stability study of c-0172 - odnzkg,4275388,/b17… · stability study of c-0172 fea and stability...

Reference 30147 Revision nr. 7 Date 14-12-2016 Subject C-0172 Page(s) 1/39

Stability study of C-0172

FEA and stability calculations

A16012 - Stability calculations of C0172_rev7.docx 2/39

Table of contents

Table of contents ........................................................................................................................................... 2

Samenvatting ................................................................................................................................................. 4

Introduction ................................................................................................................................................... 5

1. Technical Details of C-0172 ....................................................................................................................... 5

2. FEA Calculation for Jacking Purposes ......................................................................................................... 6

2.1. Results ................................................................................................................................................. 6

3. Stability Calculation .................................................................................................................................. 9

3.1. Annular ring ......................................................................................................................................... 9

3.2. 1st Shell course: Operating .................................................................................................................. 10

3.3. 1st Shell course: Test ........................................................................................................................... 11

3.4. 2nd Shell course: Operating ................................................................................................................. 12

3.5. 2nd Shell course: Test .......................................................................................................................... 13

3.6. 3rd Shell course: Operating .................................................................................................................. 14

3.7. 3rd Shell course: Test ........................................................................................................................... 15

3.8. 4th Shell course: Operating .................................................................................................................. 16

3.9. 4th Shell course: Test ........................................................................................................................... 17







3.16. Primary Wind Girder ........................................................................................................................... 24

3.17. Secondary stiffening ring .................................................................................................................... 25

3.18. Overturning moment .......................................................................................................................... 26

3.19. Restistance to overturning .................................................................................................................. 27

3.20. Conclusion .......................................................................................................................................... 28

4. Aluminium Dome Load............................................................................................................................ 29

4.1. Dome details ...................................................................................................................................... 29

4.2. Dome Load Analysis ............................................................................................................................ 29

4.2.1. Model setup .................................................................................................................................. 29

4.3. Result ................................................................................................................................................. 29

5. Conclusion .............................................................................................................................................. 30


A. FEM calculations dome load in shell ........................................................................................................ 31

A.1.1 Model properties ................................................................................................................................ 31

A.1.2 Units ................................................................................................................................................... 31

A.1.3 Material Properties ............................................................................................................................. 32

A.1.4 Loads and Fixtures ............................................................................................................................... 33

A.2 Mesh...................................................................................................................................................... 35

A.2.1 Mesh details ........................................................................................................................................ 35

A.2.3 Mesh control ....................................................................................................................................... 36

A.3 Results ................................................................................................................................................... 37

A.3.1 Stresses ............................................................................................................................................... 37

A.3.1 Displacement ...................................................................................................................................... 38

A.3.1 Equivalent strain ................................................................................................................................. 39


Samenvatting

Tank C0172 is gecontroleerd op stabiliteit (gemeten wanddikte vergeleken met wanddikte als vereist volgens de norm). Daarbij zijn de volgende normen gebruikt als basis:

EEMUA159 Hierbij is voor de operationele condities (vulhoogte 15.6 meter met gas olie) rekening gehouden met 80% van de yield strength en 80% van de yield strength voor de test condities (vulhoogte 15.6 meter met water).

Omschrijving Gemeten (gemiddelde) dikte (mm)

Vereiste wanddikte

Operationele condities Test condities

EEMUA159 EEMUA159

1e ring 12.2 9.26 11.09

2e ring 9.4 7.77 9.30

3e ring 9.5 6.27 7.51

4e ring 7.8 4.78 5.72

5e ring 7.9 4.96 5.94

6e ring 7.2 2.71 3.24

7e ring 7.0 0.45 0.54

Omschrijving Voldoet?

Operationele condities Test condities

EEMUA159 EEMUA159

1e ring Ja Ja

2e ring Ja Ja

3e ring Ja Ja

4e ring Ja Ja

5e ring Ja Ja

6e ring Ja Ja

7e ring Ja Ja

Alle gemeten ringen voldoen voor zowel de operationele conditities (gas olie) als de test condities (water) aan de gestelde norm (EEMUA159, 80% van de yield strength) voor een vulhoogte van 15.6 meter. Eén extra verstijvingsring moet op de tank geplaatst worden, rekening houdend met een windsnelheid van 46.5 m/s. Voor de belasting als gevolg van vijzelen van de tank is een FEM analyse uitgevoerd. De maximale spanning die uit deze analyse volgt is 54 N/mm2 ter plaatse van de verbinding tussen de annulaire ring en de eerste tank ring. De maximaal toelatbare spanning (80% of de yield strength van 355 N/mm2 = 288 N/mm2) is een fator 5 hoger. Verder is ook een FEM analyse uitgevoerd met de belasting van het nieuw te plaatsen aluminium dak op de tank wand, wat resulteert in een spanning van 113 N/mm2.


