SOLUTION ASSIGNMENT #1 (DUE FEBRUARY 9, 2008) · PDF fileEN 8673 Subsea Pipeline Engineering...

ENGI 8673 Subsea Pipeline Engineering Faculty of Engineering and Applied Science

Shawn Kenny, Ph.D., P.Eng. Winter 2009

Assignment #1 of 16

SOLUTION ASSIGNMENT #1 (DUE: FEBRUARY 9, 2008) Problem 1-1 Calculate the unfactored hoop stress for a 406.4 mm (16“) nominal outside diameter pipeline with D/t ratios (15, 20, 25, 30, 35, 40 45) using Barlow, Thin Wall and Lamé’s equations for the following conditions:

(a) Internal pressure of 10 MPa and external pressure of 0 MPa [5]

Unfactored Hoop Stress Do t Di Pi Pe

Barlow Thin Wall Lamé - Di Lamé - Do

(mm)

D/t

(mm) (mm) (MPa) (MPa) (MPa) (MPa) (MPa) (MPa)

406.4 15 27.1 352.2 10 0 75 65 70 60

406.4 20 20.3 365.8 10 0 100 90 95 85

407.4 25 16.3 374.8 10 0 125 115 120 110

408.4 30 13.6 381.2 10 0 150 140 145 135

409.4 35 11.7 386.0 10 0 175 165 170 160

410.4 40 10.3 389.9 10 0 200 190 195 185

(b) Internal pressure of 10 MPa and external pressure in 200 m water depth assuming gravitional

constant of 10 m/s2 and water density of 1000 kg/m3. [5]

Unfactored Hoop Stress Do t Di Pi Pe

Barlow Thin Wall Lamé - Di Lamé - Do

(mm)

D/t

(mm) (mm) (MPa) (MPa) (MPa) (MPa) (MPa) (MPa)

406.4 15 27.1 352.2 10 2 75 50 54 46

406.4 20 20.3 365.8 10 2 100 70 74 66

407.4 25 16.3 374.8 10 2 125 90 94 86

408.4 30 13.6 381.2 10 2 150 110 114 106

409.4 35 11.7 386.0 10 2 175 130 134 126

410.4 40 10.3 389.9 10 2 200 150 154 146



Assignment #1 of 16

(c) Is the Barlow stress equation conservative or unconservative? [5] Barlow's equation is conservative and neglects the beneficial effects of external pressure on reducing the net hoop stress for pressurized pipeline.

(d) What specific characteristic can be observed for the hoop stress calculated using thin wall theory in comparison with Lamé’s equation? [5] Thin wall theory predicts the mean (average) stress relative to the Lamé stress calculation for the inner and outer pipeline surface.



Assignment #1 of 16

Problem 1-2 Consider a thick-walled pipeline with a 406.4 mm (16“) nominal outside diameter and 20.3 mm wall thickness. Use Lamé’s equation to plot the distribution of tangential stress and radial stress as a function of the pipeline wall thickness using the dimensionless ratio (r/a) for the following load cases:

(a) Internal overpressure where Pi = 20MPa and Pe = 10MPa [10]

(b) External overpressure where Pi = 10MPa and Pe = 20MPa [10]

Use 10 data points through thickness. Compare with the results from thin wall theory.



Assignment #1 of 16

Problem 1-3 A jacket platform is located in 50m water depth. The 609.6mm diameter pipeline, with an initial assumed 14.1mm wall thickness and 50mm concrete weight coating, connects the subsea manifold to the production facility. The total pipeline length is 50km. The pipeline profile is schematically illustrated in the following figure. The offshore linepipe is DSAW grade 450 and has a density of 7850kg/m3. The pipeline has concrete weight coating with a density of 3050 kg/m3. The corrosion allowance is 3mm. The design pressure is 13.5MPag and referenced at the topside tie-in flange with an elevation of 25m at mean sea level (MSL). Assume the inlet temperature at the subsea tie-in with the manifold of 100°C is constant along the pipeline length. The oil has an API of 38°, viscosity of 10 centipoise and wax appearance temperature of 20°C. The oil density (kg/m3) can be determined by the expression

ρ = 1000 kgm3

141.5131.5 + API

⎛⎝⎜

⎞⎠⎟

(a) Does the pipeline have negative buoyancy? Assume the water density is 1025 kg/m3. [5]

Yes.

