4.15 Supports and Attachments v2

4.15-1

4.15 Design Rules For Supports and Attachments (Revision 2)

4.15.0 Table of Contents............................................................................................................ 1 4.15.1 Scope ............................................................................................................................... 1 4.15.2 Design of Supports......................................................................................................... 1 4.15.3 Saddle Supports for Horizontal Vessels ...................................................................... 1 4.15.4 Skirt Supports for Vertical Vessels............................................................................... 8 4.15.5 Lug And Leg Supports ................................................................................................... 8 4.15.6 Nomenclature ................................................................................................................ 10 4.15.7 Tables............................................................................................................................. 11 4.15.8 Figures ........................................................................................................................... 13

4.15.1 Scope The rules in this paragraph cover requirements for the design of structural support system(s) for vessels. The structural support system may be saddles for a horizontal vessel, a skirt for a vertical vessel, or lug and leg type supports for either of these vessel configurations.

4.15.2 Design of Supports

4.15.2.1 All vessels shall be supported for all design conditions. The design conditions including load and load case combinations defined in paragraph 4.1.5.3 shall be considered in the design of all vessel supports.

4.15.2.2 Unless otherwise defined in this paragraph, if a stress analysis of the vessel and support attachment configuration is performed, the stress results in the vessel and in the support within the jurisdiction of this Division shall satisfy the acceptance criteria in Part 5 .

4.15.2.3 The vessel support attachment shall be subject to the fatigue screening criteria of paragraph 5.5.2. In this evaluation, supports welded to the vessel may be considered as integral attachments.

4.15.2.4 All supports should be designed to prevent excessive localized stresses due to deformations produced by the internal pressure or to thermal gradients in the vessel or the vessel and support system.

4.15.2.5 Vessel support systems composed of structural steel shapes shall be designed in accordance with a recognized code or standard that cover structural design (i.e. Manual for Steel Construction published by the American Institute of Steel Construction). If the support is at a temperature above ambient due to vessel operation and the recognized code or standard does not provide allowable stresses at temperatures above ambient conditions, then the allowable stresses shall be determined using Annex 3.A using a material with a similar minimum specified yield strength and ultimate tensile strength.

4.15.2.6 Attachment welds for structural supports shall be in accordance with paragraph 4.2.

4.15.2.7 Reinforcing plates and saddles attached to the outside of a vessel shall be provided with at least one telltale hole that may be tapped for a preliminary compressed air and soap solution (or equivalent) test for tightness of welds that seal off the inside of the vessel. These telltale holes may be left open or may be plugged when the vessel is in service. If the holes are plugged, the plugging material used shall not be capable of sustaining pressure between the reinforcing plate and the vessel wall. Telltale holes shall not be plugged during heat treatment.

4.15.2.8 If nonpressure parts such as support lugs, brackets, leg supports and saddles extend over pressure retaining welds, then these welds shall be ground flush for the portion of weld that is covered, or the nonpressure parts shall be notch or coped to clear these welds.

4.15.3 Saddle Supports for Horizontal Vessels

4.15-2 ASME Section VIII, Division 2 ReWrite Revision 2 _______________________________________________________________________________________________

4.15.3.1 Application Of Rules

a) Design Method � The design method in this paragraph is based on an analysis of the longitudinal stresses exerted within the cylindrical shell by the overall bending of the vessel, considered as a beam on two single supports, the shear stresses generated by the transmission of the loads on the supports, and the circumferential stresses within the cylindrical shell, and the possible stiffening rings of this shell, by this transmission of the loads on the supports. The stress calculation method is based on linear elastic mechanics and covers modes of failure by excessive deformation and elastic instability. Saddle supports may also be designed using limit load or plastic collapse design methods in Part 5 .

b) Geometry � A typical horizontal vessel geometry is shown in Figure 4.15.1. Saddle supports for horizontal vessels shall be configured to provide continuous support for at least one-third of the shell circumference, or 0120θ ≥ .

c) Reinforcing Plates � If a wear plate is included in the design to reduce the stresses in the cylindrical shell at the saddle support, then the width of the reinforcing plate, 1b , shall satisfy Equation (4.15.1) and provide a supporting arc length that satisfies Equation (4.15.2). A typical wear plate arrangement is shown in Figure 4.15.2.

