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API 20K Flange Design Task Group API SC6 Task Group

API 20K Flange Design Task Group API SC6 Task Group. Date: June 26, 2008. Design Flange. Functional Design Speci f ication Static Loads per Task Group Consensus Dynamic Loads-TBD. Sealability Analysis. Design Verification . Fatigue Analysis. Design meets Static Load requirements.

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API 20K Flange Design Task Group API SC6 Task Group

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  1. API 20K Flange Design Task GroupAPI SC6 Task Group Date: June 26, 2008.

  2. Design Flange Functional Design Specification Static Loads per Task Group Consensus Dynamic Loads-TBD Sealability Analysis Design Verification Fatigue Analysis Design meets Static Load requirements Redesign Design meets Fatigue life requirements Redesign No No Yes Yes Design Validation Testing Design Analysis Procedure

  3. BoltDiameter Estimation • Observation: Large Bolt Diameter. • Concerns/Design Considerations: • 1. For High Strength Bolts-Tapped Hole depth need to be adjusted for material yield differences. • Availability of bolt material with uniform cross sectional properties. • Ability to achieve uniform make-up through applied torque. • Larger Flange OD. Increase in equipment weight. Increased cost. • Monolithic equipment design: Increased Handling weight & Machining Cost.

  4. Alternate Bolt Materials • Higher Strength, >120 to130 ksi yield may be needed • Higher than 120 Yield Strength Inconel 718 not included in API 6A718 --- 130 ksi/150 ksi may be included in next revision. • Inconel 925 is being considered by NACE • Alloy bolting, hardness 35 Rc/strength is limited due to Hydrogen Embrittlement when connected to C P protection

  5. BX-164 Seal Ring Gasket • At Make-up condition entire gasket(316 S.S,) cross section yields • Gasket leakage concerns: (a) Cyclic loads, (b) At high temperature • New Cross section to be designed. (Reference: R. Eichenberg’s method.) New Cross section is under development. • Design guidelines & Test protocol for Gasket needs to be established. • Concerns: Cost of testing . Material Selected will verify performance of that material.

  6. BX-164 Seal Ring GasketDesign Parameters Check per Eichenberg Method

  7. Hydril 18-3/4” 20 ksi Flange Design (Preliminary) Stress Calculations Method: ASME Section VIII, Division 2, Appendix 3

  8. Flange Design • API 6A Flange Design: Reference: API TR 6AF2 • ASME Methodology, ASME Section VIII, Div2, Appendix 4 • Design Allowable per API 6A, Based on Tresca Theory (Stress Intensity): For API 75K Material • Working Pressure: Sm = (2/ 3)*Sy • Test Pressure: ST = (0.83)* Sy • Bolt Allowable: API 6A: • 83 % of Yield, Max Stress, • Make up load 50% of Sy • ASME Method, Section VIII, Div2, 2007 Edition: • Sm = Lower of (2/ 3)*Sy or ST = TS/2.4 • Sbm= Allowable @ Hydrostatic Pressure: Sbm = 0.95 Sy Sbm + Sbb = lower of 1.43 SY or 2.43 SY-1.5Sbm

  9. Summary • Bolt Size affects flange OD. • Need higher strength bolt material • Deepwater application requires considerations for affects of CP protection and potential exposure to well bore fluid when insulated, • Bolting Allowable being reviewed. Recommendation to follow. • BX-164 Gasket is inadequate. New Gasket is needed. • Material selection for subsea use may qualify only one gasket material • Flange Design Method/Allowable being reviewed. Recommendation to follow. • API 6A + ASME Sect VIII (Edition referenced in API 6A) or • ASME Sect VIII, 2007 Edition

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