the other 1/4. These statistics should remain constant and there should be no transition of weight from the top support to the bottom during therm elongation.

The space below the pipe would allow for a const spring support but it would block the walkway.

The bottom tube support will be around 1 ton for reference.

I am aware of the possibility of leaks and other errors, especially since the cylinders would be around high temperatures. I have reached out to a few companies and got some suggestions for upgraded seals and casing for high temperatures.

I briefly checked on gas springs/struts but those would most likely lead to issues with the load and environment.

 

[1503-44]

If you think spring cans are expensive, wait 'til you get the proposal from whomever will build your custom job.

Never build what you can buy off the shelf.

Little Inch is correct. Forget anything pneumatic powered. Nothing about gas pressure wants to stay constant. That's why we spend all our time trying to control it.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[Texas Piper]

@tdt108

A little more detail would help here. What is the pipeline size? Design/Operating Temp & Pressure? Material? Etc. What amount of growth are you anticipating?

Depending on the line size, adding an extra bend or two to the line may be more economical than a spring support. That said, IME spring supports are not terribly cost prohibitive when used appropriately.

As far as hydraulic supports go, they do exist and are known as snubbers. Their purpose typically is to absorb rapid expansion in cases of steam/water hammer or seismic event and not act as a constant load support.