Shawn Kenny, Ph.D., P.Eng.Assistant ProfessorFaculty of
Engineering and Applied ScienceMemorial University of
[email protected] 8673 Subsea Pipeline
EngineeringLecture 16:Bottom Roughness2ENGI 8673 Subsea Pipeline
Engineering Lecture 16 2008 S. Kenny, Ph.D., P.Eng.Lecture 16
Objective to examine engineering analysis methods to evaluate
pipeline mechanical response with respect to bottom roughness3ENGI
8673 Subsea Pipeline Engineering Lecture 16 2008 S. Kenny, Ph.D.,
P.Eng.On-Bottom Roughness Mechanical Design Calculation
InputPipeline configurationSeabed roughness (profile)Pipeline
heading alignment Load CasesAs-laidFloodedHydrotestOperations
OutputPipeline stress & strain responseSpan length &
heightPre-lay & post-lay intervention assessmentRef: Hansen
(2005), Langley (2005)4ENGI 8673 Subsea Pipeline Engineering
Lecture 16 2008 S. Kenny, Ph.D., P.Eng.On-Bottom Roughness (cont.)
Mechanical Analysis Internal pressure, axial load, and momentWater
DepthEffectiveForceBending Moment5ENGI 8673 Subsea Pipeline
Engineering Lecture 16 2008 S. Kenny, Ph.D., P.Eng.On-Bottom
Roughness (cont.) Design Criteria and Code Checks?6ENGI 8673 Subsea
Pipeline Engineering Lecture 16 2008 S. Kenny, Ph.D.,
P.Eng.Pipeline Span Free Body Diagram Location of
maximumstress?Ref: Mousselli (1981)7ENGI 8673 Subsea Pipeline
Engineering Lecture 16 2008 S. Kenny, Ph.D., P.Eng.Pipeline Span
(cont.) Maximum Stress, mRef: Mousselli (1981)8ENGI 8673 Subsea
Pipeline Engineering Lecture 16 2008 S. Kenny, Ph.D.,
P.Eng.Pipeline Span (cont.) MidspanStress, oRef: Mousselli
(1981)9ENGI 8673 Subsea Pipeline Engineering Lecture 16 2008 S.
Kenny, Ph.D., P.Eng.Pipeline Span (cont.) MidspanDeflection, Ref:
Mousselli (1981)10ENGI 8673 Subsea Pipeline Engineering Lecture 16
2008 S. Kenny, Ph.D., P.Eng.Pipeline Span (cont.) Induced Span,
lRef: Mousselli (1981)11ENGI 8673 Subsea Pipeline Engineering
Lecture 16 2008 S. Kenny, Ph.D., P.Eng.Example 16-01 For the
following pipeline system, calculate the maximum stress,
midspanstress, midspan deflection and induced span length for an
observed span length of155m and an effective residual lay tension
of 85kN.EN 8673 Subsea Pipeline Engineering Lecture 15Example
15-01Winter 2008Example 16-01Calculate themaximum stress, midspan
stress, midspan deflection and induced span length.DEFINED UNITSMPa
106Pa := kPa 103Pa := GPa 109Pa := C K := kN 103N :=PIPELINE SYSTEM
PARAMETERSNominal Outside DiameterDo609.6mm :=Initial Selection
Nominal Wall Thickness (Sec.5 C203 Table 5-3)tnom22.2mm :=External
Corrosion Protection Coating Thicknesstcpc0mm :=Fabrication Process
(Sec.7 B300 Table 7-1) [SMLS, HFW, SAW]FAB "SMLS" :=Corrosion
