Introduction To Free Spanning Pipelines DNV-RP-F105
introduction toDNV-RP-F105 Free Spanning PipelinesIntroductionpresented byOlav FyrileivPrincipal EngineerDet Norske VeritasSlide 12/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
Historical Perspective - VIV Maximum allowable span lengthImplicitly assumes natural frequency f0 controlled by free span length.Do not account for free span scenario, loading phenomenon or environment70ties Fatigue Criteria for In-lineTrue ULS accounting for stress amplitude and number of cycles (η 0.1)Arbitrary models and SN-curves applied. Effect of waves?80ties Onset criteria for Cross-flow1998 Fatigue Criteria for Cross-flowCross-flow VIV not allowed. OK for “short” spans and current conditionsDo not account for stress ranges and time to failure if exceeded.True FLS accounting for stress amplitude and number of cyclesProvides robust decision criteria.Other failure modes may be governing (in-line fatigue, over-stress)Slide 22/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
Historical Perspective - VIV1998 DNV Guideline (GL14)‘Free Spanning PipelinesUpdated and released as2002Slide 3 DNVRecommended Practice (RP-F105)‘Free Spanning Pipelines’2/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
Free Span Assessment Multidiscipline Environmental conditions– Flow conditions from combined wave and current– Local topography Loading Mechanism– Vortex Induced Vibration (in-line & cross-flow)– Direct wave loads & Proximity Effects Structural Response– Soil-pipe interaction– Non-linearities (geometrical, static/dynamic properties) Acceptance criteria– SN-approach (weld, defects, )Slide 42/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
Basis for GL14/DNV-RP-F105VIV Models based on experiencefrom R&D projects & pipeline design MULTISPAN Project (1994-1996)–––Response Model for In-line VIVOn-set criteria for cross-flowReliability based calibration GUDESP PROJECT (1989-1994)––Cross-flow Response modelEffect of Waves Research projects––SVS full scale testMASPUS lab test DHI/Statoil studySlide 52/9/2005 Allows for state-of-the-art fatigueanalysesLinks in-line VIV and wave loadsAllows cross-flow vibrationsSafety philosophy in compliancewith DNV-OS-F101Introduces consistent link betweenanalysis models and safetyfactor(s)Applied in numerous projects in– North Sea– Persian Gulf– South East Asia– GOMDNV RP-F105 Free Spanning PipelinesMANAGING RISK
DNV GL 14 Æ DNV-RP-F105 - why update? Include experience feed-back from projects Include recent R&D effort:–––––––Pipe in trenchVIV response model updatesHydrodynamical coefficientsStructural response estimatesSoil stiffnessForce model (frequency domain)Recommended SN curves Make it more user-friendly:– screening (on-set) criterion– make criteria and calculation methods more complete– restructure documentSlide 62/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
Failure ModesFatigue Limit StateUltimate Limit State. accumulated damage fromstress cycles caused by:. over-stress (local buckling)due to: Slide 7Vortex Induced Vibrations(in-line & cross-flow) (RP-F105)Direct Wave Loads(RP-F105)2/9/2005 Static Bending (weight ¤t)(DNV OS-F101)VIV & Wave Loads (RP-F105)Pressure Effects (DNV OS-F101)Axial Force(DNV OS-F101)Trawl interference(GL 13)DNV RP-F105 Free Spanning PipelinesMANAGING RISK
Calculation Tool Free span assessment complex Require detailed knowledge in several disciplines:––––hydrodynamics, VIV and load modelsenvironmental conditions, long-term statisticsfatigue calculationsstructural response incl. geotechnical aspects DNV-RP-F105 still complex (and difficult?) to use Need for a calculation tool to:– make it easier to apply the RP– enable a cost-efficient span assessmentSlide 82/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
