Using Smart Positioners in Emergency Shutdown Applications

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Using Smart Positioners in Emergency Shutdown Applications

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  • A safety Instrumented System is ….
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    These target failure measures appear in the NORMATIVE part 1 of IEC61508. For the process industry, only the “demand mode of operation” column is relevant as this is the nature of any normal ESD type system which is dormant most of the time, and is only called into action when something goes wrong with the regular control system. Target failure measures are also presented for continuous/high demand mode of operation in IEC61508, but this column is not shown here.
    The risk reduction factor is the direct reciprocal of the PFDaverage presented above.
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    Notes:
    1) ASCO EF8316G302 (24VDC, Explosion Proof) or equivalent solenoid valve can be used. Above shown ASCO solenoid model number will be subject to change, if body material, size or any other parameter changes.
    2) We have shown above schematics for single acting spring diaphragm type actuator but the same applies to double acting piston type actuator with fairchild relay in the output circuit of solenoid valve and actuator.
    3) It may please be noted that this is an arrangement for Explosion Proof ESD system.
    4) FIELDVUE ESD solution can be extended to any configuration of valve styles like Rotary valves or Quarter Turn Valves, Sliding stem valves etc.
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    Notes :
    1) ASCO EF8316G302 (24VDC, Explosion Proof) solenoid valve required is of low power type. It could be a different model depending upon size, material and other variables but important aspect is that it should be of low power solenoid valve. Other make of Solenoid valve can be also used but it has to be of low power type.
    2) We have shown above schematics for single acting spring diaphragm type actuator but the same applies to double acting piston type actuator with fairchild relay in the output circuit of solenoid valve and actuator.
    3) It may please be noted that this is an arrangement for Explosion Proof ESD System.
    4) FIELDVUE ESD solution can be extended to any configuration of valve styles like Rotary valves or Quarter Turn Valves, Sliding stem valves etc.
  • Using Smart Positioners in Emergency Shutdown Applications

