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PipelayPipelay Analyses Analyses –– Concept Concept and Sensitivities Analysesand Sensitivities Analyses
January 2010 January 2010 –– AOE, IndonesiaAOE, Indonesia
ContentsContents
AOE, a Brief IntroductionAOE, a Brief IntroductionPipelayPipelay Installation, Acceptance CriteriaInstallation, Acceptance CriteriaPipelayPipelay Barge and Stinger SettingsBarge and Stinger SettingsNormal Lay AnalysesNormal Lay Analyses““What IfWhat If”” Analyses for Analyses for PipelayPipelayAbandonment And Recovery AnalysesAbandonment And Recovery AnalysesLay Barge Lay Barge RAOsRAOs modelingmodelingPipelayPipelay Dynamic AnalysesDynamic Analyses
AOE, a Brief IntroductionAOE, a Brief IntroductionArchipelago Offshore Engineering ( AOE ) believe that there is not many Installation Engineering Companies in this market because typically the Installation Engineering is carried out by Installation Contractors. So, we see that small ‐medium Installation Contractors may not have strong engineering support and Clients may not have qualified Installation Engineering Companies as their third party.
On this opportunity, AOE would like to expand the company for supporting, i.e.,‐ Installation Contractor with Installation Analyses‐ Client as a third party verification to their Contractor‐ Pipelay Builder or Owner , to do a general PipelayCapability Analyses for new build or existing Pipelay Vessel
AOE, a Brief IntroductionAOE, a Brief IntroductionThis presentation on Pipeline Installation Engineering (Pipelay) is used to show our depth knowledge on this engineering sector.
We believe that Installation Vessel is an expensive equipment. Therefore, detail installation engineering should cover all the possibilities during installation to minimize therisks of vessel standby.
We believe, it will be wise to prepare detail installation engineering onshore to cover many possibilities rather than doing the calculation offshore while on pipe laying.
We are here to help as your partner on your pipeline installation works.
PipelayPipelay Analyses, Acceptance CriteriaAnalyses, Acceptance CriteriaTraditionally in the past, we have used two main codes for pipeline installation analyses, ‐ DnV 1981 (with special formulation of combined stress)‐ BS8010 ( with standard von Mises Stress )
For DnV 1981, the acceptance criteria is‐Max Static Stress of 0.72 SMSY ( DnV Stress ) and‐Max Dynamic Stress of 0.96 SMSY ( DnV Stress )
For BS8010, the acceptance criteria is‐Max Static Stress of 0.85 SMYS ( Eq. Stress )‐Max Dynamic Stress of 1.00 SMYS ( Eq. Stress )
Note : There is reduction factor of 0.85 on the DnV Combined stress ( on Longitudinal Stress portion )
PipelayPipelay Analyses, Acceptance CriteriaAnalyses, Acceptance CriteriaWhen the water depth go deeper and pipeline go heavier, the engineer start to look for strain based design, the acceptance may subject to client specification, but typically, we used to limit our self up to 0.250% ( static for X65 ) and 0.305% ( for dynamic – For X65 ).
The Debate of the acceptance criteria is also on Sag bend and Over bend. We tend to go to higher strain on something that is controllable such as barge ramp and stinger ( on Fixed Stinger Model ) and tend to go lower on sag bend and also last roller of the stinger. And some clients specs required the last roller as free load support during static run as measured of the tension and Catenary of the pipeline
PipelayPipelay Analyses, Acceptance CriteriaAnalyses, Acceptance CriteriaNowadays, on the deepwater technology, we start to look at reliability based design, and the modern code is suggesting to use a local buckling check as an acceptance criteria for pipeline installation.
Discussions on Sag bend and over bend remain the same. However, we use a terminology of DCC ( Displacement Controlled Condition ) for Over Bend and fixed portion of stinger and LCC ( Load Controlled Condition ) for Stinger Last Roller and for Sag bend region.
The two pipeline code which suggest to use local buckling check for acceptance criteria are DnV OSF101 and API RP1111.
PipelayPipelay Analyses, Acceptance CriteriaAnalyses, Acceptance Criteria
DnV OS F101
PipelayPipelay Analyses, Acceptance CriteriaAnalyses, Acceptance Criteria
PipelayPipelay Barge and Stinger SettingBarge and Stinger Setting
Barge RadiusStinger Radius
For simplification and a quick check calculation, typically pipeline engineer uses distances and radius as the main input for the pipelay parameter ( for barge laying ramp and Stinger configuration ). This type of modeling is the easy way to predict the lay stress and tension requirements.
PipelayPipelay Barge and Stinger SettingBarge and Stinger SettingIs that simple modeling (Distances and Radius) sufficient for installing a pipeline ?
The answer most likely is ‘No’, Why ? Because:‐ The Stinger may not able to form that the given radius (The possibility of roller low‐height setting) is not enough.‐ For Lay case with different water depth, we may need to lift the stinger to avoid stinger touches the ground. And changing the stinger angle will change the form of the stinger curve. ‐With Radius as an input, we don’t have possibilities to do ‘What If’ analyses in case the stinger end depth is different between calculation and reality.
PipelayPipelay Barge and Stinger SetBarge and Stinger SettingtingOn this case, the Barge Ramp and the Stinger Roller have been set at the given height. During Pipelay the stinger angle is set at nominal position to form the curve. At very shallow water the stinger can be lifted to avoid any stinger touches the seabed. Sensitivities against the stinger angle in any depth can be analyzed.
