ASME Section VIII div 2 2010. ASME Boiler and Pressure Vessel Code. Alternative Rules
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2010 SECTION VIII, DIVISION 2
4-175
Longitudinal Line
General Note: 133 mm (5-1/4 in.)
171 mm (6-3/4 in.)
171
mm
133
mm
171
mm
133
mm
133
mm
171
mm
133
mm
p
1
= 743 mm
(29-1/4 in.)
133
mm
133
mm
Figure 4.10.3 – Example of Tube Spacing With the Pitch of Holes Varying in Every Second and Third
Row
Longitudinal Line
p
1
= 292 mm
146 mm (5-3/4 in.)
(11-1/2 in.)
p* = 163 mm
(6.42 in.)
Figure 4.10.4 – Example of Tube Spacing With the Tube Holes on Diagonal Lines
2010 SECTION VIII, DIVISION 2
4-176
C
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Ratios of p*/p1
Longitudinal Efficiency, %
20 30 40 50 60 70 80 90
Diagonal Efficiency, %
20
30
40
50
60
70
80
90
0.60
0.65
0.70
0.80
0.75
0.85
0.90
0.95
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
p*/p
1
Circumferential
Pitch
p
1
d
p*
p
1
= Longitudinal Pitch
p* = diagonal pitch
Notes:
1. Equations are provided for the curve shown above, use of these equations is permitted for values beyond the values
shown in this curve.
2. Diagonal efficiency:
()
2
1
0.25 1 0.01 0.75
*
%,
0.00375 0.005
long
JEJ
p
where J
Jp
+−−⋅ +
⎛⎞
==
⎜⎟
+⋅
⎝⎠
3. The curve of condition of equal efficiency of diagonal and circumferential ligaments is given by:
()
2
200 100 2 100 1
100
%,
1 200 0.5
+− − +
⎛⎞
−
==
⎜⎟
⎜⎟
+−
⎝⎠
long
long
long
MEM
E
where M
ME
4.
1
1
100
⎛⎞
−
=
⎜⎟
⎝⎠
long
p
d
E
p
Figure 4.10.5 – Diagram for Determining the Efficiency of Longitudinal and Diagonal Ligaments
Between Openings in Cylindrical Shells
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2010 SECTION VIII, DIVISION 2
4-177
Angle of Diagonal with Longitudinal, Theta, deg
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Equivalent Longitudinal Efficiency, %
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
p*/d=1.2
20
10
5
4
3
2.5
2
1.5
1.3
1.4
1.6
1.7
1.8
d
p*
s
Shell
Axis
p* = Diagonal Pitch
d = Diameter of Tube Hole
θ
Notes:
1.
An equation is provided for the curve shown above, the use of this equation is permitted for values
beyond the values shown in this curve.
2. Equivalent longitudinal efficiency:
22
2
sec
sec 1 3 sec
*
%
0.015 0.005sec
pd
θ
θ
θ
θ
⎛⎞
+− +
⎜⎟
⎝⎠
=
+
Figure 4.10.6 – Diagram for Determining the Equivalent Efficiency of Diagonal Ligaments Between
Openings in Cylindrical Shells
2010 SECTION VIII, DIVISION 2
4-178
4.11 Design Rules for Jacketed Vessels
4.11.1 Scope
4.11.1.1 The minimum requirements for the design of the jacketed portion of a pressure vessel shall
conform to the requirements given in paragraph 4.11. The jacketed portion of the vessel is defined as the
inner and outer walls, the closure devices and all other penetration or parts within the jacket that are
subjected to pressure stress. Parts such as nozzle closure members and stay rings are included in this
definition. For the purposes of this section, jackets are assumed to be integral pressure chambers, attached
to a vessel for one or more purposes, such as:
a) To heat the vessel and its contents,
b) To cool the vessel and its contents, or
c) To provide a sealed insulation chamber for the vessel.
4.11.1.2 Paragraph 4.11 applies only to jacketed vessels having jackets over the shell or heads as
illustrated in Figure 4.11.1, partial jackets as illustrated in Figure 4.11.2, and half–pipe jackets as illustrated in
Figure 4.11.3.
