Job No: Document No: Prepared by
Date
KML
Checked by
09-Aug-2014
MKS
Date
Approved by
11-Aug-2014
Description : Storage Tank Equipment : 0001A Client
: M/s. Kupps & Sachs / TBA
P.O Ref
:
P.O Dated : MECHANICAL DESIGN CALCULATIONS For Storage tank as per API 650
1 0 Rev
13-Aug-14 11-Aug-14 Date
For Approval For Approval Issue details
1
Issued by
REVISION TABLE PAGE
REVISION PAGE
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REVISION
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1
X
26
51
76
2
X
27
52
77
3
X
28
53
78
4
X
29
54
79
5
X
30
55
80
6
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31
56
81
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X
32
57
82
8
X
33
58
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34
59
84
10
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35
60
85
11
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36
61
86
12
X
37
62
87
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X
38
63
88
14
39
64
89
15
40
65
90
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41
66
91
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42
67
92
18
43
68
93
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44
69
94
20
45
70
95
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46
71
96
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47
72
97
23
48
73
98
24
49
74
99
25
50
75
100
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List of Applicable Drawings: SL.No
Drawing Description
Drawing No.
01
Chemical Storage tank Data Sheet
02
Detail For Tank GA
K.SI 14001-MEC-DS01001 KSI14001-MEC-DWG08001-2A
3
Rev
00 2A
INDEX
SL.No
1 2 3 4 5 6 7 8 9 10 11
Description
Cover page of calculation Revision status for design calculations List of applicable drawings Index Input Data for manual calculation Tank bottom & Shell Design Tank Roof Design Wind Load Calculations Seismic Force Calculation Shell nozzle & RF pad, Flange Lifting lug calculation
4
Page No. 1 2 3 4 5 6-7 8 9 10-11 12 13
I Input Data:
Design Code: API 650, 12 th Edition. Material of Construction
A 240 Type 316L
Nominal dia of tank
D
1.806 m
Height of shell
Hs
1.194 m
Maximum Liquid level=Height of shell
H
1.194 m
Tank bottom Slope
NA
Tank Roof type
Flat
Design Internal Pressure
Atmospheric+Liquid head
Design External Pressure
Pe (or)
0.25 kPa 0.0025 bar
Design Temp
50º C
Wind Loading
IS 875
Seismic Loading
IS 1893
Specific Gravity of Liquid
G
1.26
Spot
10 %
Joint Efficiency
E
0.85
Allowable Stress in design condition
Sd
142.20 N/mm2
Allowable Stress in Hydrotest condition
St
145.00 N/mm2
Corrosion allowance
CA
Radiography (para A.5.3 of code)
Poisson ratio
v
5
0 0.3
II Tank Bottom, Shell, Roof and Wind & Seismic Calculations Note:
a.
This tank is designed as per API Std 650, Appendix S
b.
The tank bottom has to meet the minimum thickness requirement given in para S.3.1 of design code.
c.
The Shell thickness is to be calculated per para S.3.2 of code and also the minimum thickness shall satisfy para 3.6.1.1
d.
The roof plate shall be designed for dead load plus live load of 1.2kPa Per para 3.10.2.1 & para 3.10.2.7
e.
Manual calculation as per IS 875 and seismic calculations per IS 1893.
6
II Tank Bottom (para S.3.1 of code)
Minimum required nominal thickness Provided thickness of tank bottom
tbm tb
5 6
mm mm > tbm
tb =
√ 3G*Hp*L²/ 4st
Bottom plate resting on Members. Thickness of bottom plate required Where, G = Specific gravity of stored product but not less than 1.
