API 650 Design Tanks

CONTENTS:-

SR. NO.

DESCRIPTION

1

DESIGN DATA

2

CALCULATIONS FOR MINIMUM SHELL THICKNESS

3

BOTTOM PLATE DESIGN

4

INTERMEDIATE WIND GIRDER

5

VERIFICATION OF UNSTIFFENED SHELL FOR EXTERNAL PRESSURE

6

DESIGN OF ROOF

7

CALCULATION OF ROOF STIFFENER

8

TANK STABILITY AGAINST UPLIFT DUE TO INTERNAL PRESSURE

9

STABILITY OF TANK AGAINST WIND LOADS 9.1

RESISTANCE TO SLIDING

10

SEISMIC CALCULATION

11

ANCHORAGE FOR UPLIFT LOAD CASES

12

ANCHOR CHAIR CALCULATION

13

WEIGHT SUMMARY

14

FOUNDATION LOADING DATA

15

EVALUATION OF EXTERNAL LOADS ON TANK SHELL OPENINGS AS PER P.3 OF API 650, ADD. 4, 2005

16

VRV AND VENTING CALCULATIONS

(PENDING)

17

DESIGN OF LIFTING TRUNNION

(PENDING)

1)

DESIGN DATA

Design Code

API STANDARD 650 TENTH EDITION, NOVEMBER 1998 ADDENDUM 4, DECEMBER 2005 APPENDICES: J, M & S "Process Equipment Design"

Flat Roof Design

By Lloyd E. Brownell & Edwin H. Young Item No.

:

TK-66202

Description

:

EJECTORS HOT WALL

Material

SA 240 TYPE 316

Density of Contents

: Dc

=

980

Specific Gravity of Contents

G

=

0.980

Material's Yield Strength @ Design Temperature

Fym

=

166.67

Design Temperature

TDSN

=

130

o

Operating Temperature

TOPR

=

80

o

Design Internal Pressure

Pi

=

ATM

C kPa

High Liquid Level

Hl

=

1.600

m

(HLL)

Design Liquid Level

HL1

=

1.900

m

(As Per PIPVESTA002)

Allowable Design Stress @ Design Temperature

Sd

=

148.33

MPa

(Table S-2)

Allowable Hydrostatic Stress @ Ambient Temperature

St

=

186.00

MPa

(Table S-2)

Bottom

=

0

mm

Shell

=

0

mm

Roof

=

0

mm

Structure

=

0

mm degree (Flat Roof)

kg/m3 MPa

(As Per Table S-5)

C 0

Corrosion Allowance

Slope of Tank Roof

q

=

0

Inside Diameter of Tank

Di

=

1.800

m

Outside Diameter of Tank

Do

=

1.812

m

Nominal Tank Diameter = Di + Bottom Shell Thickness

D

=

1.806

m

Height of Tank

H

=

1.900

m

Wc

=

0.348

kN

Weight of Top Curb Angle Weight of Roof Attachments

(Assumed)

W ra

=

10

kN

(Nozzles, Insulation, Railing/Platform)

Weight of Shell Attachments

(Assumed)

W sa

=

14

kN

(Nozzles, Insulation, Ladder & Partition Plates)

V

=

155

kph

Modulus of Elasticity @ Design Temperature

E

=

Live Load on Roof

Lr

=

Design Wind Velocity

2)

185000 MPa 1.20

kPa

(Table S-6) (PIP VESTA002, 3.2.D)

CALCULATIONS FOR MINIMUM SHELL THICKNESS

As per chapter 3, clause 3.6.1.1, the shell thickness for tanks with nominal tank diameter less than 15 m shall not be less than 5 mm. The required minimum thickness of shell plates shall be the greater of the values computed by the following formulas (As per Appendix S, clause S.3.2) Design Shell Thickness

td

=

4.9D (HL1 - 0.3)G + CA

Hydrostatic Test Thickness

tt

=

4.9D (HL1 - 0.3)

