STORAGE TANK DESIGN CALCULATION - API 650 1 .0
1 .1
1 .2
1 .3
1 .4
DESIGN CODE & SPECIFICATION DESIGN CODE
: API 650 11th Edition
TANK Item number Roof ( Open/Close ) Type of roof ( Cone-roof / Dome-roof / Flat-roof / NA )
: 7061T-3901 : Close : Floating Roof
GEOMETRIC DATA Inside diameter , Di ( corroded ) (@ 39,000 mm ) Nominal diameter, Dn ( new ) ( based on 1st shell course ) Nominal diameter, Dc ( corroded ) ( based on 1st shell course ) Tank height (tan/tan), H Specific gravity of operating liquid , S.G. (Actual) Specific gravity of operating liquid , S.G. (Design) Nominal capacity , V Maximum design liquid level, HL
= = = = = = = =
39,006 39,028 39,031 20,700 0.790 1.00 24736 20,700
(Atmospheric) = = = =
0.00 0.00 70 -17
PRESSURE & TEMPERATURE Design pressure : Upper , Pu : Lower , Pl Design temperature : Upper , Tu : Lower , Tl MATERIAL & MECHANICAL PROPERTIES Component
PLATE Shell Plate
( Mat'l Code # 1 ) (bot) ( Mat'l Code # 2 ) (top)
Annular Plate Bottom Plate Roof Plate STRUCTURE MEMBERS Roof structure (rafter,bracing,etc ) Top Curb Angle Intermediate Wind Girder
Material
Tensile Stress St(N/mm²)
Yield Stress Sy(N/mm²)
Corrosion Allowance c.a.(mm)
A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N
448.00 448.00 448.00 448.00 448.00
241.00 241.00 241.00 241.00 241.00
3.000 3.000 3.000 3.000 3.000
A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N
448.00 448.00 448.00
241.00 241.00 241.00
3.00 3.00 3.00
mm mm mm mm
m³ mm
mbarg mbarg Vac °C °C
SHELL THICKNESS CALCULATION BY ONE-FOOT METHOD SHELL DESIGN GEOMETRIC DATA Plate size used Shell plate min. width as per PTS 34.51.01.31 clause 6.3
2 .0 2 .1
2 .2
2,440 mm 1,500 mm
MATERIAL & MECHANICAL PROPERTIES
No
1 2 3 4 5 6 7 8 9 10
2 .3
Material used
A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N -
Specified Specified Yield stress Max. allow Max. allow min. tensile min. yield reduction fac design hydro.test stress stress ( App. M ) stress stress St (N/mm²) Sy (Nmm²) k Sd (N/mm²) St (N/mm²) 448.00 448.00 448.00 448.00 448.00 448.00 448.00 448.00 448.00 -
241.00 241.00 241.00 241.00 241.00 241.00 241.00 241.00 241.00 -
1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 -
160.67 160.67 160.67 160.67 160.67 160.67 160.67 160.67 160.67 -
Corrosion allowance c.a (mm)
180.75 180.75 180.75 180.75 180.75 180.75 180.75 180.75 180.75 -
SPECIFIED MINIMUM SHELL THICKNESS Specification Minimum thickness as per API 650 cl 5.6.1.1 Minimum thickness as per PTS 34.51.01.31
2 .4
3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 -
: API 650 11th Edition = 8.00 mm = 11.00 mm
SHELL THICKNESS CALCULATION BY ONE-FOOT METHOD ( CLAUSE 5.6.3.1 ) SI METRIC UNIT :Design shell thickness, ( in mm ) 4.9Dc ( [H+Hi] - 0.3 ).G td = + c.a Sd Hydrostatic test shell thickness , ( in mm ) 4.9Dn ( H - 0.3 ) tt = St Gravitational force = 9.81 m/s
2 .5
t.min = Min. of t.design, t.hydo & min. thickness as per PTS. tsc = Thicknes selected & used
CALCULATION & RESULTS
No. Mat'l Code No. 1 2 3 4 5 6 7 8 9
: :
1 1 1 1 1 1 1 1 1
Material
Width (mm)
Height (mm)
t.design (mm)
A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N
2,440 2,440 2,440 2,440 2,440 2,440 2,020 2,020 2,020
20,700 18,260 15,820 13,380 10,940 8,500 6,060 4,040 2,020
27.30 24.40 21.49 18.58 15.67 12.77 9.86 7.45 5.04
t.hydro. (mm)
t.min (mm)
tsc. (mm)
Result
21.60 19.02 16.43 13.85 11.26 8.68 6.10 3.96 1.82
27.30 24.40 21.49 18.58 15.67 12.77 11.00 11.00 11.00
28.00 25.00 22.00 19.00 16.00 13.00 11.00 11.00 11.00
O.K. O.K. O.K. O.K. O.K. O.K. O.K. O.K. O.K.
2 .6
MAXIMUM ALLOWABLE STRESS
No.
Height (mm)
t.min (mm)
tsc. (mm)
H' (mm)
H' max (mm)
∆H (mm)
P'max N/m²
Pmax N/m²
1 2 3 4 5 6 7 8 9
20,700 18,260 15,820 13,380 10,940 8,500 6,060 4,040 2,020
27.30 24.40 21.49 18.58 15.67 12.77 11.00 11.00 11.00
28.00 25.00 22.00 19.00 16.00 13.00 11.00 11.00 11.00
20,700 18,260 15,820 13,380 10,940 8,500 6,060 4,040 2,020
21,306.77 18,786.53 16,266.30 13,746.06 11,225.82 8,705.59 7,025.43 7,025.43 7,025.43
606.77 526.53 446.30 366.06 285.82 205.59 965.43 2985.43 5005.43
5,952.41 5,165.29 4,378.18 3,591.06 2,803.94 2,016.82 9,470.87 29,287.07 49,103.27
5,952.41 5,165.29 4,378.18 3,591.06 2,803.94 2,016.82 2,016.82 9,470.87 29,287.07
H' = H' max = P'max = Pmax =
Effective liquid head at design pressure Max. liquid head for tsc. Max. allowable stress for tsc. Max. allowable stress at shell course.
BOTTOM & ANNULAR PLATE DESIGN BOTTOM PLATE & ANNULAR PLATE DESIGN Annular plate used ? ( yes/no )
3 .0
BOTTOM PLATE (i) Minimum thickness as per Minimum thickness required Therefore, use thickness of (ii) (iii) (iv) (v)
(@
: yes
API 650 Clause 5.4.1 3.00 mm c.a ) 9.00 mm (tb) is
ANNULAR PLATE (i) Nominal thickness of 1st shell course, tsc1 Hydro. test stress in 1st shell course, 4.9Dn(H-0.3) St = tsc1 where Dn = Nominal diameter, Dn ( new ) ( based on 1st shell course ) H = Design liquid level tsc1 = Nominal thickness of 1st shell course
mm c.a. ) mm (ta) is
(ii) Min. shell-to-bottom fillet welds size (cl. 5.1.5.7) (iii) Min. width projected inside of shell to edge of overlapping (cl. 5.5.2) (iv) Min. radial width of annular plate (cl. 5.5.2) 215 ta La = (HL. SG )0.5 where ta = Annular plate thickness HL = Maximum design liquid level SG = Design specific gravity (v) Min. width projected outside of shell ( cl. 5.5.2)
6.00 mm 9.00 mm
== = =
mm 25 mm 1800 mm 50 mm
=
28.00 mm
satisfactory.
Min. width of overlapping (cl. 5.1.3.5) Min. width of plate (cl. 5.4.1) -
Annular plate thickness ( As per Table 5-1a ) Minimum thickness required (@ 3.00 Therefore , use thickness of 16.00
= =
=
139.33 N/mm²
= = =
39.028 m 20.700 m 28.000 mm
= =
6.00 mm 9.00 mm
= =
13.00 mm 600 mm
=
756.09 mm
= = = =
16.000 mm 20.70 m 1.00 50 mm
satisfactory.
