1Hamburg, Germany 27 September 2006

State of Art Review on LNG Containment System & Pump Tower Technology:

R&D Activities

Yung S. ShinABS Technology

Houston, TX

SMM CONFERENCE LNG SESSION

2Presentation topics

l Introduction - Industry Trends & Technical Issues related to LNG containment system subject to sloshing load

l Sloshing Impact Load: Analysis, model tests, scale law

l Containment system strength, vibration, fatigue: drop tests, material tests, strength tests, failure modes, structure analysis procedure including fluid structure interaction, strength assessment methodology, factor of safety

l Pump tower and base support analysis: strength, vibration, fatigue of pump tower due to sloshing, inertial and thermal loads

l Recommendations for further study

l Conclusions

3Introduction- Industry trends

l Increase of LNG market and surge of new shipbuilding of LNGC

l Large size of LNGC greater than 200K, 250K

l Partial filling condition vs Standard filling Operation

l New tank designs & configuration

l New analysis method, model tests, advanced strength assessment method are needed.

l Many technical issues identified

4ABS Sloshing Analysis

Tank Top

Insulation

C2

C1

Inner Deck

Inner BottomTank Bottom

Base Line

Pump Tower

Pump Tower

No. 2 Tank for Sloshing Analysis

LNG Ship, Tank Configuration, Pump Tower

5ENVIRONMENTAL CONDITIONS

Design Environments:

Unrestricted Services: North Atlantic Waves

Offshore Offloading Services: Site-Specific Waves

Wave Scatter Diagrams:

Unrestricted Services: IACS Recommendation No. 34

Site-Specific Services: ABS GSOWM data

Wave Spectrum:

Bretschneider or Jonswap Spectrum

Hs (m) 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5

0.5 1.3 133.7 865.6 1186.0 634.2 186.3 36.9 5.6 0.7 0.1 0.0 0.0 0.0 0.01.5 0.0 29.3 986.0 4976.0 7738.0 5569.7 2375.7 703.5 160.7 30.5 5.1 0.8 0.1 0.02.5 0.0 2.2 197.5 2158.8 6230.0 7449.5 4860.4 2066.0 644.5 160.2 33.7 6.3 1.1 0.23.5 0.0 0.2 34.9 695.5 3226.5 5675.0 5099.1 2838.0 1114.1 337.7 84.3 18.2 3.5 0.64.5 0.0 0.0 6.0 196.1 1354.3 3288.5 3857.5 2685.5 1275.2 455.1 130.9 31.9 6.9 1.35.5 0.0 0.0 1.0 51.0 498.4 1602.9 2372.7 2008.3 1126.0 463.6 150.9 41.0 9.7 2.16.5 0.0 0.0 0.2 12.6 167.0 690.3 1257.9 1268.6 825.9 386.8 140.8 42.2 10.9 2.57.5 0.0 0.0 0.0 3.0 52.1 270.1 594.4 703.2 524.9 276.7 111.7 36.7 10.2 2.58.5 0.0 0.0 0.0 0.7 15.4 97.9 255.9 350.6 296.9 174.6 77.6 27.7 8.4 2.29.5 0.0 0.0 0.0 0.2 4.3 33.2 101.9 159.9 152.2 99.2 48.3 18.7 6.1 1.7

10.5 0.0 0.0 0.0 0.0 1.2 10.7 37.9 67.5 71.7 51.5 27.3 11.4 4.0 1.211.5 0.0 0.0 0.0 0.0 0.3 3.3 13.3 26.6 31.4 24.7 14.2 6.4 2.4 0.712.5 0.0 0.0 0.0 0.0 0.1 1.0 4.4 9.9 12.8 11.0 6.8 3.3 1.3 0.413.5 0.0 0.0 0.0 0.0 0.0 0.3 1.4 3.5 5.0 4.6 3.1 1.6 0.7 0.214.5 0.0 0.0 0.0 0.0 0.0 0.1 0.4 1.2 1.8 1.8 1.3 0.7 0.3 0.115.5 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.4 0.6 0.7 0.5 0.3 0.1 0.116.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.2 0.2 0.2 0.1 0.1 0.0

Tz (sec)

6SHIP MOTIONS in WAVES

Frequency Domain or Nonlinear Analysis:

Hull Form

3D Panel Code: PRECAL

Motion and ACCL RAOs at 33 freqs and 17 headings

Ship Speed: 75% of design speed-20 -10 0 10 20

0

5

10

15

20

25

7LNG Sloshing Analysis by Critical Sloshing Domain Approach

Roll RAO T. ACCL RAO

Encountering period

Contour Map of Sloshing Pressure

Critical Sloshing Load at 70% FLVL,

EW at 70% FLVL|Encountering period Tank resonance period|

< 30% of Tank resonance Period

RAO of DLPs (Roll, Pitch, TACC, LACC)

> 50% of Max RAO

About 20+ sea conditions for each filling level

8SLOFE Features

Stream function-based model

Finite-element method

LNG tank w/o internal members

Impact-capturing scheme in low-filling

Validated w/ model test results t/T= 7.8855, Pmax=6.6

Sloshing Simulation

9SLOFE: Comparison w/ Experiment (15%H)

10

High Filling Level vs. Low Filling Level

Incident angle is less than 4 degree.

