Tank Calc - Api650 [PDF]

Zitiervorschau

STORAGE TANK DESIGN CALCULATION - API 650 1 .0

1 .1

1 .2

1 .3

1 .4

DESIGN CODE & SPECIFICATION DESIGN CODE

:

TANK Item number Roof ( Open/Close ) Type of roof ( Cone-roof / Dome-roof / Flat-roof / NA )

: : :

GEOMETRIC DATA Inside diameter , Di ( corroded ) (@ 39,000 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

mm )

PRESSURE & TEMPERATURE Design pressure : Upper , Pu : Lower , Pl Design temperature : Upper , Tu : Lower , Tl

= = = = = = = =

(Atmospheric) = = = =

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)

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

A 516 GR. 65N A 516 GR. 65N A 516 GR. 65N

448.00 448.00 448.00

241.00 241.00 241.00

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

MATERIAL & MECHANICAL PROPERTIES No

Material used

Specified min. tensile stress St (N/mm²)

Specified min. yield stress Sy (Nmm²)

Yield stress reduction fac ( App. M ) k

Max. allow design stress Sd (N/mm²)

Max. allow hydro.test stress St (N/mm²)

1 2 3 4 5 6 7 8 9 10

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 -

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 -

180.75 180.75 180.75 180.75 180.75 180.75 180.75 180.75 180.75 -

2 .3

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

: = =

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 =

tsc =

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)

t.hydro. (mm)

t.min (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

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

2 .6

MAXIMUM ALLOWABLE STRESS No.

Height (mm)

t.min (mm)

tsc. (mm)

H' (mm)

H' max (mm)

∆H (mm)

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

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.

3 .0

BOTTOM & ANNULAR PLATE DESIGN BOTTOM PLATE & ANNULAR PLATE DESIGN Annular plate used ? ( yes/no ) BOTTOM PLATE (i) Minimum thickness as per Minimum thickness required Therefore, use thickness of

(@

:

API 650 Clause 5.4.1 3.00 mm c.a ) 9.00 mm (tb) is

= = satisfactory.

(ii) (iii) Min. width of overlapping (cl. 5.1.3.5) (iv) Min. width of plate (cl. 5.4.1) (v) -

= = = =

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 Annular plate thickness ( As per Table 5-1a ) Minimum thickness required (@ Therefore , use thickness of

3.00 16.00

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)

= =

= = = = = 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

>

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

=

Section modulus, Za

=

Since Za 4 .1.2

600mm from top of tank, top curb angle is

=

>

Zmin , therefore the angle size selected is

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

: = = = = =

D=

39037

mm

X 2

C1

8 250mm

3

1 X 825 mm

L1=16.tsc.cor

A Y AY h (mm²) (mm) (mm³) (mm) 1 2048 4.00 8192 433.61141012 2 6600 420.5 2775300 17.111410118 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 1932482.351 400,777,557 787,772,655 = = = 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

Since H1 < wind girder is/are Minimum number of intermediate wind girders required, = Location of intermediate wind girders from top of tank, L1 = L2 = L3 = L4 = L5 =

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

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

: = = = = =

D=

39037

mm

X 2

C1

8 150mm

3

1 X 450 mm

L1=16.tsc.cor

A Y AY h (mm²) (mm) (mm³) (mm) 1 2048 4.00 8192 200.64252336 2 3600 233 838800 28.357476636 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) 82447200.63 2894927.332 79,479,445 164,821,573 = = = 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

= = = = = = =

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

WIND FORCE CALCULATION As per API 650 clause 5.2.1(j), the wind pressure are as follows:Wind pressure on conical surfaces, wr (@ Wind pressure on cylindrical surfaces, ws (@ Wind correction factor, kw (= V /190)²

550,045

kg )

327,512

kg )

30.00 18.00

psf ) psf )

= = =

= = =

Projected area of roof, Ar ( = 0.5.k.Do.Hr ) Projected area of shell, As ( = k.Do.Hs )

= =

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 )

= = =

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: 0.6 Mw + Mpi < MDL / 1.5 Criteria 1: Mw + 0.4 Mpi < (MDL +MF) / 2 Criteria 2: where: Mpi = =

Moment about the shell-to-bottom joint from design internal pressure Uplift thrust on roof due to internal pressure x 1/2 tank diameter

= Mw = = MDL = =

D2. Pi ). 1/2. D

=

Overturning moment about the shell-to-bottom joint from horizontal plus vertical wind pressure 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 MF =

Moment about the shell-to-bottom joint from liquid weight (wa) (wa.  D). D 1000 2

=

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

= =

= =

<
TL Ac =

2.5 K Q Fa So

Ts .TL Tc2

I Rwc

where Q = K = Fa = Fv = So = Rwi = Rwc = TL = Tc = Ts =

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

= = = = = = = = = =

7 .1.3

CONVECTIVE (SLOSHING ) PERIOD The first mode sloshing wave period, Tc = 1.8 Ks √ D where, Ks =

=

sloshing period coefficient 0.578

Ks =

3.68 H D

tanh

=

Fv . S1 Fa . Ss

Ts = where, Fa = Fv = S1 =

=

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

Ss =

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, Wi =

tanh (0.866.D/H) 0.866. D/H

. Wp

=

D H

. Wp

=

For D/H < 1.333, Wi = Since

1.0 - 0.218

D/H > 1.333 , effective impulsive portion of the liquid weight, Wi

=

Effective convective weight, Wc =

0.230

D H

tanh

3.67H D

. Wp

=

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, 0.375H

Xi =

=

For D/H < 1.333, Xi =

0.5 - 0.094

D H

.H

=

D/H > 1.333 , Xi

Since

=

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 com multiplied by the respective moment arms to the center of action of the forces. Ringwall moment, Mrw =

[Ai ( Wi. Xi + Ws. Xs + Wr. Xr)]2 + [Ac (Wc. Xc)]2

= =

7 .2.4

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

= =

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

= =

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

= = =

Weight of tank shell and portion of roof supported by the shell, Ws Wt = + wrs 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
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

=

The maximum width of annulus for determining the resisting force, 0.035 D

=

Since L And, Since Ls

=




L, the bottom/ annular plate width is

satisfactory.

SHELL COMPRESSION MECHANICALLY-ANCHORED TANKS Maximum longitudinal shell compression, c =

7 .3.4

wt ( 1 + 0.4 Av) +

1.273 Mrw D

2

1 ts

=

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, Fc =

83.ts D

=

Therefore, Fa ( < 0.5Fty ) Since c


4 Af =

K. SD1. I.

4 Tc

2

For SUG III When Tc ≤ TL Af =

K. SD1

1 Tc

When Tc > TL Af = Since SUG is

K. SD1 III

TL Tc and

For SDS = Q Fa Ss = Minimum required freeboard, sreq 7 .5 7 .5.1

7 .5.2

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 0.9

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 )

= = = = = =

: = =

Uplift force due to seismic loading, WAB =

1.273 Mrw Dc²

where Mrw = Dc = wt = 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

= = = = =

= WAB / N.Ab

=

Tensile stress, b Since b