group 2: parts and materials tech

GCRC-SOP 2nd Year International Workshop

Project 2-1

Stage 1• Fatigue and Fracture design DB

• Hydroforming of deep sea valves

• HISC welding technologies

• Numerical damage models for

materials

• Friction resistance reduction by

polymer

• 2-1: Reliability and Strength Assessment• 2-3: Welding Tech. for High Strength Mat. • 2-5: Chemical Materials for Drag. Red.

Stage 2• Fatigue and fracture assessment

• Drillship/Rig material manufacturing

• Dissimilar weld joints for offshore

Top-side

• UMAT for material nonlinear

simulation

• Polymer control technology

Stage 3• Optimal design for ships and

offshore plants

• Modular design for core parts

• HISC evaluation for weld joints

• Numerical Testing Bed

• Polymer processing technology

• 2-2: Subsea System Modulization• 2-4: Materials for Extreme Environment

Class NK/University of New Orleans

• 잔류응력 및 용접변형 관리기술

• 노후 구조물 안전성 평가 및 유지보수 기술• 극저온 재료 피로파괴성능평가 기술

Class NK/University of New Orleans

• 잔류응력 및 용접변형 관리기술

• 노후 구조물 안전성 평가 및 유지보수 기술• 극저온 재료 피로파괴성능평가 기술

참여 기업(현대/DSME/삼성/STX/비엔스틸라)

• 핵심기술 공동개발 및 기술인력 양성• 핵심 부품소재 설계 및 가공기술 사업화• 부품소재 신뢰성 및 강도 DB 공동활용

1

Group 2: Parts and Materials Tech.

Project No. 2-1: Reliability and strength assessment of core parts and material system 2

Demand for offshore structure continues to increase in recent years due to the depletion of shallow water resource and environmental issues Development of core design technology in offshore structural system

is needed

Offshore structures operate under deepwater or extreme environment (low temperature, heavy wave) Systematic reliability assessment technology is required to prevent

fatigue and brittle fracture

※ INTSOK Annual Market Report(2010)

Project No. 2-1: Reliability and strength assessment of core parts and material system 3

Fatal accident due to the fatigue fracture in offshore structures

Alexander kielland

• Data : March, 1980

• Location : Ekofisk field, North sea

• Fatalities : 123 persons

Ocean Ranger

• Data : February, 1982

• Location : Hibernia field, North atlantic

• Fatalities : 84 persons

Mandatory fracture toughness assessment for weld zone and HAZ based on standard code [BS 7448, ASTM E1820]

<Alexander L, Kielland, 1980>

4

Reliability and strength assessment of core parts and material system Acquisition of fatigue and fracture assessment DB (2011.09 ~ 2014.02)

• Fatigue strength assessment for low temperature materials

• Investigate for fracture characteristics in offshore structural steels

Development for fatigue fracture analysis method and prediction technology (2014.03 ~ 2017.02)

• Development of advanced fatigue life prediction method

• Development for residual stress/welding distortion control technology

Application of advanced design assessment method for offshore structures (2017.03 ~ 2021.02)

• Development of structural integrity assessment method

• To examine application for large welded structures

Project No. 2-1: Reliability and strength assessment of core parts and material system

• Assessment for fracture toughness in offshorestructural steels

• Investigation of fracture characteristics forHAZ/weld metal at low temperature

5

The second year (2011.9 -2013.2)


• Fatigue assessment for various weldedjoints in LNGC

• Development of advanced fatigueanalysis method

• Acquisition of Design curve for LNG cargo tankusing FEA

Fatigue assessment for low temperature

steel in LNGC

Investigation for fracture characteristics

in offshore structural steels

Acquisition of fatigue and

fracture assessment DB

6

Fatigue assessment for low temperature materials in LNGC Fatigue test for low temperature materials (SUS304L, INVAR)

Fatigue strength assessment for various weld joints in LNGC

Acquisition of design curve for welded joints in LNG cargo tank using FEA

Investigation for fracture characteristics in offshore structural steels Fracture toughness assessment for offshore structural steel

Assessment of fracture characteristics for base metal, HAZ and weld metal

Assessment of 7% nickel steel in LNG cargo tanks Fatigue test, fracture toughness assessment and FCGR for 7% nickel steel

