Section 3 Design of Typical Chemical Vessels Chapter 7 Design of Shell-and-Tube Heat Exchanger 7.1...
-
Upload
malcolm-barrett -
Category
Documents
-
view
221 -
download
2
Transcript of Section 3 Design of Typical Chemical Vessels Chapter 7 Design of Shell-and-Tube Heat Exchanger 7.1...
Section 3 Design Section 3 Design of Typical Chemical of Typical Chemical
Vessels Vessels
Chapter 7 Design ofChapter 7 Design of Shell-and-Tube Heat Shell-and-Tube Heat
ExchangerExchanger
7.1 Classification of Shell-and-7.1 Classification of Shell-and- Tube Tube (( TubularTubular ) ) Heat Heat
ExchangerExchanger
4.U Tube Type Heat Exchanger
2.Float Head Heat Exchanger
3.Stuffing Box Heat Exchanger
1.Fixed Tube Sheet Type Heat Exchanger
Fixed Tube Sheet Type Heat Exchanger
接管法兰
管箱
容器法兰 排气管 膨胀节管板拉杆 定距管
折流板 换热管
壳程接管
支座排污口
管程接管
Nozzle Flange [Pipe Connecting F.] —— 接管法兰
Vessel Flange —— 容器法兰Tube Sheet [Plate] —— 管板(Air) Vent Nozzle —— 排气管Expansion Joint —— 膨胀节Shell Nozzle —— 壳程接管Tie Rod —— 拉杆(Pipe) Spacer —— 定距管
Header [Channel (head)] —— 管箱Baffle —— 折流板Heat Exchange Tube —— 换热管Inner Pipe Nozzle —— 管程接管Drain (Outlet) —— 排污口Support —— 支座
7.2 Contents7.2 Contents of Machine Designof Machine Design
1.1.Materials’ Selection Materials’ Selection
(Shell, Heads, Tube Sheets, Tubes, etc.)(Shell, Heads, Tube Sheets, Tubes, etc.)
2.Structure Design2.Structure Design
Confirming the fabric type, position, Confirming the fabric type, position,
connecting mode, etc. of each unit connecting mode, etc. of each unit
3.Strength Design
i. Confirming the strength dimension (wall thickness S) of units like shell, heads, etc.
ii. Opening reinforcement computation
4.Tube Sheet Design
5.Calculation of Thermal [temperature (difference)] Stress
6.Calculation of Tube-to-Tubesheet Joint Load [pulling-out force of tube]
7.3 Structure of Shell-and-7.3 Structure of Shell-and-
Tube Heat ExchangerTube Heat Exchanger
1.1. Type of Shell-and-Tube Type of Shell-and-Tube
Heat Exchanger Heat Exchanger
Main
Parts
Cylinder (Shell)
Heats
Tube Sheet (Plate)
Tube (Pipe) Bundle
Baffle, Tie Rod, (Pipe) Spacer
Pass Partition (Plate)
2.2.Structure of Heat Exchange Structure of Heat Exchange TubeTube
i. Type of commonly used tubesi. Type of commonly used tubes
—— —— Bare tube (Bare tube (光管光管 ), ), Profiled tube (Profiled tube (异型管异型管 ), ),
Fin (Finned) Tube (Fin (Finned) Tube (翅片管翅片管 ))
ii. Material of commonly used tubesii. Material of commonly used tubes
—— —— Carbon Steel (10 Carbon Steel (10 、 20)20)
Low Alloy Steel (Low Alloy Steel (16Mn、 15MnV))
Alloy Steel (Alloy Steel (1Cr18Ni9Ti))
CopperCopper
3.Connection of Tube and Tube Sheeti. Expansion Joint
Before Expansion After Expansion
ii. Welding [Soldered Joint]
iii. Expanded and Welded Joint
Advantages:
(1)Strengthening the Resistance to Fatigue
at the joint
(2)Eliminating the Stress Corrosion ( 应力腐蚀 ) and Gap Corrosion ( 间隙腐蚀 ),
then raising the lifetime
Methodology:
(1)Welding before expanding ( 先焊后胀 )
(2)Expanding before welding ( 先胀后焊 )
4.Structure of tube sheet and the connection of it with shell
Depending on types of heat exchanger
Tow Types
Non-movable (Fixed) Tube Sheet
—— used to fixed Tubesheet Heat Exchanger
Detachable (Non-fixed) Tube Sheet
—— used in Float Heat, Stuffing Box, U Type Heat
Exchanger
i. Fixed Tube Sheet
—— used in Fixed Tube Sheet Type Heat Exchanger
ii. Non-fixed Tube Sheet
—— the connecting structure of Float
Head, U Type and Stuffing Box
Heat Exchanger
5.The Sealing between Tube
Sheet and Header
Taking the Double Tube Side (Pass)
as the example:
Partition of Channel Head:
Structure of Channel Head:
6.Structure of Shell Side (Pass)
Main Units in Shell Pass Baffle Supporting Plate- 支承板 By-pass Baffles (Sealing Strip)- 旁路挡板 Impingement Plate (Baffle)- 防冲板 etc.
