-Shaped Liquefied for - Gastech Barcelona Watanabe... · © 2017 MITSUBISHI HEAVY INDUSTRIES SHIPBUILDING CO., LTD. ... Detailed Analysis:Irregular excitation for 120min. Comparison

© 2017 MITSUBISHI HEAVY INDUSTRIES SHIPBUILDING CO., LTD. All Rights Reserved.

MITSUBISHI HEAVY INDUSTRIES SHIPBUILDING CO.,LTD

5 April 2017

Structural Design &

Construction Method for

“Apple-Shaped Liquefied

Natural Gas Cargo Tank” for

LNG Carriers

“Apple-Shaped Tank”:

Upgrade of the existing MOSS tank and

licensed by Moss Maritime a.s

as “Flexible Spherical Tank”(FST)

© 2017 MITSUBISHI HEAVY INDUSTRIES SHIPBUILDING CO., LTD. All Rights Reserved. 2

CONTENTS OF PRESENTATION

1. Concept of FST (Flexible Spherical Tank) = “Apple Shaped Tank”

2. Design aspect

1. Extracting verification items in structural design for FST

2. Buckling assessment

3. Sloshing assessment

3. Construction aspect

1. New Bending process for FST

2. Construction Progress

4. Conclusion


INTRODUCTION

MHISB has successfully developed and constructed the world’s first “Apple-Shaped Tank”＊MHISB: Mitsubishi Heavy Industries Shipbuilding Co., Ltd.

“Apple-Shaped Tank” : Upgrade of the existing MOSS spherical tank and

licensed by MOSS Maritime a.s as “Flexible Spherical Tank”(FST)

“Flexible” means “with high flexibility in terms of tank shape and capacity”

Purpose of this presentation :

Introduce the excellent features of FST for the trade from U.S. to Asia

1st generation 2nd generation 3rd generation

4th generation 5th generation

6th generation: SAYARINGO

1. Concept of FST


165 to180km3 New Panamax LNGC(SAYARINGO)

MHISB has received orders for a total of 8 new generation vessels,

called as “SAYARINGO”, adopting FST

Best solution for the trade from U.S. to Asia

FST (= Apple-shaped tank)Continuous Tank cover

Lighter steel weight, Improved fuel consumption

Better terminal compatibility, Better maintainability

“SAYAENDO”

3 vessels under

construction

1st vessel: 2.5 years in service


Concept of FST (Flexible Spherical Tank)

Why is “SAYARINGO” the Best solution for trade from U.S. to Asia?

Panama Cannel 49m extreme

★Freeport★Cameron

★Cove point

Long haul trade

Harsh sea

North Pacific

Restricted Breadth

Compatibility with

Existing terminals

Restricted dimensions

Japan～Gulf of Mexico

One way abt.9500sm

High structural reliability for Cargo tank system

Large cargo capacity under restricted dimensions


High structural reliability for Cargo tank system

Large cargo capacity under restricted dimensions


Ta

nk c

ove

r to

p

ab

t.4

6.9

m

155km3

Sayaendo（Stretched tank）

180km3

SAYARINGO

（FST）

180km3

Existing MOSS（Spherical tank）

Ta

nk c

ove

r to

pa

bt.4

7.0

m

Bm 48.94m

Sphere

Cylinder

Sphere

Sphere

Torus

Torus

Cylinder

Sphere

Sphere

Bm 48.94m Bm 51.9m

Sphere

One type of

MOSS tank

One type of MOSS

tank

Lower height

Low-wind resistance

Exceed the breadth

limit of Panama canal



180km3

SAYARINGO

（FST）

Sphere

Cylinder

Sphere

Sphere

Torus

Torus

180km3

Existing MOSS（Spherical tank）

Sphere

155km3

Sayaendo（Stretched tank）

Sphere

Sphere

Cylinder

“Flexible” means “with

high flexibility in terms of

tank shape and capacity”

Center of gravity

at Lower position

Center of gravity : Lower position than the existing tank

High flexibility in terms of tank shape and capacity

Excellent sloshing property : Acceptance of Any filling level

2. Design Aspect of FST


Extracting verification items in structural design for FST

Structural Design

Stress Assessment

Fatigue Assessment

Proving Small Leak Protection

Design Loads

Buckling Assessment

Membrane Stress Analysis by Elastic

Shell FE model

Surface Stress Analysis by Elastic

Solid FE model

Damage factor assessment

Crack penetration analysis

Leakage analysis

Internal / External overpressure

Interaction Force

Thermal Load

Sloshing Load

Buckling Strength Evaluation by

Theoretical formula

Buckling Strength Evaluation by Elastic-

plastic large deformation FE analysis

Inertia force due to ship motion

Crack propagation analysis of

Plate Through Crack

Additional verification items for FST

FSTExisting MOSS(Sphere)

Same design procedure as MOSS is applied to FST


Buckling Assessment for FST

External Pressure

(Tank Empty)

Medium liquid level

(Seagoing)

Internal Pressure

(Pressure Discharge)

Lateral acceleration

(Seagoing)

Additional assessment for Torus and Cylindrical part.

RED : Buckling mode specific to FST

BLUE : Buckling mode similar to existing MOSS

Transverse

acceleration

Buckling of

Torus

Buckling in Sphere/Cylinder / Torus /

Buckling in

Sphere/ Cylinder

Buckling under circumferential compression

Buckling under circumferential compression

Shear bucklingExternal pressurebuckling

Buckling of

Cylinder



Buckling test was conducted to verify the accuracy of FEM

Examined mode : Buckling in Torus part due to internal pressure

Diameters of models : 2.5m (1/20 scale)

Torus part

Cylindrical

part

Spherical part

Total

deformation

Expanding

(mode 1)

Bending

(mode 2)＝＋

Compression

Tension

Tension

Buckling in Torus part

Initial shape

Deformed shape

Model1 : Small radius of Torus (i.e. easy to buckling)

Model2 : Actual Shape

Verify the Accuracy of FEM

Confirm Buckling NOT occur

at Actual shape

Deformation due to internal pressure (FEM)



FEM result by MHISB

FEM result by DNV

Buckling occurred at Torus part.

