Transcription
Determining Remaining Strengthof Corroded PipelinesHouston SectionApril 10, 2012
Who is DCP Midstream? Formerly Duke Energy Field Services the Company wasrenamed on January 1, 2007 to align with DCPMidstream Partners. DCP Midstream, LLC is a private company. A 50-50 jointventure between Spectra Energy and ConocoPhillips. One of the nation's largest natural gas gatherers andprocessors (7 Bcf/day), the largest natural gas liquids(NGLs) producer and one of the largest NGL marketersin the U.S. Operates in 26 states, gathers raw natural gas through 62,000 miles of pipe and processes gas through 61plants, produces 360,000 bbls/day NGLs Over 3,000 employees
Introduction Pipeline Design ASME B31G Limits for B31G Misc4
Pipeline DesignBarlow’s formula relates pressure to pipeattributesP 2 St / D P Design pressureS Yield strength in psiD Outside diametert Nominal wall thickness5
Pipeline Design Barlow’s formula P (2 St/D) x F x E x TP Design pressureS Yield strength in psiD Outside diametert Nominal wall thicknessF Design factorE Longitudinal joint factorT Temperature derating factor 6
Peter BarlowPeter BarlowWoolwich -SE of London. Active 1741–19397
Pipeline DesignDesign factor (F) Liquid Pipelines 0.72 Gas Pipelines Class 1 Class 2 Class 3 Class 40.720.600.500.408
Pipeline DesignExample: Liquid line6” .219 wt X42P (2 x 42000 x .219 / 6.625)P 2777 psiPmax mop 2777 psi x .72 19999
ASME B31GA supplement to ASME B31Calculates Burst pressure with pipe parametersand metal loss Length - L depth - d10
ASME B31G11
ASME B31G12
ASME B31G13
ASME B31G Based on Battelle Institute work July 1971 ASME Guide ASME B31G - 1984 Modified B31G - 1991 Current edition B31G-200914
ASME B31G15
ASME B31GEquations are empirical or in some cases semiempirical.What is this?Empirical knowledge comes from observation only. You don't knowwhy or have any idea of why reaction A follows situation B but youhave seen it happen so many times that you KNOW that is what isgoing to happen.People knew that things fell down long before there was a theory ofgravitation. Such knowledge was empirical.Empirical knowledge not only comes from observation but also bytesting.Read more: cphttp://wiki.answers.com/Q/What is empirical knowledge#ixzz1rfGSpoND16
ASME B31G3 versions ASME B31G Modified B31G Effective Area Method17
ASME B31GDifference in methods18
ASME B31GApplication Yes for blunt metal loss Yes for external corrosion Yes for internal corrosion19
ASME B31GLimitations (RULES) Depth less than 80% wtNo CracksNo gougesNo stress ConcentratorNo selective seam corrosionNo selective weld corrosionApply operating characteristics Psafe20
ASME B31GIn operations, always Identify cause of metal loss Mitigate cause of metal loss21
B31G Company Operating Manuals KAPA (“KAPA” is an acronym for “Kiefner &Associates Pipe Assessment”) RSTRENG 22
B31G23
B31 G InteractionInteraction ruleCommonly used 1” x 6t interaction 1 inch in axial length separation 6 times pipe wall thickness for widthsepartion (.250 wt 1.5 in) If separation 1” x 6t group or cluster theanomalies together.24
Interaction B31G25
B31G26
B31G27
ASME B31G28
ASME B31GSince L 15/16” must repairWhat about Modified B31G?29
Links and //www.ttoolboxes.com/Products/Duane /478/1/NQ51187.pdf30
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Kapa32
Kapa p233
Limits for B31G Depth less than 80% wtApply operating characteristics PsafeNo CracksNo gougesNo stress ConcentratorNo selective seam corrosionNo selective weld corrosion34
Limits for B31GOK for blunt metal loss Internal Corrosion External Corrosion Welds if metal loss not selectiveMust stop cause of metal loss – remember identifythe cause, and fix35
ILI spreadsheets -example B31G calcsEVENT LOCATIONANOMALY DESCRIPTIONDISTDIST TOWHEEL FROM U/SD/SEVENT COUNTWELDWELD(ft.)(ft.)(ft.)Anomaly 103397.8127.4230.81Anomaly 111302.5132.4330.94GirthWeld l WallThicknessWidth (in)(in)1.390.25039%10.062.840.25042000W. INT/ EXT211,622.30 MetalLossEXTERNAOdometer(ft)INT /EXTDEPTH%5054RelativeAbsoluteDistance Distance Comment(ft)(ft)s19.51211,621.20 MetalLossEXTERNACLOCKANOMALY REPAIR IL.85dl(psi)990989CALC.PFAIL.85dl /MAOPCOMMENTS1.161.16RSTRENG Burst Orientatio Orientation(psi)n (clock) (Degrees)15096:3019515385:45BurstO'Clock 60.63:3129991.17936
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Introduction40
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Test Section 3 bottom view, typicalpitting 20-40 %
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Barlow’s formula relates pressure to pipe attributes. P 2 St / D. P Design pressure S Yield strength in psi D Outside diameter t Nominal wall thickness. 6. Pipeline Design. Barlow’s formula. P (2 St/D) x F x E x T.File Size: 1MBPage Count: 48
