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SIS “Final Element” Diagnostics Including The SOV, Using A Digital Valve Controller

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Presented by C B Chakradhaar and Riyaz Ali at the 2010 Emerson Exchange in San Antonio, Texas.

Presented by C B Chakradhaar and Riyaz Ali at the 2010 Emerson Exchange in San Antonio, Texas.

Published in Education , Business , Technology
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  • 1. SIS “Final Element” Diagnostics Including The SOV, Using A Digital Valve Controller
    C B Chakradhaar– Instrument & Control Specialist
    Riyaz Ali – Director Instruments
  • 2. Presenters
    • C B Chakradhaar- I & C Specialist
    • 3. Riyaz Ali – CFSP
  • Introduction
    SIS “Final Control Element” Diagnostics by Digital Valve Controller
    Basic Concepts and Need
    Traditional Test Methods
    Present Field Issues & Pains
    Digital Valve Controller to the Rescue
    SOV Health Monitoring
    Critical Evaluation of Solution
    Ras Gas (End User) Field Experience
    Evaluation of Solution
    Lesson Learned
  • 4. Basic Concepts and Need
    x x
    Plant and
    Emergency
    Response
    Emergency response layer
    Passive protection layer
    Mitigate
    Relief valve,
    Rupture disk
    Active protection layer
    Dike
    Emergency
    Shut Down
    Safety
    Instrumented
    System
    Safety layer
    Trip level alarm
    Prevent
    Process
    Shutdown
    Process control layer
    Operator
    Intervention
    Process alarm
    Basic
    Process
    Control
    System
    Process
    Value
    Process control layer
    Normal behaviour
    Safety Through Layers of Protection
  • 5. Basic Concepts and Need
    Why Focus on the Final Element ?
    Safety Instrumented System
    Basic Process Control System
    50% failures are in Final Control Element
  • 6. Typically operate in one position - only move upon an emergency
    Without mechanical movement, unreliability inherently increases
    Frequent testing ensures valve availability upon Demand
    Historically, inexpensive mechanical jammer or expensive labor intensive pneumatic testing methods are used
    Basic Concepts and Need
    Why does the SIS Final Element account for 50% of failures?
  • 7. OFF LINE
    ON LINE
    Total Stroke
    Total Stroke
    By-Pass In Service
    Process Down
    Component Test
    Partial Stroke
    Solenoid (SOV)
    Traditional Test Methods
    Test Methodology
    • Objective:
    Reduce the Probability of Failure on Demand (PFD)
    • Traditional test methods (pneumatic local panels, pin retainers, by-passing, etc.) are difficult to operate and maintain with risks and high operational costs
  • Present Field Issues & Pains
    Existing Test Methods Have High Costs
    CAPEX
    LABOUR
    Pneumatic panels
    Mechanical retainers
    Logic Solver with Limit Switch
    CAPEX
    By-pass Valve
  • 8.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 9.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    IMPROVE PFD
    Reducelaborcosts
    Improveflexibility
    Valve exercised to an extent

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 10.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    FIELDVUE Partial Stroke isdone on-line.
    FIELDVUE Partial Stroke capable of beingtrimmed to suit the process.

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 11.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    FIELDVUE Partial Stroke Test avoid to casually close the valve

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 12.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    FIELDVUE Partial Stroke Test checks valve movement and collectstravel and pressure data.

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 13.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    FIELDVUE Partial Stroke couldbestartusing a simple push button

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 14.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    FIELDVUE Partial Stroke test Speed canbevaried to Suit Process.

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 15.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    FIELDVUE Partial Stroke Test takes valve to its original position. If stuck, willprovide an alert.
    Travel, pressure and devicecondtionmonitoredregularly.

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 16.
    The Test objectives

    Maintaining the Process

    AvoidingAccidentalClosureTesting

    Final Element Variation
    FIELDVUE Partial Stroke Test resultstored in the instrument.
    ValveLink Audit Trail & Documentation

