SUPFLEX FPSO Mooring

Design FPSO SMS for offshore 8-meter height wave Superflex TSB model has completed the design and produce GSB42080 Connect Head for (Floating Production Storage and Permanently Offloading offshore FPSO spread mooring systems). Superflex special offers FPSO TSB mooring systems with 50 years limited warranty.

Why and how the Superflex TSB420080, was able during storm turbulent still make the FPSO spread mooring systems line, with safe taut stiffness soft mooring systems landing, during the offshore 8-meter height wave shock force. The first Hydrostar Ariane analysis calculation report: as below pages.

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Superflex Mooring Analysis Wave Load of FPSO

1) Calculation Theory

The FPSO hydrodynamic coefficients and wave exciting forces in incident harmonic waves are calculated by the commercial Hydrostar package, which is a standard 3D radiant-diffraction panel software for wave-body interactions, and the mooring load of lines are calculated by the commercial Ariane package developed by Bureau Veritas.

2) Calculation Conditions

2.1 Principle dimensions of FPSO

Table.1 Principle Dimensions of FPSO
Unitvalue
Lppm300
Breadth MLDm75
Depth MLDm33
Draughtm23.4
Displacementm3427568

2.2 Hydrodynamic Coefficient of FPSO

1) Global axis system

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Fig.1 Global Axis System

Where,

  • C is the origin of the global axis system;
  • CN is positive northward;
  • CE is positive eastward;
  • CZ is positive downwards;
  • CNE is in the plane of the still water level.

2) Meshing of FPSO

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Fig.2 Meshing of FPSO

The numerical coordinate system of FPSO is set on the free surface, and the COG of FPSO in Global axis system is (1.7,0,-11.2)

2.2.1 First Order Excitaytion Load

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Fig. 3 First Order Excitation Load of Fx

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Fig. 4 First Order Excitation Load of Fy

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Fig. 5 First Order Excitation Load of Fz

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Fig. 6 First Order Excitation Load of Mx

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Fig. 7 First Order Excitation Load of My

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Fig. 8 First Order Excitation Load of Mz

2.2.2 Quadratic Transfer Function

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Fig. 9 First Order Excitation Load of Fx

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Fig. 10 Second-Order Difference-Frequency Load Fy

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Fig. 11 Second-Order Difference-Frequency Load Fz

2.2.3 Mean Draft Load

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Fig. 12 Mean Drift Load Fx

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Fig. 13 Mean Drift Load Fy

2.2.4 Radiation Coefficient

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Fig. 14 Add-Mass Coefficient (Surge-Surge\Sway-Sway\Heave-Heave)

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Fig. 15 Add-Mass Coefficient (Roll-Roll\Pitch-Pitch\Yaw-Yaw)

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Fig. 16 Radiation-Damping Coefficient (Surge-Surge\Sway-Sway\Heave-Heave)

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Fig. 17 Radiation-Damping Coefficient (Roll-Roll\Pitch-Pitch\Yaw-Yaw)

3. FPSP Mooing Load Calculation

3.1 Different Load Condition as the List Below

No.SpectrumHs(m)TpWind(m/s)Current(m/s)
Case1Jonswap6(Direction 175°)16.623.7(Direction 175°)2(Direction 180)
Case2Jonswap6(Direction 180°)16.623.7(Direction 180°)2(Direction 180)
Case3Jonswap6(Direction 210°)16.623.7(Direction 210°)2(Direction 180)
Case4Jonswap6(Direction 240°)16.623.7(Direction 240°)2(Direction 180)
Case5Jonswap6(Direction 175°)7.623.7(Direction 175°)2(Direction 180)
Case6Jonswap6(Direction 180°)7.623.7(Direction 180°)2(Direction 180)
Case7Jonswap6(Direction 210°)7.623.7(Direction 210°)2(Direction 180)
Case8Jonswap6(Direction 240°)7.623.7(Direction 240°)2(Direction 180)

3.2 Mooring Design

3.2.1 Mooring Layout

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3.2.2 Mooring Line Design

The Component number of the mooring lines

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Design01: (Including Superflex Elastic Cable-SB35080)
The Component of mooring lines

NameNo.MaterialLength (M)Mass (kg/m)MBL (KN)
Multiple Elastic Mooring01132mm Studless R4k413035215964
02110mm, Spiral Strand Wire Rope15506310400
03SUPERFLEX SB35080840
04122mm, Studless R414230113964

Design02: (Including Superflex Elastic Cable-SB40060)
The Component of mooring lines

NameNo.MaterialLength (M)Mass (kg/m)MBL (KN)
Multiple Elastic Mooring01132mm Studless R4k413035215964
02110mm, Spiral Strand Wire Rope15506310400
03SUPERFLEX SB40060640
04122mm, Studless R414230113964

