design calculation r1.pdf

8/19/2019 Design Calculation R1.pdf

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Job No:

Document No:

Prepared by Date Checked by Date Approved byKML 09-Aug-2014 MKS 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 13-Aug-14 For Approval0 11-Aug-14 For Approval

Rev Date Issue details Issued by

1



REVISION TABLE

PAGE REVISION PAGE REVISION PAGE REVISION PAGE REVISION

0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 0 1 2 3 4

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

X 31

56

81

7

X 32 57 82

8

X 33 58 83

9

X 34 59 84

10

X 35 60 85

11

X 36 61 86

12

X 37 62 87

13

X 38 63 88

14 39 64 89

15 40 65 90

16 41 66 91

17 42 67 92

18 43 68 93

19 44 69 94

20 45 70 95

21 46 71 96

22 47 72 97

23

48

73

98

24 49 74 99

25 50 75 100

2



List of Applicable Drawings:

SL.No Drawing Description Drawing No. Rev

01Chemical Storage tank

Data SheetK.SI 14001-MEC-DS-01001

00

02 Detail For Tank GAKSI14001-MEC-DWG-08001-2A

2A

3



INDEX

SL.No Description Page No.

1 Cover page of calculation 1

2 Revision status for design calculations 2

3 List of applicable drawings 3

4 Index 45 Input Data for manual calculation 5

6 Tank bottom & Shell Design 6-7

7 Tank Roof Design 8

8 Wind Load Calculations 9

9 Seismic Force Calculation 10-11

10 Shell nozzle & RF pad, Flange 12

11 Lifting lug calculation 13

4



I Input Data:

Design Code: API 650, 12th 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 0.25 kPa(or) 0.0025 bar

Design Temp 50º C

Wind Loading IS 875

Seismic Loading IS 1893

Specific Gravity of Liquid G 1.26

Radiography (para A.5.3 of code) 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 0

Poisson ratio v 0.3

5



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 requirementgiven in para S.3.1 of design code.

c. The Shell thickness is to be calculated per para S.3.2 of code and alsothe minimum thickness shall satisfy para 3.6.1.1

d. The roof plate shall be designed for dead load plus live load of 1.2kPaPer 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 tbm 5 mmProvided thickness of tank bottom tb 6 mm

> tbm

Bottom plate resting on Members.

Thickness of bottom plate required tb = √ 3G*Hp*L²/ 4st

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 tank0.015 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*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)

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

Permissible external pressure on shell (para 3.2.4) 0.25 kPa

> Pe 0.25Thus the provided shell thickness 6 mm is adequate.

7



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

0.1*0.02*900²/8

Maximum bending stress

6*Mra/tr^2 σb 46.40 N/mm²6*204.76/6² < sd = 142.2 N/mm²

Maximum bending stress σb = 46.40 < AllowableStress sd = 142.2 N/mm²

Thus the provided thickness 6mm of roof is adequate.

8



V Wind Load Calculation

Where,

D1 - Dia of the tank in mm = 1812E - Efficiency of the welded points = 0.85

H - Height of the tank section in mm = 1300M - Max. Moment at the base in = N-mmh1 - Lever avg. in mm = 650ht - Distance from the base to section under consideration in mm = 3000Mt - Moment at height ht in = N-mmPw – Wind pressure in N/mm²R - Mean Radius of tank in mm = 906S - Stress value of material or actual stress in N/mm²V - Total shear in N/mm²t - Required shell thickness in mm =

Given DataBasic wind speed given = 59.01m/sSeismic zone – III

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 = 0.6 Vz²= 0.6*59.01²= 2089.30 N/m²

Determine the wind moment = 2.09*10¯³N/mm²h1=H/2 = 650 mmPw*D1*H = V * h1 = MV = Pw*D1*H1 =2.09*10¯³*1812*1300

V = 4923.20N/m2.09*10¯³ * 1812 * 1300 = 4923.20*650

M = 3200082.6 N/mm

Moment at the bottom tangent line 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 = 12M/R²ΠSE

= 12*3200082.6/906²*Π*142.2*0.85

= 0.12326 mm

t = 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 = 0.15Importance factor, I = 1.5 Nominal diameter of tank, Dc = 1800 mmTotal height of tank shell,Ht = 1200 mm

Ht.from bot.shell to COG of tank, Xs = 900 mmMaximum design liquid level, H = 1200 mm

Total weight of tank shell, Ws = 3335 NTotal weight of tank roof, Wr = 1766 NTotal weight of tank contents, Wt = 29430 N

OVERTURNING MOMENT &

EFFECTIVE MASS OF TANK CONTENTS

Ratio of Dc/H = 1.5From figure E-2,

W1/Wt = 0.93W2/Wt = 0.13Wt. of the eff.mass of tank contents that move in unison with the tank shell,W1 =Wt x (W1/Wt) = 27370 NWt. of the eff.mass of tank contents that move in the first sloshing mode,W2 =Wt x (W2/Wt) = 3830 N

From figure E-3,X1/H = 0.38X2/H = 0.78Ht. from shell bottom to centroid of lateral seismic force applied to W1,X1 =H x (X1/H) = 460 mmHt. from shell bottom to centroid of lateral seismic force applied to W2

X2 =H x (X2/H) = 936 mmLATERAL FORCE COEFFICENTS

Lateral force coefficient, C1 = 0.6 Natural period of the first sloshing mode, T (=k.{Dc/304.8}½) = 1.4 sec

Wherek = factor obtained from figure E-4 = 0.58

When T<4.5,10



Lateral force Coefficient,C2 = 0.75.S/T = 0.804

When T>4.5,Lateral force Coefficient, = 2.583

C2 = 3.375.S/T²

WhereS = 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 mmThickness of bottom shell course, tbs = 6 mmBottom/Annular plate radial width, wba = 6 mmSince 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 TANKSMaximum longitudinal shell compression,

b = wt+1.273.M/Dc² = 1.188 N

Since b/12tbs < 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

WhereFty = Min.Specified yield strength of the bottom shell course = 205.00 N/mm²

11



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 = 2 NosPosition in Top plate = 2 Nos

Moc of LL = IS 2062 Gr. AAllowable shear stress = 96 N/mm²Diameter of LL = 40mmLoad on LL (p) = 38400 NOuter Radius of LL plate R = 80mmRequired LL thickness t = P/2s(R-D1/2)

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/AwWhere,

W – Load on fillet weld in N.Aw – Length of weld in mm = 332 mmP – Allowable concentrated axial load in N = 38400w – Fillet weld leg dimension in mmf - Allowable load on fillet weld = 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

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