( ) ( )1 max 1.56 , 2mb b R t b a = + + (4.15.1)

1 12θθ θ= + (4.15.2)

d) Stiffening Rings � Stiffening rings may be used at the saddle support location, on either the inside or outside of the cylindrical shell. The stiffening rings may be mounted in the plane of the saddle (see Figure 4.15.3) or two stiffening rings may be mounted on each side of the saddle support equidistant from the saddle support (see Figure 4.15.4). In the later case, the spacing between the two stiffening rings, h , as shown in Figure 4.15.4 shall not be greater than mR . If 1.56 mh R t≤ as shown in Figure 4.15.3 Sketch (c), then both of the stiffening rings shall be considered as a single stiffening ring situated in the plane of the saddle in the stress calculations.

4.15.3.2 Moment And Shear Force

a) If the vessel is composed of a cylindrical shell with a formed head (i.e. torispherical, elliptical, or spherical) at each end that is supported by two saddle supports equally spaced and with 0.25a L≤ , then the moment at the saddle, 1M , the moment at the center of the vessel, 2M ,and the shear force at

the saddle, T , may be computed using the following equations.

2 22

12

121 41

3

mR haL aLM Qa h

L

−− +

= − − +

(4.15.3)

( )2 22

2

22

241 44 1

3

mR hQL aLM h L

L

− = + − +

(4.15.4)

( )2

21.33

Q L aT

L h−

=+

(4.15.5)

Revision 2 ASME Section VIII, Division 2 Rewrite 4.15-3 ______________________________________________________________________________________________

b) If the vessel supports are not symmetric, or more than two supports are provided, then the highest moment in the vessel, and the moment and shear force at each saddle location shall be evaluated. The moments and shear force may be determined using strength of materials (i.e. beam analysis with a shear and moment diagram).

4.15.3.3 Longitudinal Stress

a) The longitudinal membrane plus bending stresses in the cylindrical shell between the supports are given by the following equations.

( )21 22

m

m

PR M top of shellt R t

σπ

= − (4.15.6)

( )22 22

m

m

PR M bottom of shellt R t

σπ

= + (4.15.7)

b) The longitudinal stresses in the cylindrical shell at the support location are given by the following equations. The values of these stresses depend on the rigidity of the shell at the saddle support. The cylindrical shell may be considered as suitable stiffened if it incorporates stiffening rings at, or on both sides of the saddle support, or if the support is sufficiently close defined as 0.5 ma R≤ to a torispherical or elliptical head (a hemispherical head is not considered a stiffening element), a flat cover, or tubesheet.

1) Stiffened Shell � The maximum values of longitudinal membrane plus bending stresses at the saddle support are given by the following equations.

( )13 22

m

m

PR M top of shellt R t

σπ

= − (4.15.8)

( )14 22

m

m

PR M bottom of shellt R t

σπ

= + (4.15.9)

2) Unstiffened Shell � The maximum values of longitudinal membrane plus bending stresses at the saddle support are given by the following equations. The coefficients 1K and *

1K are given in Table 4.15.1.

( )* 13 2

1

52m

m

PR M points A and B in Figure 4.15.t K R t

σπ

= − (4.15.10)

( )* 14 * 2

12m

m

PR M bottom of shellt K R t

σπ

= + (4.15.11)

c) Acceptability Criteria

1) The absolute value of 1σ , 2σ , and 3σ , 4σ or *3σ , *

4σ , as applicable shall not exceed S .

2) If the any of the stresses in paragraph 4.15.3.3.c.1 above are negative, the absolute value of the stress shall not exceed cS that is given by Equation (4.15.12) where 1.0K = for normal operating

conditions and 1.35K = for exceptional operating or hydrotest condition.

