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LOGO
HESSE AND RUSHTON METHOD
Pressure Vessels
LOGO
SHELL THICKNESS
PD
tp 
 C
2Se  P
where
tp
P
D
S
e
C
= shell thickness (inch)
= Max allowable working pressure (psi)
= Inside diameter (inch)
= Max allowable tensile stress (psi) (Table 6-6)
= Efficiency of welded joint (Table 6-7)
= Corrosion allowance
LOGO
SHELL THICKNESS
PD
tp 
 C
2Se  P
Applicable if:
1. tp < 0.10D
2. tp > tmin
t min
D  100

1000
LOGO
Allowable Stress Estimation
S = Su x Fm x Fs x Fr x Fa
Where
Su
= Minimum Specified Tensile Strength
Fm
= Material Factor
Fm = 1 for Grade A material
Fm = 0.97 for Grade B material
Fm = 0.92 for Grade C material
Fs
= Temperature Factor (Use Table 6-7)
Fr
= Stress Relief (SR) Factor
Fr = 1.06 When SR is applied
Fa =
Radiographing Factor
Fa = 1.12 when Radiographing is applied and
subsequent repair of defects
LOGO
Minimum Specified Tensile Strength
ASME
Code
Spec.
No.
S-2
S-1
S-42
S-44
S-43
S-55
S-44
S-43
S-55
S-44
S-43
S-28
Material Data
and Description
Steel plates - flange and
firebox quality
Carbon steel for boilers
Carbon-silicon steel,
ordinary strength range
Molybdenum steel
Low-carbon nickel steel
Carbon-silicon steel, high
strength range, 4-1/2”
plates and under
Chrome-manganesesilicon
alloy steel
Specified
Minimum
Tensile
Strength
Grade 1000 psi
Allowable Unit Tensile Stress, Thousands psi
at Various Temperatures, °F
- 20
to
650
700
750
800
850
900
950
1000
9.0
10.0
11.0
11.0
12.0
13.0
8.8
9.6
10.4
10.4
11.4
13.0
8.4
9.0
9.5
9.5
10.4
13.0
6.9
7.5
8.0
8.5
9.1
12.5
5.7
6.0
6.3
7.2
7.4
11.5
4.4
4.4
4.4
5.6
5.6
10.0
2.6
2.6
2.5
3.8
3.8
8.0
2.0
2.0
5.0
A
13.0
12.3
11.1
9.4
7.6
5.6
3.8
2.0
B
B
B
C
C
A
14.0
14.0
14.0
15.0
14.0
13.3
13.3
15.0
14.0
11.9
11.9
15.0
13.5
10.0
10.0
14.4
12.0
7.8
7.8
12.7
10.2
5.6
5.6
10.4
8.0
3.8
3.8
8.0
5.0
2.0
2.0
5.0
15.0
14.1
12.4
10.1
7.8
5.6
3.8
2.0
A
B
45
50
A
B
A
A
55
60
65
B
70
75
85
LOGO
Temperature Factor
Metal Temperature,
°F
Plate and Forged
Steel, %
Cast Steel, %
Up to 650
700
750
800
850
900
950
1000
25.0
23.7
21.0
18.0
15.0
12.0
9.0
6.2
16.7
16.4
14.7
12.9
11.1
9.3
7.5
5.7
LOGO
Weld/Joint Efficiency
EFFICIENCY
CRITERIA
LAP WELD (For circumferential Joint)
Single Lap
Single Lap with plug weld
Double Lap
55%
65%
65%
tp < ⅝”
tp < ⅝”
tp > ⅝”
BUTT WELD (For circumferential and
longitudinal joints)
Single Butt
Single Butt with Back-up Strip
Double Butt
Double Butt with reinforce at center
70%
80%
80%
90%
tp < ⅝”
tp < 1¼”
tp > 1¼”
tp > 1¼”
LOGO
Stress Relief Factor
Stress relieving is mandatory for:
1. tp > 1¼”
D  50
2. t p 
120
(For thinner plates)
where D has a minimum value of 20 inches
3. ASTM A – 150
4. ASTM A – 149 (under certain conditions)
LOGO
Radiographing Factor
Radiographing is mandatory for:
1. ASTM A – 150
2. ASTM A – 149 (under certain conditions)
3. Lethal gases application
4. Nuclear Reactor applications
LOGO
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.
LOGO
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).
LOGO
HEAD Configurations
 Torispherical
 most common type of head used and usually the
most economical to form
 The I.C.R = I.D of the head or less
• between 90% to 95% of the I.D of the head
 The I.K.R = 6% and 10% of the I.C.R of the head
 The S.F = 10mm and 30mm
LOGO
HEAD Configurations
 2:1 Semi-Ellipsoidal
 deeper 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 greater
 The I.C.R is 0.8 of the O.D of the head
 The I.K.R is 0.154 of the O.D of the head
 The S.F =10mm and 30mm
LOGO
HEAD Configurations
 Hemispherical
 allow more pressure than any other head
 most expensive to form
 The depth of the head is half of the diameter.
LOGO
HEAD Configurations
 Shallow Head
 commonly used atmospheric tanks
 not suitable for pressure vessels
 I.C.R =1.5 to 2.0 times the I.D of the head
 I.K.R = 32mm, 51mm or 76mm (depending on the
diameter and customer requirements)
 The S.F =10mm and 30mm
LOGO
HEAD Configurations
 Cones for Pressure Vessels
 The maximum internal apex angle for cones =120O
 The I.K.R = 6% of the inside diameter of the vessel
 The S.F =10mm and 30mm
LOGO
HEAD Configurations
 Flat.
 A flat end with a knuckled outer edge
 used as bases on vertical atmospheric tanks and lids for
smaller tanks
 The I.K.R =25mm, 32mm and 51mm
 The S.F. = 10mm and 30mm
LOGO
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 diameter
LOGO
HEAD THICKNESS
Standard Ellipsoidal
PD
t
2SE
Hemispherical
Standard Dished
where
PD
t
4SE
P LW
t
2SE
L = crown radius in inches = Do – 6
Kr = knuckle radius
= 0.06 Do
LOGO
HEAD THICKNESS
Standard Dished
 Values for W or dished heads
Kr/L
W
0.06
0.07
0.08
0.09
0.10
0.11
0.12
0.13
0.14
1.8
1.7
1.65
1.6
1.55
1.50
1.47
1.44
1.41
LOGO
HEAD THICKNESS
Standard Dished
 Values for W or dished heads
Kr/L
W
0.15
0.16
0.17
0.18
0.19
0.20
0.25
0.50
1.0
1.40
1.38
1.37
1.35
1.32
1.30
1.25
1.12
1.0
LOGO
HEAD THICKNESS
Flat Heads
*Lap Welded w/ or w/o Plug Welds:
0 .3 P
t d
S
*Single or Double V Butt Welded
0.25 P
td
S
*Cut from Solid PlateStandard Dished
0 .5 P
t d
S

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