i. Baffles and Base Plate
Function: (1)Increasing the flow velocity of fluid in shell pass and changing the flow direction ——Improving the Heat Transfer Efficiency(2)Bearing the heat exchange tubes
Types:Arcuate, Disc and Doughnut Type, Fan Shaped.
ArcuateDisc and
Doughnut TypeFan Shaped
ii. By-pass Baffles
While there has clearance large enough
between shell and tube bundle, we set the
plates along the longitudinal direction and
force the fluid across the tube bundles in
order to avoid the fluid flow into the shortcut.
iii. Function of Impingement Plate
—— Preventing the fast flowing media
rushing ( 冲刷 ) the tube bundles at the
porch of shell pass
iv. For Steam Inlet Tube
—— Making as Bugle Type to decrease
the flow velocity and fulfil the buffering
function
7.4 Thermal [Temperature 7.4 Thermal [Temperature
Difference] StressDifference] Stress1.1.Thermal [Temperature Thermal [Temperature
Difference] Stress in Heat Difference] Stress in Heat ExchangerExchanger
i. Generation of Thermal T.D. Stressi. Generation of Thermal T.D. Stress
Conditions:
(1)Rigid connection between tube bundle and shell
(2)Thermal T.D. Stress occurs between tube and shell
ii. Calculation of Thermal T.D. Stress
Assumption:
Cold fluid flowing in shell pass, wall T of shell is ts
Hot fluid flowing in tube pass, wall T of tube is tt
In the course of installation tt = ts = to
In the course of operation(1)If the tube and shell can elongate freely
s = s ( ts – to) L
t = t ( tt – to) L(2)If the elongation is limited rigidly, both of them only elongate at the same length difference
Ls
t
At this moment:
Tube is compressed by compressive force Fcomp.
—— Compressive Stress (压应力 ) t occurs on the tube wall
Shell is pulled by tensile force Ftensile
—— Tensile Stress (拉应力 ) S occurs on the shell wall
This kind of stress caused by temperature
difference is called Temperature Difference
Stress or Thermal Stress.