(b) At points B and C, are wall thickness requirements for pressure containment met? [15] No for locations A, B and C. (Solution after part c) Note: Based on DNV OS F101 (2000) only Point A and B would fail the WT check for operations as the fabrication tolerance was 0.75mm. Based on the DNV OS F101 2000 version the beneficial effect of external pressure would meet the WT design check. Based on DNV OS F101 (2007), the water depth required to satisfy the design check is ~600m.

(c) At points B and C, are wall thickness requirements for system test pressure met? [10] Yes

EN 8673 Subsea Pipeline Engineering Assignment #2Problem #3

Winter 2009

Assignment #2 Problem #3 Point B (-25m Water Depth)

DEFINED UNITS

MPa 106Pa kPa 10

3Pa GPa 10

9Pa C K kN 10

3N

PIPELINE SYSTEM PARAMETERS

Nominal Outside Diameter Do 609.6mm

Initial Selection Nominal Wall Thickness (Sec.5 C203 Table 5-3) tnom 14.1mm

Fabrication Process (Sec.7 B300 Table 7-1) [SMLS, HFW, SAW] FAB "SAW"

Corrosion Allowance (Sec.6 D203) tcorr 3mm

Elastic Modulus E 205GPa

Specified Minimum Yield Stress (Sec.7 B300 Table 7-5) SMYS 450MPa

Speciifed Minimum Tensile Stress (Sec.7 B300 Table 7-5) SMTS 535MPa

Coefficient of Thermal Expansion αT 1.15 105

C1

Poisson's Ratio ν 0.3

Pipeline Route Length Lp 10km

Linepipe Density ρs 7850kg m3

Concrete Coating Thickness tc 50mm

Concrete Coating Density ρc 3050kg m3

OPERATATIONAL PARAMETERS

API Gravity API 38

Product Contents Density

ρcont 1000 kg m3

141.5

131.5 API ρcont 835 m

3kg

Design Pressure (Gauge) Pd 13.5MPa

Safety Class (Sec.2 C200-C400) [L, M, H] SC "M"

Design Pressure Reference Level href 25m

Operational Temperature To 100 C

Tie-in Temperature Tti 0 C

Maximum Water Depth hl 75 m

Seawater Density ρw 1025kg m3

Hydrotest Fluid Density ρt 1025kg m3

09/02/2009 Page 1 of 5


Winter 2009

DNV OS-F101 PARTIAL FACTORS AND DESIGN PARAMETERS

System Operations Incidental/Design Pressure Factor (Sec.3 B304) γinc_o 1.10

System Test Incidental/Design Pressure Factor (Sec.3 B304) γinc_t 1.00

Material Resistance Factor (Sec.5 C205 Table 5-4) γm 1.15

Safety Class Resistance Factor - Operations (Sec.5 C206 Table 5-5) γSC_o 1.138

Safety Class Resistance Factor - System Test (Sec.5 C206 Table 5-5) γSC_t 1.046

Material Strength Factor (Sec.5 C306 Table 5-6) αU 0.96

Maximum Fabrication Factor (Sec.5 C307 Table 5-7)

αfab 1.00 FAB "SMLS"=if

0.93 FAB "HFW"=if

0.85 FAB "SAW"=if

αfab 0.85

Diameter Fabrication Tolerance(Sec.7 G200 Table 7-17)

ΔDo max 0.5mm 0.0075 Do FAB "SMLS"= Do 610mmif

0.01 Do FAB "SMLS"= Do 610mmif

min max 0.5mm 0.0075 Do 3.2mm FAB "HFW"= Do 610mmif

min 0.005 Do 3.2mm FAB "HFW"= Do 610mmif

min max 0.5mm 0.0075 Do 3.2mm FAB "SAW"= Do 610mmif

min 0.005 Do 3.2mm FAB "SAW"= Do 610mmif

ΔDo 3.200 mm

Wall Thickness Fabrication Tolerance(Sec.7 G307 Table 7-18)

tfab 0.5mm FAB "SMLS"= tnom 4mmif

0.125 tnom FAB "SMLS"= tnom 4mmif



3mm FAB "SMLS"= tnom 30mmif

0.4mm FAB "HFW"= tnom 6mmif



0.5mm FAB "SAW"= tnom 6mmif




tfab 1.000 mm

09/02/2009 Page 2 of 5


Winter 2009

Material Derating (Sec.5 C300 Figure 2)

