FEA Analysis for Hull MEG Storage Tank T-5601AB_Rev 01

FEA ANALYSIS FOR HULL MEG STORAGE TANK T-5601A/B REV 01

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DATE REV. PREPARED BY CHECKED BY APPROVED BY 09-04-2014 01 FZL YLZ MHL


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TABLE OF CONTENT 1.0 GENERAL ............................................................................................................................ 3 1.1 Scope ................................................................................................................................... 3 1.2 Code, Standards and References......................................................................................... 3 1.3 Modelling Of Structures ........................................................................................................ 3 1.3 Strength of Materials ............................................................................................................ 4 2.0 FEA ANALYSIS ................................................................................................................... 6 2.1 Introduction .......................................................................................................................... 6 2.2 Design Data ......................................................................................................................... 6 2.2.1 Operating Condition .................................................................................................................... 7 2.2.2 Survival Condition ..................................................................................................................... 18 2.2.3 Extreme Condition .................................................................................................................... 29 3.0 FEA RESULTS .................................................................................................................. 40 3.1 Plate Centre Stresses Summary .................................................................................................. 40 3.2 Deflection Plot ............................................................................................................................... 43


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1.0 GENERAL 1.1 SCOPE

This document represents the FEA Analysis for Hull MEG Storage Tank of Malikai EPC TLP Project.

1.2 CODE, STANDARDS AND REFERENCES

1 Roarks Formula of Stresses and Strain, 8th Edition 2011. 2 AISC-ASD 9th Edition 1989, Manual of Steel Construction Allowable Stress Design. 3 API RP 2A, Recommended Practice for Planning, Designing and Construction Fixed Offshore Platform - WSD 4 DEP 37.81.10.31-Gen, Structural Steel Design of Small Deepwater Offshore Skids, Facility Packages, and Subsea Sleds Manifolds. 5 Topsides General Design Condition, Environmental and Utility Data, MLK-011-300-CS-1980-0001 6 Topsides Structural Design Basis, MLK-011-300-CS-7880-0001 7 Hull Storage Tanks Technical Specification, MLK-011-200-CX-7771-0001 8 Datasheet for MEG Hull Storage Tank, MLK-011-200-CX-2180-0002

1.3 MODELLING OF STRUCTURES

The analysis is based on a three dimensional (3D) model generated by ANSYS. The model is further analysed by general packages FEA program ANSYS. The modelling procedures, boundary conditions and loading are described in this section together with detail results obtained from the FEA analysis.

The completed Tank Structure T-5601A/B arrangement and dimension based on the sketch drawing attached are used to generate the detailed FEA model.

The element type used is 3D tetrahedral with mid side node. The complete model is meshed with local refinement to achieve results with minimum error. The aspect ratio is maintained below 0.272. The generated of the meshing is shown in Figure 2.2.

The bottom beam support level of tank are considered fully restraint (fixed support). For the support oval collar are considered displacement support on the support at top of the deck structure. ANSYS automatically calculates the self-weight of the modelled structure.

The complete plots of loading and boundary condition are presented in Section 2.3.


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1.3 STRENGTH OF MATERIALS

Structural Materials: a) ASTM A36 or equivalent

1. Yield Strength, Fy = 250 MPa

2. Tensile Strength, Fu = 400 MPa.

3. Modulus of Elastic, E = 205 kN/m2

4. Poissons Ratio = 0.3

5. Density = 7850kg/m3

(Tank bottom beam W24x62)

b) SA 240 or equivalent

1. Yield Strength, Fy = 170 MPa

2. Tensile Strength, Fu = 485 MPa.

3. Modulus of Elastic, E = 197 kN/m2

4. Poissons Ratio = 0.3

5. Density = 8030kg/m3

Following are the material using

Table 1.3: Material for Structure Beam/Plate

Item Description Material

1 W24X62 ASTM A36

2 WALL PLATE 12MM THK SA 240 SS 316L

3 TOP OVAL PLATE 30MM THK SA 240 SS 316L

4 WALL OVAL PLATE 24MM THK SA 240 SS 316L

5 OVAL SUPPORT PLATE 25MM THK SA 240 SS 316L


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Figure 1.3: Modelling for Tank T-5601 Structural Tank

1

2

3

4

5


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2.0 FEA ANALYSIS 2.1 INTRODUCTION

The FEA analysis has considered the Hull MEG Storage Tank in its operational condition. The design has also accounted for the critical loading imposed onto the platform during operation in maximum and minimum loading conditions.