Calculation of Thermal [Temperature
Difference] Stress:
If the deformation caused by temperature
difference is among the range of elasticity,
according to the Hook’s Law:
E E LA
F LA
F
(1) EA
FL
(2) tt
tt AE
FL
(3) ss
ss AE
FL
(4) )( ottt tt
(5) )( osss tt
And ∵
Compressive Length of
tube:Stretched
Length of shell:
Equ. (2) + Equ. (3), and putting Equ. (4) and (5) into it, working up:
(6) 11
)()(
sstt
ossott
AEAE
ttttF
(7) t
t A
F
(8) s
s A
F
∴ Thermal Stress on tube wall
Thermal Stress on shell wall
In these equations:
At —— Total sectional area of heat
exchange tubes, mm2
As —— Area of intersect surface on shell
wall, mm2
Et 、 Es —— Materials’ Modulus of
Elasticity of tube and shell
respectively, MPa
2.Calculation of Tube-to-Tubesheet Joint Load [Pulling-out Force]
Pulling-out Force q is the force that is endured
by the surface of per square meter expanding
perimeter of tubes, MPa
i. Pulling-out Force q p caused by pressure of media
ld
fpq
op
ofArea
Acting
perimeter expanding
media of force
In this equation:
P —— Design Pressure, choosing the larger
value between pressure in tube pass Pt and
pressure in shell pass PS, MPa
l
Pt
PS
do —— Outside Diameter of tube, mm
l —— Expanding Length of tube, mm
f —— Area among per four tubes, mm2
f
In-line Triangular Pitch( 三角形排列 )
a f
Square Pitch Arrangement[In-line Square Pitch]
正方形排列
a
2222
4866.0
460sin oo dadaf
22
4 odaf
In-line Triangular Pitch
In-line Square Pitch
ii. Pulling-out Force qt caused by Thermal Stress
t —— Thermal Stress inside tubes, Mpa
at —— Area of intersect surface of tube wall per tube, mm2
ld
aq
o
ttt
Area
StressThermal
Perimeter Expandingof
ld
dd
ld
dd
o
iot
o
iot
4 4
2222
iii. Superposition of qp and qt
Total pulling-out force
equal to their algebra sum: q = qp + qt
iv. Allowable Pulling-out Force [q] [q] depends on the joint type of expansion joint between tube and tube sheet.
Expanding Structure Type of tube and tube sheet [q] MPa
Non-flanged pipe end and non-notched tube
sheet holes 2.0
Flanged pipe end and notched tube sheet holes 4.0
v. Strength Conditions of Expanding
To assure the expanding joint undamaged and locked, should satisfying:
q —— Pulling-out Force of tubes, MPa
[q] —— Allowable Pulling-out Force, MPa
[q] q [q] q
3.Thermal Stress CompensationCompensation Measures:i. Decreasing the temperature difference
between tube and shell wall(1)Letting the fluid with larger Film
Coefficient of heat transfer flow across the shell pass
(2)When shell wall T tS < tube wall T tt, the insulating measures should be taken to shell wall in order to increase the temperature of it and then to decrease the temperature difference between tube and shell wall.
ii. Eliminating the rigid restriction between shell and tubes
(1)Erecting baffling units ( 挠性构件 ) on shell
—— Expansion Joint
Used in: Fixed Tube Sheet Heat Exchanger
(2)Making the shell and tube bundles expand
freely
Heat Exchangers with this kind of structure
—— Stuffing Box Heat Exchanger
Float Head Heat Exchanger
U Type Tube Heat Exchanger
Chapter 8 Machine Chapter 8 Machine Design ofDesign of
Tower Equipment Tower Equipment (( 塔设备塔设备 ))
7.1 Structure of Tower Set and 7.1 Structure of Tower Set and
Calculating Methods of LoadCalculating Methods of Load
1.Structure of Tower Set
i. Tower Body ( 塔体 )
—— (Cylindrical) Shell Section ( 筒节 )、Heads
( 封头 )、 Connecting Flange ( 连接法兰 )
ii. Internal Parts ( 内件 )
—— Tray ( 塔板 )、 Packing ( 填料 )、 Supporting
Sets ( 支撑装置 )
iii. Support (Saddle) ( 支座 )
—— Skirt Support
iv. Attachments ( 附件 )
—— Manhole ( 人孔 )、 Nozzle of input and
output ( 进出料接管 )、 Apparatus
Nozzle ( 仪表接管 )、 Distributor ( 分布 器 )、 Ladders outside the tower ( 塔外的扶 梯 )、 Platform ( 平台 )、 Insulation ( 保温
层 )
2.Loads and their Calculation Methods
Loads
Media Pressure ( 介质压力 )
Eccentric Load ( 偏心载荷 )
Wind Load ( 风载荷 )
Seismic Load ( 地震载荷 )
Dead Load ( 自重载荷 )
i. Dead Load
m01 —— The mass of shell and skirt support
of tower set
m02 —— The mass of internal parts of tower
set (trays or packing and supporting sets)
m03 —— The mass of insulating materials
m04 —— The mass of platform and ladders
m05 —— The mass of feed in tower
in course of operation
ma —— The mass of attachments such as
manholes, flanges, nozzles, etc.
