Example 2: Make a preliminary estimate for fabricating a plate thickness required for column of diameter 2.5 m and 60 m in height. Skirt support height is 2.5 m. Hundred sieve plates are equally spaced in the column.

Insulation wall thickness = 70 mm

Operating pressure = 11 bar (absolute)

Joint factor = 1

Column is made of stainless steel, with design stress and design temperature of 130 N/mm² and 210°C respectively (RC, pg 841)

 

Solution:

Design pressure is 10% more than operating pressure

                                                                             = (11-1) × 1.1 = 11 bar, say 10bar

                                                                             = 1.0 N/mm²

For a given pressure loading minimum thickness is

 

Basically base of the column needs to be much thicker to with stand the wind load and dead weights load.

For trial purpose divide the column is to five sections. We can consider the increasing thickness by 2 mm per section. Try 10, 12, 14, 16, 18 mm.

-  Dead weight of vessel

use avg thickness in the equation, mm

Take C_v = 1.15, vessel with plates

         D_m = 2.5 + 14×10^-3 = 2.514

         x = 60 m, t = 14 mm

Weight of vessel = 240 × 1.15 × 2.514 (60 + 0.8 × 2.514) 14

                          = 602382.75 N

                          = 602 KN