The dead weight, content load, nozzle load and displacement loads were considered. Following are the condition load to be consideration:

1) Operating Condition 2) Survival Condition 3) Extreme Condition

2.2 DESIGN DATA

(1) Reference: Global Performance Design Data for Topside Design

MLK-011-200-CX-1380-0108/5886-200-CN-3832-108 Rev 02A

(2) Summary of Acceleration at Point TS_SW : X = -33.91 m, Y = -33.91 m, Z = -35.25 m

0 Degree Heading

Heave Horizontal

Operating 0.248 0.852

Extreme 0.181 1.130

Survival 0.247 1.502

45 Degree Heading

Heave Horizontal


Extreme 0.237 1.013


90 Degree Heading

Heave Horizontal


Extreme 0.179 1.132


Acc (ms-2

)

Condition

Condition

Acc (ms-2

)

Condition

Acc (ms-2

)


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2.2.1 OPERATING CONDITION

MEG Tank (Operating Condition)

1) Mass Calculation

Tank Liquid Mass

Volumn A

L = 7.00 m

B = 4.00 m

H = 5.00 m

N = 1.65 m

Density 1092 kg /m3

Mass = 152880 kg

Vertical C.O.G from tank bottom = 2.50 m

Volumn B (Not filled) 0 kg

Tank Structure Mass 34950 kg


Pump Mass 2000 kg


Total Mass 189830 kg

1862.232 kN

Total Mass C.O.G = 2.54 m

Volumn A

Volumn B

1.6

5 m

5.0

m


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2) TOC level Nozzle Reaction Load Calculation

Horizontal :

Fh acc = 61.8 kN or 30.9 kN per nozzle

Vertical:

Fv acc (Pump & Tank Structure)= 3.9 kN

TOC Pressure Load Contributary Area = 14.0 m2

Fv TOC Pressure Load 29.7 kPa = 70 kN (Nominal 5kPa)

Total Fv = 73.9 kN or 37.0 kN per nozzle

Bending Moment = 97.0 kN m or 48.5 kNm per nozzle

3) Relative Deflection Between TOC and Deck 3 (from FE Analysis)

Horizontal = 3.5 mm from global strength analysis

Vertical = 5 mm from local model with full

tank liquid but TOC with zero pressure load


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Figure 2.2.1a: Structural tank Self weight


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Figure 2.2.1b: Tank Liquid Mass


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Figure 2.2.1c: Horizontal Nozzle Reaction


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Figure 2.2.1d: Vertical Nozzle Reaction


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Figure 2.2.1e: Moment Nozzle Reaction


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Figure 2.2.1f: Vertical Displacement at Oval Support


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Figure 2.2.1g: Horizontal Displacement at Oval Support


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Figure 2.2.1h: Bottom Fixed Support


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Figure 2.2.1j: Loading and Boundary condition


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2.2.2 SURVIVAL CONDITION

MEG Tank (Survival Condition)

1) Mass Calculation

Tank Liquid Mass

Volumn A

L = 7.00 m

B = 4.00 m

H = 5.00 m

N = 1.65 m

Density 1092 kg /m3

Mass = 152880 kg





Pump Mass 2000 kg



1862.232


Volumn A

Volumn B

1.6

5 m

5.0

m


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Horizontal :


Vertical:



Fv TOC Pressure Load 29.7 kPa = 415.8 kN (29.7kPa is based on minimum air

gap water head above TOC in survival case)




Horizontal = 5 mm from global strength analysis

Vertical = 5 mm from local model with full tank liquid

but TOC with zero pressure load


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2.2.3 EXTREME CONDITION

MEG Tank (Extreme Condition)

1) Mass Calculation

Tank Liquid Mass

Volumn A

L = 7.00 m

B = 4.00 m

H = 5.00 m

N = 1.65 m

Density 1092 kg /m3

Mass = 152880 kg





Pump Mass 2000 kg



1862.232 kN


Volumn A

Volumn B

1.6

5 m

5.0

m


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Horizontal :


Vertical:



Fv TOC Pressure Load 29.7 kPa = 70 kN (Nominal 5 kPa)




Horizontal = 4 mm from global strength analysis

Vertical = 5 mm from local model with full tank liquid

but TOC with zero pressure load


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3.0 FEA RESULTS 3.1 PLATE CENTRE STRESSES SUMMARY

For detailed FE analysis the allowable stress based on the Von Misses criteria [1].

Figure 3.1a: Von Misses Plot for Operating Cases


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Figure 3.1b: Von Misses Plot for Survival Cases


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Figure 3.1c: Von Misses Plot for Extreme Cases

Allowable Strength for SA240 SS316L (Table 2A: ASME Stress Table) at Temperature 70C = 113 MPa----OK Allowable Strength for ASTM A36 (Table 2A: ASME Stress Table) at Temperature 70C = 134.03 MPa----OK


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3.2 DEFLECTION PLOT

Figure 3.2a: Deflection Plot Dir-X for Operating Cases


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Figure 3.2b: Deflection Plot Dir-Y for Operating Cases


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Figure 3.2c: Deflection Plot Dir-Z for Operating Cases


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Figure 3.2d: Deflection Plot Dir-X for Survival Cases


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Figure 3.2e: Deflection Plot Dir-Y for Survival Cases


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Figure 3.2f: Deflection Plot Dir-Z for Survival Cases


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Figure 3.2g: Deflection Plot Dir-X for Extreme Cases


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Figure 3.2h: Deflection Plot Dir-Y for Extreme Cases


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Figure 3.2j: Deflection Plot Dir-Z for Extreme Cases

Documents

FEA Analysis for Hull MEG Storage Tank T-5601AB_Rev 01