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.