16y

cm

KtES

R= (4.15.12)


4.15.3.4 Shear Stresses

a) The shear stress in the cylindrical shell with a stiffening ring in the plane of the saddle support is a maximum at Points C and D of Figure 4.15.5 Sketch (b) and shall be computed using Equation (4.15.13).

1m

TR t

τπ

= (4.15.13)

b) The shear stress in the cylindrical shell with stiffening rings on both sides of the saddle support is a maximum at Points E and F of Figure 4.15.5 Sketch (c) and shall be computed using Equation (4.15.14). The coefficient 2K is given in Table 4.15.1.

22

m

K TR t

τπ

= (4.15.14)

c) The shear stress in a cylindrical shell without stiffening ring(s) that is not stiffened by a formed head, flat cover, or tubesheet shall be computed using Equation (4.15.14).

d) The shear stress in the cylindrical shell without stiffening ring(s) and stiffened by a torispherical, elliptical, flat cover, or tubesheet, is a maximum at Points E and F of Figure 4.15.5 Sketch (c) and shall be computed using the equations shown below. In addition to the shear stress, the membrane stress in the formed head, if applicable, shall also be computed using the equations shown below.

1) Shear stress, the coefficient 3K is given in Table 4.15.1.

( )33

m

K T in the cylindrical shellR t

τ = (4.15.15)

( )* 33

m h

K T in the formed headR t

τ = (4.15.16)

2) Membrane stress in a torispherical or elliptical acting as a stiffener, the coefficient 4K is given in Table 4.15.1.

( )45 2

i

m h h

PRK Q torispherical headR t t

σ = + (4.15.17)

( )45

22i i

m h h

PR RK Q ellipitcal headR t t h

σ

= +

(4.15.18)

( )5 0 flat coverσ = (4.15.19)

( )5 0 flat coverσ = (4.15.20)

e) Acceptability Criteria

1) The absolute value of 1τ , 2τ , and 3τ , as applicable, shall not exceed 0.8S for ferritic materials

and 0.6S for all other materials.

2) The absolute value of *3τ shall not exceed 0.8 hS for ferritic materials and 0.6 hS for all other

materials.


3) The absolute value of 5σ shall not exceed 1.25 hS .

4.15.3.5 Circumferential Stress

a) Maximum circumferential bending moment � the distribution of the circumferential bending moment at the saddle support is dependent on the use of stiffeners at the saddle location.

1) Cylindrical shell without a stiffening ring or with a stiffening ring in the plane of the saddle � the maximum circumferential bending moment is shown in Figure 4.15.6 Sketch (a) and shall be computed using Equation (4.15.21). The coefficient 7K is given in Table 4.15.1.

7 mM K QRβ = (4.15.21)

2) Cylindrical shell with stiffening rings on both side of the saddle � the maximum circumferential bending moment is shown in Figure 4.15.6 Sketch (b) shall be computed using Equation (4.15.22). The coefficient 10K is given in Table 4.15.1.

10 mM K QRβ = (4.15.22)

b) Width of cylindrical shell � the width of the cylindrical shell that contributes to the strength of the cylindrical shell at the saddle location shall be determined using Equation (4.15.23). If the width 1x

extends beyond the limits in Figures 4.15.2, 4.15.3 or 4.15.4, as applicable, then the width 1x shall be reduced not to exceed this limit.

1 2, 0.78 mx x R t≤ (4.15.23)

c) Circumferential stresses in the cylindrical shell without stiffening ring(s)

1) The maximum compressive circumferential membrane stress in the cylindrical shell at the base of the saddle support shall be computed using Equation (4.15.24). The coefficient 5K is given in Table 4.15.1.

( )5

61 2

K Qkt b x x

σ −=

+ + (4.15.24)

2) The circumferential compressive membrane plus bending stress at Points G and H of Figure 4.15.6 Sketch (a) is determined as follows. The coefficient 7K is given in Table 4.15.1.

i) If 4 mL R≥ , then the circumferential compressive membrane plus bending stress shall be computed using Equation (4.15.25).