ΔSMYS 0MPa To 50Cif

To 50 C 30MPa

50 C

50 C To 100Cif

30MPa To 100 C 40MPa

100 C

otherwise

ΔSMYS 30.00 MPa

ΔSMTS 0MPa To 50Cif

To 50 C 30MPa

50 C

50 C To 100Cif


100 C

otherwise

ΔSMYS 30.00 MPa

fy SMYS ΔSMYS( ) αU fy 403 MPa

fu SMTS ΔSMTS( ) αU fu 485 MPa

09/02/2009 Page 3 of 5


Winter 2009

ENGINEERING ANALYSIS

PIPELINE GEOMETRIC PROPERTIES

Astπ

4Do

2Do 2 tnom 2

Ast 2.64 10

4 mm

2

Acπ

4Do 2 tc 2 Do

2

Ac 1.04 10

5 mm

2

Apπ

4Do 2 tc 2 Ap 3.95 10

5 mm

2

BUOYANCY FORCE CALCULATION

BF g m ρw Ap ρc Ac ρs Ast BF 1.15 kN

Buoyancy Force Check

BFchk "NEGATIVE BUOYANCY" BF 0if

"FLOTATION" otherwise

BFchk "NEGATIVE BUOYANCY"

PRESSURE CONTAINMENT (Sec.5 D200)

Local Incidental Pressure During Operations (Sec.4 B202; Sec.5 D203)

Pli γinc_o Pd ρcont g href hl Pli 15.67 MPa

Local Incidental Pressure System Test (Sec.4 B202; Sec.5 B203 & D203)

Plt γinc_t Pd ρt g href hl γinc_t Pd ρt g href hl Pliif

1.03 Pli SC "L"=if

1.05 Pli SC "M"=if

1.05 Pli SC "H"=if

Plt 16.45 MPa

External Hydrostatic Pressure

Pe ρw g hl Pe 0.75 MPa

Characteristic Yield Resistance - Operations (Sec.5 D203)

fcb_o min fy

fu

1.15

fcb_o 403.20 MPa

Characteristic Yield Resistance - System Test (Sec.5 D203)

fcb_t min SMYSSMTS

1.15

fcb_t 450.00 MPa

09/02/2009 Page 4 of 5


Winter 2009

Wall Thickness Requirement - Operations (Sec.5 D202 Eqn.5.7)

t1_o

Do

12

γSC_o γm Pli Pe

2

3 fcb_o

t1_o 12.52 mm

Minimum Wall Thickness - Operations (Sec.5 C202 Table 5-2)

tmin_o t1_o tfab tcorr tmin_o 16.52 mm

Wall Thickness Requirement - System Test (Sec.5 D202 Eqn.5.7)

t1_t

Do

12

γSC_t γm Plt Pe

2

3 fcb_t

t1_t 10.88 mm

Minimum Wall Thickness - System Test (Sec.5 C202 Table 5-2)

tmin_t t1_t tfab tmin_t 11.88 mm

Minimum Wall Thickness Requirement for Pressure Containment

tmin max tmin_o tmin_t tmin 16.52 mm

WALL THICKNESS DESIGN CHECK - PRESSURE CONTAINMENT

Wall Thickness Check - Pressure Containment

tmin_chk_o "WT PRESSURE CONTAINMENT OPERATIONS OK" tnom tmin_oif

"INCREASE WT PRESSURE CONTAINMENT OPERATIONS" otherwise

tmin_chk_o "INCREASE WT PRESSURE CONTAINMENT OPERATIONS"

Wall Thickness Check - System Test

tmin_chk_t "WT PRESSURE CONTAINMENT SYSTEM TEST OK" tnom tmin_tif

"INCREASE WT PRESSURE CONTAINMENT SYSTEM TEST" otherwise

tmin_chk_t "WT PRESSURE CONTAINMENT SYSTEM TEST OK"

09/02/2009 Page 5 of 5


Winter 2009

Assignment #2 Problem #3 Point C (-750m Water Depth)

DEFINED UNITS

MPa 106Pa kPa 10

3Pa GPa 10

9Pa C K kN 10

3N

PIPELINE SYSTEM PARAMETERS

Nominal Outside Diameter Do 609.6mm

Initial Selection Nominal Wall Thickness (Sec.5 C203 Table 5-3) tnom 14.1mm

Fabrication Process (Sec.7 B300 Table 7-1) [SMLS, HFW, SAW] FAB "SAW"

