Bolted Connectors: Re-Torquing To Reduce Fugitive .

Bolted Connectors: Re-Torquing to ReduceFugitive Emissions – When and When NotAnita Bausman, P.E.Senior Applications EngineerVSP TechnologiesKingsport, TNBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 1

Retorque: Why or Why Not? Consequences of Low Operational Bolt LoadCauses of Low Operational Bolt LoadOvercoming Operational Bolt Load Losses Gasket Selection/Optimization Joint Design Over-Torquing Optimized AssemblyRe-Torque When Dwell time after assembly Resources/GuidanceBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 2

Definitions:RETORQUE: Any Subsequent Re-Application Of Bolt Load After Initial FlangeAssemblyPURPOSE: Re-Establish Assembly or Operating Bolt Loads and GasketStressesBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 3

Consequences Of Low Operational BoltLoad or Gasket Stress1. Gasket Blow-Out2. Visible, Gross Leakage (gasket still intact)3. Low Operating Margin Against Failure Mechanical IntegrityEquipment ReliabilitySafetyEnvironmental4. Excessive Emissions, Permeation, External CorrosionBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 4

Excessive Emissions with Reduced BoltLoadComparison of PTFE Gaskets - NPS 3 x 150 flangesat 50psig using Relaxation @300 F per HOBTCGraphsMaterial SelectedComposites - ePTFE w/ encapsulated corrugated metalUsing TightnessParameter at Using Operating Tightness ParameterAssemblyTpKg/YrTp18951 8.60E-07 15091EstimatedEmissionsKg/YrEmissionsIncr. AfterGasket. StressLoss1.36E-0658%Composites - ePTFE with Tang Core (1/8")3991.94E-033382.71E-0340%PTFE Expanded Sheet - (1/8'')9233.63E-046956.39E-0476%PTFE Filled HS-10 Sheet - BaSO4 filled - Off-white (1/8'')14701.43E-048684.10E-04187%PTFE Filled HS-10 Sheet - Glass Microsphere filled - Blue (1/8'')14031.57E-045859.01E-04474%Bolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 5

Causes of Low Operational Bolt Load:1) Bolt Load Losses From Gasket Changes: Gasket Creep Example: PTFE gasketsSettling/Compaction of Gaskets Example: Compressed NonAsbestos (CNA),Spiral Wound gasketsThermal/Aging Degradation of Gaskets Example: Elastomer, CNA, Flexible GraphitegasketsBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 6

Causes of Low Operational Bolt Load:2) Bolt Load Losses Due to Piping or JointDesign and/or System Operating Losses: PTFE liner and HDPE Flange/Liner CreepSoft Joint Piping Thermal Expansion Effectsfrom Additional Gasket CompressionShort Effective Bolt Length Tapped Bolt HolesMinimal Assembly ElongationRigid (stiff) Flanged Joint B16.47 Series A (stiff) vs. Series B (flexible)Stiff flanges more susceptible to bolt load lossBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 7

Causes of Low Operational Bolt Load:3) Equipment with Known Low Gasket Assembly Stress /Marginally Available Bolt Load Limited assembly bolt load Stainless steel boltsGlass lined steel flangesWeak flanges FRPLap Joint flangesUnder-Bolted Flanges Hinged ManwaysMany Appendix 2 Designed FlangesFull Face GasketsBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 8

Causes of Low Operational Bolt Load:4) Questionable / Undocumented Assembly Practices / TorqueValues Elastic interactionQuestionable skills/capabilities of assembly crewsImpact wrench assemblyUnlubricated fastenersUsed or damaged fastenersUnknown or undocumented assembly torque levelsUnknown or undocumented assembly patterns/procedures/toolsBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 9

Causes of Low Operational Bolt Load:5) Joint Design: Pressure Energized Manways/Drum Doors Operational pressure supplies significant additional gasket compressionAssembly bolt load is completely lostBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 10

Summary: Causes Of Low Operational Bolt Loador Gasket Stress1. Gasket Creep (ex. PTFE), LinerCreep (ex. PTFE/PE), Flange Creep(ex. HDPE)2. Gasket Settling/Compaction (PTFE,CNA, Flexible Graphite, SpiralWound3. Gasket Degradation (thickness loss)– CNA, Flexible Graphite @ T 600 F4. Hydrostatic Unloading of Gasket(larger diameter connections, highpressure)5. System Pressure EnergizedCompression of Gasket (DrumDoors/Internal sealing Manways)6. Piping System Thermal Expansion(Spiral Wound Gaskets)7. Poor Assembly Practice/Guidance8. In-Adequate Assembly Load orGasket Stress (FRP, Glass Lined,Hinged Manways, etc.)9. Low Assembly bolt load or bolt strainBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 11

Overcoming Operational Bolt Load Loss(without a Re-Torque)Gasket Selection / OptimizationJoint DesignOver Shoot TorqueOptimized AssemblyBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 12

Gasket Selection & OptimizationPVRC Project No. 96-12G – Long DurationMechanical Performance of PTFE Based GasketMaterialsPTFE Gaskets: More creep-resistant material Thinner gasket Gasket design Reduced area higher stressSpring inserted live loadBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 13

Bolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 14

Bolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 15

Gasket Selection & Optimization:Thermal Degradation: Compressed,Non-Asbestos (CNA)Compressed NonAsbestos (CNA)Fiber Gaskets:Example:“High Temp” CNA Thinner sealsbetterSteam PressureAging @ 320 C 250 F MaximumTemperature40 Days Exposure:Thermal DegradationOf The Rubber BinderCreates Porosity andStress RelaxationBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When NotGasket Stress44 MPa – 31 MPa 30% LossSteam Pressure180 Bar – 15 Bar4/3/2018Page 16

Gasket Selection & Optimization:Flexible Graphite (FG)and Corrugated MetalGraphite-faced Gaskets: 600 F Maximumtemperature Specify OxidationInhibited FG Failure Mode is Oxidation@ T 600 F (for a 5yr life)Bolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 17

Flanged Joint Arrangements / Design:Hard Joint Metal to Metal contactSoft Joint No metal to metal contact (soft gasket between)Hard Joints are Less Susceptible to Load LossSoft Joints with Sheet Gaskets:Hard Joints w/SW with Inner and Outer Rings: IF Fully Compressed During Assembly, Subject to creep, degradation, boltotherwise can further compressload loss Belleville washers for more flexibility CammprofileBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 18

Deliberate Overshoot Torque:Knowing there will be Bolt Load Loss from Gasket Creep,Settling/Compaction, and Operational Lossess . Compensate for Expected Losses by Increasing Intial Assembly Load Within the Flange and Bolting Allowable Stresses at OperatingConditions FEA/Flange Analysis is Often Required Gasket Maximum StressFlange Maximum StressBolting Maximum StressBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 19

Consider PTFE Relaxation with Temperature:Higher Assembly Bolt Loads Shifts TheRelaxation Curve UpBlow-Out, Increased LeakageIf Residual Stress Too LowCycles To AmbientBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 20

Optimize Assembly: Overcome Flange Bolt Interactions (“Cross Talk”) Achieves Target Assembly Bolt Load Use Slower Assembly 5 (or more) passes instead of 3Multiple final rotational passes Recoup Gasket Creep Losses During Assembly Process (Retorque During Assembly)Bolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 21

Bolt Load Distribution During AssemblyNPS 4 Class 900, Weld-Neck Flange100% Bolt Load Not Achieved Until 3 Final CircularPassesLoad after 3 Star PatternPassesLoad after 6 Passes (3 Star 3 Rotational)*Bolt #4 datanot includeddue to straingaugemalfunctionBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 22

Glass Column Body JointPTFE Envelope GasketAS-6117B Column Torque300 F Operation, 6 Month Torque CheckBody Flange #Pass5Star-Pattern Assembly, (1) Final Rotational400370 ft-lb Assembly Torque300Retorque to:Ft - Lbs Torque287.6 Average Torque200Bolt TorqueAssemblyTorque 370 Ft-LbNote: Initial Torque 370 Ft-Lbs100Retorque Necessary0159131721252933374145Bolt Number495357616569737781AverageResidualTorque 288 Ft-LbBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 23

Glass Column Body JointExpanded PTFE Envelope GasketAS-6117A Column TorqueBody Flange # 1300 F Operation, 6 Month Torque Check12/14/09Through 2/15/10PassesStar-Pattern Assembly,Multiple FinalRotational400320 Ft-Lb Assembly Torque316.0 Average TorqueFt - Lbs Torque300AssemblyTorque 320 Ft-Lb200Initial Torque 320 Ft-LbsAverageResidualTorque 316 Ft-Lb100Retorque Not olt NumberBolted Connectors:Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 24

If Component, Design or AssemblyImprovements Are Not Possible:THEN Re-Torque – Timing Options: Ambient Temperature Re-Torque Prior To Start-Up Re-Torque 2 – 24 Hours After Assembly, But Before Start-Up Dwell-time based primarily on GASKET creep properties Ambient Temperature Re-Torque After Operation/Process Cycle Re-Torque After Operation/Cycle, While Vessel Is At Ambient Temperature & Pressure Start-Up Hot Torque Re-Torque While Vessel Is Coming Up To Temperature Not recommended for PTFE based gaskets On-Line Re-Torque (Hot Re-Torque) Re-Torque After Operation, While Vessel Is At Temperature, Preferably At Low or AmbientPressureBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 25

Guidance & Resources:ASME Post Construction Committee PCC-1-2013 Section 10.4 Start-Up Re-TorqueAppendix B Definitions & Guidance on Hot Bolting, Half Bolting, and Live TighteningPCC-2-2015 Article 3.10 Hot Bolting (still under development)Note: Hot bolting can also be used to check residual bolt stress after a period of operationor to retighten loose bolts. Hot bolting for these purposes is beyond the scope of PCC-2.Plastics Pipe Institute TN-38 - July 2011 – Bolt torques for Polyethylene flanged jointsGasket Manufacturer, 3rd Party Test Data HOBTC (Hot Blowout with Thermal Cycles) testBFC Engineering & Component SuppliersBolted Connectors: Re-Torquing to Reduce FugitiveEmissions – When and When Not4/3/2018Page 26

Thermal/Aging Degradation of Gaskets . and Corrugated Metal Graphite-faced Gaskets: 600 F Maximum temperature Specify Oxidation Inhibited FG Failure Mode is Oxidation @ T 600 F (for a 5yr life) 4/3/2018 Page 18 Bolted Connectors: Re-Torquing to Reduce Fugitive