Dear all,
Refer the attached file. Can some one help me, is it required stress analysis. Design Temperature: 400 deg F and Design pressure:75 psig, Material: SA 106 gr B.

Due to the high design temperature and the low amount of flexibility, I would say YES. Especially if the horizontal vessel is long and allowed to grow in a particular direction.

Additionally, I can assure you that you will not be able to meet the nozzle loads neither for the column nozzle nor for the vessel in this configuration.

If this is not a standard design (i.e if you're not allowed to add flexibility by Process), then only FE analysis can save you!!!

Good Luck, mate!!!