RULE-BASED METHODOLOGY FOR SEAL SELECTION IN PIPELINE APPLICATIONS
- 1. Rule Based Seal Selection For Pipeline Services
- 2. Presenter – Raul Escontrias, John Crane Raul Escontrias is the North American Pipeline Account Manager for John Crane based out of Houston, TX. He joined John Crane in 1997 and in his current role serves as a technical resource specific to the pipeline industry. His primary duties are interfacing with corporate engineering groups for pipeline operators to establish best practices for design criteria, assist with on-site troubleshooting, formulation of recommendations on new applications and to facilitate client training. He has held additional engineering roles within John Crane, including Reliability and Regional Engineering positions in the United States in the refining, specialty chemical processing and petrochemical markets. As a graduate of Texas A&M University with a BS in Engineering, he has over 25 years of technical field expertise. Contact Information Mobile: +1 832-257-4638 E-Mail: rkescontrias@johncrane.com
- 3. Introduction: Acceptable pipeline sealing solutions must have: • Extended reliability in all products • Resist hang-up and wear • Withstand contaminates and abrasives • Operate 2 bar (30 psig) to 100 bar (1450 psig) dynamic, 150 bar (2200 psig) static. • Secondary containment ensures no leakage
- 4. Challenges with Pipeline Applications: Multiphase batch operations Pumps in series Seal chamber face squareness to shaft Mixed products High viscosity start-up Low lubricating products High hydrostatic pressure rating Remote/unmanned pumping stations Leakage containment; no flare or disposal Pump equipment shaft shuttling VFD Operation Pipeline Rouge & Contaminate
- 5. Pressure Limits for Mechanical Seals API 682 does not apply to pipeline seals (yet), it is useful to note that it defines three pressure terms that relate to the mechanical seal: • Static • Maximum Static Sealing Pressure (MSSP) • Static Sealing Pressure Rating (SSPR) • Dynamic • Maximum Dynamic Sealing Pressure (MDSP) • Dynamic Sealing Pressure Rating (DSPR) • MAWP (Maximum Allowable Working Pressure) API 682 defines the pressure casing as including the seal chamber but excluding the stationary and rotating members of the mechanical seal. This means there is no requirement that the seal has the same maximum allowable working pressure as the pump.
- 6. Face Treatments For Mechanical Seals
- 7. Material Considerations - Faces
- 8. • Unreliable in dirty and solids duties - Fretting • O-ring travel in one year is ~150 miles with shaft shuttling of 0.005” • Non-pusher design eliminates dynamic O-ring • Longer operational life and potentially lower cost maintenance. • Eliminates hang-up and wear Material Considerations – Secondary Seals • Evaluate material compatibility by process • Pressures beyond 1440 PSIG, a increase durometer. • Thermoplastics / energized polymer seals have been used in extreme pressure cases. • Non-pusher secondary seals have documented advantages in many midstream applications.
- 9. • 316 Stainless Steel (UNS S31600) –Nickel and Molybdenum (Mo) content improve corrosion resistance • Duplex Stainless Steel (UNS S31803) –Increased tensile and yield strength. To 2160 PSIG (149 BARG), adaptive hardware benefits • Large dia hardware components, > 4.33” (110 MM) Material Considerations - Hardware
- 10. Pressure Limits for Mechanical Seals
- 11. Sealing Strategies by Fluid – Crude Oil • Varying API gravity and viscosities • High concentration of contaminates • Filtration and separators typically not effective • Susceptible to hang-up and clogging • Pump configuration may be susceptible to axial shaft shuttling
