Dr. S. NEELAMANI  Senior Research Scientist & Program Manager       Coastal Management ProgramEnvironment & Urban Developm...
Typical view of pipeline entering from land to sea
Coastal pipelines during laying
A lay barge for laying submarine pipeline
Main Pipeline along with smaller cluster pipesduring laying
Buoyancy chamber attachment on the pipelineduring laying
Offshore effluent pipeline deployed and ready for sinking into position                 (See the concrete collars for stab...
Collar installation onto new offshore effluent outfall pipeline
Installation of collars during gradual    shore delivery of new pipeline
Submarine pipeline used for marine outfall
Submarine pipelines discharging effluents in themarine environment
Typical cross section of a submarine pipeline withdifferent forces acting on it
FB                                                    FB               FL                                                 ...
FB         FB                    FB                                                        FL         FL                  ...
SWL                        SWL              FB                          Sea Bed              FVs  c                     ...
Armor rock                                                                    Beam                                        ...
Sea bed                             Trench wall                                                      Natural fill         ...
L           Hi                         Sea Water Level                                               d      Sea Bed       ...
MINIMUM SAFE BURIAL DEPTH OFSUBMARINE PIPELINE DEPENDS ON    DESIGN WAVE CONDITION    TYPE OF SEA BED MATERIAL    ENVIR...
ARABIANKUWAIT   GULF
Sabiya Coastal Soil
Al-Koot Coastal Soil
Shuaiba Coastal Soil
Al-Khiran Coastal Soil
Hydrodynamic parameter                             Range                     UnitSignificant Wave Height and            (5...
Soil location      Soil Property               Unit      Sabiya   Al-Koot      Shuaiba      Al-Khiran             D10     ...
Incident wave and  corresponding horizontal        wave forces on   the submarine pipe fore/D = 0.0, 0.5, 1.0, 1.5 and 2.0...
Fig. 6. Vertical wave forces on   the submarine pipe fore/D = 0.0, 0.5, 1.0, 1.5 and 2.0   respectively from top to       ...
Effect of relative burial depth ofsubmarine pipeline on shorewardforce coefficients for four different soiltypes (Hi/d=0.6...
Effect of relative burial depth ofsubmarine pipeline on downwardforce coefficients for four differentsoil types (Hi/d=0.66...
Conclusions For all the four soil types, the horizontal force reduced  nonlinearly with increase in depth of burial; wher...
Conclusions Among the soils, well graded and high hydraulic conductivity soil (Shuaiba soil with k=1.84 mm/s) is good for...
Conclusions In general, if the hydraulic conductivity is high (order  of 1.84 mm/s), then varying the burial from e/D=0.5...
Conclusions In general, the horizontal wave force dictates the  stability of the submarine pipeline, if the pipeline is  ...
Workout ExampleInput conditions:Steel Pipe; OD: 1.0 m; Wall Thickness:15 mmWater depth: 2.25 m; Wave period: 6.7 s;Design ...
Minimum                                  MinimumLocation e/D         FSUplift   Minimum FSHorizontal   Minimum     Safe e/...
Acknowledgements Kuwait Foundation for Advancement of Science and Kuwait Pipe Industries and Oil Services Company (K.S.C)...
Subramaniam neelamani   minimum safe burial depth of submarine pipelines for different marine conditions
Subramaniam neelamani   minimum safe burial depth of submarine pipelines for different marine conditions
Subramaniam neelamani   minimum safe burial depth of submarine pipelines for different marine conditions
Subramaniam neelamani   minimum safe burial depth of submarine pipelines for different marine conditions
Subramaniam neelamani   minimum safe burial depth of submarine pipelines for different marine conditions
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Subramaniam neelamani minimum safe burial depth of submarine pipelines for different marine conditions

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Subramaniam neelamani minimum safe burial depth of submarine pipelines for different marine conditions

  1. 1. Dr. S. NEELAMANI Senior Research Scientist & Program Manager Coastal Management ProgramEnvironment & Urban Development Division Kuwait Institute for Scientific Research KUWAIT Email: nsubram@kisr.edu.kw
  2. 2. Typical view of pipeline entering from land to sea
  3. 3. Coastal pipelines during laying
  4. 4. A lay barge for laying submarine pipeline
  5. 5. Main Pipeline along with smaller cluster pipesduring laying
  6. 6. Buoyancy chamber attachment on the pipelineduring laying
  7. 7. Offshore effluent pipeline deployed and ready for sinking into position (See the concrete collars for stability)
  8. 8. Collar installation onto new offshore effluent outfall pipeline
  9. 9. Installation of collars during gradual shore delivery of new pipeline
  10. 10. Submarine pipeline used for marine outfall
  11. 11. Submarine pipelines discharging effluents in themarine environment
  12. 12. Typical cross section of a submarine pipeline withdifferent forces acting on it
  13. 13. FB FB FL FL FD FI FD FI e es  c FW FP s  c FW FS FO FC FC FC ELEVATED PIPE LINE 13
  14. 14. FB FB FB FL FL FL FD FI FD FI FD FIs  c B s  c Fp s  c Fp Fs B FW FW Fs Fs FW FC FC SURFACE or PARTIALLY BURIED PIPELINE 14
  15. 15. SWL SWL FB Sea Bed FVs  c FB s  c FH FV FH FW FW FC BURIED PIPELINE FC 15
  16. 16. Armor rock Beam Sea bed Sea bed Pile Ballasted pipe Pile supported pipe Hold down strap Concrete saddle Sea bedSea bed Screw or Explosive Anchor Pipe Saddle Pipe Anchor Stabilization methods for Exposed submarine pipeline 16
  17. 17. Sea bed Trench wall Natural fill Buried pipe- Natural Fill Jetted in pipe Armor rock Tremie concrete Back fill Bedding BeddingBuried pipe- Armor Cover Buried pipe- Concrete CoverStabilization Methods for buried Submarine pipeline 17
  18. 18. L Hi Sea Water Level d Sea Bed What is theEngineering & MinimumHydraulic Properties of D e safe Burialthe soil Depth? Challenging Question?