4.11.1.3 The jacketed vessels shown in Figure 4.11.1 are categorized as five types shown below. For
these types of vessels, the jackets shall be continuous circumferentially for Types 1, 2, 4 or 5 and shall be
circular in cross section for Type 3. The use of any combination of the types shown is permitted on a single
vessel provided the individual requirements for each are met. Nozzles or other openings in Type 1, 2, 4 or 5
jackets that also penetrate the vessel shell or head shall be designed in accordance with paragraph 4.5.
Paragraph 4.11 does not cover dimpled or embossed jackets.
a) Type 1 – Jacket of any length confined entirely to the cylindrical shell
b) Type 2 – Jacket covering a portion of the cylindrical shell and one head
c) Type 3 – Jacket covering a portion of one head
d) Type 4 – Jacket with addition of stay or equalizer rings to the cylindrical shell portion to reduce the
effective length
e) Type 5 – Jacket covering the cylindrical shell and any portion of either head.
4.11.1.4 Paragraph 4.11 does not contain rules to cover all details of design and construction. Jacket
types defined in paragraph 4.11.1.3 subject to general loading conditions (i.e. thermal gradients) or jacket
types of different configurations subject to general loading conditions shall be designed using Part 5.
4.11.1.5 If the internal pressure is 100 kPa (15 psi) or less, and any combination of pressures and vacuum
in the vessel and jacket will produce a total pressure greater than 100 kPa (15 psi) on the inner vessel wall,
then the entire jacket is within the scope of paragraph 4.11.
4.11.2 Design of Jacketed Shells and Jacketed Heads
4.11.2.1 Shell and head thickness shall be determined using paragraphs 4.3 and 4.4 as applicable. In
consideration of the loadings given in paragraph 4.1, particular attention shall be given to the effects of local
internal and external pressure loads and differential thermal expansion (see paragraph 4.11.1.4). Where
vessel supports are attached to the jacket, consideration shall be given to the transfer of the supported load
of the inner vessel and contents.
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2010 SECTION VIII, DIVISION 2
4-179
4.11.2.2 The requirements for inspection openings in jackets shall be in accordance with paragraph 4.5.16
except that the maximum size of inspection openings in the jacketed portion of the vessel need not exceed
DN 50 (NPS 2) pipe for all diameter vessels.
4.11.2.3 The use of impingement plates or baffles at the jacket inlet connection to reduce erosion of the
inner wall shall be considered for media where vapors are condensed (i.e. steam).
4.11.2.4 Flat plate regions of jacketed vessels may be designed as braced and stayed surfaces using the
rules of paragraph 4.9.
4.11.3 Design of Closure Member of Jacket to Vessel
4.11.3.1 The design of jacket closure members shall be in accordance with Table 4.11.1 and the
additional requirements of paragraph 4.11.3. Alternative geometries to those illustrated may be used in
accordance with paragraph 4.11.1.4.
4.11.3.2 Any radial welds in closure members shall be butt-welded joints penetrating through the full
thickness of the member and shall be ground flush where attachment welds are to be made.
4.11.3.3 Partial penetration and fillet welds are permitted when both of the following requirements are
satisfied.
a) The material of construction satisfies the following equation.
0.625
yT
u
S
S
≤ (4.11.1)
b) The component is not in cyclic service, i.e. a fatigue analysis is not required in accordance with
paragraph 4.1.1.4.
4.11.3.4 Closures for any type of stay-bolted jacket may be designed in accordance with the requirements
of Type 1 jackets shown in Figure 4.11.1 provided the entire jacket is stay-bolted to compensate for pressure
end forces.
4.11.4 Design of Penetrations Through Jackets
4.11.4.1 The design of openings through the jacket space shall be in accordance with the rules given in
paragraph 4.5. Reinforcement of the opening in the jacket shall not be required for penetrations of the type
shown in Table 4.11.2 since the opening is stayed by virtue of the nozzle or neck of the closure member.
4.11.4.2 Jacket penetration closure member designs shown in Table 4.11.2 shall conform to the following
requirements stipulated in this table and the following provisions. Alternative geometries to those illustrated
may be used if the design is based on Part 5.
a) The jacket penetration closure member minimum thickness considers only pressure membrane loading.
