Otc-19372 Xhpht Pip Final1

‘Investigation into the Limit State Design of XHPHT PIP Flowlines using

Local and Global Finite Element Analysis Methods’

May 2008

OTC 19372, Houston.

Paul Jukes, Jason Sun, Ayman EltaherJ P Kenny, Inc., Houston, USA.

Overview of Presentation• Introduction :

– Design Challenges

• Limit State Based Design

• SIMULATOR

• Global and Local FEA Models

• Conclusions

Introduction : Design Challenges

• 10,000ft (3000m) WD• Hydrostatic Collapse• Installation Issues

• Pressure 700bar (10,000psi)• Temperatures 177°C (350°F)• High Thermal Performance

Deepwater

HP / HT

• Span Length > 200m (660ft)• Multimode Vibration• Limitations of Design Codes

Super Spans

Introduction : Why Use Advanced FEA?

• Highly Non-linear Problems• Not Possible with Stress Based Design• ‘Added-Value’• Deepwater & HT Solution• Optimize Design Solution• Significant Financial Savings!!

Limit State Based Design

Advanced Analysis Tools

Limit State Based Design

Overview:• Limit States:

– Local Buckling– Hoop Ratcheting– Strain Capacity– Low cycle Fatigue

• Codes/Guidance:– HOTPIPE, DNV OS-F101, – DNV-RP-F110, SAFEBUCK,– API-1111

• Advanced Finite Element Analysis Tools

‘Simulator’ FEA

190

192

194

196

198

200

202

1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100

Distance Along Pipeline [m]

Lat

eral

Pos

ition

[m]

Embedded Boulders


‘Simulator’ Suite

• Tailored Software• ABAQUS FE Engine• Calibrated• Highly non-linear• Single Pipe/PIP

Steel Flowline

Thermal Insulation

Outer Steel Sleeve

Protective Coating

Corrosion Coating

‘Simulator’ Suite Gold Standard

• ‘Gold Standard’ Finite Element Models– Reeling Analysis – Lateral Buckling Analysis – Upheaval Buckling Analysis– Spanning and VIV Analysis – Trawlboard Pullover 180

185

190

195

200

205

1800 1850 1900 1950 2000 2050 2100 2150 2200


Lat

eral

Pos

ition

[m]

190

192

194

196

198

200

202

1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100


Lat

eral

Pos

ition

[m]

Embedded Boulders

‘Simulator’ Suites

Soil Friction Model – User Subroutine

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 1 2 3 4 5 6 7 8 9 10Lateral Movement, in

Fric

tion

Fact

or

Upper Bound

Mean Value

Lower Bound

Examples : Spans and VIV Analysis

Phase 7 Trunkline Free Span Exceeding Fatigue Limits within 25 Year Design Life74

74.5

75

75.5

76

76.5

77

77.5

7828.9 28.9 28.9 28.9 28.9 29.0 29.0 29.0 29.0 29.0 29.1

KP (km)

Wat

er D

epth

(m)

Seabed

Bottom of Pipe (operation condition)

• Detailed Span and VIV Analysis• Modal Analysis• ‘Added Value’

– Reduced Intervention

Examples : Lateral Buckling Simulation

-20

0

20

40

60

80

100

120

350 450 550 650 750 850 950

Pipe Distance, ft

Late

ral D

ispl

acem

ent,

in

36F49F69F80F95F110F120F134F146F165F180F

• Post Buckle Formation• Limit State Based Design• ‘Added Value’• Thermal Buckle Management

Examples : Pipeline Walking Analysis

0

20

40

60

80

100

120

140

160

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Pipe Distance, ft

Tem

pera

ture

, F

0.0844494 [h] 0.250011 [h] 0.416798 [h] 0.583757 [h]0.750233 [h] 0.916866 [h] 1.00023 [h] 1.16706 [h]1.33336 [h] 1.50014 [h] 1.66668 [h] 2.00018 [h]3.00019 [h] 7.00009 [h] 48.0001 [h]

-20

-10

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10

Operating Temperature Cycle

Axi

al D

ispl

acem

ent (

in)

D6D7

+ : From D6 to D7- : From D7 to D6

Examples : Reeling & Lateral Buckling

Overview• Long model

– 250m reeling– 500m lateral

• PIP• Ultimate Limit States.

Pipe

Ramp Aligner

Tensioner

Straightener

Reel

Global and Local FEA Study


180

185

190

195

200

205

1800 1850 1900 1950 2000 2050 2100 2150 2200


Lat

eral

Pos

ition

[m]

‘Global’ PIP FE Model

Loadshare

1,500m (4,921ft)

