UHX-13.5.11 Step 11, Bending Stress due to Joint Interaction [Sigmasb]

[Dennysurf]

Hello,

For calculating the tubesheet of fixed tubesheet heat exchangers (integrated with the shell) again I'm struggling with the Shell Bending Stress due to Joint Interaction [Sigmasb]. (acc to UHX-13.5.11 Step 11)

Because of this value (negative and positive) I have to increase the tubesheet thickness double the calculated value. Increasing the shellpipe thickness, or placing a shell-band at the shellpipe-tubesheet connection doesn't help really much. only by increasing the tubesheet thickness a lot I can manage to fit the Sigmasb to an acceptable level.

Does somebody know how to lower the Sigmasb without increasing the tubesheet thickness to much?

Thanx for your help,
Denny


ps:
For an other heat exchanter I also had this problem while a expansion below was used, how is this possible?

 

[gr2vessels]

Dennysurf,
You can increase the local shell thickness at the junction with the tubesheet as indicated in UHX-13.5.11 and in conjunction with Fig. UW-13.2 and UW-13.3(c), particularly the Note 1 of the later Clause.
Cheers,
gr2vessels