PipelayPipelay Barge and Stinger SettingBarge and Stinger SettingSimilar case on Different Pipelay Barge
PipelayPipelay Barge and Stinger SettingBarge and Stinger SettingCase for Pipelay Barge with 2 Stinger Sections / AnglesNote : Some Software does not allow the user to input 2 stinger angles
PipelayPipelay Barge and Stinger SettingBarge and Stinger SettingCase for Pipelay Barge with 2 Stinger Sections / AnglesNote : Some Software does not allow the user to input 2 stinger angles
Static Normal Lay AnalysesStatic Normal Lay AnalysesAfter we set the barge and the Stinger (Roller Heights and Stinger angle), the Pipelay analyses can be analyzed, see below the typical result
Top Tension = 650kN
Gap on Last Roller = 0.006
TDP = -204.57m
Top Tension : 650kNTDP: 204mLast Roller Gap: 0.006mBottom Tension: 538kNMax Stress at‐ Over Bend : 79.85%‐ Sag bend : 39.73%
Length Gain : 8.383mMax Roller Reaction‐ Barge : 159.35kN‐ Stinger : 108.53kN
Static Normal Lay AnalysesStatic Normal Lay AnalysesFrom the Pipelay Analyses Output, We will see table below
Static Normal Lay AnalysesStatic Normal Lay AnalysesFrom the Pipelay Output, we will see the table below
There are a lot of Information inside Pipeline Lay Analyses tabulated Output, but we may not need all of that information. The important information for Pipelay parameter typically are ‐ Top and Bottom Tension‐ Location of TDP‐Max Stress at Sag bend and over bend‐Max reaction Loads‐Max Separation on Last Roller‐ Pipe Length Gain
Static Normal Lay AnalysesStatic Normal Lay AnalysesNormal Pipelay Summary Table
Water Stinger Lay Bottom Touch PipeDepth Angle Tension Tension Down length At Sting At Sag T2 RB-1 S1 S2 S3 S4 S5 S6 S7 S8 S6 S7 S8
Point gain & Ramp Bend React React React React React React React React React React Gap Gap Gap( m ) ( m ) ( kN ) ( kN ) ( m ) ( m ) ( % ) ( % ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( m ) ( m ) ( m )
50.00 14.50 650.0 538.0 -204.57 8.383 79.85 39.73 63.18 159.35 78.49 31.31 36.62 29.32 40.27 13.03 108.53 0.00 0.000 0.000 0.006
Max Stress React at barge Stinger Reactions Support Stinger Support Separation
But during Actual Pipelay Operation, some parameter s predicted may not match with field observation, i.e., ‐ Laying Top Tension is smaller or bigger‐ TDP is shorter or longer‐ Last Roller Gaps is less or more than predicted‐ End Stinger Depth is different with the proposed depth‐ The Barge has different Trim angles‐ Stinger Angle is different proposed stinger angle‐ There is current during pipelay operation‐ etc….
‘‘What IfWhat If’’ Analyses for Analyses for PipelayPipelayThe Engineering Calculation is only our way to predict engineering phenomena based on the input data given during the calculation process, so all the output is depending on the input data and the assumption.
In the real life, our input data or assumption may different from actual observations during the actual operation. So, we need to prepare ‘What If’ analyses. Then, we will be ready to answer any question Offshore. It will be wise to prepare all the possibilities Onshore because Offshore Operation is very expensive operation.
For Pipelay analyses, the ‘What If’, it could be in terms of tension range, stinger depth/angle range, TDP range, Current, Barge Trim, etc
‘‘What IfWhat If’’ Analyses for Analyses for PipelayPipelayRange of Tension and Stinger Angles ( Stinger End Depth )
Water Stinger Lay Bottom Touch PipeDepth Angle Tension Tension Down length At Sting At Sag T2 RB-1 S1 S2 S3 S4 S5 S6 S7 S8 S6 S7 S8
Point gain & Ramp Bend React React React React React React React React React React Gap Gap Gap( m ) ( m ) ( kN ) ( kN ) ( m ) ( m ) ( % ) ( % ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( m ) ( m ) ( m )
60.00 13.50 800.0 669.5 -242.26 10.094 78.88 34.62 71.02 176.55 22.36 91.19 29.34 38.76 41.43 31.53 45.99 89.58 0.000 0.000 0.00060.00 13.50 825.0 694.5 -245.34 9.974 79.22 33.89 71.68 178.42 23.63 91.82 30.33 39.39 43.19 28.95 60.13 75.23 0.000 0.000 0.00060.00 13.50 850.0 719.5 -248.37 9.864 79.56 33.22 72.35 180.30 24.90 92.44 31.32 40.02 44.93 26.44 74.01 60.98 0.000 0.000 0.00060.00 13.50 875.0 744.5 -251.37 9.754 79.90 32.60 73.01 182.18 26.17 93.07 32.31 40.65 46.66 24.00 87.66 46.85 0.000 0.000 0.00060.00 13.50 900.0 769.5 -254.32 9.654 80.24 32.04 73.68 184.05 27.44 93.69 33.29 41.29 48.36 21.61 101.08 32.83 0.000 0.000 0.000
60.00 14.00 800.0 669.5 -241.15 10.124 80.43 34.62 69.03 174.03 55.40 62.86 35.79 36.61 43.38 25.30 69.29 62.56 0.000 0.000 0.00060.00 14.00 825.0 694.5 -244.21 10.004 80.77 33.89 69.69 175.99 56.86 63.44 36.79 37.23 45.15 22.66 83.66 47.78 0.000 0.000 0.00060.00 14.00 850.0 719.5 -247.24 9.894 81.12 33.22 70.34 177.94 58.31 64.03 37.78 37.86 46.91 20.09 97.78 33.11 0.000 0.000 0.00060.00 14.00 875.0 744.5 -250.22 9.784 81.47 32.60 71.00 179.90 59.77 64.61 38.78 38.49 48.64 17.59 111.65 18.56 0.000 0.000 0.00060.00 14.00 900.0 769.5 -253.16 9.684 81.81 32.04 71.65 181.85 61.22 65.20 39.77 39.12 50.36 15.16 125.28 4.11 0.000 0.000 0.000