( )7

7 21 2

34 2

K QQt b x x t

σ −= −

+ + (4.15.25)

ii) If 4 mL R< , then the circumferential compressive membrane plus bending stress shall be computed using Equation (4.15.26).

( )* 77 2

1 2

64

mK QRQt b x x Lt

σ −= −

+ + (4.15.26)


3) The stresses 6σ , 7σ , and *7σ may be reduced by adding a reinforcement or wear plate at the

saddle location that is welded to the cylindrical shell that satisfies the requirements of paragraph 4.15.3.1.c. The stress can be computed using the equations shown below.

( )5

6,1

rr

K Qkb t t

ση

−=

+ (4.15.27)

( ) ( )7

7, 21

34 2

rr r

K QQt t b t t

ση

−= −

+ + (4.15.28)

( ) ( )* 77, 2

1

64

mr

r r

K QRQt t b L t t

ση

−= −

+ + (4.15.29)

where

min , 1.0rSS

η = (4.15.30)

4) If 2rt t> , then the compressive membrane plus bending stress at the ends of the reinforcing plate (points G1 and H1 in Figure 4.15.2 Sketch (b)) shall be computed using the equations shown below. In these equations, coefficient 7,1K is computed using the Equation for 7K in Table 4.15.1

evaluated at the angle 1θ , see Equation (4.15.2).

i) If 4 mL R≥ , then the circumferential compressive membrane plus bending stress shall be computed using Equation (4.15.31)

( )7,1

7,1 21 2

34 2

K QQt b x x t

σ −= −

+ + (4.15.31)

ii) If 4 mL R< , then the circumferential compressive membrane plus bending stress shall be computed using Equation (4.15.32).

( )7,1*

7,1 21 2

64

mK QRQt b x x Lt

σ −= −

+ + (4.15.32)

d) Circumferential stresses in the cylindrical shell with a stiffening ring along the plane of the saddle support.

1) The maximum compressive circumferential membrane stress in the cylindrical shell shall be computed using Equation (4.15.33). The coefficient 5K is given in Table 4.15.1.

* 56

K QkA

σ −= (4.15.33)

2) The circumferential compressive membrane plus bending stress at Points G and H of Figure 4.15.6 Sketch (a) for stiffening rings located on the inside of the shell are determined as follows. The coefficients 8K and 6K are given in Table 4.15.1.


( )8 6 18

mK Q K QR c stress in the shellA I

σ −= − (4.15.34)

( )8 6 29

mK Q K QR c stress in the stiffening ringA I

σ −= + (4.15.35)

3) The circumferential compressive membrane plus bending stress at Points G and H of Figure 4.15.6 Sketch (a) for stiffening rings located on the outside of the shell are determined as follows. The coefficients 8K and 6K are given in Table 4.15.1.

( )* 8 6 18


σ −= + (4.15.36)

( )* 8 6 29


σ −= − (4.15.37)

e) Circumferential stresses in the cylindrical shell with stiffening rings on both sides of the saddle support

1) The maximum compressive circumferential membrane stress in the cylindrical shell shall be computed using Equation (4.15.38). The coefficient 5K is given in Table 4.15.1.

( )5

622

K Qkt b x

σ −=

+ (4.15.38)

2) The circumferential compressive membrane plus bending stress at Points I and J of Figure 4.15.6 Sketch (b) for stiffening rings located on the inside of the shell are determined as follows. The coefficients 9K and 10K are given in Table 4.15.1.

( )9 10 110


σ −= + (4.15.39)

( )9 10 211


σ −= − (4.15.40)

3) The circumferential compressive membrane plus bending stress at Points I and J of Figure 4.15.6 Sketch (b) for stiffening rings located on the outside of the shell are determined as follows. The coefficients 9K and 10K are given in Table 4.15.1.