Introduction

Tank C0172 has been selected for renovation, the renovation included the following:

- Removal of the current floating roof

- Removal of the current floor plates, excluding the annular ring

- Jacking up of the tank to perform foundation repair

- Installing a new tank floor “coned down”

- Installing an aluminium domed roof

- Installing an IFR, at a later stage.

A survey report was performed on the tank on the 10th March 2016, by the company Rosen. The contents of the report form the basis of any hereafter following calculations.

Seeing a change of service is envisage for the tank, age of the tank and the results of the Rosen survey report, it has been decided to perform a few calculations on the tank in question.

Calculations to be performed:

- FEA calculation to see if the tank can withstand jacking

- Stability calculation according to the EEMUA159, manual calculation in excel

- FEA calculation to see if the tank can withstand the additional stress of the aluminum domed roof.

1. Technical Details of C-0172

Diameter : 42 mtr Tank total height : 15.93 mtr Filling height : Currently 15.8 mtr Last known medium : Gasoil

- Specific gravity : 0.835 kg/ltr Shell courses : 7 Materials used

- Annular ring : Ste 36 = DH 36 - 1st to 4th shell course : Ste 36 = DH 36 - 5th to 7th shell course : Ste 37-2 = S235JR

Top angle : Angle 85x67x6.9mm Wind speed used in calculations : 46.5 m/s Location primary girder : 1100 mm below the top of the tank Tubelures and tank penetrations : Not included in any calculation, assumed OK Summation of the Rosen Report

Description Height (m) Average Thickness (mm) Material : Assumed

Annular ring n/a 9.1 Ste 36

1st shell course 2.46 12.8 Ste 36

2nd shell course 2.47 10.2 Ste 36

3rd shell course 2.47 10.1 Ste 36

4th shell course 2.47 7.8 Ste 36

5th shell course 2.47 8 Ste 37-2

6th shell course 2.47 7.1 Ste 37-2

7th shell course 1.12 6.8 Ste 37-2


2. FEA Calculation for Jacking Purposes

36 Jacking brackets are to be welded to the first shell course of the tank, in order to lift it so that the foundation repair can take place. Prior to jacking, the following will already have been done:

- The existing floor plates will have been removed - The current floating roof will have been removed

Fixed points used:

- The cross bars of the jacking brackets, 36x Loading

- Own weight of the tank, by means of std gravity.

2.1. Results

Mesh:

In order to perform a FEA calculation a so-called mesh is needed, this “cuts” the entire model into small pieces, these small pieces form the basis of the calculation


Jacking brackets and fixed points (36x) in the circumference:

The cross bar, purple, is used as the fixed points for the calculation


Stress Results:

A maximum stress of 54 N/mm2 is found at the junction of the annular ring and the 1st shell course. Conclusion: Seeing that the allowable stress in the material for jacking purposes is 0.8 x Re value of the material used/ in our case the Re value is 355 N/mm2 0.8 x 355 = 284 N/mm2 This value is decidedly larger than the resulting stress from the FEA calculation Is can be safely assumed that no adverse effects will occur when jacking the tank.


3. Stability Calculation

The stability calculation is performed according to the EEMUA159, whereby: - 80% of the material Re is allowed during operating conditions and 80% during the test conditions.

For the operating conditions the specific gravity of gasoil was used to perform the calculation, this being 0.835 kg/ltr. Corrosion allowance for the design conditions is set at 0mm.

3.1. Annular ring

EEMUA159 : Annular Ring Calculation

Given / Assumed

Thickness 1st Shell Course 12.8 mm e1

- excl CA

Average thickness annular ring 9.1 mm

Calculation

A

ea = 3.0 + (e1/3)

= 7.27 mm GOVERNING

B

ea = 6 mm as a minimum

NOT GOVERNING

Notes

In the Rosen Report (Appendix A4) the average thickness of the

annular ring was measured as 9.1 mm.