ROOF TO SHELL JUNCTION CALCULATION 4 .1 4 .1.1
DESIGN OF OPEN ROOF TANK - TOP STIFFENER RING TOP CURB ANGLE If the top wind girder is located 600 mm below top of the tank, top curn angle shall be provided. Location of top wind girders from top of tank, L = Since L is
>
600mm from top of tank, top curb angle is
required.
MINIMUM REQUIREMENT Minimum required size as per API 650 clause 5.9.3.2
=
Section modulus,Z min
=
MEMBER SIZE USED FOR TOP CURB ANGLE Actual size for top curb angle
= 75 x 75x 10
Section modulus, Za
=
Since Za 4 .1.2
1000 mm
>
Zmin , therefore the angle size selected is
76 x 76 x 6.4 8380 mm3
13500 mm3
satisfactory.
TOP WIND GIRDER The required minimum section modulus of the stiffening ring shall be as follows:Dc².H2 17
Z= where Dc H2 V
V 190
2
= =
= Nominal Tank Diameter = Height of tank shell = Wind Velocity
= = =
MEMBER SIZE USED FOR TOP WIND GIDER Available section modulus Fabricated Tee- Girder Web plate length, L2 Toe plate length, L3 Web plate thk, t2 Toe plate thk, t3 Min. shell thickness where top wind girder located, tsc.cor tsc.cor = 8.00 mm 10 mm
1007 cm³ 1,007,140 mm³ 39.031 m 20.7 m 140.00 km/hr
: T 825 x 250 x 8 x 10 = 825 mm = 250 mm = 8 mm = 10 mm = 8.00 mm
D=
39037
mm
X 2
C1
8 250 mm
3
1 X 825 mm
L1=16.tsc.cor
A Y AY h (mm²) (mm) (mm³) (mm) 1 2048 4.00 8192 433.61141 2 6600 420.5 2775300 17.11141 3 2,500 838.00 2,095,000 400.39 TOTAL 11,148 4,878,492 Neutral axis of combined section, C1 Moment of inertia of section , Ix-x Section modulus available, Za Since Za > Zmin , therefore the angle size selected is
=
A.h² (mm4) 385062615 1932482.4 ######### #########
128
mm
I = (bd³)/12 (mm4) 10,923 374343750 20,833 374,375,506 = 438 mm = 1,162,148,161 mm4 = 2,655,662 mm³ satisfactory.
INTERMEDIATE WIND GIRDERS CALCULATION INTERMEDIATE WIND GIRDERS DESIGN MAXIMUM HEIGHT OF THE UNSTIFFENED SHELL ( CLAUSE 5.9.7.1 )
5 .0 5 .1
SI METRIC UNIT :H1 = (9.47 ts.cor) where
5 .2
ts.cor Dc
3
x
190 ² V
ts.cor = Top shell course thickness Dc = Nominal tank diameter V = Wind design speed LOCATION OF INTERMEDIATE WIND GIRDERS Shell Shell Actual Transposed course thickness width width tsc.cor W Wtr (mm) (mm) (mm) 1 25.00 2,440 141 2 22.00 2,440 195 3 19.00 2,440 281 4 16.00 2,440 431 5 13.00 2,440 725 6 10.00 2,440 1,397 7 8.00 2,020 2,020 8 8.00 2,020 2,020 9 8.00 2,020 2,020 10 11 12 13 14 15 Height of transformed shell, H2 =
9,230
= =
9.182 m 9182 mm
= = =
8.00 mm 39.03 m 140.00 km/hr
Since H1 < H2, therefore the intermediate wind girder is/are required Minimum number of intermediate wind girders required, = 1 Location of intermediate wind girders from top of tank, L1 = 4615 mm L2 = - mm L3 = - mm L4 = - mm L5 = - mm
mm
5 .3
SIZE OF INTERMEDIATE WIND GIRDERS (a) Required minimum section modulus of intermediate wind girder ( clause 5.9.7.6 ) SI METRIC UNIT :Dc². H1 17
Z.min =
V 190
2
= =
225.812 cm³ 225,812.032 mm³
where Dc = Nominal tank diameter H1 = Vertical dist. between inter. wind girder & top angle V = Wind design speed
= = =
(b) Available section modulus for intermediate wind girder Fabricated Tee- Girder Web plate length, L2 Toe plate length, L3 Web plate thk, t2 Toe plate thk, t3 Min. shell thickness where top wind girder located, tsc.cor tsc.cor = 8.00 mm 8 mm
39.031 m 4.615 m 140.40 km/hr
: T 405 x 150 = 450 = 150 = 8 = 8 = 8.00
D=
39037
mm mm mm mm mm
mm
X 2
C1
8 150 mm
3
1 X 450 mm
L1=16.tsc.cor
A Y AY h (mm²) (mm) (mm³) (mm) 1 2048 4.00 8192 200.64252 2 3600 233 838800 28.357477 3 1,200 462.00 554,400 257.36 TOTAL 6,848 1,401,392 Neutral axis of combined section, C1 Moment of inertia of section , Ix-x Section modulus available, Za Since Za > Zmin , therefore the angle size selected is
=
A.h² (mm4) 82447201 2894927.3 79,479,445 #########
128
mm
I = (bd³)/12 (mm4) 10,923 60750000 6,400 60,767,323 = 205 mm = 225,588,896 mm4 = 863,143 mm³ satisfactory.
6 .0 6 .1
WIND LOAD CALCULATION (OVERTURNING STABILITY) WIND DESIGN CALCULATION Internal design pressure, Pi ( @ 0.0 mbarg. ) Insulation thickness, ti
= =
Nominal diameter of tank, D Tank height , Hs Roof slope, ß° Roof height, Hr Height from tank bottom to shell centre, Ls Height from tank bottom to roof centre,Lr Min. depth of product (always present in tank) , Hw
= = = = = = =
39,000 20,700 0.000 0 10,350 20,700 0
= = =
5,395,939 N 0N 3,212,898 N
= = =
0.0014369 N/mm² 0.0008621 N/mm² 1.00
Weight of tank,Wt (corroded condition) (@ Weight of product (always present in tank) , Ww Weight of shell + top angle (corroded ), WDL (@ 6 .2
6 .3
550,045
kg )
327,512
kg )
WIND FORCE CALCULATION As per API 650 clause 5.2.1(j), the wind pressure are as follows:Wind pressure on conical surfaces, wr (@ 30.00 Wind pressure on cylindrical surfaces, ws (@ 18.00 Wind correction factor, kw (= V /190)²
psf ) psf )
0 N/mm² 75 mm mm mm ° mm mm mm mm
Projected area of roof, Ar ( = 0.5.k.Do.Hr ) Projected area of shell, As ( = k.Do.Hs )
= =
0 mm² 811,564,200 mm²
Total wind load exerted on roof, Fr ( = wr.kw.Ar ) Total wind load exerted on shell, Fs ( = ws.kw.As ) Total wind moment on tank, Mw ( = Fr.Lr + Fs.Ls )
= = =
0N 699,681 N 7,241,700,964 Nmm
OVERTURNING STABILITY AGAINST WIND LOADING Wind Uplift Load
Internal Pressure Load D/2
Wind load on shell, Fr
H
H/2
Momment about shell to bottom joint Dead Load (WDL)
Liquid hold down weight (wa) For tank to be structurally stable without anchorage, the following uplift criteria shall satisfy: Criteria 1: 0.6 Mw + Mpi < MDL / 1.5 Criteria 2: Mw + 0.4 Mpi < (MDL +MF) / 2 where: Mpi = = = Mw =
Moment about the shell-to-bottom joint from design internal pressure Uplift thrust on roof due to internal pressure x 1/2 tank diameter ( 1/4 p. D2. Pi ). 1/2. D Overturning moment about the shell-to-bottom joint from horizontal plus vertical wind pressure
=
0 Nmm
= MDL = =
Total wind moment on tank, ( = Fr.Lr + Fs.Ls ) Moment about the shell-to-bottom joint from the weight of the shell and the roof supported by the shell. 0.5. D. WDL Weight of roof = 0,since it is floating on liquid
=
7,241,700,964 Nmm
= 62,651,502,376 Nmm
MF = =
Moment about the shell-to-bottom joint from liquid weight (wa) (wa. p D). D 1000 2
= 153,419,379,181 Nmm
wa = H= tb =
Weight of liquid = 59 tb Fby. H Design liquid height Thickness of Bottom plate under the shell
= = =
Fby =
Minimum specified yeid stress of the bottom plate under the shell
=
FOR CRITERIA 1 0.6 Mw + Mpi MDL / 1.5
0.6 Mw + Mpi < MDL / 1.5
FOR CRITERIA 2 Mw + 0.4 Mpi (MDL +MF) / 2
Mw + 0.4 Mpi < (MDL +MF) / 2
Since, 0.6 Mw + Mpi Mw +0.4 Mpi
64,214.21 N/m 19.2 m 16 mm 241 N/mm2
= 4,345,020,578 Nmm = 41,767,668,251 Nmm
= 7,241,700,964 Nmm = 108,035,440,779 Nmm
< <
MDL/1.5, and 1/2 (MDL+ MF)
The tank anchorage is NOT REQUIRED.