Development of fatigue design methodology for independent tank

Assessment of fracture toughness and fatigue strength at cryogenic temperature


7

Fatigue assessment of heavy plates considering thickness effect Development of fatigue life estimation method considering plate thickness

effect

Evaluation of thickness exponent through fatigue test for T-joint

Development of structural health monitoring system using smart material Direct stress intensity factor measurement during fatigue crack growth

using the MFC sensor

Fatigue life estimation of structure using MFC sensor


8

Results of Topic 1

9

Fatigue assessment for various weld joints in LNGC barrier Sloshing impact and thermal loads Fatigue fracture

Fatigue strength of the structural components such as 1st , 2nd barrier in LNG CCS need to be guaranteed


10Project No. 2-1: Reliability and strength assessment of core parts and material system

The inner tank material for LNG tanks Typical materials for 1st ,2nd barrier at low temperature (SUS304L, INVAR)

These materials need to guarantee excellent mechanical properties under the cryogenic temperature of -163°C

No. 96 TypeMark-Ⅲ Type Moss Type

TypeMembrane Independent

GTT MARK Ⅲ GTT NO96-2 MOSS IHI-SPB

TankMaterial SUS304L Invar steel Al alloy (Al5083)

Thickness 1.2mm 0.7mm 50mm 30mm

Insulationsystem

Material R-PUFPlywood +

PerlitePUF PUF

Thickness 250mm 530mm 250mm 200mm


Assessment of cryogenic fatigue performance for LNG cargo tank Characterization of fatigue strength for 1st ,2nd barrier at cryogenic

temperaturePart Temperature

Primary barrier -163°C

Secondarybarrier -110°C

Mastic -40°C

<1st barrier of Mark Ⅲ type>


Assessment of fatigue strength for various welded joints in LNG cargo tank

INVAR-INVAR joint

SUS304-INVAR joint

INVAR-INVAR joint


Assessment of fatigue strength by hotspot stress approach

<INVAR-INVAR joint>

<SUS304-INVAR joint><INVAR-INVAR lap joint>


Assessment of fatigue strength by Notch stress approach

<INVAR-INVAR joint>

<SUS304-INVAR and INVAR-INVAR lap joint>

15

Results of Topic 2

16

Very thick plates required to offshore structures compared to commercial ships Increase in plate thickness causes decrease of fracture toughness

Strict requirement on the safety and reliability of the offshore structures operating under very extreme conditions Demand to thicker, higher performance, and better toughness


<Offshore structures operating at cryogenic temperature>

Plane stress(Thin)

Plane strain(Thick)

Fra

ctu

re t

ou

gh

nes

s (

)

Plate thickness

17

Assessment for fracture toughness to offshore structural steel based on BS 7448


Notch locations Thickness Width Span length Notch length

WM CGHAZ SCHAZ

76 76 294 33

18

Evaluation of fracture toughness at low temperature The fracture tests were carried out to obtain CTOD value

DBTT of API 2W Gr.50 is

Weld metal : -75°C CGHAZ : -40°C SCHAZ : -60°C

The fracture toughness of API 2W Gr.50 is higher than that of EH40


<DBTT, EH40> <DBTT, API 2W Gr.50>

A well-known general relation between J and CTOD is

ymJ J : J integral

m : Plastic Constraint Factor (PCF)

: Yield strength

: CTODy

[SINTAP Report]

[ASTM E1820]

Comparison of PCFs b/w analytical and experimental values

Analytical PCF is higher than experimental PCF at low temperature

Analytical PCF does not consider characteristic of welding zone

Analytical PCF require calibration considering low temperature and welding zone

21

Results of Topic 3

22

Cleveland, Ohio LNG disaster -1944 Caused by 3.5% Ni steel

Since the disaster, Ni amount has been

increased to 9% from 3.5%

Current 9% Ni for SPB cargo tanks $50 million/tank

25% weld material($12.5million)

Weld material

• KOBE $93,200/ton

• UTP $50,000/ton

Replacing by 7% Ni Decrease of the cost for base metals and weld materials


Fracture characteristic for base metal

23

Fatigue strength assessment of 7% Ni steel

Assessment of fatigue performance characterized by S-N curve

Fatigue strength characterization with respect to various conditions

Evaluation of fatigue crack initiation and propagation characteristics

Characterization of failure modes for base/weld metals


crack initiation

24

Fracture characteristics assessment of 7% Ni steel

Evaluation of fracture toughness of welded joints by CTOD tests

Observation of unstable crack propagation behavior and brittle fracture

Characterization of failure modes for base/weld metals

Investigation of fracture resistance for various welding process


25

Fatigue crack growth rate assessment of 7% Ni steel

Evaluation of fatigue crack growth rate for 7% Ni steel

Fatigue crack growth rate test at Cryogenic temperature

Comparison of fatigue crack growth rate for 7% Ni steel and 9% Ni steel


<da/dN curve for 7% Ni steel> <da/dN curve for 9% Ni steel>

26

Results of Topic 4

27

Thickness effect decreases the fatigue strength for welded structures TR Gurney has proposed thickness exponent 0.25 in 1982


