DESCRIPTION PAGE 1 DESIGN DATA 3 2 CALCULATIONS FOR MINIMUM SHELL THICKNESS 4 3 BOTTOM PLATE DESIGN 5 4 INTERMEDIATE WIND GIRDER 4.1 AS PER API 650 SEC. 3.9.7 6 5 SUPPORTED CONICAL ROOF 5.1 DESIGN OF ROOF PLATE 7 5.2 DESIGN OF ROOF PLATE WITH STIFFENING 7 5.3 DESIGN OF COMPRESSION RING 8 5.4 DESIGN OF ROOF RAFTERS 10 6 COMPRESSION AREA AT ROOF TO SHELL JOINT 6.1 DESIGN OF COMPRESSION AREA AS PER API 650 App. F 11 7 STABILITY OF TANK AGAINST WIND LOADS 7.1)RESISTANCE TO SLIDING 13 8 FOUNDATION LOADING DATA 14 9 VENTING CALCULATIONS 16 10 NOZZLE FLEXIBILITY ANALYSIS AS PER APPENDIX P 19 11 SHELL TO ROOF RAFTER JOINT STRESS ANALYSIS 20 CONTENTS :- Sr.No .
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DESCRIPTION PAGE
1 DESIGN DATA 32 CALCULATIONS FOR MINIMUM SHELL THICKNESS 4
3 BOTTOM PLATE DESIGN 54 INTERMEDIATE WIND GIRDER
4.1 AS PER API 650 SEC. 3.9.7 65 SUPPORTED CONICAL ROOF
5.1 DESIGN OF ROOF PLATE 75.2 DESIGN OF ROOF PLATE WITH STIFFENING 75.3 DESIGN OF COMPRESSION RING 85.4 DESIGN OF ROOF RAFTERS 10
6 COMPRESSION AREA AT ROOF TO SHELL JOINT
6.1 DESIGN OF COMPRESSION AREA AS PER API 650 App. F 117 STABILITY OF TANK AGAINST WIND LOADS
7.1)RESISTANCE TO SLIDING 138 FOUNDATION LOADING DATA 149 VENTING CALCULATIONS 1610 NOZZLE FLEXIBILITY ANALYSIS AS PER APPENDIX P 1911 SHELL TO ROOF RAFTER JOINT STRESS ANALYSIS 20
CONTENTS:-
Sr.No.
Design Code : API 650, 10th Edition, Add.4 2005, Appendix F
Client's Specs. : 32-SAMSS-005, BD-407062 Rev.00C
Fluid : FIRE / UTILITY / WASH WATER TANK
Material : SA-516 Gr 70.
Density of contents = 1004.9
Specific gravity of contents G = 1.0049
Material's yield strength = 260 MPa API 650 Table-3.2
Design Temperature T = 71
Internal Pressure Pi = 0.747 Kpa = 3.0 inch of water
External Pressure Pe = 0.245 Kpa = 1.0 inch of water
High Liquid Level = 8.560 m
Design Liquid Level = 9.000 m
Allowable Design Stress at Design Temp. = 173.00 MPa API 650 Table-3.2
Allowable Test Stress for Hydrostatic Test Condition St = 195.00 MPa API 650 Table-3.2
Total weight of corroded shell + Shell attachments, = 120.78 KN
2) CALCULATIONS FOR MIN. SHELL THICKNESS
Design Shell Thickness td = 4.9D (H
L1 - 0.3)G + CA
Sd
Hydrostatic Test Thickness tt = 4.9D (H
L1 - 0.3)
St
HL = Design liquid level for course under consideration
W1
HL1
td
tt
t1
W2
HL2
td
tt
t2
W3
HL3
td
tt
t3
W4
HL4
td
tt
t4
W'ST
As per API 650 Sec. 3.4.1
All bottom plates shall have minimum nominal thickness of 6mm, exclusive of any corrosion allowance.