= 1.26
Hp = uniform loading on the bottom plate in N/mm2 due to maximum read of liquid in the tank 0.015 N/mm². L = Length of bottom plate freely supported between suggestive beam in mm = 350. St = Max. Allowable bending stress in plate in N/mm2 = 0.67*142.2=95.274 N/mm2. Tb = √ 3*1.26*0.015*400² / 4*95 = 4.27 mm. Thus the provided tank bottom thickness 6 mm is adequate. III Shell Thickness
Minimum required nom thickness (para 3.6.1.1)
t
6 mm
Shell thickness reqd for design condition (para S.3.2)
tr
0.06 mm
4.9*1.806*(1.194-0.3)/(145*0.85)
tt
0.063 mm
Provided thickness of shell
ts > > >
6 mm t td tt
(4.9*D*(H-0.3)*G/(sd*E))+CA 4.9*1.806/142.2*0.85*(1.194-0.3)*1.26 Shell thickness reqd for hydrotest condition (para S.3.2)
Permissible external pressure on shell (para 3.2.4) Thus the provided shell thickness 6 mm is adequate . 7
0.25 > Pe
kPa 0.25
IV Tank Roof thickness-(API 650 para-3.10.2.7)
OD of roof plate
Dr
1.902 m
Provided thickness of roof plate
tr
6 mm
Self weight of roof plate per unit area
48 kg/m2
Weight of roof nozzle & Manhole
~
75 kg
Nozzle & manhole weight per unit area of roof
15 kg/m2
Dead load of roof
55 kg/m2 (or) 0.0054 bar
Live load on roof(para 3.10.2.1 of code)
1.96 kPa (or) 0.0196 bar
External pressure on roof
Pe
0.0025 bar
Uniform distributed load on plate (dead load + live load) + Pe
q
0.0275 bar
Inside rad of roof plate contact ever cure angle
a
900 mm
Maximum bending moment at fixed periphery (0.1*q*a^2/8)
Mra
278.44 N.mm/mm
6*Mra/tr^2 6*204.76/6²
σb
46.40 N/mm² < sd = 142.2 N/mm²
Maximum bending stress
σb
= 46.40 < Allowable Stress sd = 142.2 N/mm²
0.1*0.02*900²/8 Maximum bending stress
Thus the provided thickness 6mm of roof is adequate.
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V Wind Load Calculation
Where, D1 - Dia of the tank in mm E - Efficiency of the welded points H - Height of the tank section in mm M - Max. Moment at the base in h1 - Lever avg. in mm ht - Distance from the base to section under consideration in mm Mt - Moment at height ht in Pw – Wind pressure in N/mm² R - Mean Radius of tank in mm S - Stress value of material or actual stress in N/mm² V - Total shear in N/mm² t - Required shell thickness in mm Given Data
Basic wind speed given Seismic zone – III
= 1812 = 0.85 = 1300 = N-mm = 650 = 3000 = N-mm = 906 = = 59.01m/s
As per IS 875 part.3
Design wind speed Vz
= Vb K1K2K3
Where, Vz – Design wind speed at any height z in m/sec
= 59.01
K1 – Probability factor (risk coefficient)
= 1.0
K2 – Terrain, height and structure size factor
= 1.05
K3 – Topography factor
= 12
Design wind pressure Pw Determine the wind moment h1=H/2 Pw*D1*H = V * h1 V = Pw*D1*H1 V 2.09*10¯³ * 1812 * 1300 M Moment at the bottom tangent line
= 0.6 Vz² = 0.6*59.01² = 2089.30 N/m² = 2.09*10¯³N/mm² = 650 mm =M =2.09*10¯³*1812*1300 = 4923.20N/m = 4923.20*650 = 3200082.6 N/mm
Mt = M-ht (V-0.5 Pw*D1*ht) = 3200082.6-3 (4923.2-0.5*2089.3*1.812*1.3) Mt = 3185313 N/mm²
Required thickness.
9
t
t
=
12M/R²ΠSE
=
12*3200082.6/906²*Π*142.2*0.85
=
0.12326 mm
=
0.1233mm < provided shell thickness is 6mm
Thus the design is safe for wind .