7 .0 7 .1 7 .1.1
SEISMIC FORCE CALCULATION SEISMIC LOADS DESIGN GEOMETRIC DATA Seismic peak ground acceleration, Sp Importance factor, I Site Class Seismic Use Group, SUG
= = = =
Nominal diameter of tank, D Total height of tank shell, Ht Ht.from bottom shell to COG of shell,Xs Maximum design liquid level, H Ht.from bottom shell to COG of roof,Xr Design specific gravity of liquid, G
= = = = = =
39,031 20,700 10,350 20,700 0 1
= = = =
3,462,418 0 242,581,931 833,471
Total weight of tank shell, Ws Total weight of tank roof, Wr Total weight of tank contents, Wp Total weight of tank bottom, Wf
7 .1.2
(@ (@ (@ (@
352,948 0 24,728,026 84,961
kg ) kg ) kg ) kg )
0.3 g 1.50 D III mm mm mm mm mm
N N N N
Note: The total weight of the tank roof will be added to the weight of tank content, since the roof is floating on the liquid. DESIGN SPECTRAL RESPONSE ACCELERATIONS Impulsive spectral acceleration parameter, Ai Ai =
I Rwi
2.5 Q Fa So
=
0.34
≤ Ai
=
-
≤ Ai
=
0.063298299
Convective spectral acceleration parameter, Ac When Tc ≤ TL Ac =
2.5 K Q Fa So
Ts Tc
I Rwc
When Tc > TL Ac = where Q = K = Fa = Fv = So = Rwi = Rwc = TL = Tc = Ts =
2.5 K Q Fa So
Ts .TL Tc2
I Rwc
Scaling factor Coefficient to adjust the spectral damping from 5% - 0.5% Acceleration based site coefficient as per Table E-1 Velocity-based site coefficient as per Table E-2 Substitution for seismic peak ground acceleration Sp Force reduction coefficient for impulsive mode as per Table E-4 Force reduction coefficient for convective mode as per Table E-4 Regional dependent transition period for longer period ground motion First mode sloshing wave period for convective mode Fv. S1/ Fa. Ss
= = = = = = = =
1 1.5 1.2 1.65 0.3 4 2 4s
= =
6.63 s 0.69
7 .1.3
CONVECTIVE (SLOSHING ) PERIOD The first mode sloshing wave period, Tc = 1.8 Ks √ D where, Ks =
=
6.63 s
=
0.59
=
0.69
= =
1.2 1.6500
= =
0.375 0.75
= =
0.06 0.34
sloshing period coefficient 0.578
Ks =
Ts = where, Fa = Fv = S1 = Ss =
3.68 H D
tanh
Fv . S1 Fa . Ss
Acceleration based site coefficient (at 0.2 sec perios) as per Table E-1 Velocity-based site coefficient (at 1 sec. period) as per Table E-2 Maximum considered earthquake, 5% damped, spectral response acceleration parameter at the period of one second, %g Maximum considered earthquake, 5% damped, spectral response acceleration parameter at shorts period of 0.2 second, %g
For regions outside USA, sites not defined by ASCE 7 method, S1 = 1.25 Sp Ss = 2.5 Sp Since Tc > TL , the convective spectral acceleration parameter Ac and the impulsive spectral acceleration parameter Ai 7 .2 7 .2.1
OVERTURNING STABILITY AGAINST SEISMIC LOADING EFFECTIVE MASS OF TANK CONTENTS Effective impulsive portion of the liquid weight, For D/H ≥ 1.333, tanh (0.866.D/H) 0.866. D/H
Wi =
. Wp
= 137,636,499.10 N
. Wp
=
For D/H < 1.333, Wi = Since
1.0 - 0.218
D H
D/H > 1.333 , effective impulsive portion of the liquid weight, Wi
-
N
= 137,636,499.10 N
Effective convective weight, Wc =
0.230
D H
tanh
3.67H D
. Wp
= 100,998,137.14 N
7 .2.2
CENTER OF ACTION FOR EFFECTIVE LATERAL FORCES The height from the bottom of the Tank Shell to the center of action of the lateral seismic forces related to the impulsive liquid force for ringwall moment, For D/H ≥ 1.333, Xi =
0.375H
=
7762.5 mm
For D/H < 1.333, Xi = Since
0.5 - 0.094
D .H H
D/H > 1.333 , Xi
=
-
mm
=
7,762.50 mm
=
12,722.55 mm
The height from the bottom of the Tank Shell to the center of action of the lateral seismic forces related to the convective liquid force for ringwall moment,
Xc = 1.0 -
7 .2.3
cosh
3.67 H D
3.67H D
sinh
-1 3.67 H D
.H
OVERTURNING MOMENT The seismic overturning moment at the base of the tank shell shall be the SRSS summation of the impulsive and convective components multiplied by the respective moment arms to the center of action of the forces. Ringwall moment, Mrw =
7 .2.4
[Ai ( Wi. Xi + Ws. Xs + Wr. Xr)]2 + [Ac (Wc. Xc)]2
3.81453E+11 Nmm
=
381453029.8 Nm
SHEAR FORCE The seismic base shear shall be defined as the SRSS combination of the impulsive and convective components. V=
Vi2 + Vc2
where,
7 .3 7 .3.1
=
Vi = Vc =
Ai (Ws + Wr +Wf + Wi) Ac. Wc
=
48,326,902.75 N
= =
47,902,181.05 N 6,393,010.26 N
RESISTANCE TO OVERTURNING THICKNESS OF THE BOTTOM PLATE UNDER THE SHELL & ITS RADIAL WIDTH Bottom/Annular plate thickness , ta = Thickness of bottom shell course, ts = Bottom/Annular plate radial width, Ls = Min. specified yield strength of bottom annulus, Fy Min. specified yield strength of bottom shell course, Fty
= =
16.00 mm 28.00 mm 1200.0 mm 241.0 N/mm2 241.0 N/mm2
Anchorage Ratio, J J= where, Av = Wt = wa =
Mrw D2 ( Wt (1 - 0.4 Av) + Wa )
=
Vertical earthquake acceleration coefficient Tank and roof weight acting at base of shell Resisting force of the annulus
= = =
2.17
0.7 28.24 N/mm 94.93 N/mm
Weight of tank shell and portion of roof supported by the shell, Ws Wt = + wrs p. D wrs =
Roof load acting on the shell, including 10% of specified snow load. ( Zero for floating roof)
The resisting force of the annulus, wa = 99 ta Fy. H. Ge wa
≤ 196. H. D. Ge <
196.H.D.Ge =
=
28.24 N/mm
=
0 N/mm
=
94,932.54 N/m
=
0.72
114,016,732,704.00
Ge = Effective specific gravity including vertical seismic effect = G. (1 - 0.4 Av)
Since the anchorage ratio, J > 1.54, the tank is not stable and cannot be self-anchored for the design load. The tank shall be mechanically anchored. 7 .3.2
ANNULAR PLATE REQUIREMENT If the thickness of the bottom plate under the shell is thicker than the remainder of the bottom, then the minimum radial width of the bottom plate, L=
7 .3.3
0.01723 ta
Fy H. Ge
=
1,108.57 mm
The maximum width of annulus for determining the resisting force, 0.035 D
=
1,366.09 mm
Since L And, Since Ls
=
1,108.57 mm
<
0.035 D, the minimum radial width should be
>
L, the bottom/ annular plate width is
satisfactory.