60.00 14.50 800.0 669.5 -240.04 10.154 81.98 34.62 67.05 171.56 88.35 34.64 42.29 34.45 45.32 19.06 92.61 35.53 0.000 0.000 0.00060.00 14.50 825.0 694.5 -243.09 10.034 82.34 33.89 67.69 173.59 89.99 35.18 43.29 35.07 47.11 16.37 107.21 20.32 0.000 0.000 0.00060.00 14.50 850.0 719.5 -246.09 9.924 82.69 33.22 68.34 175.62 91.63 35.72 44.30 35.69 48.88 13.75 121.54 5.23 0.000 0.000 0.00060.00 14.50 875.0 744.5 -249.11 9.814 83.04 32.60 68.98 177.65 93.26 36.31 45.13 36.99 47.98 21.48 117.81 0.00 0.000 0.000 0.00860.00 14.50 900.0 769.5 -252.13 9.714 83.40 32.04 69.63 179.69 94.89 36.92 45.87 38.64 45.72 34.54 104.58 0.00 0.000 0.000 0.019
60.00 15.00 800.0 669.5 -238.92 10.204 83.54 34.62 65.06 169.12 121.20 6.51 48.83 32.29 47.27 12.83 115.92 8.51 0.000 0.000 0.00060.00 15.00 825.0 694.5 -241.99 10.084 83.90 33.89 65.69 171.23 123.02 7.04 49.71 33.40 47.11 17.69 117.63 0.00 0.000 0.000 0.00660.00 15.00 850.0 719.5 -245.07 9.964 84.26 33.22 66.32 173.34 124.84 7.61 50.45 35.09 44.67 31.44 103.77 0.00 0.000 0.000 0.01860.00 15.00 875.0 744.5 -248.11 9.854 84.62 32.60 66.96 175.45 126.65 8.18 51.19 36.77 42.29 44.95 90.02 0.00 0.000 0.000 0.03060.00 15.00 900.0 769.5 -251.11 9.744 84.98 32.04 67.59 177.56 128.46 8.75 51.94 38.43 39.97 58.23 76.37 0.00 0.000 0.000 0.041
60.00 15.50 800.0 669.5 -237.89 10.234 90.41 34.62 62.50 168.80 142.39 0.00 38.11 38.34 42.32 26.91 105.01 0.00 0.000 0.000 0.01560.00 15.50 825.0 694.5 -241.00 10.114 90.86 33.89 63.14 170.94 144.68 0.00 39.28 39.88 39.80 41.13 90.61 0.00 0.000 0.000 0.02760.00 15.50 850.0 719.5 -244.07 9.994 91.31 33.22 63.78 173.07 146.96 0.00 40.45 41.40 37.35 55.09 76.33 0.00 0.000 0.000 0.04060.00 15.50 875.0 744.5 -247.10 9.884 91.76 32.60 64.42 175.21 149.24 0.00 41.62 42.91 34.97 68.81 62.15 0.00 0.000 0.000 0.05260.00 15.50 900.0 769.5 -250.09 9.784 92.21 32.04 65.06 177.35 151.53 0.00 42.80 44.40 32.65 82.30 48.09 0.00 0.000 0.000 0.064
Max Stress Stinger Reactions Support Stinger Support SeparationReact at barge
Notes : One Line represent one Pipelay Analyses Run
‘‘What IfWhat If’’ Analyses for Analyses for PipelayPipelayRange of Tension and Barge Trim Angles
Notes : One Line represent one Pipelay Analyses Run
Water Stinger Lay Bottom Touch Pipe VesselDepth Angle Tension Tension Down+F67 length At Sting At Sag T2 RB-1 S1 S2 S3 S4 S5 S6 S7 S8 S7 S8 trim
Point gain & Ramp Bend React React React React React React React React React React Gap Gap Angle( m ) ( m ) ( kN ) ( kN ) ( m ) ( m ) ( % ) ( % ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( m ) ( m ) ( Deg )
60.00 14.50 800.0 669.5 -240.04 10.154 81.98 34.62 67.05 171.56 88.35 34.64 42.29 34.45 45.32 19.06 92.61 35.54 0.000 0.000 0.00060.00 14.50 825.0 694.5 -243.09 10.044 82.34 33.89 67.69 173.59 89.99 35.18 43.29 35.07 47.11 16.37 107.21 20.32 0.000 0.000 0.00060.00 14.50 850.0 719.5 -246.09 9.934 82.69 33.22 68.34 175.62 91.63 35.72 44.30 35.69 48.88 13.75 121.54 5.23 0.000 0.000 0.00060.00 14.50 875.0 744.5 -249.11 9.824 83.04 32.60 68.98 177.65 93.26 36.31 45.13 36.99 47.98 21.48 117.81 0.00 0.000 0.008 0.00060.00 14.50 900.0 769.5 -252.13 9.714 83.40 32.04 69.63 179.69 94.89 36.92 45.87 38.64 45.72 34.54 104.58 0.00 0.000 0.019 0.000
60.00 14.50 800.0 670.0 -239.02 10.125 81.98 34.60 67.03 171.51 87.70 32.50 41.19 34.34 46.24 15.22 107.29 18.52 0.000 0.000 0.25060.00 14.50 825.0 695.0 -242.04 10.015 82.33 33.87 67.67 173.54 89.34 33.04 42.20 34.95 48.03 12.50 121.99 3.09 0.000 0.000 0.25060.00 14.50 850.0 720.0 -245.10 9.895 82.68 33.21 68.32 175.58 90.97 33.64 42.99 36.42 46.47 22.83 114.02 0.00 0.000 0.010 0.25060.00 14.50 875.0 745.0 -248.14 9.785 83.04 32.59 68.96 177.61 92.60 34.25 43.72 38.09 44.12 36.21 100.47 0.00 0.000 0.021 0.25060.00 14.50 900.0 770.0 -251.13 9.675 83.39 32.03 69.61 179.64 94.23 34.86 44.47 39.74 41.84 49.37 87.02 0.00 0.000 0.033 0.250
60.00 14.50 800.0 670.5 -237.98 10.096 81.98 34.59 66.98 171.54 85.69 30.16 41.59 33.98 47.22 11.35 122.01 1.48 0.000 0.000 0.50060.00 14.50 825.0 695.5 -241.07 9.976 82.34 33.86 67.63 173.57 87.32 30.77 42.34 35.58 45.13 23.74 110.74 0.00 0.000 0.011 0.50060.00 14.50 850.0 720.5 -244.13 9.856 82.69 33.19 68.27 175.61 88.94 31.38 43.07 37.28 42.69 37.47 96.87 0.00 0.000 0.023 0.50060.00 14.50 875.0 745.5 -247.15 9.746 83.04 32.58 68.92 177.64 90.57 31.99 43.81 38.95 40.32 50.95 83.10 0.00 0.000 0.035 0.50060.00 14.50 900.0 770.5 -250.13 9.646 83.40 32.02 69.56 179.67 92.20 32.60 44.55 40.61 38.01 64.21 69.43 0.00 0.000 0.047 0.500
60.00 14.50 800.0 671.1 -237.03 10.057 81.99 34.57 66.94 171.56 83.74 27.99 41.69 34.72 43.89 24.22 108.00 0.00 0.000 0.012 0.75060.00 14.50 825.0 696.1 -240.11 9.937 82.34 33.85 67.59 173.60 85.37 28.60 42.41 36.44 41.36 38.30 93.79 0.00 0.000 0.025 0.75060.00 14.50 850.0 721.1 -243.16 9.827 82.70 33.18 68.23 175.63 87.00 29.21 43.14 38.14 38.90 52.13 79.69 0.00 0.000 0.037 0.75060.00 14.50 875.0 746.1 -246.16 9.717 83.05 32.57 68.88 177.66 88.63 29.83 43.88 39.82 36.50 65.72 65.70 0.00 0.000 0.049 0.75060.00 14.50 900.0 771.1 -249.13 9.607 83.40 32.00 69.52 179.70 90.25 30.44 44.61 41.48 34.17 79.08 51.82 0.00 0.000 0.061 0.750