Corrosion Allowance (Sec.6 D203) tcorr 3mm

Elastic Modulus E 205GPa

Specified Minimum Yield Stress (Sec.7 B300 Table 7-5) SMYS 450MPa

Speciifed Minimum Tensile Stress (Sec.7 B300 Table 7-5) SMTS 535MPa

Coefficient of Thermal Expansion αT 1.15 105

C1

Poisson's Ratio ν 0.3

Pipeline Route Length Lp 10km

Linepipe Density ρs 7850kg m3

Concrete Coating Thickness tc 50mm

Concrete Coating Density ρc 3050kg m3

OPERATATIONAL PARAMETERS

API Gravity API 38

Product Contents Density

ρcont 1000 kg m3

141.5

131.5 API ρcont 835 m

3kg

Design Pressure (Gauge) Pd 13.5MPa

Safety Class (Sec.2 C200-C400) [L, M, H] SC "M"

Design Pressure Reference Level href 25m

Operational Temperature To 100 C

Tie-in Temperature Tti 0 C

Maximum Water Depth hl 750 m

Seawater Density ρw 1025kg m3

Hydrotest Fluid Density ρt 1025kg m3

19/02/2009 Page 1 of 5


Winter 2009

DNV OS-F101 PARTIAL FACTORS AND DESIGN PARAMETERS

System Operations Incidental/Design Pressure Factor (Sec.3 B304) γinc_o 1.10

System Test Incidental/Design Pressure Factor (Sec.3 B304) γinc_t 1.00

Material Resistance Factor (Sec.5 C205 Table 5-4) γm 1.15

Safety Class Resistance Factor - Operatiosn (Sec.5 C206 Table 5-5) γSC_o 1.138

Safety Class Resistance Factor - System Test (Sec.5 C206 Table 5-5) γSC_t 1.046

Material Strength Factor (Sec.5 C306 Table 5-6) αU 0.96

Maximum Fabrication Factor (Sec.5 C307 Table 5-7)

αfab 1.00 FAB "SMLS"=if

0.93 FAB "HFW"=if

0.85 FAB "SAW"=if

αfab 0.85

Diameter Fabrication Tolerance(Sec.7 G200 Table 7-17)

ΔDo max 0.5mm 0.0075 Do FAB "SMLS"= Do 610mmif

0.01 Do FAB "SMLS"= Do 610mmif

min max 0.5mm 0.0075 Do 3.2mm FAB "HFW"= Do 610mmif

min 0.005 Do 3.2mm FAB "HFW"= Do 610mmif

min max 0.5mm 0.0075 Do 3.2mm FAB "SAW"= Do 610mmif

min 0.005 Do 3.2mm FAB "SAW"= Do 610mmif

ΔDo 3.200 mm

Wall Thickness Fabrication Tolerance(Sec.7 G307 Table 7-18)

tfab 0.5mm FAB "SMLS"= tnom 4mmif




3mm FAB "SMLS"= tnom 30mmif








tfab 1.000 mm

19/02/2009 Page 2 of 5


Winter 2009

Material Derating (Sec.5 C300 Figure 2)

ΔSMYS 0MPa To 50Cif

To 50 C 30MPa

50 C

50 C To 100Cif


100 C

otherwise

ΔSMYS 30.00 MPa

ΔSMTS 0MPa To 50Cif

To 50 C 30MPa

50 C

50 C To 100Cif


100 C

otherwise

ΔSMYS 30.00 MPa

fy SMYS ΔSMYS( ) αU fy 403 MPa

fu SMTS ΔSMTS( ) αU fu 485 MPa

19/02/2009 Page 3 of 5


Winter 2009

ENGINEERING ANALYSIS

PIPELINE GEOMETRIC PROPERTIES

Astπ

4Do

2Do 2 tnom 2

Ast 2.64 10

4 mm

2

Acπ

4Do 2 tc 2 Do

2

Ac 1.04 10

5 mm

2

Apπ

4Do 2 tc 2 Ap 3.95 10

5 mm

2

BUOYANCY FORCE CALCULATION

BF g m ρw Ap ρc Ac ρs Ast BF 1.15 kN

Buoyancy Force Check

BFchk "NEGATIVE BUOYANCY" BF 0if

"FLOTATION" otherwise

BFchk "NEGATIVE BUOYANCY"

PRESSURE CONTAINMENT (Sec.5 D200)

Local Incidental Pressure During Operations (Sec.4 B202; Sec.5 D203)

Pli γinc_o Pd ρcont g href hl Pli 21.19 MPa

Local Incidental Pressure System Test (Sec.4 B202; Sec.5 B203 & D203)