SHELL COMPRESSION MECHANICALLY-ANCHORED TANKS Maximum longitudinal shell compression, sc =
7 .3.4
wt ( 1 + 0.4 Av) +
1.273 Mrw D2
1 ts
=
12.67 N/mm
=
40.223 m³/mm²
=
57.94 N/mm²
MAXIMUM ALLOWABLE SHELL COMPRESSION A=
GHD² ts²
( D in m )
For GHD²/(ts²) < 44 m³/mm², Fc =
83.ts 2.5D
+ 7.5{G.H}½
For GHD²/(ts²) 44 m³/mm², 83.ts D
=
Therefore, Fa ( < 0.5Fty )
=
Fc =
Since sc
<
Fc, therefore the tank is structurally
stable.
-
N/mm²
57.94 N/mm²
7 .4
FREE BOARD FOR SLOSHING WAVE HEIGHT Sloshing wave height above the product design height, ds = 0.5 D. Af
=
1,647.06 mm
where: For SUG I and II, When Tc ≤ 4 Af =
1 Tc
K. SD1. I.
=
2.5 K Q Fa So I
Ts Tc
=
0.21
=
2.5 K Q Fa So I
4Ts Tc 2
=
0.13
=
2.5 K Q Fa So
Ts Tc
=
0.14
=
2.5 K Q Fa So
=
0.08
=
0.08
=
1,647.06 mm
When Tc > 4 Af =
4
K. SD1. I.
Tc 2
For SUG III When Tc ≤ TL Af =
1 Tc
K. SD1
When Tc > TL Af = Since SUG is
TL
K. SD1 III
Tc 2 and
For SDS = Q Fa Ss = 0.9 Minimum required freeboard, dsreq 7 .5 7 .5.1
7 .5.2
TANK ANCHORAGE GEOMETRIC DATA Number of bolts , N Dia. of anchor bolt, d Dia. of anchor bolt,d.corr (less c.a.= Bolts circle diameter, Da Root area of each hold down bolt, Ab Spacing between anchor bolts, Sp
Tc > TL
Ts. TL Tc 2 , Af
> 0.33g, ( as per Table E-7)
3.000
mm) (min.size.25.4 mm )
MATERIAL & MECHANICAL PROPERTIES Material used Specific minimum yield stress, Sy Allowable tensile strength, St.all ( 0.80Sy ) ( Table 5-21a )
= = = = = =
86 64 58 39,320 2,642 1,436
: = =
SA 320 Gr L7 551.5 N/mm² 441.20 N/mm²
mm mm mm mm² mm
Uplift force due to seismic loading, W AB = where Mrw = Dc = wt = Av = wint =
1.273 Mrw Dc²
=
- wt ( 1 - 0.4 Av) + wint
Overturing moment due to seismic Nominal diameter of tank Tank and roof weight acting at base of shell, Vertical earthquake acceleration coefficient Uplift thrust due to internal pressure
= = = = =
Tensile stress, sb = WAB / N.Ab Since sb
<
St.all,therefore the anchor bolt size is
= satisfactory.
36,592,019 N
3.81453E+11 39,031 28.24 0.70 0
Nmm mm N/mm N/mm
161.04 N/mm²
8 .0
DESIGN OF SINGLE DECK FLOATING ROOF FOR A STORAGE TANK 75 1 64
Top pontoon plt
8 Rafter
L 75 x 75 x 6
Outer Rim
975
Inner Rim
15
Deck Plate
8
Post
525 Btm Angle Bulkhead
198
2181
34248 38610
Shell I.D
39006 ( All dimensions in mm unless otherwise stated. )
8 .1
8 .2
8 .3
TANK GEOMETRY DATA Inside diameter , Di ( corroded ) (@ Tank height (tan/tan), H
39,000
mm )
= =
39,006 mm
Material of Construction Specific Minimum Yield Stress, Sy Modulus of Elasticity Density of Material, r (plate)
: SA 516 Gr 65N = 275 N/mm² = 209,000 N/mm² = 7,850 kg/m³
Corrosion Allowance Min. Specific Gravity of product Max. Specific Gravity of product
= = =
GEOMETRY DATA Outer Rim Height, Hor Inner Rim Height, Hir Pontoon width, w Rim Gap Outer Rim Extend above pontoon, Hext
= = = = =
975 525 2181 198 75
No. of Pontoons, N
=
22
Outer Rim Diameter, Øor Inner Rim Diameter, Øir
= =
38610 mm 34248 mm
Bulkhead Outer heigh, Boh Bulkhead Inner heigh, Bih Bulkhead Width, wb
= = =
884 mm 509 mm 2157 mm
MEMBER SIZE & PROPERTIES Outer Rim Thk, Tor Inner Rim Thk, Tir Top Pontoon Thk, Ttp Btm Pontoon Thk, Tbp Bulkheads Thk, Tb Deck Plate Thickness, Td Circumferential Truss Plates
= = = = = = =
Rafter Posts
44 Nos. of 44 Nos. of
L 75 x 75 x 6 L 75 x 75 x 6
@ unit weight of @ unit weight of
3 mm 0.7 1
9 15 8 8 8 8 8
mm mm mm mm mm
mm mm mm mm mm mm mm
6.85 kg/m 6.85 kg/m
8 .4 8 .4.1
8 .4.2
8 .5
9 .0
ROOF SUPPORT LEG ( Refer to Design of Supporting Legs) PONTOON LEG No. of Pontoon Leg, Np Pontoon Leg Size 3" pipe x Sch. 80 Pontoon Leg Housing 4" pipe x Sch. 80 Pontoon Leg length Pontoon Leg Housing length DECK LEG No. of Deck Leg, Nd Deck Leg Size Deck Leg Housing Deck Leg length Deck Leg Housing length
(Area od deck / 30m² / leg ) 3" pipe x Sch. 80 4" pipe x Sch. 80
=
22 15.27 22.32 2940 1084
kg/m kg/m mm mm
= =
30 15.27 22.32 2927 823
kg/m kg/m mm mm
@ unit wt @ unit wt = =
= @ unit wt @ unit wt
WEIGHT CALCULATION Top Pontoon Bottom Pontoon
=
p /4 x( Øor² - Øir²) x Ttp x r (plate) p /4 x( Øor² - Øir²) x Tbp x r (plate)
= =
15,675.18 kg 15,675.18 kg
Inner Rim Outer Rim
= =
p x Øir x Hir x Tir x r p x Øor x Hor x Tor x r
= =
6,651.28 kg 8,355.38 kg
Bulkheads
=
1/2 x (Boh - Bih)x wb x Tb x r x N
=
2,075.65 kg
Deck Plate
=
p /4 x Øir x Td x r
=
57,852.21 kg kg kg kg kg
Pontoon Legs Pontoon Legs housing Deck Legs Deck Legs housing
= = = =
987.66 532.29 1340.86 551.08
TOTAL WEIGHT Pontoon Components: (Wpontoon) Deck Components: (Wdeck) Total Weight of Floating Roof, (Wroof)
= = =
55,248.45 kg 57,852.21 kg 113,100.66 kg
PONTOON VOLUME O. Rim Ø
38610mm
I. Rim Ø + 2 x 2/3 w h3 = 0.03
37156 mm
3 I. Rim Ø
h1 = 0.35
34248 mm
2
h2 = 0.53
1 2
Volume 1
=
40.70 m³
Volume 2
=
120.17 m³
Volume 3
=
3.85 m³
Total Pontoon Volume, Vol(pontoon)
=
164.72 m³
9 .0 9 .1
SETTING DECK LEVEL OPERATION FLOATATION LEVEL - DECK Deck Floatation Depth Deck Thk
Density of Deck Density of Product
=
r (deck) r (product)
Floatation Depth, D(deck) =
9 .2
x Td
=
89.71 mm
=
78.93 m³
=
153.15 mm
OPERATION FLOATATION LEVEL - PONTOON = =
Buoyant Force, FB r x Vdisplacement x g
Fpontoon W (Pontoon) x g Pontoon Weight, W(pontoon) r (product)
Product Displacement, Vdisplacement =
To find Floatation Depth of Pontoon from Inner Corner of Pontoon, D(pontoon) =
Vol. Displacement above Inner corner of Pontoon Pontoon Cross Area in Vol. 2 Vdisplacement - Vbackslope (Vol.1) 1/4 x p x (Øor² - Øir²)
D(pontoon) =
Freeboard above deck, 494.56 Product Level
3 89.71