Gas pocket can be found before impact.

High-Filling Level:

Standing Wave

Low-Filling Level:

Progressive Wave

Incident angle is greater than 10 degree.

No gas pocket.

11

3D Sloshing Impact Simulation

Roll 10 deg., Pitch 5 deg Period 6.64 s

55 60 65 70 75 80 85 90 95 100t (sec)

0

5

10

15

Pre

ssur

e (b

ar)

3D Surge2D Surge

3D Surge

2D Surge

Sway Motion in beam sea Surge Motion in head sea Roll Motion in oblique sea

12

Two Phase Flows Simulations for Tank Sloshing

13

MARINTEK 138K Partial Filling Model Test

Seakeeping Analysis

Irregular Sloshing Analysis

Critical Wave Condition

Maximum Sloshing Load in the

North Atlantic Waves

Sloshing Model Test

701703

772

716

776 785

756744

747

735 741

784782

710732 702

20

20

TYP.2.5

TY

P. 2.5

TY

P. 5.0

TYP. 5.0

STBD

FWD

Clustered pressure sensors

14

Six DOF Sloshing Test Rig & Comparison

15

138K Model Test for Partial Filling Study

Check duration to validate Froude scaling

Measured Local Pressure Time History

1:50 scale ModelFroude Scaling for Impact PressureAir & Water at room temperature and atmospheric pressureRigid tank wallNo corrugation3 hr MPEV of impact pressure

Ensemble pressure for clustered pressure sensors (Panel pressure)

ABS Procedure for Data InterpretationValidation

Design load for Impact Strength Assessment

16

GTT Model Test for Larbi Ben M'hidi Damage Study

Model Scale Pressure (kPa) Scale Factor

Full Scale Pressure

(kPa)

Froude Scaling 89 33.1 2947GTT Damage Study 89 6.7 600Mach Scaling 89 4.0 352

Scale Law to Full Scale Pressure

Scale law is not unique & full scale value can be significantly different

Different scale law should be applied for different impact type and filling level

Empirical scale law is an averaged scale law for different impact type for high filling conditions and may not be applicable to low filling conditions.

Scale Law for Sloshing Impact Pressure

17

Hidden factor of safety & Conservatism

l Ship motion-sloshing interaction

l Cushioning due to corrugation

l Dynamic material properties

l Conservative environmental and loading scenario

18

Ship motion Sloshing interaction

l Similar to Anti-roll tank

l Significant effect on roll and accelerations

l Reduction of sloshing pressures

19

Large LNGC Analysis:Ship and Tank Size Comparison

138K: 276 (m)

LLNGC: 322 (m)46m longer

LLNGC over 200K : 51 (m)8.4m wider

138K: 42.6 (m)

20

Sloshing Analysis for Large LNGC

Maximum Panel Pressure at Corner

0

1

2

3

4

5

6

7

8

70% 80% 90% 95%

Filling Level

P (

bar

) 138K_L43

200K_L51

200K_L55

Sloshing pressure at corners

l 28% increase of sloshing load on insulation box over 138K standard size

l Model test confirmed approximately 30% increase of sloshing pressure

21

Dry Drop Tests for Impact Strength

Full-Scale Insulation Model

Impact Duration Controlled by Drop Weight

Impact Magnitude by Drop Height

Failure Mode of Insulation System

Fracture and Crack Propagation

Impact Strength

22

Drop Test for Corrugation Effect

23

Simplified Strength Assessment Procedure

Sloshing Load

Ship Motion

Model Scale Sloshing Pressure

Full Scale Sloshing Pressure

Cushioning due to corrugation

Strength of Containment System

Static Strength

Impact Strength

Factor of Safety = Impact Strength

Max. Full Scale Sloshing Impact Load

24

Advanced Strength Assessment Procedure

Sloshing Analysis/Model TestIdentification of Critical Sloshing

Impact LoadRigid Impact Pressure

Impact Strength TestScheme Validation

Failure ModeImpact Strength

Hydroelastic AnalysisStructural Response

Resultant Impact Pressure

Dynamic Material PropertyVisco-elasticity

Damping

Acceptance Criteria

LoadImpact Resultant StrengthImpactSafetyofFactor =

25

Material Property Testing at Low Temperature

26

Structure Responses of Containment System

Mark III

NO 96

LNG

Structure

Strikerbar

Incident bar Transmitted barSpecimen

Strain gaugeV0 Embedded quartz loadcell

Strength Assessment at Level 1

Static Stress FE Analysis

Buckling FE Analysis

Strength Assessment at Level 2

Linear Dynamic FE Analysis

Dashpot System Representing LNG Damping

Buckling FE Analysis

Strength Assessment at Level 3

Nonlinear Dynamic FE Analysis

Fluid-Structure Interaction

Visco-elasticity

Dynamic Material Property Test

27

Structure Analysis of Containment System for Fluid-Structure Interaction

LNG

Foam

Pressure reduction due to Structural Motion

Stress propagation & dissipation

Stress concentration on mastic

Acoustic wave emission

P U

28

Buckling Analysis on NO 96 Containment System

Critical buckling load

29

( )( )tptp

FactorLoadelasticHydrorigidt

flext

max

max-

Hydro-elastic Effect on NO 96 Containment System

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014 0.016

Duration [s]