(Sd) (E) (St) (E) td = Design shell thickness, mm tt = Hydrostatic test shell thickness, mm G = Specific Gravity of Fluid to be Stored

=

0.980

D = Nominal Dia. of Tank HL1 = Design Liquid Level

= =

1.806 1.900

m m

CA = Corrosion Allowance Sd = Allowable Stress for Design Condition

= =

0 148.33

mm MPa

St = Allowable Stress for Hydrostatic condition

=

186.00

E = Weld Joint Efficiency

=

0.85

MPa (Table S-4)

Shell Course W1

=

1.900 m

HL1

=

1.900 m

Design Shell Thickness

td

=

0.110 mm

Hydrostatic Test Thickness

tt

=

0.090 mm

Shell Thickness Provided

t1

=

6.00

mm

Total Shell Weight (Uncorroded)

=

5.08

kN

Total Shell Weight (including partition plates) (Corroded)

=

5.08

kN

x =

6 780

Thk.

Weight of Top Curb Angle (Uncorroded)

=

0.35

kN

Weight of Top Curb Angle (Corroded)

=

0.35

kN

Width of course

(Including Curb Angle)

Design Height for Shell Course

az Shell Course

1.90

Shell Thickness, mm (Uncorroded)

6.00

Shell Thickness, mm (Corroded)

6.00

Shell Weight, kN (Uncorroded)

5.08

Shell Weight, kN (Corroded)

5.08

Top Curb Angle

(Formed Section) Cross-sectional Area of the Top Curb Angle

3)

1

Shell Width, m

L

65

x

65

mm2

BOTTOM PLATE DESIGN As per API 650, Appendix S, Clause S.3.1 All bottom plates shall have minimum nominal thickness of 5 mm, exclusive of any corrosion allowance. Required Bottom Plate Thickness Used Bottom Plate Thickness

tb

=

tb

=

5

mm

tb used

=

6.00

mm

5+ CA mm

*Weight of Bottom Plate (Uncorroded)

=

137.82

kg

=

1.35

kN

*Weight of Bottom Plate (Corroded)

=

137.82

kg

=

1.35

kN

*Including 50mm Projection Outside of Bottom Shell Course As per API 650, Appendix J, Clause J.3.2 All bottom plates shall have a minimum nominal thickness of 6 mm.

Required Bottom Plate Thickness Used Bottom Plate Thickness

tb

=

6

mm

tb used

=

6.00

mm

Weight of Bottom Plate (Uncorroded)

=

137.82

kg

=

1.35

kN

Weight of Bottom Plate (Corroded)

=

137.82

kg

=

1.35

kN

4)

INTERMEDIATE WIND GIRDERS Maximum Unstiffened Height As per API 650, Chapter 3, Clause 3.9.7 The maximum height of the unstiffened shell shall be calculated as follows: H1 = 9.47 t (t /D)3/2 (190/V)2 As Ordered Thickness of Top Shell Course

t

=

6.00

Nominal Tank Diameter

D

=

1.806 m

Design Wind Speed

V

=

Maximum Height of the Unstiffened Shell

H1

=

517.01 m

=

0.9585

=

495.58 m

Modification Factor as per S.3.6.7

=

Modulus Of Elasticity at Design Temp.

155

mm kph

Modulus Of Elasticity at 40oC *Maximum Height of the Unstiffened Shell (Modified As Per S.3.6.7)

H1

Transformed Shell Height As per API 650, Chapter 3, Clause 3.9.7.2 Transposed width of each shell course W tr = W x (tuniform/tactual)5/2 W = Actual Width of Each Shell Course, mm tuniform = As Ordered Thickness of top Shell Course, mm

6.00 mm

=

tactual = As Ordered Thickness of Shell Course for Which Transposed Width is Being Calculated (mm) Shell Course Thickness of Shell Course W tr1 = W 1 x (ttop/t1)5/2

Transformed Height of Tank Shell

t1

=

6.00

W tr1

=

1900 mm

Htr

=

1900 mm

=

1.90

[As Htr < H1, Intermediate Wind Girders are not required]