60.00 14.50 800.0 671.6 -236.08 10.017 81.99 34.56 66.90 171.58 81.88 25.92 41.75 35.58 40.15 38.70 91.23 0.00 0.000 0.026 1.00060.00 14.50 825.0 696.6 -239.15 9.897 82.35 33.83 67.54 173.62 83.50 26.53 42.47 37.30 37.59 52.89 76.80 0.00 0.000 0.039 1.00060.00 14.50 850.0 721.6 -242.17 9.787 82.70 33.16 68.19 175.65 85.13 27.15 43.20 39.01 35.10 66.82 62.49 0.00 0.000 0.051 1.00060.00 14.50 875.0 746.6 -245.16 9.687 83.06 32.55 68.83 177.68 86.76 27.76 43.93 40.69 32.68 80.51 48.28 0.00 0.000 0.063 1.00060.00 14.50 900.0 771.6 -248.11 9.577 83.41 31.99 69.48 179.72 88.39 28.37 44.67 42.36 30.33 93.97 34.19 0.00 0.000 0.075 1.000
Max Stress React at barge Stinger Reactions Support Stinger Gap
‘‘What IfWhat If’’ Analyses for Analyses for PipelayPipelayRange of Tension and Effect of Current / Direction
Notes : One Line represent one Pipelay Analyses Run
Water Stinger Lay Bottom Touch Pipe CurrentDepth Angle Tension Tension Down length At Sting At Sag T2 RB-1 S1 S2 S3 S4 S5 S6 S7 S8 S7 S8 Direction
Point gain & Ramp Bend React React React React React React React React React React Gap Gap( m ) ( m ) ( kN ) ( kN ) ( m ) ( m ) ( % ) ( % ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( m ) ( m ) ( Deg )
60.00 14.50 800.0 669.5 -239.88 10.174 81.98 34.64 67.05 171.56 88.34 34.66 42.33 34.56 45.23 19.83 90.13 38.83 0.000 0.000 0.060.00 14.50 825.0 694.5 -242.93 10.054 82.34 33.91 67.69 173.59 89.99 35.20 43.33 35.17 47.02 17.12 104.80 23.54 0.000 0.000 0.060.00 14.50 850.0 719.5 -245.94 9.944 82.69 33.24 68.34 175.62 91.63 35.74 44.34 35.79 48.79 14.48 119.21 8.39 0.000 0.000 0.060.00 14.50 875.0 744.5 -248.95 9.834 83.04 32.62 68.98 177.65 93.26 36.32 45.22 36.88 48.74 18.93 121.19 0.00 0.000 0.005 0.060.00 14.50 900.0 769.5 -251.96 9.724 83.40 32.05 69.63 179.69 94.89 36.93 45.96 38.53 46.46 32.06 107.89 0.00 0.000 0.017 0.0
60.00 14.50 800.0 669.5 -239.74 10.174 81.98 34.69 67.05 171.56 88.34 34.68 42.38 34.64 45.20 20.22 88.88 40.42 0.000 0.000 45.060.00 14.50 825.0 694.5 -242.79 10.064 82.34 33.95 67.69 173.59 89.98 35.22 43.38 35.25 46.99 17.51 103.54 25.15 0.000 0.000 45.060.00 14.50 850.0 719.5 -245.79 9.954 82.69 33.28 68.34 175.62 91.63 35.77 44.38 35.87 48.76 14.87 117.94 10.01 0.000 0.000 45.060.00 14.50 875.0 744.5 -248.79 9.844 83.04 32.66 68.98 177.65 93.26 36.33 45.30 36.84 49.15 17.58 122.93 0.00 0.000 0.004 45.060.00 14.50 900.0 769.5 -251.80 9.734 83.40 32.09 69.63 179.69 94.89 36.94 46.04 38.50 46.88 30.70 109.65 0.00 0.000 0.015 45.0
60.00 14.50 800.0 669.5 -240.04 10.164 81.98 34.63 67.05 171.56 88.35 34.64 42.29 34.45 45.32 19.06 92.60 35.52 0.000 0.000 90.060.00 14.50 825.0 694.5 -243.09 10.044 82.34 33.90 67.69 173.59 89.99 35.18 43.29 35.07 47.11 16.37 107.20 20.31 0.000 0.000 90.060.00 14.50 850.0 719.5 -246.09 9.934 82.69 33.23 68.34 175.62 91.63 35.72 44.30 35.69 48.88 13.75 121.54 5.22 0.000 0.000 90.060.00 14.50 875.0 744.5 -249.11 9.824 83.04 32.61 68.98 177.66 93.26 36.31 45.13 36.99 47.98 21.47 117.81 -0.02 0.000 0.008 90.060.00 14.50 900.0 769.5 -252.13 9.714 83.40 32.05 69.63 179.69 94.89 36.92 45.87 38.64 45.72 34.53 104.58 -0.02 0.000 0.019 90.0
60.00 14.50 800.0 669.5 -240.34 10.144 81.98 34.56 67.05 171.56 88.35 34.59 42.20 34.27 45.45 17.91 96.31 30.67 0.000 0.000 135.060.00 14.50 825.0 694.5 -243.39 10.024 82.34 33.83 67.69 173.59 89.99 35.13 43.21 34.88 47.23 15.24 110.85 15.51 0.000 0.000 135.060.00 14.50 850.0 719.5 -246.39 9.914 82.69 33.17 68.34 175.62 91.64 35.68 44.21 35.51 48.99 12.63 125.12 0.47 0.000 0.000 135.060.00 14.50 875.0 744.5 -249.44 9.804 83.04 32.56 68.98 177.65 93.26 36.28 44.96 37.13 46.81 25.35 112.71 0.00 0.000 0.011 135.060.00 14.50 900.0 769.5 -252.46 9.694 83.40 31.99 69.63 179.69 94.89 36.89 45.70 38.78 44.57 38.35 99.53 0.00 0.000 0.023 135.0
60.00 14.50 800.0 669.5 -240.20 10.144 81.98 34.60 67.05 171.56 88.35 34.62 42.25 34.35 45.42 18.30 95.07 32.25 0.000 0.000 180.060.00 14.50 825.0 694.5 -243.24 10.034 82.34 33.87 67.69 173.59 89.99 35.16 43.26 34.96 47.20 15.62 109.60 17.11 0.000 0.000 180.060.00 14.50 850.0 719.5 -246.25 9.924 82.69 33.20 68.34 175.62 91.63 35.70 44.26 35.58 48.96 13.02 123.87 2.09 0.000 0.000 180.060.00 14.50 875.0 744.5 -249.28 9.814 83.04 32.59 68.98 177.65 93.26 36.30 45.04 37.10 47.23 24.02 114.44 0.00 0.000 0.010 180.060.00 14.50 900.0 769.5 -252.30 9.704 83.40 32.03 69.63 179.69 94.89 36.91 45.78 38.74 44.98 37.01 101.28 0.00 0.000 0.021 180.0
Max Stress React at barge Stinger Reactions Support Stinger Gap
Abandonment & Recovery AnalysesAbandonment & Recovery AnalysesAbandonment is a process of paying out cable while the pipelay barge moving forward. This process is started from certain distance from target box ( length gain ) until pipe/end cable reaches the seabed. Recovery is the reverse of abandonment process. It is used to pick up pipeline from seabed up to the barge pipe lay system.
