Jacketed vessel bulging on inside

[kwisatz_haderach]

We have a jacket heated agitated thin film dryer in our plant . 6 months ago it bulged on the inside. We fabricated a new vessel and after running for 6 months, it again got damaged by bulging on the inside on 6 locations like a flower. What might be the reason for this? This vessel is empty on the inside with blades scraping the inside of the shell and outside it is jacketed and heated by 2 bar steam through spiral baffles. Please tell me your thoughts about possible reasons behind this? Is the thickness sufficient. Please tell me how to calculate the thickness for external pressure. I got stuck on the unsupported length since it is stiffened by spiral baffles.

 

[r6155]

See ASME VIII Div 1 2023 Mandatory Appendix 9 JACKETED VESSELS

(c) Where the internal design pressure is 15 psi
(100 kPa) or less, and any combination of pressures
and vacuum in the vessel and jacket will produce a total
external pressure greater than 15 psi (100 kPa) on the inner vessel wall, then the entire jacket shall be interpreted as within the scope of this part.

Regards

 

[LittleInch]

Depends whether ASME VIII applies in India....

And who knows what the original design pressure was for the jacket. It might have been 1 bar, but then run at 2 bar.... and failed at 3.

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