Spacer, 2m (6ft)Inner Pipe

Outer PipeSleeper

Seabed Friction

Friction Coefficient 0.2

Element Selected

• PIPE31H, 3D Pipe Element– Inner Pipe– Outer Pipe

• ITT31, 3D Tube-to-Tube Contact Element– Spacer

• CONN32, Connector Element– Loadshare– Sleeper– Boundary

‘Local’ Full Size PIP FE Model

Composition of 3D PIP FE Model

• 4-node 3D shell element, S4R– Inner Pipe– Outer Pipe

• 8-node 3D stress element, C3D8R– Spacer– Bulkhead

• Constraint– Spacer to Inner Pipe– Pipeline to Bulkhead

• Interaction/Contact– Spacer to Outer Pipe

Pipeline Data To Build FE Model

0.591 (15.0)0.787 (20.0)Wall Thickness inch (mm)

12.750 (0.324)8.625 (0.219)Diameter inch (m)

490 (7850)490 (7850)Density lb/ft3 (kg/m3)

X70X70Pipeline Material

Outer PipeInner Pipe

Pipe Material & GeometryParameter

• Pipe and Geometry

Pipeline Data To Build FE Model

1.31 x 10-5

(13.1 x 10-6)6.5 x 10-6

(11.7 x 10-6)Coeff. Thermal Expansion

°F-1(°C-1)

72.4 (499)82.7 (570)SMTS ksi (MPa)

61.2 (422)70 (482.6)SMYS ksi (MPa)

0.30.3Poisson Ratio

29.9 x 106 (206)30.0 x 106 (207)Material Modulus psi (GPa)

Temp 350°F(177°C)Temp 68°F(20°C)

Pipe PropertiesParameter• Material and Operating Condition

350 (177)Design Temperature °F (°C)

6,500 psi (44.8 MPa)Inner Pressure MAOP psi (MPa)

40 (4.4)Seabed Temperature °F (°C)

4,500 (1,371.6)Water Depth WD ft (M)

Pipe Operating ConditionParameter

Results


Study Case #1: Straight Pipeline vs. Lateral Buckled Pipeline

Pipeline Buckles with Initial Imperfection

Lateral Buckle Releases Inner Pipe Compression

Inner Pipe Axial Force

-750

-700

-650

-600

-550

-500

-450

-400

-350

-300

2 822 1642 2462 3282 4103

Pipeline Distance (ft)

Axi

al F

orce

(kip

s)

Buckled Axial Force, Inner Pipe Not Buckled Axial Force, Inner Pipe

Local FEA Response

•Pipeline

3D Helix of Inner Pipe Under XHT @350°F (Scale x80)

Inner Pipe Displacement Relative to Outer Pipe(Lateral Direction)

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

356 534 712 890 1069

Distance (ft)

Dis

plac

emen

t (in

)

Local Stress and Strain Response

• Inner Pipe lateral Displacement

3D Helix Observed in Buckled Global PIP Model (Scale x400)

•Data off Buckle Region

3D Helix of Inner Pipe Under XHT (Scale x100)


•Inner Pipe


•Outer Pipe


•Spacer

Full Size PIP FE vs. Global PIP Model

-19.2-21.5-9.3-7.317.919.1Outer Pipe

34.229.1-33.6-36.658.457.0Inner Pipe

3D FEGlobal FE3D FEGlobal FE3D FEGlobal FE

Hoop StressAxial StressVon Mises Stress

Peak Stresses (ksi)Parts

• Good Match between Local (3D) and Global FE Results

Limit State Results : Local Buckling

0.196N/AAPI

0.7440.060DNV, DC

0.9830.922DNV, LC

1,000m (3,050ft)

0.281N/AAPI

0.8030.070DNV, DC

1.0470.964DNV, LC

1,500m (4,920ft)

0.382N/AAPI

0.8670.080DNV, DC

1.1591.008DNV, LC

No Sleeper


Limit State Unity CheckDesign CodeSleeper Intervals

Limit State Results : Hoop Stress Ratcheting

0.8850.9871,000m (3,050ft)

0.9951.0731,500m (4,920ft)

1.0301.125No Sleeper


Limit State Unity Check

Sleeper Intervals

Limit State Results : Strain Capacity

0.1800.1781,000m (3,050ft)

0.3060.2731,500m (4,920ft)

0.2930.279No Sleeper


Limit State Unity Check

Sleeper Intervals

Limit State Results : Low Cycle Fatigue Check

2984341,4892,170Outer

1,9508899,7494,444Inner1,000m (3,050ft)

2103061,0481,528Outer

1,5176927,5863,458Inner1,500m (4,920ft)

1992759441,376Outer

1,3145996,5712,996InnerNo Sleeper

Class FClass DClass FClass D

DNV Factored No. of Cycles

Allowable No. Cycles

PipeSleeper Intervals

Conclusions


Conclusions

• A Global & Local PIP FE model presented

• Local full size PIP FE model,– Pipeline response at component

level• Global and Local FE models present

comparable results• Limit State Based Design• Allows Deepwater XHTHP PIP Designs• Advanced FEA is the way forward!


Thank you!Any Questions?

‘Investigation into the Limit State Design of XHPHT PIP Flowlines using

Local and Global Finite Element Analysis Methods’

May 2008

OTC 19372, Houston.

Paul Jukes, Jason Sun, Ayman EltaherJ P Kenny, Inc., Houston, USA.

Otc-19372 Xhpht Pip Final1

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