Axial pressure loadings and secondary loadings given in paragraph 4.1 shall be considered in the
design.
b) The design Details 2, 3, 4, 5 and 6 shown in Table 4.11.2 provide some flexibility. Only pressure
membrane loading is considered in establishing the minimum thickness of the penetration closure
member. If the localized stresses at the penetration detail need to be established, the methodology in
Part 5 shall be used.
c) All radial welds in opening sealer membranes shall be butt-welded joints that penetrate through the full
thickness of the member.
2010 SECTION VIII, DIVISION 2
4-180
d) Closure member welds shall be circular, elliptical or obround in shape where possible. Rectangular
member welds are permissible provided that corners are rounded to a suitable radius.
e) The requirements of paragraph 4.11.3.3 shall be satisfied.
4.11.5 Design of Partial Jackets
4.11.5.1 Partial jackets include jackets that encompass less than the full circumference of the vessel.
Some variations are shown in Figure 4.11.2.
4.11.5.2 The rules for construction of jacketed vessels in the preceding paragraphs also apply to partial
jackets, with the following exceptions.
a) Stayed partial jackets shall be designed and constructed in accordance with paragraph 4.9 with closures
designed in accordance with paragraph 4.11.3.
b) Partial jackets that, by virtue of their service or configuration, do not lend themselves to staybolt
construction may be fabricated by other means provided they are designed using Part 5.
4.11.6 Design of Half–Pipe Jackets
4.11.6.1 The rules in this section are applicable for the design of half-pipe jackets constructed of NPS 2, 3
or 4 pipes and subjected to internal pressure loading (see Figure 4.11.3). Configurations that do not satisfy
the rules in paragraph 4.11.6.1 may be designed in accordance with Part 5.
4.11.6.2 The fillet weld attaching the half-pipe jacket to the vessel shall have a throat thickness not less
than the smaller of the jacket or shell thickness. Consideration should be given to the selection of the half-
pipe jacket pitch needed to provide welder access. In addition, the requirements of paragraph 4.11.3.3 shall
be satisfied.
4.11.6.3 The minimum required thickness of a half pipe jacket is given by the following equation. For a
design to be acceptable, the additional condition that
jjpm
PP
≤
where
jpm
P is given by Equation (4.11.3)
must also be satisfied.
0.85 0.6
jp
rp
jj
Pr
t
SP
=
−
(4.11.2)
4.11.6.4 The maximum permissible pressure in the half-pipe jacket,
jpm
P , shall be determine using the
following equation.
p
jpm
p
F
P
K
=
(4.11.3)
where
()
*
min 1.5 , 1.5
p
FSSS
⎡⎤
=−
⎣⎦
(4.11.4)
0.5 1.5 2 2.5 3 3.5 4 4.5
12 3 4 5 6 7 8 9 10p
K C CD CD CD CD CD CD CD CD C D=+ + + + + + + + + (4.11.5)
The coefficients for Equation (4.11.5) are provided in Table 4.11.3.
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2010 SECTION VIII, DIVISION 2
4-181
4.11.7 Nomenclature
D inside diameter of the inner vessel.
pj
D
nominal pipe size of the half-pipe jacket.
p
K half-pipe jacket rating factor.
j
P design pressure in the jacket chamber.
j
pm
P permissible jacket pressure based on the jacket and shell geometry.
j
jacket space defined as the inside radius of the jacket minus the outside radius of the inner
vessel.
L length of the jacket.
c
t nominal thickness of the closure member.
j
t nominal thickness of the outer jacket wall.
n
t nominal thickness of the nozzle.
s
t nominal thickness of the shell inner wall.
rj
t required minimum thickness of the outer jacket wall.
rc
t required minimum thickness of the closure member.
rp
t
required minimum thickness of the half-pipe jacket.
j
R
inside radius of the jacket.
p
R
radius of the opening in the jacket at the jacket penetration
s
R
outside radius of the inner vessel.
r corner radius of torus closures.
p
r inside radius of the half-pipe jacket.
S allowable stress of the inner shell from Annex 3.A at the design temperature.
c
S allowable stress of the jacket closure from Annex 3.A at the design temperature.
j
S allowable stress of the jacket from Annex 3.A at the design temperature.
yT
S
yield strength from Annex 3.D at the design temperature.
u
S minimum specified ultimate tensile strength from Annex 3.D.
*
S actual longitudinal tensile stress in the head or shell due to internal pressure and other axial
forces; when axial forces are negligible,
*
4
s
SPDt= . If the combination of axial forces and
pressure results in a negative value of
*
S , then
*
0S
=
.