Plt γinc_t Pd ρt g href hl γinc_t Pd ρt g href hl Pliif

1.03 Pli SC "L"=if

1.05 Pli SC "M"=if

1.05 Pli SC "H"=if

Plt 22.25 MPa

External Hydrostatic Pressure

Pe ρw g hl Pe 7.54 MPa

Characteristic Yield Resistance - Operations (Sec.5 D203)

fcb_o min fy

fu

1.15

fcb_o 403.20 MPa

Characteristic Yield Resistance - System Test (Sec.5 D203)

fcb_t min SMYSSMTS

1.15

fcb_t 450.00 MPa

19/02/2009 Page 4 of 5


Winter 2009

Wall Thickness Requirement - Operations (Sec.5 D202 Eqn.5.7)

t1_o

Do

12

γSC_o γm Pli Pe

2

3 fcb_o

t1_o 11.48 mm

Minimum Wall Thickness -Operations (Sec.5 C202 Table 5-2)

tmin_o t1_o tfab tcorr tmin_o 15.48 mm

Wall Thickness Requirement - System Test (Sec.5 D202 Eqn.5.7)

t1_t

Do

12

γSC_t γm Plt Pe

2

3 fcb_t

t1_t 10.21 mm

Minimum Wall Thickness - System Test (Sec.5 C202 Table 5-2)

tmin_t t1_t tfab tmin_t 11.21 mm

Minimum Wall Thickness Requirement for Pressure Containment

tmin max tmin_o tmin_t tmin 15.48 mm

WALL THICKNESS DESIGN CHECK - PRESSURE CONTAINMENT

Wall Thickness Check - Pressure Containment

tmin_chk_o "WT PRESSURE CONTAINMENT OPERATIONS OK" tnom tmin_oif

"INCREASE WT PRESSURE CONTAINMENT OPERATIONS" otherwise

tmin_chk_o "INCREASE WT PRESSURE CONTAINMENT OPERATIONS"

Wall Thickness Check - System Test

tmin_chk_t "WT PRESSURE CONTAINMENT SYSTEM TEST OK" tnom tmin_tif

"INCREASE WT PRESSURE CONTAINMENT SYSTEM TEST" otherwise

tmin_chk_t "WT PRESSURE CONTAINMENT SYSTEM TEST OK"

19/02/2009 Page 5 of 5



Assignment #1 of 16

Problem 1-4 Consider the following offshore single-phase natural gas pipeline system located outside the 500m excursion zone.

Pipeline diameter 914.4mm Linepipe grade 450 Linepipe fabrication UOE Initial ovality 0.01 Water density 1025kg/m3

(a) Illustrate graphically the variation in the collapse pressure, propagating pressure and allowable

external pressure as a function of the nominal D/t ratio (20, 25, 30, 35, 40 and 45) for the installation case with pmin = 0. [10]

0

10

20

30

40

50

60

20 25 30 35 40 45

Pre

ss

ure

(M

Pa

)

D/t1

Elastic Collapse Pressure

[5.11]

Plastic Collapse Pressure

[5.12]

Characteristic Collapse

Pressure [13.13]

Allowable External Collapse

Pressure [5.14]

Propagating Pressure [5.16]

Allowable External

Propagation Pressure [5.15]



Assignment #1 of 16

(b) As a function of D/t ratio (20, 25, 30, 35, 40 and 45) compare the collapse pressure and propagation pressure predicted by Langner (1999) ) OTC 10711 with DNV OS-F101. [15]

(c) If the numerical procedures of Langner (1999) were used in the analysis rather than DNV OS-F101, would the design be comparatively conservative? (Yes or No). [5] Langner solution would be non-conservative for collapse pressure and propagation pressure in comparison with DNV OS-F101.

0

5

10

15

20

25

30

35

40

20 25 30 35 40 45

Pre

ss

ure

(M

Pa

)

D/t1

Characteristic Collapse

Pressure [13.13]

Collapse Pressure Langner [1]

Propagating Pressure [5.16]

Propagation Pressure Langner

[2]

SOLUTION ASSIGNMENT #1 (DUE FEBRUARY 9, 2008) · PDF fileEN 8673 Subsea Pipeline Engineering...

Documents

Transcript of SOLUTION ASSIGNMENT #1 (DUE FEBRUARY 9, 2008) · PDF fileEN 8673 Subsea Pipeline Engineering...