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Boot calculation fails App. 1-7(b)

Boot calculation fails App. 1-7(b)

Boot calculation fails App. 1-7(b)

(OP)
hi
I have a 9' ID vessel with a 4.5' ID drop leg (boot), but it's failing cause of bending moment due to large diameter, acc. to App. 1-7(b).
Is there any way to solve this problem without boot diameter changing?

RE: Boot calculation fails App. 1-7(b)

insert plate

RE: Boot calculation fails App. 1-7(b)

(OP)
Thanks,

Do you mean repad? I have added a repad already and it passes for internal pressure, the problem is about bending moment cause of big boot diameter. Although I increase repad, it doesn't help

RE: Boot calculation fails App. 1-7(b)

raf2007,

Try the following:

1. Increase boot thickness
2. Increase vessel shell thickness (at the can where the boot is located)
3. Both 1 & 2 above

RE: Boot calculation fails App. 1-7(b)

(OP)
Thanks doct9960, it worked increasing boot thk. As it is an existing vessel, can't increase vessel thk (1.328"), of course new boot thk is very thick now= 1.6875"

RE: Boot calculation fails App. 1-7(b)

doct9960 was way ahead of me (he is good). Increasing the boot thickness is more effective in increasing the moment of inertia of the cross-section resisting the bending moment than would be if increasing the shell thickness or adding a reinforcing pad.

For such a large diameter nozzle I would expect a large thickness at that location. You can use the heavy thickness for a short distance near the junction, then transition to a thinner plate for the balance of the nozzle's projection.

RE: Boot calculation fails App. 1-7(b)

hi Raf2007,

hope you misunderstood Vesselfab's word "Insert Plate". This is different from Repad.

A part of the shell is cut and welded with a plate known as "Insert plate" which is 2d of the boots dia. Usually IP has a higher thickness than the local shell thickness and the boot hole will be cut in the IP and fabricated.

This eliminates the use of repad or increase in shell thickness.

RE: Boot calculation fails App. 1-7(b)

raf2007,

If increasing boot shell thickness or insert plate is infeasible/ not solving the problem, then make the boot shell into a self reinforced one as shown in sketch Fig UW-16.1 g. this can then be welded to a shell plaate and a head therby forming a boot (or sump)

Obviously, since you are now using a forging cost will increase.

hope this helps.

-jehan

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