When are expansion joints in the suction required?

[DerekLJ]

Our client is asking us to put expansion joints on the suction of all pumps in the thermal power plant that we are designing and building. pneumatic, centrifigal, everything.

What defines the need of expansion joints in these pumps? I imagine anywhere where there is heat or vibration, but at what levels should i start considering expansion joints?

thank you

 

[nickelkid]

When do you need and expansion joint? When you are unable (&/or unwilling) to design piping with adequate flexibility.

 

[BigInch]

Only when you cannot build in enough flexibility or get enough pipe supports or the right pipe supports, guides and anchors within the configuration of the piping to achive loads to the equipment flanges that are less than allowables. Do not use an expansion joint unless you have tried everything else... at least twice.

**********************
"Pumping systems account for nearly 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[pennpiper]

RCHandy and BigInch are 100% correct in what they have said.

 

[pennpiper]

Also see this:
EXPANSION JOINTS
thread378-230168

 

[insult2injury]

Sometimes, it is also wise to include them if:
- the pipe is not routed/designed and loads are unknown
- the pump is not purchased and allowable loads are unknown

This may not result in optimal solution, but it does prevent costly rework in projects where activities are a little out of sync.

I2I

 

[nickelkid]

DerekLJ,

If you need to use EJ's, be sure to design your piping correctly. Just throwing an EJ in a system may have unintended consequences. A few examples how to install them correctly on pumps:

http://www.psi-linedpipe.com/ExpJointInstll.htm

 

[Artisi]

Have a look at an earlier discussion re expansion joints - it will give yuo a bit more ionfo

http://www.eng-tips.com/viewthread.cfm?qid=230168&page=2

 

[stanier]

Expansion joints are used because the suction piping is usually directly in line to prevent turbulent effects on the impeller. Refer ANSI/HI 9.8. Thus you need a device that allows the erection and maintenance of the suction valve. The expansion joint provides such an animal.

In addition in building services noise transmission via the piping can be thus avoided.

Also trades these days are not as skilled or diligent and the flexibility afforded is welcomed.