5)

VERIFICATION OF UNSTIFFENED SHELL FOR EXTERNAL PRESSURE Need not to be evaluated as the design external pressure is zero. As per Chapter 3, Clause 3.2.1.i, design external pressure shall not be less than 0.25 kPa. The tanks designed as per API 650 can sustain this minimum pressure.

mm

m

6)

DESIGN OF ROOF Roof Plate Thickness Verification for Structurally Stiffened Flat Roof Methodology: Consider a strip of roof plate 1 in. wide located at the outer periphery of the flat roof, and disregard the support offered by the shell. This strip is considered to be essentially a straight, flat, continuous, uniformly loaded beam, the controlling bending moment is equal to wl2 / 12 and occurs over the supporting stiffeners and wl 2 / 24 occurs at the midspan. M max = -w l 2 / 12 = -p(1) l 2 / 12 = -p l 2 / 12

Over supporting rafters

M max = -w l 2 / 24 = -p(1) l 2 / 24 = -p l 2 / 24

At midspan

where l = length of beam (strip) between stiffeners, inches, p = unit load, psi. Introducing the stress resulting from flexure, f=M/z For a rectangular beam, z = bt 2 / 6 where b = width of beam, inches, and, t = thickness of beam, inches. a = Di

For this case, b = 1.0 in. Hence, z = t2 / 6

l=b

f = p l 2 / 2t 2 l = t * SQRT ( ( 2 * f ) / p ) t = l / SQRT ( ( 2 * f ) / p ) Ref. "Process Equipment Design" By Lloyd E. Brownell & Edwin H. Young Chapter 4, Section 4.3 (Roof Design) Allowable Stresses for Roof Plate Material Assumed Roof Plate Thickness

=

6

mm

=

0.2362 in.

Allowable Design Stress @ Design Temperature

=

148.33

MPa

=

21513 psi

Loadings & Critical Combinations Dead Load

DL

=

kPa 4.40

psi 0.64

lb/in. 0.64

Live Load

Lr

=

1.20

0.17

0.17

External Pressure

Pe

=

0.00

0.00

0.00

Internal Pressure

Pi

=

0.00

0.00

0.00

Load Combination 1

p = DL + Lr + Pe

=

5.60

0.81

0.81

Load Combination 2

p = DL + Pi

=

4.40

0.64

0.64

UNIT

Check Adequacy Against Load Combination 1 ( DL + Lr + Pe ) MID

ENDS

Length of beam (strip) between stiffeners

l

=

25.67

25.67

in.

Load Combination 1

p

=

0.812

0.812

lb/in.

Induced Bending Moment

M

=

22

45

lb-in.

Thickness of the beam (strip)

t

=

0.236

0.236

in.

Section Modulus Allowable Bending Stresses

z

= =

0.009

0.009

in.3

21513

21513

psi

Allowable Bending Moment

M allow

=

200

200

lb-in.

Fb M < M allow

[Satisfactory]

(Fb = Sd)

[ Table S - 5 ]

Check Adequacy Against Load Combination 2 ( DL + Pi ) MID

ENDS 25.67

UNIT in.

0.638

lb/in. lb-in.

Length of beam (strip) between stiffeners

l

=

25.67

Load Combination 2

p

=

0.638

Induced Bending Moment

M

=

18

35

Thickness of the beam (strip)

t

=

0.236

0.236

in.

Section Modulus Allowable Bending Stresses

z

0.009

0.009

in.3

Fb

= =

21513

21513

psi

Allowable Bending Moment

M allow

=

200

200

lb-in.