The Annular ring is thus OK


3.2. 1st Shell course: Operating

EEMUA159 : 1st Shell Course Calculation : Design Conditions

Given / Assumed

Symbol

Outside Diameter Tank 42 mtr D

Average thickness shell plate 12.8 mm

Shell height 2.46 mtr

Liquid Height 15.6 mtr Hc

Yield Strength 355 N/mm2 Ste 36 Re

Corrossion Allowance 0 mm c

Design pressure 10 mbar p

Used in calculation 0 0 if 10 mbar or less

Medium Gasoil

Specific gravity medium 0.835 kg/l W

Calculation : Shell Course Thickness

ec = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re

Allowable Material Stress = 284 N/mm2 S

ec = 9.26 mm

Result

Actual average plate thickness 12.8 mm

EEMUA159

0.80 x Re

Required plate thickness incl CA 9.26 mm

SUFFICIENT

NON GOVERNING

Comments

Ste 36 is equivalent to GH36 and has a Re value of 355 N/mm2


3.3. 1st Shell course: Test

EEMUA159 : 1st Shell Course Calculation : Test Conditions

Given / Assumed

Symbol






Design pressure 0 mbar 1.1 x p = pt

0 if 10 mbar or less

Medium Water

Specific gravity medium 1 kg/l W


et = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


et = 11.09 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

GOVERNING

Comments



3.4. 2nd Shell course: Operating

EEMUA159 : 2nd Shell Course Calculation : Design Conditions

Given / Assumed

Symbol









Medium Gasoil



ec = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


ec = 7.77 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

NON GOVERNING

Comments



3.5. 2nd Shell course: Test

EEMUA159 : 2nd Shell Course Calculation : Test Conditions

Given / Assumed

Symbol








Medium Water



et = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


et = 9.30 mm

Result


EEMUA159

0.80 x Re


NOT SUFFICIENT

GOVERNING

Comments



3.6. 3rd Shell course: Operating

EEMUA159 : 3rd Shell Course Calculation : Design Conditions

Given / Assumed

Symbol









Medium Gasoil



ec = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


ec = 6.27 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

NON GOVERNING

Comments



3.7. 3rd Shell course: Test

EEMUA159 : 3rd Shell Course Calculation : Test Conditions

Given / Assumed

Symbol








Medium Water



et = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


et = 7.51 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

GOVERNING

Comments



3.8. 4th Shell course: Operating

EEMUA159 : 4th Shell Course Calculation : Design Conditions

Given / Assumed

Symbol









Medium Gasoil



ec = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


ec = 4.78 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

NON GOVERNING

Comments



3.9. 4th Shell course: Test

EEMUA159 : 4th Shell Course Calculation : Test Conditions

Given / Assumed

Symbol








Medium Water



et = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


et = 5.72 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

GOVERNING

Comments





Given / Assumed

Symbol





Yield Strength 235 N/mm2 Ste 37-2 Re




Medium Gasoil



ec = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


ec = 4.96 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

NON GOVERNING

Comments

Ste 37-2 is equivalent to SJ235JR and has a Re value of 235 N/mm2




Given / Assumed

Symbol








Medium Water



et = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


et = 5.94 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

GOVERNING

Comments





Given / Assumed

Symbol









Medium Gasoil



ec = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


ec = 2.71 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

NON GOVERNING

Comments





Given / Assumed

Symbol








Medium Water



et = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


et = 3.24 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

GOVERNING

Comments





Given / Assumed

Symbol









Medium Gasoil



ec = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


ec = 0.45 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

NON GOVERNING

Comments





Given / Assumed

Symbol








Medium Water



et = (D/20.S).(98.W.(Hc-0.3)+p) + c

EEMUA159

0.80 x Re


et = 0.54 mm

Result


EEMUA159

0.80 x Re


SUFFICIENT

GOVERNING

Comments



3.16. Primary Wind Girder

Limited details were available on the design of this girder. Position and width of the girder were given factors.

EN14015 : Primary Wind Girder

Given / Assumed

Required Section Modulus Z

Total Height of tank 15.93 mtr Ht

Wind Speed 167.4 km/hr Vw

= 46.5 m/s

Diameter Tank 42 m D

Calculation

Section Modulus Required

Z = 0.058 . D2.Ht.(Vw2/452)

= 1740 cm3 Required

Current Top Stiffner

- Aka walkway Length 815 cm b

Width 8 cm assumed d

Section Modulus Available Z

Z = b.d2/6

= 8693 cm3 Available

Current Setup is: ACCEPTABLE


3.17. Secondary stiffening ring

As standard Geldof use an angle profile of 150x150x10mm, which exceeds the minimum design requirements of the EN14015.