mw —— The mass of liquid in tower in course
of hydrostatic pressure test
me —— Eccentric mass
Operation Mass:
m0= m01+ m02 +m03 +m04 +m05 +ma +me
Hydrostatic Pressure Test Mass:
mmax= m01+ m02 +m03 +m04 +mw +ma +me
Lifting (Hoisting) Mass [ 吊装质量 ]:
mmin= m01+ 0.2m02 +m03 +m04 +ma +me
ii. Seismic LoadD
ispe
rsin
g th
e M
ass
Model
—— Cantilever ( overhanging beam ) with
multi-mass system
Main factors effecting seismic force:
(1)Types and structure of tower
(2)Basis of tower ( 塔的基础 )
(3)Vibration Mode ( 振型 )
Seismic loads must be considered when design seismic intensity is larger than 7 grade
●
●
●
●
●
●
Mode I (Basic Mode)
●
●
●
●
●
●
Mode II
(1)Horizontal Seismic Force FK ( 水平地震力 )
In tower body, at the position where the
height is hK, the horizontal seismic force
caused by central load ( 集中载荷 ) mK:
(N) 1 gmCF kkzk
mk —— The mass of the section of column
at height hk, kgCz —— combined influent coefficient of structure ( 塔体结构综合影响系数 ) For cylindrical perpendicular equipments: Cz = 0.51 ——seismic influence coefficient ( 地震影响系
数 ) under the basic natural vibration period ( 基本自振周期 ) T1of equipments, confirming its value according to P237 Fig.8-5
T1 —— Basic natural vibration period of equipments under Basic Mode (Mode I), S To equipments with equal diameter and wall thickness:
k —— Mode Factor (Parameter) at the
position whose height is hk, its value is confirmed according to P238 Equation 8-7.
(s) 1033.90 3-31 ie
o
DES
HmHT
(2) Vertical seismic force FV ( 垂直地震力 )
To columns lie in the region with 8 or 9
degree seismic intensity, the vertical seismic
force should be taken into account.
FV of Section 0-0
at the bottom of tower:]
FV of random position
with quality i:
gmF eqvV max00
,2,1(
00
)ni
Fhm
hmF Vn
ikkk
iiIIV
●
●
●
●
●
●
●m1
m2
mi
mn
FV
hi
In these equations:
αV.max. —— Vertical seismic effecting coefficient ( 垂直地震影响系数 )
αV.max= 0.65αmax
meq —— Equilibrium quality of columns ( 当 量质量 ), kg
meq= 0.75 mo
hk —— Height of the functional point with
concentrated quality mk which is above Section I—I referring to the ground(??), mm
The Axial [Longitudinal] Stress σV ( 轴向应力 )
caused by vertical seismic force FV:
ei
VV SD
F
(3)Seismic Bending Moment ( 地震弯矩 )
*Moment that horizontal
seismic force FK acts
on random section:
* section I-I:
●
●
●
●
●
●
●m1
m2
mk
mn
F1
F2
Fk
Fn
hhk
hn
I I
)(
)(...)()( 11
hhF
hhFhhFhhFM
i
n
kii
kknnnnII
E
iii. Wind Load
10)( 6..21
ieioiii DlqfKKp
o o
1 1
2 2
i i
i+1 i+1
n n
l nl i+
1l i
l 2l 1
l o
qo
q1
q2
q3
Pn
Pi+1
Pi
P2
P1
Po
In the equation:Pi —— Wind load N between two neighboring sectionsqo —— Wind Velocity Pressure ( 基本风压值 ) of the position at the height of 10 meter, N / m2, checking the value according to P240 Table 8-4
li —— Distance between the two neighboring
calculating section, m
