Pipe Vibration

[juremo81]

Hello,
I have a structural engineer who is asking me for the vibration in chilled water and vapor pipings. He is also asking me for the "magnitude of the force" that is causing the vibration????
This is the first time I have came across with a vibration problem, so I really don't know where to start... Whould yo recommend buying an FEA software or should it be a straightforward problem? I have search the internet for related articles but haven't had any luck. Any links, articles or tips that you can give me will be much appreciated. Thank you!

 

[drawoh]

juremo81,

Are your pipes actually vibrating, or is the engineer concerned about the possibility of it?

JHG

 

[juremo81]

The engineer is concerned about the possibility. he wants to put neoprene on the supports

 

[juremo81]

so I guess that's why he wants to know the vibration and force causing the vibration...

 

[drawoh]

juremo81,

How experienced are you at whatever it is you are doing?

Is this request from the engineer unusual?

Are you doing anything unusual, like running longer, unsupported pipes?

Do you have anything in your system that will generate vibration?

Is the engineer looking at something unusual that should not be vibrated by your pipes?

There are handbooks that will provide you with resonant frequencies of various cantilever beams. I cannot see how FEA would help you. I would assume that any vibration input to your system will be transmitted throughout. unless you can rigidly clamp down the joints.

I have no real experience in piping system design. I know they worry about thermal expansion. I would not be surprised to be told that vibration is an issue too.

JHG

 

[Spud6414]

Ask him what type of vibration he seems to be worring about, transmitted or inherent. In other words is he worried about vibration from background machinery at the facility or from the fluid/vapor flows themselves. It seems awful general this request of his.

Spud says; Meticulous effort and willingness to learn are honorable traits.

 

[juremo81]

drawoh/Spud6414,

First of all, thank you for ypur responses...

I've been in the HVAC bussiness for almost 5 years now, not that much experience but I can say I've worked in many commercial and industrial projects and had never been asked this question before (related to vibrations).I've asked some of my more experienced co-workers and they coincide that this is not a typicall question.

There's nothing unusual on the piping support. Right now there's no vibration on the pipes eventhough we have pumps connected to the system.

I've used an FEA software called CAEPIPE but it doesn't seem to calculate the frequencies generated by the fluids.

Here's the Structural Engineers concern: This is a Hospital project, right beneath the piping in question, there is an MRI (which cannot have any type of vibration transmitted to it), so let's say this is more of a precautionary meassure.

I've asked the Structural Engineer, and he told me his concern is more about the vibration caused by the fluid inside the piping, in our case Chilled water and water vapor...


Once again, thank you for your help

 

[drawoh]

juremo81,

You can mount your pipes so that they are isolated from the structure around the MRI machine. Also, you can select pumps and stuff that reduce or eliminate pulsing of your fluids and otherwise, not vibrate your pipes.

What is to stop someone five years from now, from moving into the room next to the MRI and installing something that shakes the floor?

I think the best you can do here is promise not to be the cause of the vibrations that mess up the MRI machine. If this thing must not be shaken, the engineer is going to have to design good anti-vibration mounts.

JHG