2 153.15
Deck Level
1
63.44 mm
The Deck is set at the difference of floation depth in Pontoon & Deck, D(deck) - D(pontoon) 9 .3
=
63.44 mm
NORMAL OPERATION FLOATATION LEVEL FOR ROOF - PONTOON & DECK
Actual Product
161.57 m³
Level Deck
Deck
Level
H, Floatation Height Above Deck Total Volume Displaced by the roof = Volume Displaced by the Backslope, V1 + Partial Volume Displaced in Pontoon below the deck level, Va + Volume Displaced by the Deck, Vb Total Volume Displaced by the roof, Vdisplacement (roof): Vdisplacement (roof) =
Roof Total Weight, W(roof) r (product)
=
161.57 m³
i)
Volume Displaced by the Backslope, Volume 1
ii)
Partial Volume Displaced in Pontoon below the deck level: Deck level Height, h Bulk head outer height, Bih
iii)
x
Vol. 2
40.70
=
14.98 m³
Volume Displaced by the Deck: Area of Deck Plate x Floatation Height Above Deck p /4 x Øir 2 x H
Hence, The Floatation Height Above Deck, H
94
=
=
921.21 H
=
0.11 m 114.95 mm
FLOATATION LEVEL FOR ROOF - PONTOON & DECK FOR 10" (254MM) OF ACCUMULATED RAIN WATER For deck to support 10" (254mm) of rain water: Volume of rain water collected at the deck, Vrain = Vrain = Adeck x Hrain
=
233.99
m³
where
p /4 x Øir 2 Area of deck = Rain accumulation of 10"
Adeck = Hrain =
2 = 921,213,536.64 mm = 254.00 mm
Total Volume Displaced by the roof with the 10" of rain water accumulation, V displacement (rain): W(roof) + Wt(rain) = 495.84 Vdisplacement (rain) = r (product) where W(roof) =
Total weight of roof
Wt(rain) =
Weight of 10" rain water
Floatation Height above Deck, H(rain) = Vdisplacement (rain) - Vol.1 - partial of Vol.2 (ii) Area of roof 10 0 10 1
= =
m³
0.38 m 375.95 mm
CHECKING THE STRESSES AND DEFLECTION IN THE CENTRE DECK (Ref. to Roark's Formulas For Stress And Strain, 7th Edition) CASE 1: NORMAL CASE - NO PONTOON PUNCTURED
qa Et
sa Et Where: t= a= q= = y= sb = sd = s= v= E=
4 4
2 2
= K
= K
1
y K t
3
y K t
2
4
y t
3
y t
2
( 11.11.1)
Plate thickness, Deck (mm) = Td = Outer radius of the deck plate = Øir / 2 = Unit lateral pressure (equiv. weight of deck that float on product)
( 11.11.2)
8 17124
Td x ( r(plate) - r(product) ) = 0.000561 Maximum deflection bending stress diaphragm stress sb + sd = Maximum stress due to flexure and diaphragm tension combined Poisson's ratio = 0.3 Modulus of Elasticity = 209,000
N/mm2
N/mm²
The deck plate is fixed and held at its outer edge by the pontoon, hence condition is consider as: Fixed and Held. Uniform pressure q over entire plate (Case 3 in Roark's Formulas) 5.33
K1 =
1 - n2 2.6
K2 =
1 - n2
=
5.86
=
2.86
=
2.86
=
0.976
=
4.40
=
1.73
=
56,361.13
=
56,249.31
At the Centre, 2 1- n
K3 = K4 At the edge,
4 1 - n2
K3 = K4 4
qα Et4
For
And
y t
K1
+ K2
y t
y
q α4 Et4
3
=
215.81 mm
=
Solving equation 11.11.2 σα² E. t 2
=
K3
y t = =
At Deck Center,
At Deck Edge,
+
K4 787.3494954 1377.567315
y t
2
(at Deck Center) (at Deck Edge)
σtotal σbending σdiaphgram
= = =
2 35.92 N/mm 2 3.52 N/mm 2 32.40 N/mm
σtotal σbending σdiaphgram
= = =
2 62.84 N/mm 2 5.41 N/mm 2 57.43 N/mm
It is the diaphragm stress at the edge which causes the tension at the outer edge of the Deck. Hence, the radial force on the inner rim, Rh = σ diaphgram x deck thickness =
459.44 N/mm
10 2 10 .2.1
PONTOON STRESS DESIGN - CASE 1 PONTOON PROPERTIES Nominal diameter of Inner Rim, Øir Pontoon Inside Width Inner Rim Thickness, Tir Outer Rim Thickness, Tor Top Pontoon Thk, Ttp Btm Pontoon Thk, Tbp
2 2160 525 4 900
a
= = = = = =
34248 2160 12 9 8 8
mm mm mm mm
2187 3 Top Pontoon slope angle @ 1 : 64 = Backslope angle, a = A Y (mm²) (mm) 1 6300 6 2 17282 1092 3 17494 1092 4 8100 2176.5 TOTAL 49,176 Neutral axis of combined section, C1
10 .2.2
10 .2.3
AY (mm³) 37,800 18,872,063 19,103,800 17,629,650 55,643,313
h (mm) 1,126 40 40 1,045
0.02 rad 0.16 rad
A.h² I = (bd³)/12 (mm4) (mm4) ########### 75,600 26,969,435 6,720,924,525 27,300,602 6,971,562,462 ########### 54,675 16,880,189,001 13,692,617,263 = 1132 mm
Moment of inertia of section , Ix-x Section modulus available, Za
= 30,572,806,264 mm4 = 27,019,626 mm³
MATERIAL PROPERTIES Material Properties Specified minimum yield stress, Sy Yield strength reduction factor, k ( Table M-1 ) Allowable stress reduction factor ( App. M.3.5 ), Ks ( = k.Sy/206.7 ) Allowable bending stress, Fb Allowable compressive stress, Fc
: SA 516 Gr. 65N = 275.00 N/mm² = 1.000 = 1.00 = 183.33 N/mm² = 165.00 N/mm²
PONTOON RING DESIGN The uniform radial force acting on the Inner Rim is modelled as load point at each mm of circumference, with a very small angle between load point approximtaed to uniform distributed load in the circular ring design. Rh a° Mid Point
Number of load point @ each mm, Nlp = p x Øir = 107,593.27 Angle a° = 1/2 x 360/ Nlp = 0.001673 ° Radial load on rim, Rh = 459.44 N ( Note : Rh is negative for inward force )
(Reference to Roark's Formulas For Stress and Strain, 7th Edition, Table 9.2 Case 7) At Mid-Point, Bending moment,
Circ. tensile force, Rh.Do
Mm
1
1
=
4
sin a
a
Rh.Do
1
1
At Reaction-Point, Bending moment, Mr
=-
Rh Tm
= 2.sin a
Circ. tensile force, -
4 a tan a ( Do= Qir, nonimial diamter of inner ring)
Rh Tr
= 2 tan a
10 .2.4
RESULT RING STABILITY CHECK
10 .3
MID-POINT
LOAD-POINT
Bending Moment Circumferential force Bending Stress Circumferential stress
( Nmm ) (N) ( N/mm² ) ( N/mm² )
19.14 7,867,429 0.0000007 159.98
-38.29 7,867,429 -0.000001 159.98
Allow. bending stress Allow. axial stress Unity Check Condition
( N/mm² ) ( N/mm² )
183 165 0.97 OK.
