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# Are EXPANSION JOINTS necessary in piping with small temperature change ?

## Are EXPANSION JOINTS necessary in piping with small temperature change ?

(OP)

Hello everybody,

I am investigating whether the use of expansion joints is necessary in a certain piping system.

To be more precise:

Material = Steel

L = 20 m

Delta T = 25 K

Delta L = 5.75 mm (due to temperature effect)

Test pressure = 12 bar ( Working = 6 bar)

So far I have come to the conclusion that the expansion joint is not necessary if we have sufficient routing/elbows and that the axial expansion load is compensated by natural flexibility of the system.

Also, I was wondering if the flange connections can take any axial expansion load or they are the same as anchor points ?

Thanks,

Young HVAC Engineer

### RE: Are EXPANSION JOINTS necessary in piping with small temperature change ?

Hello matkomatko,

I am on my last year of studying a double degree on Building, Business Management and Administration, and yesterday in the Installations subject we were just talking about expansion joints.

I can't answer your question with total certainty based on the data you provide, but I comment the advice that our teacher told us, and it was that whenever we can and if we doubt, we should always put expansion joints on that critical points.

Anyway I let you here this link: https://www.corzan.com/blog-sp/considerar-expansio... ; that belongs to a company which is specialized in piping.

So I hope that you could find some useful information there.

Regards,
Young Construction Student

### RE: Are EXPANSION JOINTS necessary in piping with small temperature change ?

I'll let a mechanical guy reply, but I would think that you would want to avoid totally 'rigid' connectons and accommodate a small amount of movement, in general.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

### RE: Are EXPANSION JOINTS necessary in piping with small temperature change ?

5.75mm displacement seems to me not "ignorable". 5.75mm of displacement load on flanges is high amount. Consider simple bar of 100mm^2 cross section and 1000mm length and of steel with E=2.1E5 N/mm^2. The load due to 5.75mm axial deflection is 121kN/12 metric tons. Flanges considered anchors for analysis is not actual scenario. Flanges are quite flexible but the high eccentric load could cause the flange joint to leak.

Refer Design of piping system by M W Kellogg for flexibility analysis of piping loops and decide based on that.

### RE: Are EXPANSION JOINTS necessary in piping with small temperature change ?

Thanks... NRP

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

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