Mathematically on the program, Abandonment is a process of replacing the pipe property with cable until Pipe/Cable connection reaches the seabed. On the program some time, we don’t really see the barge movement and the location of the barge against the target box.
The location of the barge during this process, the barge movements are important on this process.
Abandonment & Recovery AnalysesAbandonment & Recovery AnalysesAbandonment/Recovery with Vessel Position
Target Box
Vessel End Position
Vessel Start Position
Cable/WirePipe
Cable/WirePipe
End VesselStart
Stresses Output`
Note : With this method, the position of the vessel and its movement are shown in detail which will make abandonment process clear and easy to follow,
Abandonment & Recovery AnalysesAbandonment & Recovery AnalysesMathematical Model of Abandonment Process
On this model, during the process, the pipe is replaced by the cable and the vessel is stationed and the pipe/wire connection is moving.
It is easy to model but it requires post processing on the output to get the vessel position against the target box and the vessel movement on each steps.
Abandonment & Recovery AnalysesAbandonment & Recovery AnalysesAbandonment and Recovery Table, Stinger Angle : 14.50Deg
Water Stinger LastDepth Angle Length Locat ion Tension X Dist X Dist Y Fr tagret Vessel At Sting At Sag S1 S2 S3 S4 S5 S6 S7 S8 Roller
Fr T1 Name at Top Fr Stern Fr target Fr WL Box Move & Ramp Bend React React React React React React React React Gap,S8( m ) ( m ) ( m ) ( ) ( kN ) ( m ) ( m ) ( m ) ( m ) ( m ) ( % ) ( % ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( m )
50.00 14.50 0.0 None 650.8 32.65 8.37 4.35 41.02 0.0 79.80 39.70 78.69 31.25 36.66 29.37 40.18 13.51 108.06 0.00 0.00750.00 14.50 24.3 RB1 647.5 8.33 8.39 3.30 16.72 24.3 94.44 39.70 202.82 0.00 19.45 39.55 37.55 14.16 107.94 0.00 0.00750.00 14.50 38.2 S1 641.8 -5.66 8.48 1.49 2.82 38.2 72.59 39.63 0.00 39.99 107.60 11.06 44.75 13.09 107.55 0.00 0.00850.00 14.50 44.5 S2 636.1 -11.81 8.33 0.31 -3.48 44.5 73.96 39.64 26.29 0.00 2.26 123.14 15.90 20.07 106.39 0.00 0.00750.00 14.50 50.8 S3 633.1 -17.91 8.13 -1.09 -9.78 50.8 73.23 39.63 37.20 10.91 0.00 0.00 123.39 0.00 108.48 0.00 0.007
50.00 14.50 57.1 S4 630.5 -23.95 7.87 -2.71 -16.08 56.6 72.32 39.61 37.06 22.55 11.07 0.00 0.31 107.21 90.91 0.00 0.00450.00 14.50 63.3 S5 626.0 -29.94 7.66 -4.54 -22.28 63.3 72.98 39.68 36.80 22.40 22.28 10.47 0.00 0.00 166.26 0.00 0.01750.00 14.50 69.6 S6 623.0 -35.87 7.29 -6.57 -28.58 69.6 38.32 39.66 36.63 22.29 22.19 22.15 9.22 0.00 66.77 68.01 0.00050.00 14.50 75.9 S7 623.5 -41.73 6.85 -8.86 -34.88 75.9 30.10 39.41 36.66 22.31 22.21 22.18 22.29 13.93 0.00 96.34 0.00050.00 14.50 82.2 S8 635.2 -47.55 6.37 -11.43 -41.18 82.2 5.85 38.64 37.33 22.72 22.61 22.58 22.71 22.57 23.00 50.95 0.000
50.00 14.50 90.0 sagbend 627.8 -54.37 5.39 -14.83 -48.98 87.0 0.00 38.69 36.91 22.46 22.35 22.32 22.45 22.32 22.73 39.07 0.00050.00 14.50 100.0 sagbend 609.1 -63.48 4.50 -18.95 -58.98 100.0 0.00 39.20 35.84 21.81 21.71 21.68 21.79 21.67 22.06 25.88 0.00050.00 14.50 110.0 sagbend 581.7 -72.72 3.74 -22.79 -68.98 110.0 0.00 40.15 34.27 20.86 20.75 20.72 20.84 20.71 21.08 15.13 0.00050.00 14.50 120.0 sagbend 546.3 -82.06 3.08 -26.40 -78.98 120.0 0.00 41.54 32.26 19.63 19.53 19.50 19.60 19.49 19.83 6.64 0.00050.00 14.50 130.0 sagbend 504.0 -91.47 2.49 -29.81 -88.98 130.0 0.00 43.38 29.84 18.16 18.06 18.03 18.13 18.02 18.33 0.24 0.000
50.00 14.50 140.0 sagbend 454.3 -100.95 1.96 -33.07 -98.99 133.6 0.00 45.62 27.01 16.43 16.33 16.31 16.39 16.29 12.72 0.00 0.05450.00 14.50 150.0 sagbend 400.6 -110.46 1.47 -36.19 -108.99 150.0 0.00 47.81 23.94 14.56 14.47 14.44 14.52 14.43 8.29 0.00 0.10250.00 14.50 160.0 sagbend 345.2 -120.03 1.04 -39.19 -118.99 160.0 0.00 49.28 20.78 12.63 12.54 12.52 12.58 12.50 5.08 0.00 0.14150.00 14.50 170.0 sagbend 291.0 -129.65 0.66 -42.01 -128.99 170.0 0.00 49.12 17.68 10.74 10.66 10.64 10.69 10.62 2.83 0.00 0.17550.00 14.50 180.0 sagbend 240.1 -139.34 0.34 -44.59 -139.00 180.0 0.00 46.10 14.78 8.97 8.90 8.87 8.91 8.86 1.33 0.00 0.204
50.00 14.50 190.0 sagbend 192.4 -149.13 0.13 -46.88 -149.00 181.8 0.00 39.26 12.06 7.31 7.24 7.22 7.25 7.20 0.51 0.00 0.22650.00 14.50 200.0 sagbend 142.2 -159.01 0.01 -48.81 -159.00 200.0 0.00 26.77 9.19 5.56 5.50 5.48 5.50 5.46 0.61 0.00 0.22250.00 14.50 210.0 sagbend 68.3 -168.99 0.00 -49.96 -169.00 210.0 0.00 5.15 4.98 2.99 2.93 2.91 2.92 2.89 2.83 0.00 0.00950.00 14.50 220.0 sagbend 42.5 -178.98 0.00 -50.00 -179.00 220.0 0.00 1.38 3.50 2.09 2.04 2.02 2.02 2.00 2.01 1.95 0.00050.00 14.50 230.0 sagbend 37.6 -188.98 0.00 -50.01 -189.00 230.0 0.00 1.32 3.23 1.92 1.87 1.85 1.85 1.83 1.84 2.34 0.000
Abo/Recovery Wire Pipe End Coordinates Vessel Stern Pos Max Stress Stinger Reactions Support
Notes : See the High Stress on Step 2, and ‘What If’’ we change the stinger angle ?