183.33 165 0.97 OK.
CASE 2:
INFLUENCE OF 10" (254mm) OF RAIN ACCUMULATED ON CENTER DECK
10" Rain
For deck to support 10" (254mm) of rain water: Volume of rain water collected at the deck, Vrain = Adeck x Hrain
=
where Adeck = Hrain =
= 921,213,536.64 mm³ = 254 mm
p /4 x Øir 2 Area of deck = Rain accumulation of 10"
Weight of 10" accumulated rain water, Wrain =
75
Vol. rain x r rain
233.99
m³
=
233,988.24 kg
Upward Bouyant Load = Deck Area x Floatation Height x Product density = p /4 x (Øir) 2 x H (rain) x r
=
242,429.27 kg
Downward load due to deck steel and rain water, = W deck + W rain
=
291,840.45 kg
=
53.64
Nett downward force acting on deck = (Upward bouyant load - Downward Load) = Deck Area
qa Et
sa Et
4 4
2 2
= K
= K
1
y K t
3
y K t
2
4
y t
3
y t
2
kg/m2
( 11.11.1)
( 11.11.2)
Where: t= a= q= y= sb = sd = s= v= E=
Plate thickness, Deck (mm) = Td = Outer radius of the deck plate = Øir / 2 = Unit lateral pressure = Maximum deflection bending stress diaphragm stress sb + sd = Maximum stress due to flexure and diaphragm tension combined Poisson's ratio = Modulus of Elasticity =
8 17124 0.000526 N/mm2
0.3 200,000 N/mm²
The deck plate is fixed and held at its outer edge by the pontoon, hence condition is consider as: Case 3 Fixed and Held. Uniform pressure q over entire plate K1 =
5.33 1 - n2
K2 =
2.6 1 - n2
=
5.86
=
2.86
=
2.86
=
0.976
=
4.40
K4
=
1.73
q α4 Et4
=
55,228.70
=
55,140.73
K 3 =
2 1 v
At the Centre, 2 1- n
K3 = K4 At the edge,
4 1 - n2
K3 =
For
And
y t
K1
+ K2
y t
y
q α4 Et4
3
= =
214.38325 mm
Solving equation 11.11.2 σα² E. t 2
=
K3
y t = =
At Deck Center,
At Deck edge,
+
K4 777.4581306 1360.154003
y t
2
(at Deck Center) (at Deck Edge)
σtotal σbending σdiaphgram
= = =
2 33.94 N/mm 2 3.34 N/mm 2 30.60 N/mm
σtotal σbending σdiaphgram
= = =
2 59.37 N/mm 3 5.14 N/mm 4 54.23 N/mm
It is the diaphragm stress at the edge which causes the tension at the outer edge of the Deck. Hence, the radial force on the inner rim, Rh = σ diaphgram x deck thickness =
433.85 N/mm
10 4 10 .4.1
10 .4.2
10 .4.3
PONTOON STRESS DESIGN - CASE 2 PONTOON PROPERTIES Nominal diameter of Inner Rim, Øir
=
Section modulus available, Za2 = Cross sectional area, Aa
= =
MATERIAL PROPERTIES Material Properties Specified minimum yield stress, Sy Yield strength reduction factor, k ( Table M-1 ) Allowable stress reduction factor ( App. M.3.5 ), Ks ( = k.Sy/206.7 ) Allowable bending stress, Fb Allowable compressive stress, Fc
: SA 516 Gr. 65N = 275.00 N/mm² = 1.000 = 1.00 = 183.33 N/mm² = 165.00 N/mm²
34248 mm 27019626.01 mm3 49,176 mm²
PONTOON RING DESIGN The uniform radial force acting on the Inner Rim is modelled as load point at each mm of circumference, with a very small angle between load point approximtaed to uniform distributed load in the circular ring design. Rh Number of load point @ each mm, Nlp = p x Øir = 107593.27 Angle a° = 1/2 x 360/ Nlp = 0.001673 ° Radial load on rim, Rh = 433.85 N/ load pt ( Note : Rh is negative for inward force )
a° Mid Point
(Reference to Roark's Formulas For Stress and Strain, 7th Edition, Table 9.2 Case 7) At Mid-Point, Bending moment,
Circ. tensile force, Rh.Do
Mm
1
1
=
Rh
-
Tm
4
sin a
a
Rh.Do
1
1
2.sin a
At Reaction-Point, Bending moment, Mr
Circ. tensile force,
=
Rh
4
10 .4.4
a
Tr tan a
= 2 tan a
RESULT RING STABILITY CHECK
10 .4.5
=
MID-POINT
LOAD-POINT
Bending Moment Circumferential force Bending Stress Circumferential stress
( Nmm ) (N) ( N/mm² ) ( N/mm² )
18.08 7,429,209 0.0000007 151.07
-36.15 7,429,209 -0.000001 151.07
Allow. bending stress Allow. axial stress Unity Check Condition
( N/mm² ) ( N/mm² )
183 165 0.92 OK.
183 165 0.92 OK.