( )* 9 10 110


σ −= − (4.15.41)

( )* 9 10 211


σ −= + (4.15.42)

f) Acceptability Criteria

1) The absolute value of 6σ or 6,rσ , as applicable, shall not exceed S .

2) The absolute value of *6σ , as applicable, shall not exceed [ ]min , rS S .


3) The absolute value of 7σ , *7σ , 7,rσ , *

7,rσ , 7,1σ , *7,1σ , 8σ , *

8σ , 10σ , and *10σ , as applicable, shall

not exceed 1.25S .

4) The absolute value of 9σ , *9σ , 11σ , and *

11σ , as applicable, shall not exceed 1.25 sS .

4.15.3.6 Saddle Support The horizontal force at the minimum section at the low point of the saddle is given by Equation (4.15.43). The saddle shall be design to resist this force.

21 cos 0.5sinsin coshF Q β β

π β β β + −

= − + (4.15.43)

4.15.4 Skirt Supports for Vertical Vessels

4.15.4.1 The following shall be considered in the design of vertical vessels supported on skirts.

a) The skirt reaction

1) The weight of vessel and contents transmitted in compression to the skirt by the shell above the level of the skirt attachment;

2) The weight of vessel and contents transmitted to the skirt by the weight in the shell below the level of skirt attachment;

3) The load due to externally applied moments and forces when these are a factor, e.g., wind, earthquake, or piping loads.

b) Localized Stresses At The Skirt Attachment Location � High localized stresses may exist in the shell and skirt in the vicinity of the skirt attachment if the skirt reaction is not substantially tangent to the vessel wall. When the skirt is attached below the head tangent line, localized stresses are introduced in proportion to the component of the skirt reaction which is normal to the head surface at the point of attachment. When the mean diameter of the skirt and shell approximately coincide (see Figure 4.15.7) and a generous knuckle radius is used (e.g., a 2:1 ellipsoidal head), the localized stresses are minimized and are not considered objectionable. In other cases an investigation of local effects may be warranted depending on the magnitude of the loading, location of skirt attachment, etc., and an additional thickness of vessel wall or compression rings may be necessary.

c) Thermal Gradients � Thermal gradients may produce high localized stresses in the vicinity of the vessel to skirt attachment. A �hot-box� detail (see Figure 4.15.8) shall be considered to minimize thermal gradients and localized stresses at the skirt attachment to vessel wall location. If a hot-box is used, the thermal analysis shall consider convection and thermal radiation in the hot-box cavity.

4.15.4.2 The rules of paragraph 4.3.11 shall be used to determine the thickness requirements for the skirt support. Skirt supports may be designed using limit load or plastic collapse design methods in Part 5 .

4.15.5 Lug And Leg Supports

4.15.5.1 Lugs supports may be used on horizontal or vertical vessels.

4.15.5.2 The localized stresses at the lug support locations on the shell may be evaluated using one of the following methods. The results from this analysis shall be evaluated in accordance with paragraph 4.15.2.6. Lug supports may be designed using limit load or plastic collapse design methods in Part 5 .

a) Numerical analysis in accordance with Part 5 .

b) Welding Research Council Bulletin Number 107, Local Stresses in Spherical and Cylindrical Shells Due to External Loadings.

c) Welding Research Council Bulletin 198, Part 1, Secondary Stress Indices for Integral Structural Attachments to Straight Pipes; Part 2, Stress Indices at Lug Supports on Piping Systems.


d) Welding Research Council Bulletin 353, Position Paper On Nuclear Plant Pipe Supports.

e) Welding Research Council Bulletin 448, Evaluation of Welded Attachments on Pipe and Elbows.

f) Other analytical methods contained in recognized codes and standards for pressure vessel construction (i.e. British Standard PD-5500, Specification for Fusion Welded Pressure Vessels (Advanced Design and Construction) for Use in the Chemical, Petroleum, and Allied Industries).