Required Bottom Plate Thickness = 6+ CA mm
= 9.20 mm
Used bottom plate thickness = 10.00 mm
Weight of bottom Plate = 11430.3 kg = 112.13 KN
Weight of bottom Plate ( Corroded ) = 7772.6 kg = 76.25 KN
(API 650 Sec. 3.5)
Hydrostatic test stress for first shell course == 119.97 M Pa < 172 M Pa OK
If hydrostatic test stress for first course is less than 172 Mpa, lap welded bottom plates may be used in lieu of butt-welded annular bottom plates.
Thickness of annular bottom plate = 10.00 mm
Max. design liquid level = 9.08 m
Width of annular bottom plate =
(between shell ID & lap of bottom plate with annular plate)
Required width of annular bottom plate = 711.91 mm
Width of annular bottom plate provided = 800.0 mm
3) BOTTOM PLATE DESIGN
tb
tb
3.1) ANNULAR PLATE DESIGN
Sh
(4.9D (H1 - 0.3)/t
sc)
tb
HL1
Wap
215 x tb / (H
L1 x G)1/2
Wap
Wact
The maximum height of the unstiffened shell = API 650 Sec.3.9.7.1
Where,
t = As ordered thickness of top shell course = 6.00 mm
t = As Per Article 3.9.7.1 of 32-SAMSS-005 = 2.80 mm
D = Nominal tank diameter = 13.508 m
V = Design wind speed = 154.00 Km/hr
The maximum height of the unstiffened shell = 3.81 m
Transposed width of each shell course = API 650 Sec.3.9.7.2
Where,
W = Actual width of each shell course (mm)
= 6.00 mm
1st Shell Course
As ordered thickness of 1st shell course = 8.00 mm
Actual width of 1st shell course = 2500 mm
Transposed width of 1st shell course = 1218 mm
2nd Shell Course
As ordered thickness of 2nd shell course = 8.00 mm
Actual width of 2nd shell course = 2500 mm
Transposed width of 2nd shell course = 1218 mm
3rd Shell Course
As ordered thickness of 3rd shell course = 6.00 mm
Actual width of 3rd shell course = 1880 mm
Transposed width of 3rd shell course = 1880 mm
4th Shell Course
As ordered thickness of 4th shell course = 6.00 mm
Actual width of 4th shell course = 2120 mm
Transposed width of 4th shell course = 2120 mm
Height of transformed Shell =
= 6436 mm = 6.436 m
As Htr > H1 Intermediate Wind Girder is Required
Intermediate Wind Girder
The required minimum section modulus of an intermediate wind girder shall be calculated as follows.
API 650 Sec.3.9.7.6
17
angle of the shell = 3.218 m
D = Nominal Tank diameter = 13.508 m
22.69
From Table 3-20 we provide one angle of 102*76*6 as intermediate wind girder as per fig. 3-20 detail c
Section modulus provided = 50.2
4) INTERMEDIATE WIND GIRDER 4.1) As per API 650 Sec. 3.9.7
H1 9.47 t (t / D)3/2 x (190/V)2
H1
Height of transformed Shell
Wtr
W x (tuniform
/tactual
)5/2
tuniform
= As ordered thickness of top shell course
tactual
= As ordered thickness of shell course for which transposed width is being calculated (mm)
t1
W1
Wtr1
t2
W2
Wtr2
t3
W3
Wtr3
t4
W4
Wtr4
Htr
Wtr1
+ Wtr2
+ Wtr3
+ Wtr4
Zreq
. = D 2 H 1 x (V/190)2
Where: Z = Required minimum section modulus of intermediate wind girder. (cm3)
H1 = Vertical distance (m) between the intermediate wind girder and the top
Zreq
. = cm3
Zpro
.= cm3
(Including shell participating width & corroded thickness of 2.8mm)
As Apov.>Areq. The Intermediate Wind Girder Is Ok
5.1) Supported Conical Roof
Minimum roof plate thickness=
D x √Tr/2.2 API 650 Sec.3.10.5.1
Where, Tr = Greater of load combinations (e)(1) and (e)(2) as per App. R
Combination i, API 650 App. R (e)(1)
Combination ii, API 650 App. R (e)(2)
Where, Dead Load of the roof, = 0.981 kPa
Live Load on the roof, Lr = 1.200 kPa
External Pressure, Pe = 0.245 kPa
Snow Load, S = 0.000 kPa
= 2.279 kPa
= 1.706 kPa
Tr = 2.279 kPa API 650 Sec. 3.10.5
= 17.43 mm ≥ 5 mm
= 20.63 mm
As per API Sec. 3.10.5.1 the Maximum thickness for self supported roof is 12.5mm (excluding corrosion allowance)
but due to high value of calculated roof thickness, it is proposed to provide supported roof.