- 12. • Typical operating parameters: –Suction Pressure: 3.5 to 100 BAR (50 to 1500 PSIG) –Max Discharge Pressure: 152 BAR (2200 PSIG) –Speed Range: 600 to 3600 RPM –Temperature: 10 to 38 °C (50 to 110 °F) –Viscosity@ Pumping Temperature: 3 to 1,000 cP –Specific Gravity: 0.73 to 0.93 –Shaft Diameter: 67 to 165 mm (2.625 to 6.500”) –Mode of Operation: 2 to 6 pumps in series Sealing Strategies by Fluid – Crude Oil
- 13. API Piping Plan 11 w/ 66A/B, 65A/B API Piping Plan: Plan 11 w/ 75 API Piping Plan 53B or 54 Sealing Strategies by Fluid – Crude Oil
- 14. Sealing Strategy by Fluid – Refined Products • Refined crude oil yields hydrocarbon products: –Gasoline, Diesel Fuel, Jet Fuel • Low vapor pressure fluids • Lower viscosity vs crude oil, but higher when compared to NGLs • Pump configuration may be susceptible to axial shaft shuttling
- 15. • Typical operating parameters: –Suction Pressure: 3.5 to 80 BAR (50 to 1200 PSIG) –Max Discharge Pressure: 125 BAR (1800 PSIG) –Speed Range: 1800 to 3600 RPM –Temperature: 10 to 38 °C (50 to 110 °F) –Viscosity@ Pumping Temperature: 0.5 to 3.0 cP –Specific Gravity: 0.70 to 0.86 –Shaft Diameter: 67 to 165 mm (2.625 to 6.500”) –Mode of Operation: 2 to 3 pumps in series Sealing Strategy by Fluid – Refined Products
- 16. • API piping plan 11 or 31 w/ 66A/B, 65A/B • Some users have opted for 99(12) - filtration • API Piping plan 11 or 31 w/ 75 • Option for 99(12) - filtration Sealing Strategy by Fluid – Refined Products
- 17. • Raw Natural Gas Liquids or Y-Grade variations –Separated from natural gas resources, fractionated into base components. • Definition of “flashing hydrocarbon” from API 682: –3.1.36 liquid hydrocarbon or other fluid with absolute vapor pressure greater than 0.1 MPa (1 bar) (14.7 psia) at the pumping temperature, or a fluid that will readily boil at ambient conditions. Sealing Strategy by Fluid – Flashing HC’s
- 18. • Typical operating parameters: –Suction Pressure: 6.9 to 80 BAR (100 to 1200 PSIG) –Max Discharge Pressure: 152 BAR (2200 PSIG) –Speed Range: 1800 to 3600 RPM –Temperature: 15.7 to 44 °C (60 to 110 °F) –Viscosity@ Pumping Temperature: 0.06 to 0.15 cP –Specific Gravity: 0.42 to 0.58 –Shaft Diameter: 67 to 165 mm (2.625 to 6.500”) –Mode of Operation: 2 to 4 pumps in series Sealing Strategy by Fluid – Flashing HC’s
- 19. API Piping plan 11 or 99 (12) w/ 76 API Piping plan 11 or 99 (12) w/ 76 Sealing Strategy by Fluid – Flashing HC’s
- 20. Flow guide for improved cooling and flush distribution is recommend for flashing HC applications Sealing Strategy by Fluid – Flashing HC’s
- 21. • Include Ethane, Ethane-Propane mix, CO2 • Operate beyond critical pressure / temperature • Dense vapors • Extremely limited lubricity properties Sealing Strategy by Fluid – Supercritical
- 22. • Typical operating parameters: –Suction Pressure: 41 to 97 BAR (600 to 1400 PSIG) –Max Discharge Pressure: 152 BAR (2200 PSIG) –Speed Range: 1800 to 3600 RPM –Temperature: 10 to 33 °C (50 to 90 °F) –Viscosity@ Pumping Temperature: 0.02 to 0.04 cP –Specific Gravity: 0.30 – 0.40 –Shaft Diameter: 67 to 165 mm (2.625 to 6.500”) –Mode of Operation: 2 to 3 pumps in parallel Sealing Strategies by Fluid – Supercritical
- 23. API Piping plan 99 (12) w/ 76 API Piping plan 53B or 54 Sealing Strategies by Fluid – Supercritical
- 24. • Filtration systems have proven to be effective • Increased reliability • Classified as API Plan 99 (12) –Duplex for redundancy –Magnetic separation –Double block and bleeds –Continuous Flow Transfer Valve Mechanical Seal Filtration Systems
- 25. • Complete isolation of mechanical seals from process fluid • Maximum process fluid containment • Requires barrier fluid compatible with process • Added complexity and cost to sealing system High Pressure Lubricators – Piping Plan 54
- 26. Thank you for your time!