EN14015 : Secondary Stiffening Ring

Diameter of the tank 42 m D

Maximum space between secondary rings m HP

Stable full shell height m HE

Stable height per course m He

Height below girder m h

Minimum thickness top course 6.3 mm emin

Thickness of each course mm e

K-factor - K

Internal pressure 5 mbar pv

Wind speed 46.5 m/s Vw

Calculation He = h.(emin/e)5/2

e h He Sum h Sum He

Transformed height

difference

Effective height

difference

Effective height

[m]

Shell 1 12.8 2.46 0.42 2.46 0.42

Shell 2 10.2 2.47 0.74 4.93 1.16 Shell 3 10.1 2.47 0.76 7.4 1.92 Shell 4 7.8 2.47 1.45 9.87 3.37 1.36 2.32 9.72

Shell 5 8.0 2.47 1.36 12.34 4.73 Shell 6 8.1 2.47 1.83 14.81 6.56

HE 6.56 m HE = Sum He

K = 95000 / ((3.563*Vw2)+(580*pv))

= 8.96

HP = K.(emin5/D3)1/2

= 3.28 m Max distance between secondary rings

HP < HE < 2HP

3.28 < 6.56 < 6.56

Conclusion being, one (1) extra stiffening ring is required.

Spacing secondary girder = (Height of prim. girder- HZ)/3

2.75 mtr below primary girder


3.18. Overturning moment

EN14015 : Overturning Moment

Given / Assumed

Overturning Moment kNm M

Lateral Force Coeeficient - assumed 1 G1

Lateral Force Coeeficient G2

Total Height Tank Shell 15.92 m HL

Effective mass of tank contents 7000 kg T1

Effective mass of tank contents - sloshing 8630 kg T2

Total weight of tank roof 16970 kg Tr

Total weight of tank shell 159209 kg Tt

Height bottom tank shell to centroid lat force T1 5.85 m X1

Height bottom tank shell to centroid lat force T2 9 m X2

Height bottom to COG Shell 6.76 m Xs

Site amplification factor, table G.1 1.5 j

Given / Assumed

T1 and T2 determined by means of figure G.1

X1 and X2 determined by means of figure G.2

Ks determined from figure G.3 = 0.63

Ts = 1.8. Ks.D1/2

= 7.35

G2 = 1.25.G1.j / Ts

= 0.26

M = (G1.((Tt.Xs)+(Tr.HL)+(T1.X1) + (G2.T2.X2)) / 102

= 13795.89 kN.m


3.19. Restistance to overturning

EN14015 : Resistance to overturning

Given / Assumed

Maximum force of tank contents kNm WL

thickness anular plate 9.1 mm tab

Minimum Yield Strength anular ring 355 N/mm2 Reb

Maximum density cotained liquid 1 kg/l Ws

Maximum filling height 15.8 m HT

Calculation

WL = 0.1.tba.SQR(Reb.Ws.HT)

= 68.15 kN.m

Condition

WL <= Ws.HT.D

663.6 kN.m

OK


3.20. Conclusion

Based on the assumptions regarding the materials, the following can be concluded:

- The wall thickness of all shell rings are sufficient considering the required wall thickness as stipulated EEMUA159 (80% of yield strength).

One extra secondary stiffening rings are required, allowing a maximum wind velocity of 46.5 m/s.


4. Aluminium Dome Load

4.1. Dome details

Total Weight of the Dome : 16970 kg Nr. of support shoes : 35 Dead weight per shoe : 485 kg per shoe Used in FEM calculation : 500 kg (5000 N) Set-up: Fixed point : Annular ring Std Gavity : 9.8 m/s Loads : 500 per pipe shoe

4.2. Dome Load Analysis

See appendix A for the FEM calculation of the stresses in the shell as a result of the dome load..

4.2.1. Model setup

A FEM model has been set-up as follows:

- Small section of the tank modeled. 10.3° as there is 10.29° between IFR shoes. - Single IFR shoe modelled. - Wind girder modelled - 2x Stiffener modelled

- Annular plate as fixed point. - Loading from LC2 / 35, =1734.8 kN/35 = 49566 N per IFR shoe.

4.3. Result

The maximum simulated stress in the shell is 113 N/mm2, see appendix A for detailed results.


5. Conclusion

Jacking of the vessel using 36 brackets results in a maximum stress of 54 N/mm2, well within the allowable limits.

A stability analysis shows that a single extra secondary wind girder is required, allowing a maximum wind velocity of 46.5 m/s

The vessel is capable of supporting the new aluminum dome as designed. The FEM analysis of the dome weight on the shell result in a maximum stress of 113 N/mm2.