De.i —— Effective diameter of each portion, m
fi —— Coefficient of height variation
( 高度变化系数 ), checking the
value according to P240 Table 8-5
K1 —— Type??? Coefficient ( 体型系数 ),
K1 = 0.7
K2.i —— Wind Vibration (force) Coefficient
( 风振系数 )
If H ≤ 20 m, K2.i =1.7
If H > 20 m, calculating it from
the following equation:
i
ziii f
K
12
In the previous equation:ξ —— Accretion Coefficient of Fluctuation ( 脉动增大系数 ), checking from P241 Table 8-6
νi—— Effecting Coefficient of the portion No.i Fluctuation (第 i 段脉动影响系数 ), checking from P241Table 8-7
φzi——Mode Coefficient of the portion No.i (第 i 段振型系数 ), checking from P241 Table 8-8
Computation of Wind Bending Moment
( 风弯矩 )
Wind bending moment at random section
of tower:
)2
...(
...)2
()2
(2
21
212
11
niiin
iiii
iii
ii
iiw
llllP
lllP
llP
lPM
4.Eccentric Load When some attachments are
hinging on the top of the tower,
their weight will affect the
tower body generating the
Eccentric Load.
The eccentric moment ( 偏心矩 )
is:
egmM ee
e me g●
Me —— Eccentric Bending Moment
( 偏心弯矩 ), N. m
me —— Eccentric Mass ( 偏心质量 ), kg
e —— Distance from the C.G. (center of
gravity) of eccentric units to C.L.
(center line) of tower, m0
7.2 Stability of Tower its 7.2 Stability of Tower its
Strength VerificationStrength Verification
1.1.Stress inside the tower bodyStress inside the tower body
i. Axial (Longitudinal) Stress i. Axial (Longitudinal) Stress m ( ( 轴向轴向 // 经向应力经向应力 ) )
and Hoop Stress and Hoop Stress (( 环向应力环向应力 ) ) caused by caused by
media pressure (media pressure ( 介质压力 )
ie
i
ie
im
S
PD
S
PD
.
.
2
4
ii. Axial Stress caused by weight loadii2
iei
iiii
SD
gm
.2
iim —— Mass of the part in tower body above random calculating section i-i, Kg
At Section i-i of tower:
iii. Axial Stress caused by bending moment ii3
Section i-i of tower:iei
iiii
SD
M
W
M
.2
max3
4
maxiiM —— Maximum bending moment at
the calculating section
max
max25.0
eii
wii
E
eii
wii
MMM
MMM
2.Stress Combination on sections of tower
There are three types of stress on tower body,
considering various dangerous situation,
combining 1 、 2 、 3, and calculating the
maximum combined stress value to verify the
strength and stability of tower body.
To internal pressure tower ( 内压塔 )
i. The maximum combined axial tensile stress
( 最大组合轴向拉应力 ) (comb.tensile)max is on the
surface toward wind ( 迎风面 ) of tower on
operation.
ii. The maximum combined axial compressive
stress ( 最大组合轴向压应力 ) (comb.comp.)max is
on the leeward side ( 背风面 ) of tower in time
of shut-down.
To external pressure tower ( 外压塔 )i. The maximum combined axial
tensile stress (comb.tensile)max is on the surface toward
wind of tower in time of shut-down.ii. The maximum combined axial
compressive stress (comb.comp.)max is on the leeward
side of tower on operation.