Slide 92/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
LEVEL 1 SPANSOPTIONSLEVEL 2 SPANSUSER HELPLEVEL 3 SPANSPRINT RESULTSFATFREECurrent ModellingUc HistogramRP-F105Return Period ValuesAutomatic GeneratedUPDATE S HEETCALCULATEExpiry date: 2002-12-31Project:References:Wave ModellingCodeDirectionalityDiscrete - C dir.Environmental DataWave-templateCurrentyrsyrsyrsyrsDeep Water TechnologyFatFree Main SheetFree Span ScenarioFlat sea-bedh [m]L [m]e [m]d [m]θpipe200503.0000.0D [m]L/D0.500100cross-flow directionFATIGUE LIFEOlav Fyrileiv (Olav.Fyrileiv@dnv.com)2002-06-10 Calculations byVerified byResponse DataUser Definedfo(in-line)0.722fo(cr-flow)2.000Ain (in-line)186Acr mpingUser Definedζstruc0.000ζsoil (in-line)0.000ζsoil (cr-flow)0.000ζh,RM0.000SN-CurvesF2 (CN in-line)KS(cr-flow)S0 [MPa]SCF0.001.00Peak Stressσx(1 year)0.0σx(10 year)0.0σx(100 year)0.00.000.00Soil stiffnessSand - MediumKVKLKV,S2.10E 008.33E 05Kim Mørk (Kim.Mork@dnv.com )Release NoteDate:Leff,v/LIn-line (Response Model)In-line (Force Model)In-line (Combined)Cross-FlowProgram by:Vers. 9.0FATIGUE ANALYSIS OF FREE SPANNING PIPELINESDNV versionFATFREE COMPLETEDNo Wave CaseCalculation OptionsAnalysis Level 32002-06-10CurrentDamage distribution vs directionRM (In-Line)FM 501.301.201.051.10ΨR1.00Well Defined Span1.907E 071.430E 075.300E 05DYNAMIC STRESS [MPa] in-line directionPeak StressV. Mises Stressσx(1 year)319.822.0σx(10 year)319.822.0σx(100 year)319.822.0Safety FactorsNORMALEXTREME CONDITIONSV. Mises StressCurrent113.7UC(1 year)0.76113.7UC(10 year)0.76UC(100 year)113.70.76WavesUS(1 year)0.00US(10 year)0.00US(100 year)0.00pdf for omnidirectional 0.000.200.400.60velocity0.801.00STRUCTURAL MODELLINGStatic Stress [MPa]σh48.0σN6.8σM,cr299.9σM,in (100y)66.6Slide 10Transfer valuesEIsteel1.80E 08me472q670Seff-3.99E 052/9/20051.00CaCSF0.00ρs/ρ1.342Areas [m e0.00000Ae0.19635Pipe Dimensions 00Coating dataDNV RP-F105 Free Spanning Pipelineskc0.00fcn (MPa)45Functional LoadsHeff [N]0.00E 00p [bar]60 T [oC]0Constantsν0.30α [oC-1]1.17E-05E [N/m2]2.07E 11CD(current)1.003Densities [kg/m ]ρsteel78500ρconcreteρcoating0ρcont200MANAGING RISKρwater1027
Experience with DNV-RP-F105 Slight relaxation compared to Guideline 14.Pipe-in-trench effect significant, relevant for free spans due toscouring.Effect of thick concrete coating significant.Updated boundary condition coefficients provides goodestimates for the structural response of single free spans.DNV-RP-F105 allows significantly longer spans than oldercodes.DNV-RP-F105 represents state-of-art in free span designand minimise the costs related to seabed correction andspan intervention work.Slide 112/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
API RP 1111 (1999)DNV GL14Æ Updated and released as DNV-RP-F105Slide 122/9/2005DNV RP-F105 Free Spanning PipelinesMANAGING RISK
DNV
(DNV OS-F101) VIV & Wave Loads (RP-F105) Pressure Effects (DNV OS-F101) Axial Force (DNV OS-F101) Trawl interference (GL 13) Slide 7 2/9/2005 DNV RP-F105 Free Spanning Pipelines ; MANAGING RISK ; Calculation Tool Free span assessment complex Require detailed knowledge in several disciplines: .
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ASME SA312 ASTM A 312 TP310S Stainless-Steel Tubes ASTM A312 / A 312M, ASME SA312 TP310S is the standard including seamless and welded stainless pipes ASME SA312 TP310S Stainless Steel Pipes ASTM A312 /A312M ASME SA312 Covers seamless, straight-seam welded, and heavily cold worked welded austenitic stainless-steel pipe intended for high-temperature and general corrosive service. ASTM A312 .