STRESSES SUMMARY
σtotal ( N/mm² ) σbending ( N/mm² ) σdiaphgram ( N/mm² )
LOAD CASE 1 Deck Center Deck Edge 35.92 62.84
LOAD CASE 2 Deck Center Deck Edge 33.94 59.37
3.52
5.41
3.34
5.14
32.40
57.43
30.60
54.23
11 .0
ROOF SUPPORT LEG DESIGN 22 15 10 5
11 .1
11 .2
11 .3
Nos. at R4 Nos. at R3 Nos. at R2 Nos. at R1
18541.00 13716.00 8839.00 4267.00
GEOMETRIC DATA Support leg size
= 3" Sch. 80
Pipe outside diameter
= 88.9
mm
Pipe Thickness,
= 7.62
mm
Pipe Area, Aleg Radius of gyration, r =
= 1,945.76
mm2
I Aleg
Do2 - Di2 4
MATERIAL PROPERTIES Material of Construction for roof support leg Specific Minimum Yield Stress, Sy Modulus of Elasticity Density of Material, r (plate) Leg Material LOADING DATA Support leg length at i) R1 : ii) R2 : iii) R3 : iv) R4 :
= 24.89
: SA 333 Gr 6 = 241 N/mm² = 209,000 N/mm² = 7,850 kg/m³
Lsp1 Lsp2 Lsp3 Lsp4
= = = =
Deck O.D Deck Thickness, td
2927 2927 2927 2940
mm mm mm mm
= 34231 =8
Deck Area, Adeck Center deck weight, Wdeck
mm mm 2 = 920,299,220.87 mm = 57,794.79 kg
Design Live Load, Llive
= 1.2
KN/m2
Effective radius for area of deck supported by leg: 1/2(Øir/2-R3) = 15415.75 R2eff = 1/2(R3-R2) = 11277.5 R1eff= 1/2(R2-R1) = 6553
R3eff =
Area of deck supported by legs at 2 = 134,905,671.69 mm
i)
R1 = p(R1eff)2
ii)
R2 = p((R2eff) - (R1eff) )
2 = 264,648,384.82 mm
iii)
R3 = p((R3eff) - (R2eff) )
iv)
2
2
2
2
2 = 347,030,823.13 mm
2
2
2 = 173,714,341.24 mm
R4 = p((Ødeck) - (R3eff) )
11 .4
SUPPORT LEG AT INNER DECK R1 No. of legs at R1
=
Area of deck supported by legs at R1, A1
= 134,905,671.69 mm2
Deck area on each leg, A1' Deck load on one leg = Live load on one leg = Total load on one leg =
= Wdeck x
A1' Adeck
Llive x A1' Deck load + Live load
Stress on support leg at inner deck R1, P1 = 11 .4.1
Total Load / Aleg
ALLOWABLE STRESS As per AISC code, Slenderness ratio, l = K.Lsp1 / Rx-x where K Column slenderness ratio dividing elastic and inelastic buckling, 2p²E Cc = Sy When l Cc, [ 1 - l² / 2Cc² ].Sy Sc.all = (i) 5/3 + 3l /8Cc - l³/8Cc³ When Cc l 120, 12p²E Sc.all = (ii) 23 l² When 120 l 200, Smaller of (i) or (ii) Sc.all = 1.6 - l/200 In this case, the allowable stress Sc.all is Since P1
11 .5
=
<
Sc.all, the support leg at inner deck R1 is
26,981,134.34 mm2 1,694.42 kg
= = =
16.62 KN 32.38 KN 49.00 KN
=
2 25.18 N/mm
=
118
=
1
=
130.84
=
75.08 N/mm²
=
77.80 N/mm²
=
74.20 N/mm²
=
75.08 N/mm²
satisfactory.
SUPPORT LEG AT INNER DECK R2 No. of legs at R2
=
Area of deck supported by legs at R2, A2
= 264,648,384.82 mm2
Deck area on each leg, A2'
=
Deck load on one leg = Live load on one leg = Total load on one leg =
Wdeck x
A2' Adeck
Llive x A2' Deck load + Live load
Stresses on support leg at inner deck R2, P2 = 11 .5.1
5
ALLOWABLE STRESS As per AISC code, Slenderness ratio, l = K.Lsp2 / Rx-x where K Column slenderness ratio dividing elastic and inelastic buckling, 2p²E Cc = Sy
=
10 26,464,838.48 mm2 1,661.99 kg
= = =
16.30 KN 31.76 KN 48.06 KN
=
2 24.70 N/mm
=
118
=
1
=
130.84
When l Cc, [ 1 - l² / 2Cc² ].Sy Sc.all
=
5/3 + 3l /8Cc - l³/8Cc³ When Cc l 120, 12p²E Sc.all = 23 l² When 120 l 200, Smaller of (i) or (ii) Sc.all = 1.6 - l/200 In this case, the allowable stress Sc.all is Since P2 11 .6
<
=
75.08 N/mm²
(ii)
=
77.80 N/mm²
=
74.20 N/mm²
=
75.08 N/mm²
Sc.all, the support leg at inner deck R2 is
satisfactory.
SUPPORT LEG AT INNER DECK R3 No. of legs at R3
=
Area of deck supported by legs at R3, A3
= 347,030,823.13 mm2
Deck area on each leg, A3'
=
Deck load on one leg = Live load on one leg = Total load on one leg =
Wdeck x
A3' Adeck
Total Load / Aleg
ALLOWABLE STRESS As per AISC code, Slenderness ratio, l = K.Lsp3 / Rx-x where K Column slenderness ratio dividing elastic and inelastic buckling, 2p²E Cc = Sy When l Cc, [ 1 - l² / 2Cc² ].Sy Sc.all = (i) 5/3 + 3l /8Cc - l³/8Cc³ When Cc l 120, 12p²E Sc.all = (ii) 23 l² When 120 l 200, Smaller of (i) or (ii) Sc.all = 1.6 - l/200 In this case, the allowable stress Sc.all is Since P3
<
15 23,135,388.21 mm2
=
Llive x A3' Deck load + Live load
Stresses on support leg at inner deck R3, P3 = 11 .6.1
(i)
Sc.all, the support leg at inner deck R3 is
1,452.90 kg
= = =
14.25 KN 27.76 KN 42.02 KN
=
2 21.59 N/mm
=
118
=
1
=
130.84
=
75.08 N/mm²
=
77.80 N/mm²
=
74.20 N/mm²
=
75.08 N/mm²
satisfactory.
11 .7
SUPPORT LEG AT PONTOON No. of legs at R4
=
Area of deck supported by legs at R4, A4
= 173,714,341.24 mm2
Deck area on each leg, A4' Deck load on one leg =
= Wdeck x
A4' Adeck
Llive x A4' Deck load + Live load + Pontoon weight
Stresses on support leg at Pontoon, P4 = 11 .7.1
11 .8
Total Load / Aleg
ALLOWABLE STRESS As per AISC code, Slenderness ratio, l = K.Lsp4 / Rx-x where K Column slenderness ratio dividing elastic and inelastic buckling, 2p²E Cc = Sy When l Cc, [ 1 - l² / 2Cc² ].Sy Sc.all = (i) 5/3 + 3l /8Cc - l³/8Cc³ When Cc l 120, 12p²E Sc.all = (ii) 23 l² When 120 l 200, Smaller of (i) or (ii) Sc.all = 1.6 - l/200 In this case, the allowable stress Sc.all is Since P3
<
Sc.all, the support leg at inner deck R3 is
STRESSES SUMMARY
Leg at radius
No. of leg
4267.00 8839.00 13716.00 18541.00
5.00 10.00 15.00 22.00
Actual stress, (N/mm2) 25.18 24.70 21.59 31.33
6,433,864.49 mm2
=
Pontoon weight, Wpontoon Pontoon weight on one leg, Wpontoon' Live load on one leg = Total load on one leg =
27
Allowable stress, (N/mm2) 75.08 75.08 75.08 74.62
RESULT OK OK OK OK
= = = = = = =
404.05 kg 3.96 55,248.45 5,022.59 49.27 7.72 60.96
KN kg kg KN KN KN
2 31.33 N/mm
=
118
=
1
=
130.84
=
74.62 N/mm²
=
77.12 N/mm²
=
73.93 N/mm²
=
74.62 N/mm²
satisfactory.