A. FEM calculations dome load in shell

A.1.1 Model properties

Study name Dome load

Analysis type Stress

Mesh type Mixed Mesh

Number of modes 1

Solver type FFEPlus

Incompatible bonding options Automatic

Thermal Effect: On

Thermal option Include temperature loads

Zero strain temperature 298 Kelvin

Include fluid pressure effects from SOLIDWORKS Flow Simulation

Off

Soft Spring: Off

Result folder SOLIDWORKS document (D:\IPSS\Geldof 2016-009\Vijzelen\Buckling)

A.1.2 Units

Unit system: SI (MKS)

Length/Displacement mm

Temperature Kelvin

Angular velocity Rad/sec

Pressure/Stress N/m^2


A.1.3 Material Properties

Model Reference Properties Components

Name: 1.0044 (S275JR)

Model type: Linear Elastic Isotropic

Default failure criterion: Unknown

Yield strength: 2.75e+008 N/m^2

Tensile strength: 4.1e+008 N/m^2

Elastic modulus: 2.1e+011 N/m^2

Poisson's ratio: 0.28

Mass density: 7800 kg/m^3

Shear modulus: 7.9e+010 N/m^2

Thermal expansion coefficient:

1.1e-005 /Kelvin

SolidBody 1(Cut-Extrude1)(Anular ring b-1),

SolidBody 1(Cut-Extrude2)(ring 1b-1)

Curve Data:N/A

Name: Plain Carbon Steel










1.3e-005 /Kelvin

SolidBody 1(Boss-Extrude1)(IFR shoe-1/guide-1),

SolidBody 1(Boss-Extrude1)(IFR shoe-1/plaat-1),

SolidBody 1(Cut-Extrude1)(angle-1),

SolidBody 1(Cut-Extrude1)(stiffener b-1),

SolidBody 1(Cut-Extrude1)(stiffener b-2),

SolidBody 1(Cut-Extrude1)(windligger b-1)

Curve Data:N/A

Name: 1.0037 (S235JR)





SolidBody 1(Fillet1)(IFR shoe-1/support 1-1),

SolidBody 1(Cut-Extrude1)(ring 2b-1),








1.1e-005 /Kelvin





SolidBody 1(Cut-Extrude1)(top ring support b-1)

Curve Data:N/A

A.1.4 Loads and Fixtures

Fixture name Fixture Image Fixture Details

Fixed-1

Entities: 1 face(s)

Type: Fixed Geometry

Resultant Forces

Components X Y Z Resultant

Reaction force(N) 1.45425 96503.4 1.71269 96503.4

Reaction Moment(N.m) 0 0 0 0


Load name Load Image Load Details

Gravity-1

Reference: Top Plane

Values: 0 0 -9.81

Units: m/s^2

Force-1

Entities: 1 face(s)

Type: Apply normal force

Value: 49566 N


A.2 Mesh

Mesh type Solid Mesh

Mesher Used: Curvature-based mesh

Jacobian points 4 Points

Maximum element size 473.231 mm

Minimum element size 94.6462 mm

Mesh Quality Plot High

Remesh failed parts with incompatible mesh On

A.2.1 Mesh details

Total Nodes 25780

Total Elements 12361

Maximum Aspect Ratio 15531

% of elements with Aspect Ratio < 3 5.51

% of elements with Aspect Ratio > 10 37.4

% of distorted elements(Jacobian) 0

Time to complete mesh(hh;mm;ss): 00:00:02

Computer name: MSBE


A.2.3 Mesh control

Mesh Control Name Mesh Control Image Mesh Control Details

Control-1

Entities: 1 component(s)

Units: mm

Size: 88.7519

Ratio: 1.5


A.3 Results

A.3.1 Stresses

Name Type Min Max

Stress1 VON: von Mises Stress

1.288e-005N/mm^2 (MPa)

Node: 11290

1.133e+002N/mm^2 (MPa)

Node: 562

Buckling-Static 1-Stress-Stress1


A.3.1 Displacement

Name Type Min Max

Displacement1 URES: Resultant Displacement 0.000e+000mm

Node: 5

7.809e+001mm

Node: 10237

Buckling-Static 1-Displacement-Displacement1


A.3.1 Equivalent strain

Name Type Min Max

Strain1 ESTRN: Equivalent Strain 8.908e-011

Element: 4107

1.787e-004

Element: 7323

Buckling-Static 1-Strain-Strain1

stability study of c-0172 - odnzkg,4275388,/b17… · stability study of c-0172 fea and stability...

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