2010 SECTION VIII, DIVISION 2
4-182
4.11.8 Tables
Table 4.11.1 – Design Of Closure Member Of Jacket To Shell
Detail Requirements Figure
1 Closure details (a) and (b) shall only be
used when the requirements of paragraph
4.11.3.3 are satisfied.
These closures may be used on Types 1,
2, and 4 jacketed vessels as shown in
Figure 4.11.1 and shall have
rc
t of at
least equal to
rj
t and corner radius r
shall not be less than
3
c
t .
These closure designs are limited to a
maximum thickness
rc
t of 16 mm (0.625
in.)
When this construction is used on Type 1
jacketed vessels, the weld dimension
Y
shall be not less than
0.7
c
t ; and when
used on Type 2 and 4 jacketed vessels,
the weld dimension
Y shall be not less
than
0.83
c
t .
Y
Min. 2t
c
but need
not exceed
13 mm (0.5 in)
t
s
j t
j
R
s
R
j
r
r min. = 3t
c
t
c
(a) Type 1 Jackets
(b) Types 2 and 4 Jackets
t
c
min.
30° max.
t
c
Min. throat
dimension = t
c
1.5t
c
(Elongated to
maintain min.
throat dimension)
t
c
t
c
min.
Y
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2010 SECTION VIII, DIVISION 2
4-183
Table 4.11.1 – Design Of Closure Member Of Jacket To Shell
Detail Requirements Figure
2
These closures shall have
rc
t at least
equal to
rj
t . In addition for Detail (c),
rc
t
shall be not less than the following:
0.707
j
rc
c
P
tj
S
=
A groove weld attaching the closure to the
inner vessel and fully penetrating the
closure thickness
c
t
may be used with
any of the types of jacketed vessels
shown in Figure 4.11.1. However, a fillet
weld having a minimum throat dimension
of
0.7
c
t may also be used to join the
closure of the inner vessel on Type 1
jacketed vessels of Figure 4.11.1.
The closure and jacket shell may be one-
piece construction or welded using a full
penetration butt weld. A backing strip
may be used.
R
s
R
j
t
s
j t
j
1.25t
c
min
t
c
r min = j
R
s
R
j
t
s
t
j
1.25t
c
min
t
c
r= 2t
c
mim
θ
max = 60°
j
(c)
R
s
R
j
t
s
j t
j
r
min
= 3t
c
1.25t
c
min
t
c
(b)
(a)
3 This closure shall be used only on Type 1
jacketed vessels shown in Figure 4.11.1.
The closure thickness
rc
t shall be
computed using the Equation for a conical
shell in paragraph 4.3, but shall be not
less than
rj
t
. The angle
θ
shall be
limited to 30 degrees maximum.
R
s
R
j
t
s
j
t
c
min
t
c
min
t
j
max = 30°
θ
t
c
2010 SECTION VIII, DIVISION 2
4-184
Table 4.11.1 – Design Of Closure Member Of Jacket To Shell
Detail Requirements Figure
4 Closure details (a), (b), and (c) shall only
be used when the requirements of
paragraph 4.11.3.3 are satisfied.
These closures shall be used only on
Type 1 jacketed vessels as shown in
Figure 4.11.1 and with the further
limitation that
rj
t
does not exceed 16 mm
(0.625 in.).
The required minimum thickness for the
closure bar shall be equal to:
max 2 , 0.707
j
rc rj
c
P
ttj
S
⎡⎤
⎛⎞
⎢⎥
=
⎜⎟
⎜⎟
⎢⎥
⎝⎠
⎣⎦
Fillet weld sizes shall be as follows:
[
]
min 0.75 , 0.75
cs
Ytt≥ and
0.7 mincY=
j
Z
t≥ and 0.7 minbZ=
t
s
j
R
s
R
j
Y
Y
Y
c
Y
c
t
j
t
c
b
Z
Z
(a)
t
c
t
j
t
s
j
R
s
R
j
b
Z
Y
Y
Z
Y
c
Y
c
R
s
R
j
t
j
t
s
j
Y
Y
Y
c
c
Y
t
c
Z
Z
R
s
R
j
t
j
t
s
j
Backing Strip
May Be Used
Y
Y
Y
c
c
(b)
(c)
(d)
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