Hyd

ro-e

last

ic L

oad

Fac

tor

Sigma=0.2Sigma=1.0Sigma=1.8

30

Guidance Notes for Strength Assessment of Membrane-Type LNG Containment System

l Objective is to provide evaluation procedure and criteria based on sloshing analysis, model test and structure analysis of containment system

l Both new novel design and conventional design are considered

l Standard filling condition and any partial filling conditions are addressed

l Interaction between LNG liquid and structure and dynamic behavior of containment system are considered using advanced analysis techniques

l Three different levels of structure analysis, static, simplified dynamic and non-linear dynamic structure analysis are offered.

31

Adt

dUCDUUC

dzdF

md r+r= 21

Morrison equation for sectional force

Time-domain simulation of sloshing

Structural analysis

NASTRAN, SACS, API Code

SLOFE for Sloshing & Load by

Long-term prediction of Ship motion

Design life in the North Atlantic Waves

Pump Tower Analysis

Liquid Dome Cover

Base Plate

Pump TowerMain Section

32

Pump Tower Structure

Top-Details

Discharge Pipe

Emergency Pipe

Bottom-Details

Standard Strut

Filling Pipe

Base Plate

33

Drag phase

Inertial phase

Pump Tower Load at low filling level (25%H)

40 44 48time (sec)

-4E+005

-2E+005

0E+000

2E+005

4E+005F

orce

(N

)

Force on membe r 1Total forceInertia forceDrag force

-20 -15 -10 -5 0 5 10 15 20Velocity (m/s)

0

0.2

0.4

0.6

0.8

1

Rel

ativ

e he

ight

-150 -100 -50 0 50 100 150Accele ration (m/s2)

-1E+005 -5E+004 0E+000 5E+004 1E+005Sectional Force (N/m)

VelocityAccelerationSectional force

-20 -15 -10 - 5 0 5 10 15 20Velocity (m/s)

0

0.2

0.4

0.6

0.8

1

Rel

ativ

e he

ight

-150 -100 -50 0 50 100 150Acceleration (m/s2)

-1E+005 -5E+004 0E+000 5E+004 1E+005Sectional Force (N/m)

Velocity

AccelerationSectional force

34

Loads & Responses of Pump Tower

l Sloshing Loads on Pump Tower

l Gravitational Load due to Pitch and Roll Motion and Self-Weight

l Inertial Load

l Thermal load

35

API Code Checking- Brace Members & Connections in Partial Filling: Example Analysis

Combined Axial Compression and Bending - Unity CheckCombined Axial Compression and Bending - Unity Check

Element 61Element 61Element 61

Element 62Element 62Element 62

Element 89Element 89Element 89

Element AxialStress/Allowable

(kgf/cm2)

In Plane BendingStress /Allowable

(kgf/cm2)

Out-of-Plane BendingStress/Allowable

(kgf/cm2)

Max CombUnityCheck

61 -1013/855 -534/1301 125/1301 1.8462 1072/1040 -306/1301 47/1301 1.26989 -624/1040 174/1301 3.0/1301 1.016

Design change for reinforcement may be required for partial filling condition

36

Vibration of pump tower structure

l Natural Frequencies and Mode shapes

l Resonance check by comparison between natural frequency and exciting frequencies of hull girder vibration and engine vibration

l Forced vibration and acceptance criteria

37

Spectral Fatigue Analysis or Simplified Fatigue Analysis

Fatigue Damage during Lifetime Service Period

Weibull Parameter

SN CurveStress Range at Reference Prob. Level

Fatigue Loads due to Sloshing

38

Pump Tower Base Support FE Analysis

39

Stress Distribution of Mastic

40

Stresses on Densified Plywood

41

FE Analysis on Hull Structure with Mark III Containment System under Ice Loads

42

Mark III Containment System

Hull Structure with Mark III Containment System

43

Recommendations for further study

l Corrugation effect on sloshing

l Fluid & gas interaction in CFD simulation

l Ship motion and sloshing coupling effect

l Full scale measurement for scale law

l Vibration effect on containment system

l Membrane fatigue

l Harsh wave environment analysis

l Containment system for Arctic operation

l Ship to ship and ship to terminal cargo transfer

44

The End of Presentation

&

Questions & Answers