Allowance (Sec.6 D203)tcorr3mm :=Elastic ModulusE 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 ExpansionT1.15105 C1 :=Poisson's
Ratio 0.3 :=Pipeline Route LengthLp25km :=Linepipe Densitys7850kgm3
:=Concrete Coating Thicknesstc0mm :=Concrete Coating
Densityc3050kgm3 :=Effective TensionTeff85kN :=OPERATATIONAL
PARAMETERSAPI GravityAPI 38 :=Product Contents Densitycont1000kg m3
141.5131.5 API + := cont835m3 kg =Design Pressure (Gauge)Pd10MPa
:=Safety Class (Sec.2 C200-C400) [L, M, H]SC "M" :=Design Pressure
Reference Levelhref10m :=Temperature DifferentialT 45C :=Maximum
Water Depthhl1000 m :=Seawater Densityw1025kgm3 :=Hydrotest Fluid
Densityt1025kgm3 :=3/6/2008 Page 1 of 5EN 8673 Subsea Pipeline
Engineering Lecture 15Example 15-01Winter 2008DNV OS-F101 PARTIAL
FACTORS AND DESIGN PARAMETERSSystem Operations Incidental/Design
Pressure Factor (Sec.3 B304) inc_o1.10 :=System Test
Incidental/Design Pressure Factor (Sec.3 B304) inc_t1.00 :=Material
Resistance Factor (Sec.5 C205 Table 5-4) m1.15 :=Safety Class
Resistance Factor (Sec.5 C206 Table 5-5) SC1.138 :=Material
Strength Factor (Sec.5 C306 Table 5-6) U0.96 :=Maximum Fabrication
Factor (Sec.5 C307 Table 5-7)fab1.00 FAB "SMLS" = if0.93 FAB "HFW"
= if0.85 FAB "SAW" = if:= fab1.00 =Diameter Fabrication
Tolerance(Sec.7 G200 Table 7-17)Domax 0.5mm0.0075Do ,( ) FAB "SMLS"
= Do610mm if0.01Do FAB "SMLS" = Do610mm > ifmin max
0.5mm0.0075Do ,( ) 3.2mm ,( ) FAB "HFW" = Do610mm ifmin 0.005Do
3.2mm ,( ) FAB "HFW" = Do610mm > ifmin max 0.5mm0.0075Do ,( )
3.2mm ,( ) FAB "SAW" = Do610mm ifmin 0.005Do 3.2mm ,( ) FAB "SAW" =
Do610mm > if:= Do4.572mm =Wall Thickness Fabrication
Tolerance(Sec.7 G307 Table 7-18)tfab0.5mm FAB "SMLS" = tnom4mm
if0.125tnom FAB "SMLS" = tnom4mm > if0.125tnom FAB "SMLS" =
tnom10mm if0.100tnom FAB "SMLS" = tnom25mm if3mm FAB "SMLS" =
tnom30mm if0.4mm FAB "HFW" = tnom6mm if0.7mm FAB "HFW" = tnom6mm
> if1.0mm FAB "HFW" = tnom15mm > if0.5mm FAB "SAW" = tnom6mm
if0.7mm FAB "SAW" = tnom6mm > if1.0mm FAB "SAW" = tnom10mm >
if1.0mm FAB "SAW" = tnom20mm > if:= tfab2.775mm =3/6/2008 Page 2
of 5EN 8673 Subsea Pipeline Engineering Lecture 15Example
15-01Winter 2008Material Derating (Sec.5 C300 Figure 2)SMYS 0MPa T
50C < ifT 50C ( )30MPa50C 50C T < 100C < if30MPa T 100C (
)40MPa100C +otherwise:= SMYS 0.00MPa =SMTS 0MPa T 50C < ifT 50C
( )30MPa50C 50C T < 100C < if30MPa T 100C ( )40MPa100C
+otherwise:= SMYS 0.00MPa =fySMYS SMYS ( ) U := fy432MPa =fuSMTS
SMTS ( ) U := fu514MPa =ENGINEERING ANALYSISPIPELINE GEOMETRIC
PROPERTIESInside Pipeline Diameter (Operations Case)Di_oDo2. tcorr
2. tfab := Di_o598.05mm =Inside Pipeline Radius (Operations
Case)Ri_o0.5Di_o := Ri_o299.02mm =Effective Outside Pipeline