Abandonment & Recovery AnalysesAbandonment & Recovery Analyses‘What If’ Analyses on Abandonment/Recovery–Stinger Angles
On this case, lower the stinger will reduce the stress during the abandonment process
Stinger Angle : 15.50 Deg
Max Stress : 109%
Stinger Angle : 13.50 Deg
Max Stress : 77%
Stinger Angle : 14.50 Deg
Max Stress : 94%
Abandonment & Recovery AnalysesAbandonment & Recovery AnalysesAbandonment and Recovery Table, Stinger Angle : 15.50Deg
Water Stinger LastDepth Angle Length Location Tension X Dist X Dist Y Fr tagret Vessel At Sting At Sag S1 S2 S3 S4 S5 S6 S7 S8 Roller
Fr T1 Name at Top Fr Stern Fr target Fr WL Box Move & Ramp Bend React React React React React React React React Gap,S8( m ) ( m ) ( m ) ( ) ( kN ) ( m ) ( m ) ( m ) ( m ) ( m ) ( % ) ( % ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( m )
50.00 15.50 0.0 None 659.8 32.65 8.41 4.35 41.06 0.0 87.92 39.27 129.85 0.00 29.96 37.23 26.46 63.53 53.09 0.00 0.05450.00 15.50 24.3 RB1 656.6 8.33 8.43 3.30 16.76 24.3 109.19 39.27 237.78 0.00 0.00 41.91 28.82 62.93 53.21 0.00 0.05450.00 15.50 38.2 S1 650.8 -5.67 8.52 1.40 2.85 38.2 71.57 39.21 0.00 55.67 94.80 17.58 31.36 63.05 52.58 0.00 0.05550.00 15.50 44.5 S2 644.2 -11.81 8.36 0.12 -3.45 44.5 74.29 39.22 34.03 0.00 0.00 126.77 3.38 69.77 51.50 0.00 0.05450.00 15.50 50.8 S3 641.2 -17.88 8.13 -1.40 -9.75 50.8 73.45 39.22 45.10 11.32 0.00 0.00 118.23 42.59 56.22 0.00 0.055
50.00 15.50 57.1 S4 638.8 -23.89 7.84 -3.11 -16.05 56.5 74.33 39.19 44.95 22.81 10.51 0.00 0.00 143.46 40.90 0.00 0.05250.00 15.50 63.3 S5 633.4 -29.85 7.60 -5.05 -22.25 63.3 56.74 39.29 44.58 22.64 22.53 10.49 0.00 31.05 120.41 0.00 0.06850.00 15.50 69.6 S6 638.9 -35.75 7.20 -7.17 -28.55 69.6 36.57 38.87 44.96 22.83 22.73 22.69 8.65 0.00 106.26 12.67 0.00050.00 15.50 75.9 S7 629.8 -41.54 6.69 -9.65 -34.85 75.9 21.59 39.02 44.33 22.51 22.41 22.39 22.51 22.02 0.00 72.80 0.00050.00 15.50 82.2 S8 636.7 -47.34 6.19 -12.24 -41.15 82.2 5.86 38.49 44.80 22.75 22.65 22.63 22.75 22.62 23.03 36.26 0.000
50.00 15.50 90.0 sagbend 629.8 -54.18 5.23 -15.60 -48.95 86.8 0.00 38.54 44.33 22.51 22.41 22.39 22.51 22.38 22.78 24.53 0.00050.00 15.50 100.0 sagbend 610.9 -63.32 4.37 -19.67 -58.95 100.0 0.00 39.05 43.04 21.86 21.76 21.73 21.85 21.73 22.10 11.76 0.00050.00 15.50 110.0 sagbend 583.1 -72.58 3.63 -23.46 -68.95 110.0 0.00 40.01 41.12 20.89 20.79 20.77 20.88 20.76 21.11 1.66 0.00050.00 15.50 120.0 sagbend 545.0 -81.94 2.99 -27.00 -78.95 120.0 0.00 41.54 38.50 19.56 19.47 19.45 19.55 19.43 14.40 0.00 0.06350.00 15.50 130.0 sagbend 499.9 -91.38 2.43 -30.36 -88.95 130.0 0.00 43.49 35.41 18.00 17.90 17.88 17.98 17.86 7.99 0.00 0.130
50.00 15.50 140.0 sagbend 449.6 -100.86 1.90 -33.58 -98.96 133.5 0.00 45.75 31.95 16.25 16.16 16.14 16.22 16.11 3.26 0.00 0.18650.00 15.50 150.0 sagbend 395.4 -110.39 1.43 -36.67 -108.96 150.0 0.00 47.84 28.23 14.36 14.28 14.26 14.33 14.23 0.01 0.00 0.23350.00 15.50 160.0 sagbend 339.1 -119.96 1.00 -39.63 -118.96 160.0 0.00 49.27 24.37 12.40 12.32 12.31 12.36 10.43 0.00 0.00 0.30550.00 15.50 170.0 sagbend 284.6 -129.59 0.63 -42.41 -128.96 170.0 0.00 48.80 20.62 10.51 10.43 10.41 10.46 7.52 0.00 0.00 0.36550.00 15.50 180.0 sagbend 233.9 -139.30 0.33 -44.95 -138.97 180.0 0.00 45.32 17.14 8.74 8.67 8.65 8.69 5.35 0.00 0.00 0.418
50.00 15.50 190.0 sagbend 186.0 -149.11 0.14 -47.19 -148.97 181.8 0.00 37.82 13.85 7.08 7.01 6.99 7.02 3.90 0.00 0.00 0.45450.00 15.50 200.0 sagbend 134.3 -159.01 0.04 -49.05 -158.97 200.0 0.00 23.98 10.30 5.28 5.21 5.20 5.22 3.33 0.00 0.00 0.42750.00 15.50 210.0 sagbend 61.2 -168.99 0.01 -49.98 -168.98 210.0 0.00 3.99 5.28 2.74 2.68 2.66 2.67 2.64 1.86 0.00 0.08650.00 15.50 220.0 sagbend 41.9 -178.98 0.01 -50.01 -178.97 220.0 0.00 1.37 3.95 2.06 2.00 1.99 1.99 1.97 1.98 1.09 0.00050.00 15.50 230.0 sagbend 37.6 -188.98 0.01 -50.01 -188.97 230.0 0.00 1.32 3.65 1.91 1.86 1.84 1.84 1.82 1.83 1.53 0.000
Stinger Reactions SupportAbo/Recovery Wire Pipe End Coordinates Vessel Stern Pos Max Stress