M < Mallow

[Satisfactory]

Stresses in Roof Plate Segment Between the Stiffeners Ref. Table 11.4, Formulas for Flat Plates With Straight Boundaries and Constant Thickness Case no. 8. Rectangular plate, all edges fixed (Uniform loading over entire plate) Smax = ( β2 q b2 ) / t2

(At center) 1.8 0.4872

2.000 0.4974

∞ 0.500

β2

0.1386 0.1794 0.2094 0.2286 0.2406

0.2472

0.250

α

0.0138 0.0188 0.0226 0.0251 0.0267

0.0277

0.028

a/b β1

1 1.2 1.4 0.3078 0.3834 0.4356

a

=

b

=

a/b β2

= =

1.6 0.468

1.800 m 0.652 m

a = Longer Dimension b = Shorter Dimension

2.76 0.25

( See Table Above )

Check Plate Stresses Against Load Combination 1 ( D L + Lr + Pe ) (p = q = DL + Lr + Pe)

Total Design Load

=

5.60

kPa

In Shorter Direction

Smax =

17 MPa

<

148.33 MPa

[Satisfactory]

In Longer Direction

Smax =

126 MPa

<

148.33 MPa

[Satisfactory]

Check Adequacy Against Load Combination 2 ( DL + Pi ) (p = q = DL + Lr + Pe)

Total Design Load

=

4.40

kPa

In Shorter Direction

Smax =

13 MPa

<

148.33 MPa

[Satisfactory]

In Longer Direction

Smax =

99 MPa

<

148.33 MPa

[Satisfactory]

(Fb = Sd)

7)

CALCULATION FOR ROOF STIFFENER

Flange Breadth

55

mm

6

mm

94

mm

6

mm

Thk. Web Depth Thk.

Roof Plate Reference for Centroid Calculation

Built up Tee Section

Table for Centroid Calculation Plate

A

Y

AY

1

564

47

26508

2

564

97.0

54708

Σ

1128

81216

Centroid

=

72 mm

Table for Moment of Inertia Calculation b

h

Ic

A 4

Yc 2

A x Yc2

I = Ic + A x Yc2

4

mm

mm

mm

mm

mm

mm

mm4

6

94

415292

564

25.00

352500

767792

55

6

990

330

25.00

206250

207240

Moment of Inertia of Built Up Tee Section

=

4 975032 mm

Section Modulus

Zprov'd

=

3 34823 mm

Span of Stiffener

a

=

1.80 m

Self Weight of Stiffener

=

0.16 kN

Weight of Roof Plate Within Stiffined Section Weight of Roof Attachments

= =

0.55 kN 10.00 kN

Live Load on Roof

=

1.41 kN

=

6.73 kN/m

Mmax

=

2.7 kN-m

Zreq'd

=

Total Design Load Per Unit Length

W

(Approx.) (Nozzles, Insulation, Railing/Platform)

Considering simply supported end conditions for the stiffener,

27270 mm3

[As Zreq'd < Zprov'd, The stiffener design is adequate] 8)

TANK STABILITY AGAINST UPLIFT DUE TO INTERNAL PRESSURE Need not to be evaluated as the design internal pressure is zero in our case.

W x a2 / 8 Mmax / (0.6 x Fym)

9)

STABILITY OF TANK AGAINST WIND LOAD

(ASCE 7-05)

Wind velocity

V

=

155

kph

Roof Height Above Shell

HR

=

0.04

m

=

43

m/s

Shell Height

H

=

1.90

m

Height of Tank Including Roof Height

HT

=

1.94

m

Effective Wind Gust Factor

G

=

0.85

ASCE 7-05,6.5.8.1

Force Co- Efficient

Cf

=

0.80

By Interpolation (ASCE 7-05, Fig. 6-21)

Wind Directionally Factor

Kd

=

1.3

Velocity Pressure Exposure Co-Eff.