Buckling area

Measured point

of displacement

Buckling occurrence

Reflect to FEM

Pressure test

MODEL1

Result of FEM accurately match with Experiment

Measurement of

Imperfection

Third party evaluation



Measured imperfection

FEM result

Buckling did NOT occur

even in twice pressure(420kPa) as

Emergency pressure discharge condition

Pressure test

MODEL2 Torus part :

No buckling deformation

Buckling did NOT occur, Because deformation

is small and linear

At max press: 420 kPa

Measurement of

Imperfection

Out-of-plane displacement(mm)

Inte

rnal p

ressu

re(k

Pa)

Buckling in Torus would never occur due to internal pressure


Sloshing Assessment for FST

FST’s sloshing property

Gradual change of shape from MOSS(Spherical shape)

MHISB have verified if FST has the same level of

excellent sloshing property as MOSS, just to be safe

Procedure of Sloshing Assessment

1st Step: Regular wave approach

Verification of CFD Analysis

Comparison of FST & MOSS by CFD

Comparison of Exp. & CFD

2nd Step: Irregular wave approach

Third party evaluation

by DNV-GL

Evaluation by MHISB


Sloshing Assessment : Regular wave excitation by MHISB

0.0

0.2

0.4

0.6

0.8

1.0

0 50 100 150 200

tan

k h

eig

ht/

tan

k d

iam

ete

r

impulsive pressure [kPa]

CFD results(non-spherical tank)

test results(non-spherical tank,excluding pressure spike)

Verify the accuracy of CFD

CFDEXP.

Comparison of MOSS(Sphere) & FST

MOSS(SPHERE)FST

Results of CFD SIMULATION

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80

he

igh

t /

tan

k d

iam

ete

r

impulsive pressure [kPa]

FST(CFD)amplitude:4.0m

spherical tank(CFD)amplitude:4.0m

MOSS(Sphere)

FST

Pressure: Same level as Sphere

Impulsive pressure [kPa]

Impulsive pressure [kPa]

Heig

ht

/ T

an

k d

iam

ete

r

Heig

ht

/ T

an

k d

iam

ete

r

Experiment CFD by Exp. model

Comparison : Experiment vs CFD

Analysis accuracy is verified


Sloshing Assessment : Irregular wave excitation by DNV-GL

Screening #1 :Irregular excitation for30min.

Identify Worst Filling Ratio (H/D = 0.6,0.7)

Identify Worst Sea-state (H, T) = (15m,10.5sec)

Screening #2 :Irregular excitation for30min.

Same Volume

Sphere FST

67,500 74,300

66,350 72,490

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

Filling ratio = 0.6 Filling ratio = 0.7

Glo

bal

load

[kN

]

FST MOSS

Slo

sh

ing

lo

ad

[k

N]

Detailed Analysis:Irregular excitation for 120min.

Comparison of Sloshing load (FST vs MOSS)

Sloshing load:

Same level as MOSS(Sphere)

3. Construction Aspect of FST


Development of New Bending process for Torus part

ABC

Sphere: Only one radius

Torus: Radius of A to C are different

Necessity of many bending mold & adjusting bending load→ Lot of Time & Cost for Bending Process of Torus part

MHISB developed the Method of Bending Process by One mold & Uniform bending Load

A

C

B

Meridian dir.

Latitudinal dir.

Latitudinal dir.



Meridian & Latitudinal Radii are different

Different Radii of Latitudinal dir. shall be formed

by One Mold (One radius)

Identify the optimal

Mold property & Bending procedure

FEM Simulation for Press sequence

Lati

tud

inal d

ir.

La

titu

din

al d

ir.

Press Head

Press Bed

Plate

Meridian dir.

Press location

Press

Combination setting:

Mold property

(Press Head & Bed)

Press Load

Sequence of Press

Press headPress bed

Two different radii of Mold to be applied

for Meridian & Latitudinal dir.



Identify the optimal

Mold property & Bending procedure

Press experiment using the 1/20

scaled-down model die (Die A)

Bending for Actual product

Accurate shape for Target

FEM Simulation for Press sequence

(2) Measurement of Formed Shape

by 3D Laser equipment

(1) Press according to FEM simulation

Research for further improvement of

Press accuracy & Shortening time

(3) Re-simulation by using the

results of measurement

(4) Decision of Next Press condition

(5) Press, later repetition of (2) to (5)


Construction Progress

MHISB has received orders for a total of 8 new generation vessels

FST for first vessel in SAYARINGO series : Grand Assembly Completed


CONCLUSIONS

MHISB has developed the Apple-shaped tank (FST) as an upgrade

of the existing MOSS spherical tank.

The design & construction method for FST successfully established.

FST has the following advantage.

Inherit all excellent properties of MOSS spherical tank system

Lower height & Lower center of gravity compared with Conventional MOSS( Spherical tank & Stretched tank)

Possible to design the tank capacity flexibly responding to the need of customers

MHISB will actively continue the development of the new innovative

key technology such as FST, corresponding to the needs of

customers.

Documents

-Shaped Liquefied for - Gastech Barcelona Watanabe... · © 2017 MITSUBISHI HEAVY INDUSTRIES SHIPBUILDING CO., LTD. ... Detailed Analysis:Irregular excitation for 120min. Comparison