Abandonment & Recovery AnalysesAbandonment & Recovery AnalysesAbandonment and Recovery Table, Stinger Angle : 13.50Deg
Water Stinger LastDepth Angle Length Locat ion Tension X Dist X Dist Y Fr tagret Vessel At Sting At Sag S1 S2 S3 S4 S5 S6 S7 S8 Roller
Fr T1 Name at Top Fr Stern Fr target Fr WL Box Move & Ramp Bend React React React React React React React React Gap,S8( m ) ( m ) ( m ) ( ) ( kN ) ( m ) ( m ) ( m ) ( m ) ( m ) ( % ) ( % ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( kN ) ( m )
50.00 13.50 0.0 None 640.0 32.65 8.34 4.35 40.99 0.0 76.63 40.23 14.37 87.02 23.52 32.80 37.89 17.91 71.31 49.10 0.00050.00 13.50 24.3 RB1 636.7 8.33 8.36 3.30 16.69 24.3 77.74 40.22 157.13 12.16 42.91 27.82 39.18 17.58 71.44 49.04 0.00050.00 13.50 38.2 S1 631.2 -5.64 8.43 1.59 2.79 38.2 73.53 40.15 0.00 24.70 119.65 7.96 44.38 16.09 72.62 48.16 0.00050.00 13.50 44.5 S2 626.4 -11.81 8.30 0.50 -3.51 44.5 73.80 40.15 18.66 0.00 4.44 122.28 14.88 23.61 70.77 48.50 0.00050.00 13.50 50.8 S3 623.2 -17.93 8.12 -0.79 -9.81 50.8 72.92 40.14 29.40 10.42 0.00 0.00 123.17 0.00 76.18 47.53 0.000
50.00 13.50 57.1 S4 620.4 -24.00 7.89 -2.30 -16.11 56.6 72.16 40.14 29.28 22.21 10.56 0.00 0.00 111.35 50.49 51.93 0.00050.00 13.50 63.3 S5 618.0 -30.02 7.71 -4.02 -22.31 63.3 73.73 40.12 29.17 22.13 22.02 9.46 0.00 0.00 141.78 40.39 0.00050.00 13.50 69.6 S6 612.4 -35.99 7.38 -5.96 -28.61 69.6 56.12 40.22 28.92 21.94 21.83 21.79 9.84 0.00 30.62 118.98 0.00050.00 13.50 75.9 S7 622.0 -41.91 7.00 -8.08 -34.91 75.9 38.21 39.60 29.35 22.27 22.16 22.13 22.24 6.46 0.00 118.61 0.00050.00 13.50 82.2 S8 637.6 -47.75 6.54 -10.61 -41.21 82.2 5.86 38.64 30.06 22.82 22.70 22.67 22.79 22.66 23.10 65.05 0.000
50.00 13.50 90.0 sagbend 629.3 -54.55 5.54 -14.04 -49.01 87.2 0.00 38.69 29.68 22.53 22.42 22.38 22.50 22.37 22.79 53.00 0.00050.00 13.50 100.0 sagbend 610.8 -63.65 4.64 -18.20 -59.01 100.0 0.00 39.19 28.84 21.88 21.77 21.74 21.86 21.73 22.13 39.40 0.00050.00 13.50 110.0 sagbend 583.7 -72.87 3.86 -22.09 -69.01 110.0 0.00 40.12 27.61 20.94 20.83 20.80 20.91 20.79 21.17 28.03 0.00050.00 13.50 120.0 sagbend 548.9 -82.19 3.18 -25.74 -79.01 120.0 0.00 41.51 26.03 19.73 19.63 19.59 19.70 19.58 19.93 18.72 0.00050.00 13.50 130.0 sagbend 507.2 -91.59 2.58 -29.20 -89.01 130.0 0.00 43.32 24.13 18.28 18.18 18.15 18.24 18.14 18.45 11.35 0.000
50.00 13.50 140.0 sagbend 459.7 -101.04 2.02 -32.50 -99.02 133.7 0.00 45.44 21.97 16.62 16.53 16.50 16.58 16.49 16.77 5.76 0.00050.00 13.50 150.0 sagbend 407.6 -110.55 1.53 -35.66 -109.02 150.0 0.00 47.65 19.61 14.81 14.72 14.69 14.77 14.68 14.93 1.77 0.00050.00 13.50 160.0 sagbend 352.9 -120.10 1.08 -38.69 -119.02 160.0 0.00 49.24 17.12 12.91 12.82 12.79 12.86 12.78 12.21 0.00 0.01450.00 13.50 170.0 sagbend 298.3 -129.70 0.68 -41.55 -129.02 170.0 0.00 49.35 14.64 11.01 10.93 10.90 10.95 10.88 8.84 0.00 0.04850.00 13.50 180.0 sagbend 247.0 -139.39 0.36 -44.19 -139.03 180.0 0.00 46.84 12.31 9.22 9.14 9.12 9.16 9.10 6.28 0.00 0.077
50.00 13.50 190.0 sagbend 199.1 -149.16 0.13 -46.53 -149.03 181.8 0.00 40.66 10.13 7.55 7.48 7.46 7.49 7.44 4.46 0.00 0.10050.00 13.50 200.0 sagbend 150.3 -159.03 0.00 -48.53 -159.03 200.0 0.00 29.39 7.91 5.86 5.79 5.76 5.78 5.74 3.45 0.00 0.10250.00 13.50 210.0 sagbend 79.3 -168.99 0.00 -49.91 -169.03 210.0 0.00 8.17 4.68 3.38 3.32 3.30 3.30 3.28 3.32 0.70 0.00050.00 13.50 220.0 sagbend 43.9 -178.98 0.00 -50.00 -179.03 220.0 0.00 1.40 3.08 2.15 2.09 2.07 2.07 2.05 2.07 2.77 0.00050.00 13.50 230.0 sagbend 38.0 -188.98 0.00 -50.01 -189.03 230.0 0.00 1.33 2.81 1.95 1.89 1.87 1.86 1.85 1.86 3.12 0.000
Abo/Recovery Wire Pipe End Coord inates Vessel Stern Pos Max Stress Stinger Reactions Support
Lay Barge Lay Barge RAOsRAOs modelingmodelingResponse Amplitude Operators ( RAOs ) is an important input for dynamic analyses for floating structure, including the pipelay barge. The main concern on the conventional lay barge, the mooring patterns and vessel position against its anchor and also the water depth are changed all the time during pipe laying process.