VI SEISMIC FORCE CALCULATION SEISMIC LOADS DESIGN GEOMETRIC DATA
Seismic Zone factor,Z Importance factor, I Nominal diameter of tank, Dc Total height of tank shell,Ht Ht.from bot.shell to COG of tank, Xs Maximum design liquid level, H
= 0.15 = 1.5 = 1800 mm = 1200 mm = 900 mm = 1200 mm
Total weight of tank shell, Ws Total weight of tank roof, Wr Total weight of tank contents, Wt
= 3335 N = 1766 N = 29430 N
OVERTURNING MOMENT & EFFECTIVE MASS OF TANK CONTENTS
Ratio of Dc/H From figure E-2, W1/Wt W2/Wt Wt. of the eff.mass of tank contents that move in unison with the tank shell, W1 =Wt x (W1/Wt) Wt. of the eff.mass of tank contents that move in the first sloshing mode, W2 =Wt x (W2/Wt) From figure E-3, X1/H X2/H Ht. from shell bottom to centroid of lateral seismic force applied to W1, X1 =H x (X1/H) Ht. from shell bottom to centroid of lateral seismic force applied to W2 X2 =H x (X2/H) LATERAL FORCE COEFFICENTS
Lateral force coefficient, C1 Natural period of the first sloshing mode, T (=k.{Dc/304.8}½) Where k = factor obtained from figure E-4 When T<4.5, 10
= 1.5 = 0.93 = 0.13 = 27370 N = 3830 N = 0.38 = 0.78 = 460 mm = 936 mm = 0.6 = 1.4 sec = 0.58
Lateral force Coefficient, C2 = 0.75.S/T
= 0.804
When T>4.5, Lateral force Coefficient, C2 = 3.375.S/T²
= 2.583
Where S = Site Coefficient (Table E-3)
= 1.5
Therefore, C2
= 0.804
OVERTURNING MOMENT
Overturning moment, M =ZI(C1.Ws.Xs+C1.Wr.Ht+C1.W1.X1+C2.W2.X2) = 3044336.4 Nmm
RESISTANCE TO OVERTURNING THICKNESS OF THE BOTTOM PLATE UNDER THE SHELL & ITS RADIAL WIDTH
Bottom/Annular plate thickness, tb = 6 mm Thickness of bottom shell course, tbs = 6 mm Bottom/Annular plate radial width, wba = 6 mm Since tb > greater of ( tbs, 6mm), therefore it is minimum radial width shall be met. SHELL COMPRESSION
Wt. of tank and portion of the fixed roof supported by the shell, wt = 0.00117 N/mm
ANCHORED TANKS Maximum longitudinal shell compression, b
= wt+1.273.M/Dc²
Since b/12tbs
= 1.188 N
< Fa, therefore the tank is structurally stable.
MAXIMUM ALLOWABLE SHELL COMPRESSION A
= GHDc²/tbs²
Dc in m
= 0.22 m³/mm²
a) For GHDc²/ (tbs²) < 44m³/mm², Fa = 83.tbs/2.5Dc+7.5{G.H}½
= 93.53 N/mm²
b) For GHDc²/(tbs²) > 44m³/mm², Fa = 83.tbs/Dc
= 0.23055 N/mm²
Therefore, Fa (< 0.5Fty)
= 93.53 N/mm²
Where Fty = Min.Specified yield strength of the bottom shell course 11
= 205.00 N/mm²
VII Shell Nozzle (Para S.3.3.1)
Required thickness of 2’’ NPS nozzle
Sch.80S
Provided thickness
Sch.80S
VIII Roof Nozzles
Required thickness of 2’’NPS nozzles
Standard Weight
Provided thickness
Sch.80S
IX Reinforcement pad for nozzles
Pad is not required for 2’’NPS nozzles on shell or roof. Only stiffeners should be provided as 2 nozzles @ 90 apart. X Roof manhole
500 square manhole with hinged cover is provided as specified by client The details will be in accordance with fig 3-15 of code. XI Shell Nozzle Flanges (Table 3.8 & Foot note and Fig.3-7)
Weld-neck flanges are permitted as per data sheet. But the facing dimensions shall be as per ASME B16.5, Class 150. Provided Flange type and rating
WNRF to ASME B16.5, Class 150
12
XII Lifting Lug Calculations
Considered LL Position in Top plate
= 2 Nos = 2 Nos
Moc of LL Allowable shear stress Diameter of LL Load on LL (p) Outer Radius of LL plate Required LL thickness
= IS 2062 Gr. A = 96 N/mm² = 40mm = 38400 N = 80mm = P/2s(R-D1/2)
R t
t= 38400/2*96(80-40/2)
= 3.3 mm
Proposed to provide 16mm thickness IS 2062 Gr.A material. Fillet Weld size Calculations.
W = P/Aw Where, W – Load on fillet weld in N. Aw – Length of weld in mm P – Allowable concentrated axial load in N w – Fillet weld leg dimension in mm f - Allowable load on fillet weld
= 332 mm = 38400 = 42700 N
W = 38400/332
= 115.66 N per lin in mm
w = w/f = 115.66/42700
= 2.71*10¯³ = 0.0027 mm.
Proposed to use 8 mm fillet weld for lifting lug with pad plate.
13