Kz

=

0.85

Topo Graphic Factor

Kzt

=

1

Importance Factor

I

=

Design Wind Pressure

qz

=

Considering 40 mm Thk. Insulation @ Roof

600-58H-0010 ASCE 7-05, Chapter 6, Table 6-3

1.15

600-58H-0010

0.613 x Kz x Kzt x Kd x V2 x I/1000 1.440 kN/m2

ASCE 7-2005, Chapter 6, Eq. 6-15, Clause 6.5.10

Effective Tank Diameter (De)

600-58H-0010

Insulation Thickness

=

40

(OD + 2 x insulation Thk.) x Kd

=

2.460

m

(OD + 2 x insulation Thk.) + 0.6

=

2.492

m

De

=

2.492

m

600-58H-0010

Effective Area Projected

Ae

=

4.83

m2

600-58H-0010

Design Wind Load

P1

=

Greater of

mm

Effective Projected Area (Ae = De x H)

=

qz x G x Cf x Ae 4.73

Unanchored tanks shall satisfy both of the following conditions: Case 1:

0.6 Mw + MPi < MDL / 1.5

Case 2:

Mw + 0.4MPi < ( MDL + MF ) / 2 Mw

=

P1 x H / 2

MPi

=

Pi x A X D / 2

MDL

=

(Weight of shell + roof + bottom) x D / 2

Mw

=

4.6 kN-m

MPi

=

0 kN-m

MDL

=

6.9 kN-m

MF

=

=

3387

ft-lbs

For no fluid in the tank

0

Case 1:

3

<

5

[Satisfactory]

Case 2:

5

<

3

[Unsatisfactory]

[Anchorage against wind pressure is required]

kN

ASCE 7-05, Chapter 6, Eq. 6-28, Clause 6.5.15

9.1)

Resistance To Sliding:

H/2 for Uniform pressure

The wind load pressure on projected area

=

API 650 3.11.4 0.86 kN/m2

=

PENTAGON PENTAGON

18.0 psf

(API 650, Chapter 3, Clause 3.2.1 (f))

This pressure is for wind velocity of 120 mph (190 kph), for all other wind velocities the pressure shall be adjusted in proportion of ratio (V/190)

2

Tank OD

Do

=

Design Wind Velocity

V

=

155

=

0.666

Wind Pressure on vertical plane surfaces

=

0.86

kN/m2

(API 650, Chapter 3, Clause 3.2.1 (f))

Wind Pressure on vertical conical surfaces

=

1.44

2

(API 650, Chapter 3, Clause 3.2.1 (f))

Projected area of roof

=

0.036 m2

Projected area of shell

=

4.73

Vf

Velocity Factor

Fwind

= =

Ffriction

= =

=

(V/190)2

1.812 m kph

kN/m m2

Vf (Wind Pressure on Roof x Projected Area of Roof + Wind Pressure on Shell x Projected Area of Shell) 2.74 kN

(API 650, Chapter 3, Clause 3.2.1 (f))

Maximum of 40% of Weight of Tank 12.27 kN

[Anchorage against sliding is not required]

(API 650, Chapter 3, Clause 3.11.4)

10)

Stability Calculations Against Seismic Load (As per API 650 Addendum Four 2005 ) D

=

1.806

m

Nominal dia of Tank

H

=

1.900

m

Maximum design product level

D/H

=

0.95

H/D

=

1.05

Site Class

=

E

Corroded thickness of bottom plate

tb

=

6.00

mm

Corroded thickness of 1st shell course

ts

=

6.00

mm

Over turning ring wall moment Mrw For Site class 'E'

=

As per API 650 E.4.9.1 Ai =

sqrt{[Ai(WiXi+WsXs+WrXr)]2 + [Ac(WcXc)]2}

As per API 650 E.6.1.5

2.5 x Q x Fa x So ( I / Rwi )

As per Equation E-4

Acceleration-based site coefficient

Fa

=

2.5

From Table E-1

Scaling Factor

Q Ss

= =

1 0.1

As per API 650 E.4.9.1

S1

=

0.04

So

=

0.4 X Ss

=

0.04

As per E.4.2.c

Rwi

=

4

From Table E-4

I

=

1.25

600-58H-0010

Ai

=

0.08

As per Equation E-4

As per Equation E-6, For seismic design categories E & F, 0.5S1(I/Rwi) Ai ≥

As per Equation E-6

≥

0.006

Condition staisfied Wi

=

Effective impulse weight of the liquid

Wi

=

(1-0.218D/H)Wp

Wp

=

Weight of content based on design specific gravity of the product

When D/H