Flanged & Flued (F&F) JOINT is good to accomodate very small amounts of movement only if stresses of tubes and tube-ts JOINT are acceptable provided spring rate value is inputted correctly. as the software doesnot calculate the value of spring rate itself.

And if the F&F JOINT doesnt clear with one or more convulsions due to the applied stresses then ultimately next choice is a Bellow type Expansion joint i.e. a thin walled with convolsions.

In above case, software automatically calculates the spring rate. So no worries when i will go for a Bellow type JOINT.

Question:

What value of spring rate may i use for a F&F JOINT calculations and same is not calculated by the software ?

I have used the value of spring rate from Bellow JOINT calculations but my seniors told me that F&F spring rate is much higher than a Bellow type Joint.

Here, I want to confirm how to validate the spring rate values for F&F expansion JOINT i.e. is there any reference available for taking values for spring rate.

Also is there any alternate method for an existing exchanger whose F&F expansion joint fails according to ASME code in shell hydrotest condition ?

_________________
Syed Osama Nusrat Ali
Exective Engineering (Project)
Fauji Fertilizer Company Limited
Pakistan
email: osama_ali@ffc.com.pk
Cell # +92-3025252018

Of course your question cannot be fully answered, it's too secret about any details.
Anyway, I have used the thick-walled expansion joint once. Made out of two spinned halves, 2mm stainless. I had the plumpiest guy in the shop floor step on the bellow, I measured how much it yielded under his weight and that's all I had to know. As far as I'm aware, the HX still works under heavy cycling, recovering heat from flue gas in an internal combustion engines test rig.

_________________
Konrad Anikiel

I don't know what software you used, we use pvelite ,the software can calculate spring rate value whatever bellow or thick expansion joint , IF your software can't ,you can calculate according to code , for bellow in ASME VIII-1 APP.26 ,for thick eapansion joint in ASME VIII-1 APP.5 and TEMA.

I am using PVElite as well as COMPRESS

In PVElite, for thin walled it doesnot calculate automatically but ask us to input (user input spring rate corroded / uncorroded) but in case of thick walled i.e. Flange & Flued, software analyzes according to code.

Please see it again.

_________________
Syed Osama Nusrat Ali
Exective Engineering (Project)
Fauji Fertilizer Company Limited
Pakistan
email: osama_ali@ffc.com.pk
Cell # +92-3025252018

Osama,
It's hard to understand what your problem is. Engineers are the kind of animals which prefer not to give any recomendation when they aren't sure whether it helps.
As far, I can see that you are manufacturing something and suddenly you discovered that your design fails in calculations of the expansion joint. Is it the case? What exacly expansion joint are you using? Which exactly condition is not fulfilled? Why would you expect that a thin-walled expansion joint has the same stiffness as a thick-walled one? Do you know what stiffness is at all?

_________________
Konrad Anikiel

Dear Konrad,

THE EXPANSION JOINT SPECIFICATIONS IS AS FOLLOWS:

1. Expansion Joint Type: Flanged and Flued
2. Material: SS 304
3. Annular Plate Thickness: 3 mm min. (3.5 mm max)
4. Other dimension can be read on attached drawings.
5. Design Temperuture Shell side = 70 deg.C
6. Design Pressure Shell side = 6 kg/cm2g
7. Design Temperuture Tube side = 100 deg.C
8. Design Pressure Tube side = 22 kg/cm2g

We are design engineering section and have checked the design and calculations in software COMPRESS and PVElite, but it appears that the above type of expansion joints is subject to failure and is overstressed if following conditions are not taken into account.

1. Annular plate bending stresses
2. MAWP limitations
3. Additionally, shell interaction locations (where expansion joint is welded)

Both software interpretations are little different. However, i have checked in detail the engineering calculations and the Annular Plate fails.

In view of above context, our operation engineer proposed me to reduce the design pressure to operating pressure (i.e. Opr Pressure = 3.0 kg/cm2g) but reducing the pressure still fails the expansion joint in shell-hydrotest-condition per COMPRESS and bending stresses high at shell-Interactions-points per PVElite.

This is the issue.

And in above regard, i have no option left. I can only go for the next possible option i.e. Thin Walled Bellow.

_________________
Syed Osama Nusrat Ali
Exective Engineering (Project)
Fauji Fertilizer Company Limited
Pakistan
email: osama_ali@ffc.com.pk
Cell # +92-3025252018

If you use PVElite 2010,the thick expansion joint is calculated according to TEMA Standards, Eighth Edition, 1999, RCB-7 ,so the value of spring rate in tubesheet calculation, and be calculated according to TEMA RCB 8.60 Flexible Element Stiffness (Exp. Jt. Spring rate): the symbol of spring rate is Sj (N/mm).
If you need to find spring rate for the bellow ,Kb is spring rate ,so the value can be found in bellow calculation.