  19. 19. MINIMUM SAFE BURIAL DEPTH OFSUBMARINE PIPELINE DEPENDS ON  DESIGN WAVE CONDITION  TYPE OF SEA BED MATERIAL  ENVIRONMENTAL IMPACT OF FAILURE  INITIAL COST  MAINTENANCE COST  ZONE  CARGO  RISK
  20. 20. ARABIANKUWAIT GULF
  21. 21. Sabiya Coastal Soil
  22. 22. Al-Koot Coastal Soil
  23. 23. Shuaiba Coastal Soil
  24. 24. Al-Khiran Coastal Soil
  25. 25. Hydrodynamic parameter Range UnitSignificant Wave Height and (5,1.0), (10,1.0), (15,1.0), (5,2.0), (m,s)Peak Wave Period Combinations, (10,2.0), (15,2.0), (20,2.0), (5,3.0),(Hs, Tp) (10,3.0), (15,3.0), (20,3.0)Water depth at the test section, d 0.45 m m Pipeline burial depth, e 0.0, 0.1, 0.2, 0.3 and 0.4 m Pipe dia, D 0.2 mWave length, Lp at the test section 1.491, 3.883 and 6.089 mcorresponding to peak period, Tp Relative depth of burial, e/D 0.0, 0.5, 1.0, 1.5 and 2.0 Unitless Hs/d 0.111 – 0.444 Unitless Hs/Lp 0.008 – 0.101 Unitless d/Lp 0.074 – 0.302 Unitless kd 0.465 – 1.897 Unitless D/Lp 0.033 – 0.134 Unitless kpa 0.103 – 0.422 Unitless Ur 1.22 – 81.38 Unitless Umax.SWL 0.121 – 0.505 m/s Umax.Bed 0.048 – 0.435 m/s KC 0.241 – 6.532 Unitless Re 9652.54 – 87094.7 Unitless
  26. 26. Soil location Soil Property Unit Sabiya Al-Koot Shuaiba Al-Khiran D10 mm 0.380 0.250 0.410 0.250 D30 mm 0.570 0.275 0.570 0.275 D50 mm 1.450 0.295 0.950 0.310 D60 mm 1.700 0.310 1.500 0.330 Cu Unitless 4.470 1.240 3.660 1.320 Cc Unitless 0.500 0.976 0.528 0.917 Bulk density t/m3 1.560 1.550 1.621 1.792 Saturated density t/m3 1.850 1.855 1.948 2.130 Submerged density t/m3 0.811 0.815 0.815 1.090 Porosity Unitless 0.290 0.360 0.908 0.339 Hydraulic Conductivity, k mm/s 0.412 0.286 1.840 0.652Angle of shearing resistance, Degree 31.460 32.110 32.110 27.010 ΦCoefficient of friction, tan Φ Unitless 0.612 0.628 0.628 0.510 Passive earth pressure Unitless 3.183 3.269 3.269 2.664 coefficient of the soil, Kp Remarks - Well Uniformly Almost well Uniformly graded graded graded soil graded
  27. 27. Incident wave and corresponding horizontal wave forces on the submarine pipe fore/D = 0.0, 0.5, 1.0, 1.5 and 2.0 respectively from top to bottom (Al-Khiran soil, Hi = 0.2 m, T = 2.0 s).
  28. 28. Fig. 6. Vertical wave forces on the submarine pipe fore/D = 0.0, 0.5, 1.0, 1.5 and 2.0 respectively from top to bottom (Al-Khiran soil, Hi = 0.2 m, and T = 2.0 s).