3.Conditions for the stability and strength of tower bodyi. Condition for stability
crcom ][max
min][
][
tcr
K
KB
In the previous equation:
[]cr —— Axial allowable compressive stress
( 轴向许用压应力 ), Mpa
B —— checking from the method on P183
[]t —— Allowable stress of material in design
temperature, Mpa
K —— Coefficient of load combination
( 载荷组合系数 ), K=1.2
ii. Condition for strength
In the above equation:
K —— Coefficient of load combination
( 载荷组合系数 ), K=1.2
—— Weld joint efficiency ( 焊缝系数 )
t
tensile K ][max
Dangerous sections of columns:
0-0 section —— Basis ( 基底 )
1-1 section
—— Sections on the position
of skirt supports and manholes
2-2 section
—— Section on the joint of
cylinder and skirt support
4.Calculating steps for stability and strength of columns
i. Confirming the effective thickness Se and Seh of cylinder and heads according to the calculating pressure
To cylinder:
To heads:
P
DPS
tic
][2
P
DPS
tic
h 5.0][2
valueofround
valueofround
12
1
2
CCS
CSS
CSS
dn
d
CSS ne .
ii. Calculating various loads
According to the location and various work
conditions (Installation, normal operation,
shutdown and hydrostatic pressure test, etc.)
of columns, checking some calculating section
(containing all dangerous sections) to
calculate various loads:
(1)Dead Load; (2)Seismic Load;
(3)Wind Load; (4)Eccentric Load.
iii. Assuming the effective thickness Sei of all
sections in cylinder (can be referred to Se)
Sei >= Se
Assuming the effective thickness of skirt
support shell is Ses
Ses >= 6mm
iv. Calculating the axial stress under various
loads of tower
(1)Axial stress 1 caused by media pressure
(2)Axial stress 2 caused by weight load
(3)Axial stress 3 caused by bending moment
v. Calculating the combined axial stress of tower
under the combined effect of multiplicate loads
should satisfy:
Condition for strength
Condition for stability
Else the thickness must be reassumed until satisfying all the verification conditions.
( and ( max.comb.compmaxlecomb.tensi ))
tK ][maxlecomb.tensi
cr][maxcomb.comp.
iv. Calculating the base ring and anchor
bolt according to the loads under the
above-mentioned work conditions.
5.Verification of stress in hydrostatic pressure
test ( 水压试验 )i. Testing pressure
tT Pp][
][25.1
ii. Calculating all stresses
(1)Hoop stress caused by testing pressure
(2)Axial stress caused by testing pressure
ie
ieiTT S
SDP
.
.
2
)(P)-static liquid(
ie
ieiT
S
SDP
.
.1 4
)(
(3)Axial stress caused by gravity
(4)Axial stress caused by wind bending
moment and eccentric bending moment
iei
ii
SD
gm
.
max2
iei
eii
w
SD
MM
.2
3
4
3.0
iii. Strength condition in hydrostatic pressure test
(1)Hoop stress
(2)Maximum combined axial tensile stress
(3)Maximum combined axial compressive stress
sT 9.0
sK9.0321maxlecomb.tensi
crcomp ][32max
min
9.0][
KB
K scr
7.3 Design
of Skirt
Support 1. Structure of skirt support
Exhaust opening —— 排气孔Access opening of outgoing tube —— 引出管通
孔Bed body —— 座体Manhole —— 人孔Anchor Bolt —— 地脚螺栓Bolt Base —— 螺栓座Base ring —— 基础环Bed —— 基础
2.Design of skirt supporti. Enactment an effective thickness Ses
according to the tower body
ii. Verifying the strength and stability
of dangerous sections on skirt support
Dangerous sections:
(1)Basis section ( 基底截面 )(0-0)
(2)manhole section ( 人孔截面 ) (1-1)
Dangerous Sections is illustrated like the picture:
Checking of longitudinal Checking of longitudinal stress of cylinderstress of cylinder
Longitudinal stress produced by internal or external pressure
Longitudinal stress produced by dead-weight under operating or non-operating condition
Longitudinal stress produced by bending moment
ei
ipD
41
eii
II
D
gm
14.32
eii
II
D
M
2max
3 14.3
4
Checking of stability of cylinderChecking of stability of cylinder Allowable longitudinal compressive stress
of cylinder take the lesser value Maximum combined compressive stress of
cylinder For vessels under internal pressure σ2 +σ3≤[σ]cr MPa For
vessels under external pressureσ1+σ2 +σ3≤[σ]cr MPa
KBKcr t
Checking of tensile stress of Checking of tensile stress of cylindercylinder
Maximum combined tensile stress of cylinder For vessels under internal pressure
σ1-σ2 +σ3≤KФ[σ]t MPa For vessels under external pressure -σ2 +σ3≤KФ[σ]t MPa
OK ?OK ?