Used thickness = 10.00 mm
= 10.00 mm (Including Corrosion Allowance)
Roof developed radius = 6.85 m
Roof developed Area = 147.5Weight of Roof = 114.72 KN
Weight of Roof (corroded) = 77.22 KN
Roof is designed as a supported cone roof. The system of rafters is provided to support the roof plate. The rafters are
supported at tank shell and load is transferred to tank periphery.
Maximum Spacing of Rafters at Outer Ring = 0.6 * π
= 1.88 m API 650 3.10.4.4
Maximum No. of Rafters Required N = π x D/0.6 X π
= 22.51
( Brownell & Young - 4.3b)
Roof plate shall be designed as continuous beam with uniform load comprising of roof live load and self weight of roof plate.The maximum unsupported span of roof plate is equal to the spacing of stiffeners at tank outer dia.
24.00Roof Plate Span l = 1.77 m = 69.7 inch (Maximum spacing of Rafters at tank outer dia)
Roof plate thickness tr = 6.80 mm = 0.27 inch (corroded plate thickness)
Assumed Plate width b = 1 inch
Design Live Load Lr = 1.20 6.85 ###
= 0.78
Design load for roof plate shall be comprising of roof live load and the total dead load acting on the roof.
= 1.98 = 0.29 psiAssuming width of roof plate 1 inch and calculating the bending moment for strip if roof plate 1 inch wide.
Roof Plate Span l = 69.7 inch= 0.29 lbs/inch
Bending Moment At Mid Span Mc = = 58.035 lbs inch
24
Bending Moment At Supports Ms = = 116.07 lbs inch
12
Section modulus of Plate Zp = = 0.012
Allowable Bending Stress 0.6 x Fy = 22625.88 psi ( As per API 650)
Used Curb Angle As per Fig. F2 Detail d = 120 x 120 x 10 API 650 Sec. 3.1.5.9
Curb Angle Area = 1218 (Corroded Area)Length of normal to roof from tank C.L. =
= 41,069 mm
Inside radius of tank, = 6,750 mm
Max. width of participating roof = Ref: API 650 Fig F-2
Thickness of roof plate (corroded) = 6.80 mm
= 158.54 mm
Max. width of participating shell =
Thickness of shell plate (corroded) = 2.80 mm
= 82.49 mm
Participating area of roof (corroded) =
1078
Participating area of shell (corroded) =
= 231
Total Area Provided =
= 2296
= API 650 App.F.5.1
= 295.30
Since, 2296 > 295Aprov. >Amin, Therefore used Curb Angle is satisfactory
Uplift on Tank as per F.1.2
Corroded Roof Thickness = 6.80 mm
D = 13.508 m
Area of tank =
= 143
Internal design pressure of tank = 0.747 kPa
Total upward lifting force acting on roof =
= 107 kN
Weight of roof (corroded) = 77.22 kN
107 > 77.22
Weight of shell, roof and attached framing = 224.75 kN
107 < 224.75
F.2 through F.5 are applicable
Internal design pressure is, P = API 650 F.4
= 2.85 kPa
Weight of shell and attached framing = 120.78 kN
Max. design pressure, limited by uplift at base of shell is; API 650 F.4.0
=
= 0.841 kPa
But, internal design pressure of tank is = 0.747 kPa
0.747 <= 0.841
Condition Satisified - Anchorage is not RequiredMin. Required Compression Area is Greater of the following As Per F.5.1
=
= 295.30
=
= 973.7Since, 1218 > 973.7
6) Compression Ring at Shell to Roof Joint
Ac mm2
R2 R
c / sin θ
R2
Rc
wh 0.3 x √ (R
2 x t
h)
th
wh
wc 0.6 x √ (R
c x t
s)
tc
wc
Ah
wh x t
h
mm2
As
wc x t
c
mm2
Aprov.