  29. 29. Effect of relative burial depth ofsubmarine pipeline on shorewardforce coefficients for four different soiltypes (Hi/d=0.666, d/L=0.074). Effect of relative burial depth of submarine pipeline on seaward force coefficients for four different soil types (Hi/d=0.666, d/L=0.074).
  30. 30. Effect of relative burial depth ofsubmarine pipeline on downwardforce coefficients for four differentsoil types (Hi/d=0.666, d/L=0.074).Effect of relative burial depth ofsubmarine pipeline on upwardforce coefficients for four differentsoil types (Hi/d=0.666, d/L=0.074).
  31. 31. Conclusions For all the four soil types, the horizontal force reduced nonlinearly with increase in depth of burial; whereas, the vertical force generally increases up to certain depth of burial, mainly due to the significant change in the magnitude as well as the phase difference between the dynamic pressures in the vertical direction.
  32. 32. Conclusions Among the soils, well graded and high hydraulic conductivity soil (Shuaiba soil with k=1.84 mm/s) is good for half burial of the submarine pipeline, since the least vertical force occurred for this soil. On the other hand, uniformly graded and low hydraulic conductivity soil (Al-Koot soil with k=0.286 mm/s) attracts the maximum vertical force for half burial. On the other hand, this type of soil is good for full burial or further increase of burial, since it attracts less vertical force when compared to the other soils.
  33. 33. Conclusions In general, if the hydraulic conductivity is high (order of 1.84 mm/s), then varying the burial from e/D=0.5 to 1.0 or 1.5 does not provide any advantage from vertical stability point of view, since the vertical forces are of the same order from e/D=0.5 to 1.5. On the other hand, for a soil with low hydraulic conductivity (Order of 0.29 mm/s), changing the burial from e/D=0.5 to 1.5 could reduce the force more than 50%.
  34. 34. Conclusions In general, the horizontal wave force dictates the stability of the submarine pipeline, if the pipeline is placed on the sea floor since the highest horizontal force occurs when the pipe is not buried. For buried pipeline, the horizontal force is not the main issue for stability due to significant force reduction. For the buried pipeline, the upward wave force mainly dictates the stability of the pipeline.
  35. 35. Workout ExampleInput conditions:Steel Pipe; OD: 1.0 m; Wall Thickness:15 mmWater depth: 2.25 m; Wave period: 6.7 s;Design wave height: 1.6 m.Soil Type: Four different marine soils discussed in this paperPipe line purpose: Crude oil transportFind:a. Minimum safe burial depthb. Surcharge required for stability for any selected depth of burial
  36. 36. Minimum MinimumLocation e/D FSUplift Minimum FSHorizontal Minimum Safe e/D W for Was for Was for as Safe e/D Sliding Safe e/D Value FSUplift of FSHorizontal Satisfying Value to Value to Consideri 1.5 (t/m) of Both Sliding Prevent Prevent ng Both 1.5 (t/m) FSUplift Vertical Horizonta Vertical and Pop-up l Sliding and FSHorizontal Horizonta Sliding of l Stability 1.5 (t/m) 0 1.04 0.02 0.42 1.10 1.10 0.5 e/D e/D 0.68 Sabiya 0.87 1.13 e/D in 0.68 0.09 between 1.0 0.94 10.96 between between 0.62 0.0 0.62 1.5 and 1.5 1.34 26.02 0.5 and 1.5 and 0.17 0.0 0.17 2.0 2.0 1.97 101.80 1.0 2.0 0.0 0.0 0.0 0 1.04 0.02 0.42 1.10 1.10Al-Koot 0.5 0.78 e/D bit 0.71 e/D in 0.87 0.17 0.87 1.0 0.98 more 19.82 between e/D bit 0.54 0.0 0.54 1.5 1.44 than 1.5 85.08 0.5 and more 0.06 0.0 0.06 2.0 2.05 230.83 1.0 than 1.5 0.0 0.0 0.0 0 1.04 0.02 0.42 1.10 1.10 0.5 e/D e/D 0.46 Shuaiba 1.01 1.64 0.46 0.0 between 1.0 0.96 13.12 between 0.58 0.0 0.58 1.5 and e/D=0.5 1.5 1.42 31.87 1.5 and 0.08 0.0 0.08 2.0 2.0 2.07 78.25 2.0 0.0 0.0 0.0 0 1.04 0.02 0.42 1.10 1.10Al-Khiran 0.5 0.92 1.54 0.60 0.0 0.60 1.0 1.01 e/D = 1.5 13.77 0.51 0.0 0.51 1.5 1.53 40.96 0.0 0.0 0.0 2.0 2.33 85.14 e/D=0.5 e/D = 1.5 0.0 0.0 0.0
  37. 37. Acknowledgements Kuwait Foundation for Advancement of Science and Kuwait Pipe Industries and Oil Services Company (K.S.C) for sponsoring this R&D work Kuwait Institute for Scientific Research for the infrastructure and logistic support.

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