When conditions specified can not be satisfied, it is necessary to reassume a new value for effective thickness δe or δei, and the above-mentioned calculations are repeated until requirements are fulfilled.
Checking of stress during Checking of stress during hydrostatic test of vesselhydrostatic test of vessel
Circumferential stress due to hydrostatic pressure of testing liquid
ei
eiiT Dheadliquidof
pressurestaticp
2
Longitudinal stress due to Longitudinal stress due to hydrostatic pressure of testing liquidhydrostatic pressure of testing liquid
Longitudinal stress due to dead-weight during hydrostatic test
Longitudinal stress due to dead-weight during hydrostatic test
Longitudinal stress due to bending moment
ei
iTDp
41
eii
IIT
D
gm
14.32
eii
eII
W
D
MM
23 14.3
3.04
Checking of stressesChecking of stresses
Allowable longitudinal compressive stress
KB
K s
cr
9.0
s9.0 sK9.0321
cr 32
Thickness of SkirtThickness of Skirt
Let the effective thickness of a skirt be , stresses at various selected dangerous sections should be checked according to following Articles.
Bottom sectionBottom section stress at bottom section should be
checked with following equations
tsK
KB
Asb
gmoZ sb
M oo
max
sK
KB
Asb
gmoZ sb
M w9.0
3.0 00
Section at opening on skirtSection at opening on skirt Stress at section 1-1 of man-hole or opening
for larger outlet piping on skirt should be checked with equations
tsK
KB
Asm
gm
Z sm
M
11
0
11
max
s
e
K
KB
Asm
gm
Z sm
M w9.0
3.0 11
OK?OK?
When the above-mentioned conditions can not be satisfied, it is necessary to reassume a new value for effective thickness , and the above-mentioned calculations are repeated until requirements are fulfilled.
Bearing RingBearing Ring
mm
mm
DDDD
isib
isob
400~200
400~200
Dib
Dob
DobDib
Dib
Dis Dis
δesδes
Maximum compressive stress acting Maximum compressive stress acting on concrete foundationon concrete foundation
Thickness of bearing ring without ribs (see Figure)
Thickness of bearing ring with ribs (see Figure)
Am
ZMMAm
ZM
bb
e
oo
W
b
o
b
oo
b gmax
max
max 3.0
bb
bb
max73.1
bs
b
M
6
Calculations of anchor bolts Calculations of anchor bolts
Maximum tensile stress sustained by anchor bolts in foundation should be calculated with equation
take the greater value
bb
eWE
bb
eW
B
A
gm
Z
MMMA
gm
Z
MM
00000
min00
25.0
When < 0,vessel is stable by itself. However, for the purpose of fixing the vessel at a specific position, it is still necessary to provide the foundation with a certain number of anchor bolts.
When > 0,it is imperative to use anchor bolts for the vessel. The thread root diameter d1 of anchor bolts should be calculated with equation
where C4- corrosion allowance, generally C4=3mm;
n - the number of anchor bolts is first assumed as a multiple of 4;
41 ][14.3
4C
n
Ad
bt
bB
Welded Joint Between Skirt And Welded Joint Between Skirt And ShellShell
Checking 0f lap-
welds between
skirt and shell
Shearing stress of lapShearing stress of lap-- welds welds should be checked with equation should be checked with equation
tw
W
JJ
W
JJ
A
gm
Z
M][8.00max
tw
W
JJ
W
eJJ
W
A
gm
Z
MM][8.0
3.0 max
buttbutt-- welds between skirt and welds between skirt and shellshell
Checking of buttChecking of butt-- welds welds between skirt and shellbetween skirt and shell
Tensile stress of butt- welds should checked with equation
tW
esit
JJ
esit
JJ
D
gm
D
M][6.0
14.314.3
4 02
max