Ah + A
c
Aprov. mm2
Minimum required participating area, Amin. D2 (P
i-0.08t
h) / (1.1xTanθ)
Amin mm2
6.1) Tank Design As Per Appendix F
tR
Nominal dia. of tank (Di + Shell thick)
At π x R2
m2
Pi
FR
Pi x A
t
WR
D'L
(1.1 x A x tanθ) / D2 + 0.08 x tR
W'ST
= DLS
Pmax
0.00127 x DLS
/ D2 + 0.08 x tR - 0.00425 x M
w / D3
Pi
Amin.1 D2 x (P
i-0.08t
h)/1.1(tan θ)
mm2
Amin.2 D2 x [0.4P
i-0.08t
h+0.72(V/120)2]/1.1(tan θ)
mm2
Used Curb Angle is satisfactory
7)Stability of Tank Against Wind Load ( Ref: ASCE-7)
Wind velocity V = 154.0 Km/hr = 42.78 m/s
height of tank including roof height = 10.125 m = 33.21 ft.
effective wind gust factor G = 0.85
force coefficient Cf = 0.50
wind directionally factor Kd = 0.95
Velocity Pressure Exposure Co-Eff. Kz = 0.95
Topo Graphic Factor Kzt = 1.0
Importance Factor I = 1.15
Design Wind Pressure qz =
1.164
Design Wind Load = qz x Do x G x Cf x Ht67.711 KN
=2
342.78 KN-m = 252746.5 ft-lbs
Resisting Moment Resisting Moment =
3 2
Ws' = total weight of tank shell + Curb Angle = = 120.785 KN Wr' = total weight of tank roof = 101.203 KN (Including Rafters)
Mr = 517.567 KN-m
As Mr > Mw Anchorage is Not Required
7.1)Resistance To Sliding ( Ref: API 650 3.11.4)
The wind load\ pressure on projected area of cylindrical surfaces = 0.86 18.0 psf
This pressure is for wind velocity of 100 mph (160 Km/hr) For all other wind velocities
= 13.516 m Design Wind Velocity V = 154 Km/hr
= 0.926 (Vf=Velocity Factor)
= 0.86
Wind Pressure on vertical conical surfaces = 0.72
Projected area of roof = 7.601
Projected area of shell = 121.64
= Vf(Wind Pressure on Roof X Projected Area of Roof + Wind Pressure on Shell X Projected Area of Shell)= 101.985 KN
= Maximum of 40% of Weight of Tank
= 109.702 KN
Ffriction>Fwind No Anchorage Is Required To Resist Sliding
Ht
0.613 x Kz x Kzt x Kd x V2 x I/1000
KN/m2
P1
Overturning Wind Moment Mw P
1 x H
t
Mr = 2 D (Ws' + Wr'-Uplift due to Design Pressure )
KN/m2 =
the pressure shall be adjusted in proportion of ratio (V/160)2
O.D of tank = D0
(Ve/160)2
Wind Pressure on vertical plane surfaces KN/m2
KN/m2
m2
m2
Fwind
Ffriction
The self weight of roof and live load will be transferred to tank shell
Live load transferred to foundation
1.2
Area of Roof, Ar = 147.46
176.95 KNCircumference of Tank C = 42.5 m
4.2 KN/m
Dead load transferred to foundation
Self Weight of Roof Wr = 153.41 KN (Including Rafter & Compression Ring)Self Weight of Shell Ws = 206.80 KNSelf Weight of shell Attachments Wa = 15.00 KN (Including Curb Angle & Inter. Wind Girder)
Total Dead Load acting on shell WD = 375.20 KN (Including Platform Weight)Dead Load Transferred to Foundation Wd = WD / C 8.84 KN/m
Operating & Hydrostatic Test Loads
Self Weight of Tank = 487.34 KN Uniform Load Operating Condition = Self wt.+ fluid =Weight of Fluid in Tank at Operating Conditions = Wf = 12715 KN Uniform Load Hydrotest Condition = Self wt.+ water=Weight of Water in Tank at Hydrotest Conditions = Ww = 12638 KN