The next study shows that for conventional lay barge ( with size 12om ) with quite low mooring tension ( 10Te to 30Te ), the mooring lines do not change the RAOs significantly.
Lay Barge Lay Barge RAOsRAOs modelingmodelingTypical Lay Barge Mooring Pattern
Lay Barge Lay Barge RAOsRAOs modelingmodelingLaybarge RAOs with Mooring – Computer Model
Side View
Top View
Lay Barge Lay Barge RAOsRAOs modelingmodelingLaybarge RAOs with Mooring – Computer Model
Model 1
Model 2
Lay Barge Lay Barge RAOsRAOs modelingmodelingRAOs comparison Model 1 Vs Model 2
RAOs at C.o.G - Heading : 90 Deg
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Period ( Sec )
X-A
mp,
Y-A
mp,
Z-A
m
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Rx-
Am
p, R
y-A
mp,
Rz-
Am
p
Surge - X Sway - Y Heave - Z Roll - Rx Pitch - Ry Yaw - Rz
RAOs at C.o.G - Heading : 90 Deg
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Period ( Sec )
X-A
mp,
Y-A
mp,
Z-A
m
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Rx-
Am
p, R
y-A
mp,
Rz-
Am
p
Surge - X Sway - Y Heave - Z Roll - Rx Pitch - Ry Yaw - Rz
Model 1, WD:50m, Tens=20Te
Model 2, WD:50m, Tens=20Te
RAOs at C.o.G - Heading : 90 Deg
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Period ( Sec )
X-A
mp,
Y-A
mp,
Z-A
m
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Rx-
Am
p, R
y-A
mp,
Rz-
Am
p
Surge - X Sway - Y Heave - Z Roll - Rx Pitch - Ry Yaw - Rz
Model 1, WD:30m, Tens=20Te
These RAOs comparison show that on this study case ( LayBarge with size 120 x 32 x 9m. Dead Weight around 22150 Te and 8 mooring anchors ) ‐The RAOs is not influenced by the mooring pattern and so is the tension‐ The RAOs does not change with water depth
Lay Barge Lay Barge RAOsRAOs modelingmodelingRAOs comparison Model 1 Vs Model 2
These RAOs comparison show that on this study case ( LayBarge with size 120 x 32 x 9m. Dead Weight around 22150 Te and 8 mooring anchors ) ‐The RAOs is not influenced by the mooring pattern and so is the tension‐ The RAOs does not change with water depth
RAOs at C.o.G - Heading : 0 Deg
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Period ( Sec )
X-A
mp,
Y-A
mp,
Z-A
m
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Rx-
Am
p, R
y-A
mp,
Rz-
Am
p
Surge - X Sway - Y Heave - Z Roll - Rx Pitch - Ry Yaw - Rz
Model 1, WD:50m, Tens=20Te
RAOs at C.o.G - Heading : 0 Deg
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Period ( Sec )
X-A
mp,
Y-A
mp,
Z-A
m
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Rx-
Am
p, R
y-A
mp,
Rz-
Am
p
Surge - X Sway - Y Heave - Z Roll - Rx Pitch - Ry Yaw - Rz
No Mooring System
RAOs at C.o.G - Heading : 0 Deg
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Period ( Sec )
X-A
mp,
Y-A
mp,
Z-A
m
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Rx-
Am
p, R
y-A
mp,
Rz-
Am
p
Surge - X Sway - Y Heave - Z Roll - Rx Pitch - Ry Yaw - Rz
Model 2, WD:30m, Tens=30Te
PipeLayPipeLay Dynamic Analyses {1}Dynamic Analyses {1}Pipelay Dynamic analyze is used to define the weather limitations during pipeline Installation. The dynamic analyses can be run in Regular Wave or Irregular wave.
When Regular wave is specified, the RAOs used is based on one single frequency and wave heading. When Irregular wave is used, the RAOs is inputted on the range of frequency to cover all the wave spectrum.
In the past, we used ‘regular wave’ to speed up the calculation process. But nowadays, computer time is not a problem any longer, so running on irregular wave is a better approach to choose.
PipeLayPipeLay Dynamic Analyses {2}Dynamic Analyses {2}With Dynamic Analyses, we will see all the pipelay results (pipe position, stress, reaction, tension, support gap, etc.) interms of ranges from min to max dynamic. And on each result, we can also see the time history of that result during duration of time simulation.
Dynamic time simulation is an important input for dynamic analyses, some codes suggested 3Hrs time simulation but for pipelay analyzed, time simulation around 600 sec is sufficient to get maximum peak and typically that maximum will be repeated again with period between 400 to 500 sec.
For us, We are more concerned about the max dynamic result rather than the range of results or the time history, so our table summarizes the max dynamic result only.
PipeLayPipeLay Dynamic Analyses {1}Dynamic Analyses {1}Sample Stress and Tension Ranges Dynamic Output
Max ‐ Min Dynamic and Static Strain
Max ‐ Min and Static tension along Pipe
PipeLayPipeLay Dynamic Analyses {2}Dynamic Analyses {2}Sample Time History Strain & Support Reaction
No Contact During Static on Last Roller, Some Contact on During Dynamic Simulation On Some Cases
PipeLayPipeLay Dynamic Analyses {3}Dynamic Analyses {3}Sample Dynamic Pipelay Result Table, WD:600m
Notes : The above result show that with Hs of 2.25m, with wave heading 0 to 180 deg, pipelay operation can be execute safely. ( strain and local buckling below acceptable limit )
The EndThe End
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