Pressure Vessels SHELL THICKNESS where t p shell thickness inch P Max allowable working pressure psi D Inside diameter inch S Max allowable tensile stress ID: 267759
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Slide1
HESSE AND RUSHTON METHOD
Pressure VesselsSlide2
SHELL THICKNESS
where tp
= shell thickness
(inch) P = Max allowable working pressure (psi) D = Inside diameter (inch) S = Max allowable tensile stress (psi) (Table 6-6) e = Efficiency of welded joint (Table 6-7) C = Corrosion allowanceSlide3
SHELL THICKNESSApplicable if:
1. tp
<
0.10D 2. tp > tminSlide4
Allowable Stress Estimation
S = Su
x F
m
x Fs x Fr x Fa
Where
S
u
= Minimum Specified Tensile Strength
F
m
= Material Factor
F
m
=
1 for Grade A material
F
m
= 0.97 for Grade B material
F
m
= 0.92 for Grade C material
F
s
= Temperature Factor (Use Table
6-7)
F
r
= Stress Relief (SR) Factor
F
r
= 1.06 When SR is applied
F
a
=
Radiographing
Factor
F
a
= 1.12 when
Radiographing
is applied and
subsequent
repair of defectsSlide5
Minimum Specified Tensile Strength
Specified
ASME
Minimum
Allowable Unit Tensile Stress, Thousands psi
Code
Tensile
at Various Temperatures, °F
Spec.
Material Data
Strength
- 20
No.
and Description
Grade
1000 psi
to 650
700
750
800
850
900
950
1000
S-2
Steel plates - flange and
A
45
9.0
8.8
8.4
6.9
5.7
4.4
2.6
firebox quality
B
50
10.0
9.6
9.0
7.5
6.0
4.4
2.6
S-1
Carbon steel for boilers
11.0
10.4
9.5
8.0
6.3
4.4
2.5
Carbon-silicon steel,
A
55
11.0
10.4
9.5
8.5
7.2
5.6
3.8
2.0
S-42
ordinary strength range
B
60
12.0
11.4
10.4
9.1
7.4
5.6
3.8
2.0
S-44
Molybdenum steel
A
13.0
13.0
13.0
12.5
11.5
10.0
8.0
5.0
S-43
Low-carbon nickel steel
A
S-55
Carbon-silicon
steel
, high
65
strength range, 4-1/2”
A
13.0
12.3
11.1
9.4
7.6
5.6
3.8
2.0
plates and under
S-44
B
14.0
14.0
14.0
13.5
12.0
10.2
8.0
5.0
S-43
B
70
14.0
13.3
11.9
10.0
7.8
5.6
3.8
2.0
S-55
B
14.0
13.3
11.9
10.0
7.8
5.6
3.8
2.0
S-44
C
15.0
15.0
15.0
14.4
12.7
10.4
8.0
5.0
S-43
C
75
S-28
Chrome-manganese-silicon
A
15.0
14.1
12.4
10.1
7.8
5.6
3.8
2.0
alloy steel
B
85Slide6
Temperature Factor
Metal Temperature,
Plate and Forged
°F
Steel, %
Cast Steel, %
Up to 650
25.0
16.7
700
23.7
16.4
750
21.0
14.7
800
18.0
12.9
850
15.0
11.1
900
12.0
9.3
950
9.0
7.5
1000
6.2
5.7Slide7
Weld/Joint Efficiency
EFFICIENCY
CRITERIA
LAP WELD (For circumferential Joint)
Single Lap
Single Lap with plug weld
Double Lap
BUTT
WELD (For circumferential and
longitudinal joints)
Single Butt
Single Butt with Back-up Strip
Double Butt
Double Butt with reinforce at center
55
%
65%
65%
70
%
80%
80%
90%
t
p
< ⅝”
t
p
< ⅝”
t
p
> ⅝”
t
p
< ⅝”
t
p
< 1¼”
t
p
> 1¼”
t
p
> 1¼”Slide8
Stress Relief Factor
Stress relieving is mandatory for:
1.
tp > 1¼” 2. (For thinner plates) where D has a minimum value of 20 inches 3. ASTM A – 150 4. ASTM A – 149 (under certain conditions)Slide9
Radiographing Factor
Radiographing
is mandatory
for:1. ASTM A – 1502. ASTM A – 149 (under certain conditions)3. Lethal gases application4. Nuclear Reactor applicationsSlide10
Sample Problem 1
A 12 in diameter S-2 Grade A steel has a working pressure and temperature of 500 psi and 300F respectively. Determine the type of weld to be used and plate thickness using Hesse and Rushton
method
. Assume zero corrosion allowance.Slide11
Sample Problem 2
Grade A S2 steel, butt welded pressured vessel for lethal gas application has an inside diameter of 20 inches. If the working pressure is 900 psi and the working temperature is 250ºF, what is the shell thickness of the vessel? (Use minimum corrosion allowance and Hesse and Rushton
method).Slide12
HEAD Configurations
Torisphericalmost common type of head used
and
usually the most economical to
formThe I.C.R = I.D of the head or lessbetween 90% to 95% of the I.D of the headThe I.K.R = 6% and 10% of the I.C.R of the headThe S.F = 10mm and 30mmSlide13
HEAD Configurations
2:1 Semi-Ellipsoidaldeeper and stronger than a
torispherical
head
more expensive to form than a torispherical head, but may allow a reduction in material thickness as the strength is greaterThe I.C.R is 0.8 of the O.D of the headThe I.K.R is 0.154 of the O.D of the headThe S.F =10mm and 30mmSlide14
HEAD Configurations
Hemisphericalallow more pressure than any other head
most
expensive to
formThe depth of the head is half of the diameter.Slide15
HEAD Configurations
Shallow Headcommonly used
atmospheric tanks
not
suitable for pressure vesselsI.C.R =1.5 to 2.0 times the I.D of the headI.K.R = 32mm, 51mm or 76mm (depending on the diameter and customer requirements)The S.F =10mm and 30mmSlide16
HEAD Configurations
Cones for Pressure VesselsThe maximum internal apex angle for cones
=120
O
The I.K.R = 6% of the inside diameter of the vesselThe S.F =10mm and 30mmSlide17
HEAD Configurations
Flat.A flat end with a knuckled outer edge
used
as bases on vertical atmospheric tanks and lids for smaller
tanksThe I.K.R =25mm, 32mm and 51mm The S.F. = 10mm and 30mmSlide18
HEAD Configurations
Dish.used for atmospheric tanks and vessels and for bulk heads or baffles inside horizontal tanks or
tankers
Typically
the I.C.R is equal to the diameterSlide19
HEAD THICKNESS
Standard Ellipsoidal Hemispherical
Standard
Dished where L = crown radius in inches = Do – 6 Kr = knuckle radius = 0.06 DoSlide20
HEAD THICKNESS
Standard Dished
Values for
W
or dished heads Kr/L W 0.06
1.8 0.07 1.7
0.08 1.65 0.09 1.6 0.10 1.55
0.11 1.50
0.12 1.47
0.13
1.44
0.14 1.41
Slide21
HEAD THICKNESS
Standard Dished
Values for
W
or dished heads Kr/L W 0.15 1.40
0.16 1.38 0.17
1.37
0.18
1.35
0.19
1.32
0.20
1.30
0.25
1.25
0.50
1.12
1.0
1.0
Slide22
HEAD THICKNESS
Flat Heads *Lap Welded w/ or w/o Plug Welds:
*Single or Double V Butt Welded
*Cut from Solid PlateStandard Dished