5. In designing short vessels, we firstly calculate the
thickness of shell and heads according to the
operating pressure [i.e. internal or external]. In this
case we will not do checks on the thickness as done
in tall vessels so, we will design the support directly.
6. The use of lugs is typically
limited to vessels of small to
medium diameter (1 to 10 ft.)
and moderate height-to-
diameter ratios in the range of
2:1 to 5:1.
And of Course
Sheet5: 2
problems
7. After calculating fs, you should select the dimension of pipe (lug) and check on
your selected dimensions [i.e. check if the lug supports will withstand the load
applied on it]. Following are the steps used to select the suitable pipe
dimensions:
1. From the following table, assume nominal diameter to get the inside and
outside diameter of the pipe. Begin your assumption with nominal
diameter = 2" [always take the Schedule number = 80].
Sheet5 : 2
Problems
9. 2. Calculate the radius of gyration (r) from the following
equation:
3. Calculate the value of h’/r.
4. Make the check on the selected pipe dimensions
according to the value of h’/r . Those values are
summarized in the following table:
10. r
h'
60
'
r
h
200
'
60
r
h
200
'
r
h
The Check
Relation pipe
all
pipe
s
A
f
2
.
.
'
*
1
1
r
h
A
f
pipe
pipe
all
all
pipe
s
.
.
min
.
min
'
2
'
*
*
*
5
cal
critical
s
critical
I
I
h
I
E
F
f
F
5. If the corresponding check is not correct, assume another nominal
diameter [greater than 2"] and repeat the above steps.
11. Assume:
In order to check on this assumption, use the following formula:
12. 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:
16. Assume:
I’ll go to the
section now.
I don’t know
which subject
but they told me
that Sheet5: 2
Problems
17. Design of Bearing Plate:
Assume:
Design of Anchor Bolts: only 4 bolts for fixation
Sheet5: 2
problems?
Yes
18.
19. 1. A pressurized vessel lined internally with 4 mm Nickel material is to be fabricated and installed out
of doors in Mostorod area. The vessel has the following specifications:
Shell inside diameter 1.5 m
Shell length 4 m
Maximum internal pressure 20 atm.gage
Operating temperature 150ºC
Lug support height 2 m
No. of lugs 6
Corrosion allowance 1 / 16 in.
Insulation thickness 2 in.
Shell material C.steel
Allowable tensile strength of material of construction 15000 psi
Head type Dished
Specify the design for:
- Shell & heads.
- Lug support, bearing plate & anchor bolts.
- Maximum permissible vacuum applied in the vessel.
20. 2. A process horizontal vessel is to be fabricated and installed out of doors. The vessel has the
following specifications:
Shell inside diameter 1.1 m
Shell length 2.1 m
Maximum internal pressure 10 bar
Distance between two supports 1.25 m
Operating temperature 150ºC
Support height 1 m
Fluid Heavy hydrocarbon
Corrosion allowance 3 mm
Insulation thickness 50 mm
Shell material Carbon steel
Allowable tensile stength of material of construction 1000 kg/cm2
Type of heads Dished
Specify the design for:
- Shell & heads.
- Support, bearing plate and anchor bolts.