Sref : fatigue strength of plate thickness tref (MPa)tref : reference plate thicknessZ : Thickness exponent

StandardReference

thickness (mm)Thickness exponent

Department of Energy, UK

22 0.25

BS7608 16 0.25

Standards Association of Australia (SAA)

25 0.25

EUROCODE 2 25 0.25

Many standards have used

thickness exponent 0.25

Various welded joints should be considered for calculation of thickness exponent


Investigation of thickness exponent based on various literatures and fatigue test data Reference fatigue test data

(SR202 project, Xial et al., deBack et al., Webster, Vosilovsky, UKOSRP)

PNU fatigue test data

Calculation of thickness exponent for 6 step fatigue life

(100,000 / 500,000 / 1,000,000 / 2,000,000 / 5,000,000 / 10,000,000 cycles)

10 10010

100

1000

100,000 Cycle 500,000 Cycle 1,000,000 Cycle 2,000,000 Cycle 5,000,000 Cycle 10,000,000 Cycle

Fat

igu

e S

tre

ngth

(M

Pa)

Thicness (mm)


105 106 107

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Th

ickn

ess

exp

on

en

t

Cycle

Calculation of thickness exponent considering fatigue life

Thickness exponent for 2,000,000 cycles is similar to IIW thickness

exponent for T-joint

But, thickness exponent decreased as decreasing fatigue life

Cycles Thickness exponent

100,000 0.296

500,000 0.343

1,000,000 0.346

2,000,000 0.384

5,000,000 0.411

10,000,000 0.413

IIW document Thickness correction

As-welded T-joints(proportional joints) subjected to bending load

0.33

30

Results of Topic 5


Structural health monitoring system (SHM) Purpose to inform hazard of ship/offshore structure (fatigue, impact load)

Assessment of structural integrity for welded structures

Fatigue fracture occurs due to exposure to constant fatigue load Increase in importance for fatigue

crack detection technology

Reliable structural integrity evaluation

method is needed

Development of structural health

monitoring system for defect inspection

32

Hull response monitoring systems

Fatigue monitoring sensors

Airgap sensing system

Corrosion monitoring system

Acoustic emissions monitoring sensors

Vibration based damage assessment approaches

Fiber optic sensors

Riser and anchor chain monitoring


Slit

Grating


MFC sensors is used for the real-time measurement of the stress intensity factor The tendency of analytical SIF as growing fatigue crack is similar to

experimental one

The Stress Intensity Factor(SIF) is required for the estimation of fatigue crack propagation life from the Linear Elastic Fracture Mechanics(LEFM)

(Paris law)


Publications International Journal (SCI)

• Total 7 items

Conference Presentation

• Total 8 items

Education MS Graduate

• 6 persons

Ph. D. Graduate

• 1 person

Author Paper Journal

Hyeon-Su Kim,

Min-Sung Chun,

Myung-Hyun Kim,

Jae-Myung Lee

A Comparative Evaluation of Fatigue and Fracture Characteristics of

Structural Components ofLNGC Insulation System

International Journal of

Pressure Vessel Technology

Author Conference Title City Nation

Seong Min Kim,

Jae Myung Lee,

Myung Hyun Kim

SNAME 2011Fatigue Assessment of a Bulk Carrier using the

Mesh-insensitive Structural Stress based on CSRHouston USA

35

Industry-University Liaison Research Grant

• Connector and joint strength assessment of riser (2012.03 ~ 2014.12, PNU-DSME)

• JDP for assessment of 7% Ni steel cargo tank in LNGC and FLNG

(2011.7 ~ 2013.06, PNU-NK,HHI)

• Assessment of fatigue performance of bonded connection structure

(2012.03 ~ 2013.02, PNU-SHI)

• Assessment of high temperature durability for epoxy and PU glue

(2012.09 ~ 2013.02, PNU-SHI)

• Fatigue test for 1st, 2nd barrier of HHI CCS (2011.02 ~ 2013.02, PNU-HHI)

Intellectual Properties Pending

• A Jig for the tensile and fatigue tests of thin plates at the cryogenic temperature

(2011.10)

• Anti-sloshing method using fluid rotation (2011.10)


group 2: parts and materials tech

Documents