Heat Exchanger Shell Flange

[picasa]

For a shell and tube heat exchanger when tubeside pressure changes, on the components that see tubeside pressure should be evaluated for the new design pressure. All these components need to have MAWPs greater than the design Pressure. What about the flange on the shell that bolts to the channel flange? This flange is connected to the channel flange - Does it need to be evaluated. With the stationary tubesheet between these two flanges, I guess this flange does not directly see the new tubeside pressure, still I thought I should ask if there is any other consideration that is required.

 

[Christine74]

The shell-to-tubesheet flange needs to be evaluated as well. The reason for this is that the increase in pressure on the tube side often causes a higher stress in the studs that connect the channel to the shell, which results in a higher bending moment for both flanges.

-Christine

 

[Konrad]

In a heat exchanger like that both flanges must always be calculated for higher of tubeside or shellside pressures.

Konrad

 

[johnnymist2003]

picasa,
You need to evaluate each pair of mating flanges for the highest bolt loads as calculated for EACH of the flanges in the pair.You need to check your tubeside flange for the new tubeside pressure.When you do this check, the bolt loads may increase due to the higher pressure (Wm1, Wm2 & W, ASME reference).Thus you should evaluate the shellside flange for the tubeside bolt loads.If the shellside bolt loads are higher than the tubeside bolt loads for the new pressure, then the opposite applies-you would need to evaluate the tubeside flange for the higher pressure, in addition to which the bolt loads from the shellside flange must also be used.
John