Vessel Design
TALL VERTICAL VESSEL
Design of Tall Vertical Vessels(L > 6 m)
After calculating the shell thickness from previous design methods for vessels under internal and external pressures, we should check that this thickness will withstand the loads applied on it. This check is done on three cases: operation, shutdown and erection.
Check for Operation:
Shell Height, inch.Wind Pressure (Pw, psi)
Internal Region Coastal Region
0 - < 360 0.138 0.2
360 - < 600 0.174 0.27
600 - < 1200 0.2 0.347
1200 - < 6000 0.27 0.42
∑𝑊𝑡 .=𝑊𝑡 .𝑆h 𝑒𝑙𝑙+𝑊𝑡 .𝐻𝑒𝑎𝑑𝑠+𝑊𝑡 .𝐿𝑖𝑞𝑢𝑖𝑑+𝑊𝑡 .𝐼𝑛𝑠𝑢𝑙𝑎𝑡𝑖𝑜𝑛+𝑊𝑡 .𝑇𝑟𝑎𝑦𝑠+…
Check for Shutdown:
Note: in case of shutdown, σd is calculated from the same equation of operation
but don't put the weight of liquid in Σwt.
Check for Erection:
Note: in this case we only put the weight of shell [or shell + one head] in
Σwt. in the equation of σd.
Design of Skirt Support:
Assume: Disk = 0.95 Dish
Dosk = 1.05 Dosh
Then calculate thickness of skirt:
Check on the thickness of the skirt:
Design of Bearing Plate:
Assume: Dib = 0.8 Disk
Dob = 1.2 Dosk
Then check on these assumptions:
Thickness of bearing plate
Design of Anchor Bolts:
Where:- σw is that calculated above in the
bearing plate.- σd is calculated from:
If σtension) max = - ve value: the number of bolts equal 4 used for fixation.
If σtension) max = + ve value: the number of bolts calculated from the following
equation:
SHEET 3
Sheet 4
1. A distillation tower will be erected out of doors at Alexandria. The specifications of the tower are specified
below:
Height, between tangent lines 50 m
Inside Diameter 2 m
Skirt Support 10% openings, height 3 m
100 sieve plates equally spaced with 0.45 m plate spacing. The plates are supported on rings 75 mm wide, 10 mm
deep.
Insulation, mineral wool 75 mm thick
Material of construction Stainless steel
Design stress (at the design temperature 200ºC) 135 N/mm2
Operating pressure 10 bar absolute
Vessel to be fully radiographed Welding efficiency = 1
• Specify the design for:
a. Shell at the top and at the bottom.
b. Dished heads, skirt support, bearing plate and anchor bolts.
c. If the tower will be operated at a pressure of 50 mmHg absolute, check if the thickness calculated above is
sufficient and support rings will act as effective stiffening rings.
2. A distillation tower will be erected in doors at Alexandria.
Height, between tangent lines 50 m
Inside Diameter 2 m
Skirt Support 10% openings, height 3 m
100 sieve plates equally spaced with 0.45 m plate spacing. The plates are
supported on rings 75 mm wide, 10 mm deep.
Insulation, mineral wool 75 mm thick.
Material of construction Stainless steel
Design stress 135 N/mm2
Internal pressure 0.1 bar absoluteVessel to be fully radiographed Welding efficiency = 1
• Specify the design for:
a. Shell at the top and at the bottom.
b. Dished heads, skirt support, bearing plate and anchor bolts.
c. If the tower will be operated out of doors in the same area, check if the
thickness calculated above is sufficient.