    1. 1. Customer : Saudi Aramco Technical Presentation on Fisher DVC6000-ESD Smart Positioners in Emergency Shutdown Applications
    2. 2. Using Smart Positioners in Emergency Shutdown Applications  Basic Concepts  Historical methods  Smart Positioners to the Rescue  Installation  Conclusion
    3. 3. Definition What is a Safety Instrumented System?
    4. 4. What is a Safety Instrumented System (SIS)? An SIS is a set of components such as sensors, logic solvers, and final control elements arranged for the purpose of taking the process to a safe state when predetermined conditions are violated.
    5. 5. What is a Safety Instrumented System (SIS)? Logic solver Sensor Logic Solver (Hardware and Software) Final Control Element
    6. 6. Safety Through Layers of Protection Plant and Emergency Response Mitigate Emergency response layer Passive protection layer Dike Relief valve, Rupture disk Safety Instrumented System Prevent Active protection layer Emergency Shut Down Safety layer Trip level alarm Operator Intervention Process Shutdown Process control layer Process alarm Basic Process Control System Process Value Process control layer Normal behaviour x x
    7. 7. What is SIL? SIL is a way of quantifying risk.
    8. 8. What Is SIL? – Safety Integrity Level SIL4 SIL3 Risk SIL2 SIL1 NO SIL
    9. 9. SIL Is Directly Related To Risk RISK Consequence or Frequency
    10. 10. Safety Integrity Levels PFD 1/PFD Safety Integrity Level Probability of failure on demand per year Risk Reduction Factor SIL 4 >=10-5 to <10-4 100000 to 10000 SIL 3 >=10-4 to <10-3 10000 to 1000 SIL 2 >=10-3 to <10-2 1000 to 100 SIL 1 >=10-2 to <10-1 100 to 10 (Demand mode of operation)
    11. 11. SIS Faults – Investigation Uncovers Clues What Components Cause More Faults? Logic Solver 15% Sensor 35% Valve 50%
    12. 12. SIS Faults – Where Do They Happen? Sensor Logic Solver (Hardware and Software) Final Control Element
    13. 13. Why does the ESD valve account for 50% of failures?  Typically operate in one position - only move upon an emergency  Without mechanical movement, unreliability inherently increases  Frequent testing ensures valve availability upon Demand  Historically, expensive, labor intensive pneumatic testing methods required
    14. 14. Using Smart Positioners in Emergency Shutdown Applications  Basic Concepts  Historical methods  Smart Positioners to the Rescue  Installation  Conclusion
    15. 15. Aramco Existing Pneumatic Test Methods (costly and complicated)
    16. 16. Limitations to existing pneumatic test panel  Local testing and Hard Stop  Requires bypass  Shutdown and Test  Restricted analysis  Expensive & Complex  Limit Switch and time Signal to Allow Partial Stroke
    17. 17. Using Smart Positioners in Emergency Shutdown Applications  Basic Concepts  Historical methods  Smart Positioners to the Rescue  Installation  Conclusion
    18. 18. Smart Positioners to the RescueFeatures Smart Positioner or Digital Valve Controller (microprocessor-based instrument)  Partial Stroke  Diagnostics  Vent Actuator Pressure  Collect pressure, travel data and analyze  Supply and output pressure sensors  Documentation (Compare and Storage)  Full stroke valve signatures for seat load details
    19. 19. Smart Positioners to the RescueCapabilities  Partial Stroke Test criteria – Configurable valve travel – Valve returns to normal operation, if diagnostic fails – If “valve is stuck”, alert operator – Don’t exhaust all the air – Configurable Speed of Stroke – Demand Overrides Partial Stroke Test
    20. 20. Without partial valve stroke testing – SIL2
    21. 21. With partial valve stroke testing – SIL3
    22. 22. Doing The Math Full Stroke Testing Only Assumptions: DF is 100% and TI is 1x / yr PFD avg = [(DF)(λ d) (TI/2)] = (1) (λ d) (1/2) = 0.5 (λ d) Adding Partial Stroke Testing Assumptions: DF is 70% for partial stroke and 100% for full stroke TI is 4x/yr for partial and 1x/3 yrs for full PFD avg = [(DF)(λ d) (TI/2)]p + [(DF)(λ d) (TI/2)]F = [(0.7)(λ d) (0.25/2)] + [(1-0.7) (λ d) (3/2)] = 0.09 (λ d) + 0.45 (λ d) = 0.54 (λ d) Conclusion: Partial Stroke Testing enables extending the full-stroke testing interval to 3 years and still maintaining the same PFD!
    23. 23. Smart Positioners to the Rescue -Capabilities  On Demand, digital valve controller continues to communicate  Continuous Check of Device Integrity – In case of problem, provide alert  Manual Initiation of Automated testing – Remote companion software – Handheld – Remote push button
    24. 24. Smart Positioners to the Rescue -Capabilities  Step Response Test – Initiated via Companion software – Provides analysis of overshoot, hysteresis, dead time and travel time. – This data can be utilized to extrapolate valve stroking time  Modular Construction
    25. 25. Smart Positioners to the Rescue -Capabilities  Encapsulated & Potted electronics  Pneumatic relay - mechanical beam
    26. 26. Using Smart Positioners in Emergency Shutdown Applications  Basic Concepts  Historical methods  Smart Positioners to the Rescue  Installation  Conclusion
    27. 27. Solution Proposal: Point to Point Mode Approach Logic Solver Solenoid Valve 24V DC S 4-20 mA DC Exhaust ESD Valve/Actuator Supply Pressure Travel Feedback Digital Valve Controller
    28. 28. Solution Proposal: Multi-drop Mode Approach Logic Solver Solenoid Valve S 24V DC Line Conditioner Exhaust ESD Valve/Actuator Supply Pressure Travel Feedback Digital Valve Controller
    29. 29. Using Smart Positioners in Emergency Shutdown Applications  Basic Concepts  Historical methods  Smart Positioners to the Rescue  Installation  Conclusion
    30. 30. Conclusion  Increased System Availability  Safety Defaults  Predictive Maintenance  System Audit Documentation  Valuable Time Saving  Reduced Cost Of Ownership
    31. 31. Installed Base Saudi Aramco - Yanbu Saudi Aramco Shedgum Saudi Aramco, Berri Gas Plant Saudi Aramco, Haradh Gas Plant ICI - Runcore plant - UK Doffasco - Canada TiWest - Australia SCECO - Riyadh - S. Arabia Huntsman Chemicals-Beaumont DuPont-Washington Works- USA DOW Chemicals, Freeport - USA QP (Qatar Petroleum) - Qatar ORC, Oman And more…
    32. 32. Using Smart Positioners in Emergency Shutdown Applications QUESTIONS?

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