Design03: (Without Superflex Elastic Cable)
The Component of mooring lines

NameNo.MaterialLength (M)Mass (kg/m)MBL (KN)
Multiple Elastic Mooring01132mm Studless R4k413035215964
02110mm, Spiral Strand Wire Rope15506310400
03122mm, Studless R4630113964
04122mm, Studless R414230113964

Design04: (including Superflex Elastic Cable-SB40080)
The Component of mooring lines

NameNo.MaterialLength (M)Mass (kg/m)MBL (KN)
Multiple Elastic Mooring01132mm Studless R4k413035215964
02110mm, Spiral Strand Wire Rope15506310400
03SUPERFLEX SB40080840
04122mm, Studless R414230113964

3.2.3 The curves of Two kinds of SUPERFLEX Elastic Cable Material

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Fig. 18 The Curve of SUPERFLEX EC

The curves shows that the tension at different extension rate of one strand

3.3 The Layout Number of Mooring Lines

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Fig. 19 Line Number From 1 to 12

3.4 Result No.1 (Wave Condition Hs=6, Ts=16.6)

Design1 with Superflex (TSB35080)Line No.With Superflex TSB35080 Max Tension (KN)Max Value
Case1(175°)Cas2(180°)Case3(210°)Case4(240°)
Line 1851849830826851
Line 2856854834825856
Line 3781781786767781
Line 490891496810841084
Line 5830834862926926
Line 6851856904989989
Line 711641196139814481448
Line 811061126123512471247
Line 912251273160717371737
Line 10105210319639181052
Line 1113611289110710291361
Line 12946933888854946

 

Design2 with Superflex (TSB40060)Line No.With Superflex TSB40060 Max Tension (KN)Max Value
Case1(175°)Cas2(180°)Case3(210°)Case4(240°)
Line 1859852848802859
Line 2864858851830864
Line 3789784784773789
Line 491491697510921092
Line 5836836870933933
Line 6856860910995995
Line 711771193141814901490
Line 811161121125812811281
Line 912411273161717981798
Line 10105810299799271058
Line 1111331275113910391275
Line 12952933900863952

3.5 Result No.2 (Wave condition Hs=6, Ts=7.6)

Design1 With Superflex (TSB35080)Line No.With Superflex (TSB35080) Max Tension (KN)
Cas6(180°)Case8(240°)
Superflex ECSuperflex EC
Line 1834782
Line 2840774
Line 3769742
Line 49142535
Line 58311579
Line 68572168
Line 712662929
Line 811832492
Line 913553305
Line 101056815
Line 111362872
Line 12951784

 

Design2 with Superflex (TSB40060)Line No.With Superflex TSB40060 Max Tension (KN)
Cas6(180°)Case8(240°)
Line 1851794
Line 2855783
Line 3783754
Line 49261939
Line 58421765
Line 68662413
Line 712453055
Line 811642559
Line 913353484
Line 101062825
Line 111377884
Line 12954792

 

Design3 (Without SUPERFLEX)Line No.Without Superflex Max Tension (KN)
Cas6(180°)Case8(240°)
Line 1868834
Line 2873823
Line 3802786
Line 494510421
Line 58601332
Line 68861754
Line 712852238
Line 812011493
Line 9137513299
Line 101083879
Line 111405958
Line 12973833

 

Design4 With Superflex (TSB40080)Line No.With Superflex (TSB40080) Max Tension (KN)
Cas6(180°)Case8(240°)
Superflex ECSuperflex EC
Line 1843796
Line 2856785
Line 3776754
Line 49142021
Line 58581551
Line 68722226
Line 711933009
Line 811022631
Line 912573421
Line 101093821
Line 111289894
Line 12951747

3.6 Conclusion: (Green marks stand safe, Yellow marks stand dangerous)

1. Under wave condition (H5=6, T5=16.6)
The case01--04 shows that the mooring line Load is very small.

2. Under wave condition (H5=6, T5=7.6)
The case06 and case 08 is the two remarkable case shall be listed which we get that during the computer progress. And the case08 is the most dangerous case.

  • Considering result No.2, we can know that the design-03(without SUPERFLEX) would lead the mooring lines to be broken up under case08.
  • Considering result No.2 we can know that the design 01, design 02, design 04 (with SUPERFLEX EX) could make the mooring lines be safety.
  • Under case 08 which is most condition, the SUPERFLEX EC can make the mooring Max Load be less than 3500 KN which make the mooring lines under the safe.
  • At the Max load <3500 KN. the SUPERFLEX EC extension rate is less than 75% according to the curve EC.