4.15.5.3 If vessels are supported by lugs, legs, or brackets attached to the shell, then the supporting members under these bearing attachments should be as close to the shell as possible to minimize local bending stresses in the shell.

4.15.5.4 Supports, lugs, brackets, stiffeners, and other attachments may be attached with stud bolts to the outside or inside of a vessel wall. All stud bolted attachments require a detailed fatigue analysis in accordance with the requirements of Part 5 .

4.15.5.5 Lug and column supports should be located away from structural discontinuities (i.e. cone-to-cylinder junctions) and Category A or B weld seams. If these supports are location within 1.8 Dt of these locations, then a stress analysis shall be performed and the results from this analysis shall be evaluated in accordance with paragraph 4.15.2.6.


4.15.6 Nomenclature A is the cross-sectional area of the stiffening ring(s) and the associated shell width used in the

stress calculation. a is the distance from the axis of the saddle support to the tangent line on the curve for a

dished head or to the inner face of a flat cover or tubesheet. b is the width of contact surface of the cylindrical shell and saddle support.

1b is the width of the reinforcing plate welded to the cylindrical shell at the saddle location

1 2,c c is the distance to the extreme axes of the cylinder-stiffener cross section to the neutral axis of the cylinder-stiffener cross-section

yE is the modulus of elasticity. η is the shell to reinforcing plate strength reduction factor.

hF is the saddle horizontal force.

h is the spacing between two mounted stiffening rings placed o each side of the saddle support.

2h is the depth of the elliptical head.

I is the moment of inertia of cross-sectional area A in relation to its neutral axis that is parallel to the axis of the cylindrical shell.

k is the factor to account for the vessel support condition; 1k = is the vessel is resting on the support and 0.1k = is the vessel is welded to the support.

K is the factor to set the allowable compressive stress for the cylindrical shell material. L is the length of the cylindrical shell measured from the center of the vessel to the tangent line

on the curve for a dished head or to the inner face of a flat cover or tubesheet.

1M is the net-section maximum longitudinal bending moment at the saddle support; this moment is negative when it results in a tensile stress on the top of the shell.

2M is the net-section maximum longitudinal bending moment between the saddle supports; this moment is positive when it results in a compressive stress on the top of the shell.

P is the design pressure. Q is the maximum value of the reaction at the saddle support from weight and other loads as

applicable.

iR is the inside radius of the spherical dome or a torispherical head.

mR is the mean radius of the cylindrical shell

S is the allowable design stress intensity for the cylindrical shell material.

cS is the allowable compressive stress for the cylindrical shell material.

hS is the allowable design stress intensity for the head material.

rS is the allowable design stress intensity for the wear plate material.

sS is the allowable design stress intensity for the stiffener material. t is the cylindrical shell or shell thickness, as applicable.

ht is the head thickness

rt is the wear plate thickness

T is the maximum shear force at the saddle. θ is the opening of the unsupported cylindrical shell arc.

1θ is the opening of the cylindrical shell arc engaged by a welded reinforcing plate.

1 2,x x is the width of cylindrical shell used in the circumferential normal stress strength calculation.