12 .0 12 .1
12 .2 12 .2.1
12 .2.2
12 .3 12 .3.1
12 .3.2
12 .4
BLEEDER VENT CALCULATION DESIGN OF AIR VENTING SYSTEM GEOMETRIC DATA Design Code Inside diameter, Di Tank height, H Nominal Capacity Design pressure, Pi Flash point (FP)/Normal boiling point (NBP) (@ Filling rate ( Pumping in/Flow rate to tank ), Vi Emptying rate ( Pumping out/Flow rate from tank ), Vo
FP
)
OPERATING VENTING NORMAL VACUUM VENTING Maximum liquid movement out of a tank Flow rate of free air, Vv1 ( = Vo/15.9 x 15.89 ) Thermal inbreathing Tank capacity, V From Table 2, column 2 (Thermal Venting Capacity Req't ), Flow rate of free air,Vv2 (@ 0 ft³/hr )
: API STD 2000 = 39000 = 20700 24000 = 2.50 = 67 = 427 = 1,100
mm mm m³ mbarg °C m³/hr m³/hr
=
1097.23 m³/hr
=
155,535 barrels
=
0 m³/hr
Total vacuum flow required, Vv ( = Vv1 + Vv2 )
=
1,097 m³/hr
NORMAL PRESSURE VENTING Maximum liquid movement into a tank Rate of free air per 0.159m³/hr of product import rate, m Flow rate of free air, Vp1 ( = Vi/0.159 x m )
= =
0.17 m³/hr 457 m³/hr
Thermal outbreathing From Table 2, column 3 (Thermal Venting Capacity Req't), Flow rate of free air,Vp2 (@ 0 ft³/hr )
=
0 m³/hr
Total pressure flow required, Vp ( = Vp1 + Vp2 )
=
457 m³/hr
=
1,097 m³/hr
OPEN VENT SIZING ( BLEEDER VENT SIZING ) OPEN VENT SIZING CALCULATION Maximum flow, Q ( @ Vacuum flow at ( @ Q= where K= A= g= H=
2.50
mbarg. )
K. A. 2. g. H Discharge coefficient cross sectional area of vent acceleration due to gravity Head as measure pressure differential Dp H= g
0.62
=
21 m
Minimum require cross sectional area of vent, Av_req = where Q= g= r= Dp = 12 .5
Q K. 2. g. H
=
Q K
g 2. g. Dp
Max. Air flow required Specific weight of Air Air density Differential pressure
=rg
BLEEDER VENT SELECTED Selected bleeder vent size Number of vent, N Outside diameter of the vent, do Inside Dia. of one vent , di ( @ vent pipe thickness = 8.18 mm ) Total cross sectional area of vents, Av_actual Since Av_actual > Ar_gnv, therefore the nos. & size of vents is
= =
0.0241 m² 24,124 mm²
=
0.3048 mm³/s
= = =
11.812 kg/m2s2 1.204 kg/m³ 250 N/m²
: =
8" Sch Std 1 219 = 202.64 mm = 32,251 mm² satisfactory.
13 .0
ROOF DRAIN DESIGN Rigid Pipe
1275
Flexible pipe
225 Rigid Pipe 13 .1
GEOMETRIC DATA Tank Nominal Diameter Tank Height, Roof lowest height, H Drain outlet nozzle elevation, z
= = = =
39,000 20,100 1500 225
Roof Deck Area
=
920.30 m2
Design Rain Fall
=
50 mm/hr
Design drainage required, Qreq.
=
46.01 m3/ hr
No. of Roof Drain, N Roof drain pipe size (rigid & fitting) Dain Pipe Outside Diameter, Do Drain pipe thickness
= = = =
2 4" Sch 80 101.6 mm 8.56 mm
= =
40 m 23.14 m
Drain Pipe length : L1 = Rigid L2 = Flexible 13 .2
Number of Fitting & Accessories per drain pipe - 45º elbow -
13 .3
20 m x 23.14 m x
2 1
nos. nos.
N45º
=
2
90º elbow
N90º
Valve Rigid pipe Flexible pipe
Nv
= = = =
1 1 2 1
TOTAL HEAD 2 H = h+ V 2g
mm mm mm mm
13 .4
TOTAL HEAD LOSS OF ROOF DRAIN PIPE
h=
Where H = G = K =
L' = D = 13 .5
V2 x 2g
K L' D
Total head between the lowest position of deck and the roof drain nozzle Gravity acceleration Friction Coefficient - For rigid pipe : - For flexible pipe : Total equivalent length of drain pipe Inside Diameter of drain pipe
= 1.275
K1 K2
EQUIVALENT PIPE LENGTH OF VALVE AND FITTING Accordance to NFPA 15 Table 8.5.2.1, 45º elbow, L45º Equivalent length for 4" 90º elbow, L90º Valve, Lv
13 .6
m
= 0.0168 = 0.03 = 0.08448
=
3.1
= =
1.2 0.6
m
Total equivalent pipe length for RIGID PIPE: L1' = L1 + N45º x L45º + N90º x L90º + Nv x Lv
=
48 m
Total equivalent pipe length for Flexible PIPE: L2' = L2
=
23.14 m
TOTAL HEAD LOSS OF ROOF DRAIN PIPE h=
V2 x 2g
K1 L1' D
+
K2 L2' D
V2 2g
K1 L1' D
+
K2 L2' + 1 D
H=
H=
13 .7
FLOW VELOCITY 2gH V=
13 .8
K1 L1' D
+
K2 L2' + 1 D
1.15 m/s
DRAINAGE FLOW RATE PER DRAIN PIPE Q = AREA x Velocity = p/4 x D2 x V x 3600 (s/hr)
13 .9
=
MINIMUM ROOF DRAIN REQUIRED Drainage flow rate required Nreq = Actual flow rate per drain MINIMUM REQUIRED
23.30 m3 / hr
=
= =
1.97 2
Page
14
WEIGHT ANALYSIS ITEM NO :
7061T-3901
1 GENERAL Design code : API 650 11th Edition Inside diameter : 39,000 mm Steel density Shell / Btm : 7,850 kg/m³ Roof : 8,027 kg/m³ 2 SHELL COURSES ONE - FOOT METHOD (OUTER TANK) Course No. Material 1 2 3 4 5 6 7 8 9 10
Type of roof support : NA Tank height : 20,700 Roof plates lapping factor : 20.70
Type of roof : Floating Roof mm Annular/Bottom plates lapping factor : 1
Y Thickness (mm) 28.00 25.00 22.00 19.00 16.00 13.00 11.00 11.00 11.00 -
A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N -
Width (mm) 2,440 2,440 2,440 2,440 2,440 2,440 2,020 2,020 2,020 -
Weight (kg) 65,757 58,707 51,658 44,611 37,564 30,518 21,377 21,377 21,377 -
Total weight of shell plates = 3 BOTTOM PLATES Material
Y
A 516 GR. 65N 4 TOP CURB ANGLE Material A 516 GR. 65N
A 516 GR. 65N
Qty 1
Outside Dia. (mm) 39,130
Length (mm) 122,827
Unit Weight (kg/m) 10.33
Length (mm) 125,183
Unit Weight (kg/m) 87.51
Length (mm) 124,476
Unit Weight (kg/m) 53.76
Qty
T 825 x 250 x 8 x 10
1
6 INTERMEDIATE WIND GIRDERS Material Size
=
84,961 kg
Weight (kg) 1,269
=
1,269 kg
Weight (kg) 10,955
=
10,955 kg
Weight (kg) 6,691
T 405 x 150
=
6,691 kg
1,500
=
1,500 kg
22,916
=
22,916 kg
16,820
=
16,820 kg
=
24,728,026 kg
=
24,728,026 kg
= = =
498,060 kg 25,226,086 kg 25,226,086 kg
Y Qty 1
7 NOZZLES Total weight of nozzles 8 MISCELLANEOUS Assuming
Weight (kg) 84,961
Y Size
A 516 GR. 65N
Thickness (mm) 9.00
Y Size 76 x 76 x 6.4
5 TOP WIND GIRDERS Material
352,948 kg
Y
Y 5.00
% of total weight
9 STAIRWAY & PERIMETER PLATFORM Platform Weight 165.00 KN 10 OPERATING LIQUID WEIGHT Operating liquid height
Y
(@ =
20,700
mm & sg @=
(@
20,700
mm )
11 HYDROSTATIC WATER WEIGHT Hydrostatic water height ERECTION WEIGHT (Exclude roof) OPERATING WEIGHT FIELD HYDROSTATIC TEST WEIGHT
1.00 )
218308653.xlsx.ms_office