DiameterDeDo2. tcpc + 2. tc + := De609.60mm =Pipeline Steel
AreaAst4Do2Do2tnom ( )2 := Ast4.10 104 mm2 =Concrete AreaAc4Do2tc +
( )2Do2 := Ac0.00mm2 =Effective Outside Pipeline AreaAe4Do2tc + (
)2 := Ae2.92 105 mm2 =Inside Pipeline AreaAi4Di_o2 := Ai2.81 105
mm2 =3/6/2008 Page 3 of 5EN 8673 Subsea Pipeline Engineering
Lecture 15Example 15-01Winter 2008Pipelne Steel Moment of
InertiaIst64Do4Di_o4 := Ist4.99 104 m4=BUOYANCY FORCE (per meter
basis)BF gm wAe cAc sAst ( ) := BF 0.22 kN =Buoyancy Force
CheckBFchk"NEGATIVE BUOYANCY" BF 0 < if"FLOTATION" otherwise:=
BFchk"NEGATIVE BUOYANCY" =External Hydrostatic PressurePewg hl :=
Pe10.05MPa =DIMENSIONLESS PARAMETERS (Mousselli,
1981)Characteristic LengthLcE IstBF 1m13:= Lc77.5m =Characteristic
StresscE 0.5Do ( ) Lc:= c806MPa =Dimensionless TensionT_effTeffBF
1m Lc:= T_eff5.0 =Dimensionless SpanLL_Lc155mLc:= LL_Lc2.00
=MAXIMUM BENDING STRESSDimensionless Bending Stress Factor m_c0.19
:=Maximum Bending Stressmaxm_c c := max153MPa =3/6/2008 Page 4 of
5EN 8673 Subsea Pipeline Engineering Lecture 15Example 15-01Winter
2008MIDSPAN BENDING STRESSDimensionless Bending Stress
Factoro_c0.11 :=Midspan Bending Stressmido_c c := mid89MPa =MIDSPAN
DEFLECTIONDimensionless Deflection Factor_Lc0.0375 :=Midspan
Deflectionmid_LcLc := mid2.9m =INDUCED SPAN DEFLECTIONDimensionless
Induced Span Factorl_Lc0.82 :=Midspan Deflectionindl_LcLc :=
ind63.5m =EQUIVALENT STRESS CHECKeqh2h l l2+ := heqMPa =
eqeqchk"EQUIVALENT STRESS OK" eq0.9SMYS < if"INCREASE WALL
THICKNESS" otherwise:= eqeqchk = eqchk3/6/2008 Page 5 of 517ENGI
8673 Subsea Pipeline Engineering Lecture 16 2008 S. Kenny, Ph.D.,
P.Eng.Pipeline Obstruction Free Body DiagramRef: Mousselli
(1981)18ENGI 8673 Subsea Pipeline Engineering Lecture 16 2008 S.
Kenny, Ph.D., P.Eng.Pipeline Obstruction (cont.) Span, LRef:
Mousselli (1981)19ENGI 8673 Subsea Pipeline Engineering Lecture 16
2008 S. Kenny, Ph.D., P.Eng.Pipeline Obstruction (cont.) Maximum
Stress, mRef: Mousselli (1981)20ENGI 8673 Subsea Pipeline
Engineering Lecture 16 2008 S. Kenny, Ph.D., P.Eng.References
Chaudhuri, Jand Nash, I. (2005). Medgaz: the ultra-deep pipeline.
Pipeline World, J une, 10p. DNV (2007). Submarine Pipeline Systems.
Offshore Standard, DNV OS-F101, October 2007, 240p. Hansen, B.
(2005). How Hydros Ormen Lange Project Can Contribute to the
Development of the Russian Arctic. Proc., IBC Arctic Oil and Gas
Development Conference, Challenges and Opportunities The Technology
Solution, London, UK. Langley, D. (2005). A Resourceful Industry
Lands the Serpent, J ournal of Petroleum Technology, 57(10), 6p.
Mousselli, A. (1981). Offshore pipeline design, analysis and
methods. ISBN 0-87814-156-1