4.15.7 Tables

Table 4.15.1 � Stress Coefficients For Horizontal Vessels on Saddle Supports

Stress Coefficient

2

1

2sinsin cos

sin cosK

π

∆∆ + ∆ ⋅ ∆ −

∆=∆ − ∆ ∆

2

*1

2sinsin cos

sin1K

π

∆∆ + ∆ ⋅ ∆ −

∆=∆ − ∆

2sinsin cos

K απ α α α

=− + ⋅

3sin sin cos

sin cosK α α α α

π π α α α− ⋅ = − + ⋅

2

4sin0.375sin cos

K απ α α α

= − + ⋅

51 cos

sin cosK α

π α α α+

=− + ⋅

2 22 3

6 2

3cos sin sin cos cos sin cos sin 1 sin 2sin4 0.8 4 4 2 4

sin 1 sin 222 4

K

β β β β β β β β ββ ββ β β β β β

β βπβ β

− + − + − − −

=

− −

67 0.5

4 m

K aK whenR

= ≤

7 6 611.5 0.5 12m m

a aK K K whenR R

= − < <

7 6 1m

aK K whenR

= ≥


Table 4.15.1 � Stress Coefficients For Horizontal Vessels on Saddle Supports

Stress Coefficient

2

8 2

cos 2 9sin cos sincos 1 34 4 sin

2sin 1 sin 222 4

K

β β β βββ β β β

πβ βπβ β

− + −

= +

− −

( )91 1 cot cos sin

2 2K π β β ρ ρ ρ

π = − + − +

( ) ( )10

1 3sin cos cot2 2 sin

Kπ β

ρ ρ ρ π β βπ β

− = + + − −

Notes:

1. 5

6 16π θ

∆ = +

2. 0.952θα π = −

3. 2θβ π= −

4. The relationship between ρ and θ is given by ( )tan 0.5 cotρ ρ π β β= + − . Valves for ρ for

a specified θ are shown in the table below.

Relationship Between ρ and θ

θ 120° 130° 140° 150° 160° 170° 180° ρ 93.667° 91.133° 87.333° 84.167° 79.667° 74° 66.933°

Note: ( ) ( ) ( )2 4 72 3 4158.58 7.8668 8.8037 10 4.3011 10 8.0644 10ρ θ θ θ θ− − −= − + − + −

for all values of θ that satisfy 120 180θ° °≤ ≤

5. The angles , , , and θ β ρ∆ are in radians


4.15.8 Figures

l

= =

==a

= =b

Figure 4.15.1 � Horizontal Vessel On Saddle Supports


< a

b

x1 x2

(a)

a< a

b

x1 x2

(b)

a

= =

b1

er

θ1/2

θ/2<6°

G1,H1

Figure 4.15.2 � Cylindrical Shell Without Stiffening Rings


< a

a

x1 x2

Y YC1

C2

e

< a

a

x1 x2

Y YC1

C2

e

< aa

x1

Y YC1

C2

ex2

(a)

< aa

Y YC1

C2

ex2

(b)

x1

a

YC2

C1

e

< a

a

x1

Y

tx2

h < 1.56 Rmt= =

(c)

Figure 4.15.3 � Cylindrical Shell With Stiffening Rings In The Plane Of The Saddle


< a

a

x1 x2

Y YC1

C2

t

< a

a

x1 x2

Y YC1

C2

t

x2 x2

= =

1.56 Rm t < h < Rm

x2 x2

= =

1.56 Rmt < h < Rm

< a

a

x1

Y YC1

C2

tx2

(a)

x1 x2

1.56 Rmt < h < Rm

< aa

Y YC1

C2

tx2

(b)

x1 x2x2

= == =

1.56 Rmt < h < Rm

Figure 4.15.4 � Cylindrical Shell With Stiffening Rings On Both Sides Of The Saddle


β/6

θ ∆A B

β

∆ = +β θ6 2

(a)

C D

β/20

θE F

βα

α = 0,95β

(b)

(c)

Figure 4.15.5 � Locations Of Maximum Longitudinal Normal Stress And Shear Stress In The Cylinder


θG H

β

Maximum Bending Moment:

(a)

θ

I J

β

Maximum Bending Moment:

ρ

(b)

Figure 4.15.6 � Locations Of Maximum Circumferential Normal Stresses In The Cylinder


Minimize This Offset

Vessel Head

Vessel Skirt

Figure 4.15.7 � Skirt Attachment Location On Vertical Vessels


Hot-Box Cavity - This Space To BeLeft Free Of Insulation And Vents

Typical Segmented Ring

Insulation

Typical Vent

Optional Fireproofing

Dimension established based on thermal stress analysis

Dimension established based on thermal stress analysis

Figure 4.15.8 � A Typcial Hot-Box Arrangement For Skirt Supported Vertical Vessels

Documents

4.15 Supports and Attachments v2