    Simple Operation

    Stroke Test Speed

    Ensures Valve Returns to Normal Position

    Safety Audit
    Digital Valve Controller to the Rescue
  • 17. Digital Valve Controller to the Rescue
    The Influence of Partial Stroke testing
    Increase SIL Level
    Implementation of Partial Stroking on Final Control Element improves PFD to achieve better SIL level
    Validation of SIS
    Partial Stroking Validates the proper operation of the FCE
    Final Control Elements are commonly untested and are inherently unreliable
    Maintains SIL Level
    Safely extend turnaround times
    PFDavg
    1/PFD(t)
    Test Interval
    Without testing the PFD increases
    Time
  • 18. Digital Valve Controller to the Rescue
    Unique Alert Features
    Partial Stroke “Valve Stuck” ALERT
    If the valve does not move or sticks the Digital Valve Controller STOPS the test
    Valve returns to normal operation position and alert is generated
    The valve will not slam shut, causing a plant “Spurious Trip”
    Trigger ALERT
    Captures valve movement or pressure changes
    Automatically stores travel, pressure and deviation data in the digital valve controller Supply Pressure ALERT
    Low supply pressure causes an alert
  • 19. Digital Valve Controller to the Rescue
    Specific Safeguards
    Any safety DEMAND overrides Partial Stroke Test Mode
    Remote push button test returns to normal operation if:
    partial stroke fails
    push button is held outside 3-5 seconds timeframe
    Safety DEMAND occurs
    Write Protection or ‘tamper-proof’ lock
    Deters local unauthorized access to calibration or configuration parameters
  • 20. Digital Valve Controller to the Rescue
    Diagnostics
    Diagnose VALVE failures before they happen
    Moves the SIS valve into predictive maintenance regimes
    Additional diagnostics
    Friction buildup
    Valve shaft shear
    Air supply pressure deviations
    Option to collect data during a demand
  • 21. Digital Valve Controller to the Rescue
    Diagnostics Enhancements
  • 22. Companion Software Alert Log
    Companion Software Audit Log
    Companion Software Test DataBase
    Intrument Alert Log
    Last Partial Stroke Test Stored in the Intrument
    Digital Valve Controller to the Rescue
    Audit Documentation
  • 23. Solenoid Valve Health Monitoring
    0-20 mA Point To Point
    Or 0-24 Volts Multidrop
    From Logic Solver
    0 mA or 0 Volt ESDV Closed
    20 mA or 24 Volts ESDV Open
    24 Volts DC From Logic Solver
    Supply Pressure
    Port A
    Port B
  • 24. Solenoid Valve Health Monitoring
    0-20 mA Point To Point
    Or 0-24 Volts Multidrop
    From Logic Solver
    0 mA or 0 Volt ESDV Closed
    20 mA or 24 Volts ESDV Open
    24 Volts DC from Logic Solver
    Supply Pressure
    Port A
    Port B
    Pressure Measurement Downstream SOV
  • 25. Solenoid Valve Health Monitoring
    0-20 mA Point To Point
    Or 0-24 Volts Multidrop
    From Logic Solver
    0 mA or 0 Volt ESDV Closed
    20 mA or 24 Volts ESDV Open
    24 Volts DC From Logic Solver
    PULSE
    Supply Pressure
    Port A
    Port B
  • 26. Solenoid Valve Health Monitoring
    • The solenoid valve can be pulsed for a split second
    Long enough so that the solenoid vents (verification that the solenoid valve is functional)
    Short enough so that the actuator doesn’t bleed enough pressure to make the SIS valve move.
  • 27. Critical Evaluation for Solution
    PST Scripted avoiding Human Error
    Chances of Spurious Trip Reduced during PST
    Demand Overrides PST
    “Valve Stuck” Conditions Alerted
    Health Detection of “Final Element”
    SOV Health Monitoring
    Trigger Capability to Capture Safety Demand Event
    Compare and Overlay Previous Results to Predict Valve state
    Audit Documentation by Date and Time Stamp
  • 28. Real Life Examples from Ras Gas - Qatar
  • 29. Real Life Examples from Ras Gas - Qatar
  • 30. Real Life Examples from Ras Gas - Qatar
    AMS Valve Link Suite opened Via Pactware
  • 31. Real Life Examples from Ras Gas - Qatar
    Digital Valve Controller access via AMS ValveLinkTM Software
  • 32. Real Life Examples from Ras Gas - Qatar
    Full Stroke Test Initiated
  • 33. Real Life Examples from Ras Gas - Qatar
    FST signature taken and saved
  • 34. Real Life Examples from Ras Gas - Qatar
    Initiating a PST
  • 35. Real Life Examples from Ras Gas - Qatar
    PST signature taken and saved
  • 36. Real Life Examples from Ras Gas - Qatar
    SOV test setup
  • 37. Real Life Examples from Ras Gas - Qatar
    SOV test initiated from DCS
  • 38. Real Life Examples from Ras Gas - Qatar
    Response graph taken and saved
  • 39. Real Life Examples from Ras Gas - Qatar
    Valve Step Response Test
  • 40. Real Life Examples from Ras Gas - Qatar
    Benefits realized
    • FST and PST signatures taken during loop check
    • 41. FST signature compared with Factory signature to study valve wear and tear
    • 42. PST performed with 10% valve movement
    • 43. PST – SOV test signature saved
    • 44. Diagnostic errors assist in identifying issues and enable taking necessary corrective actions
  • Lesson Learned
    PST Recommendations / Learning
    Use the valve signature to refine the partial stroke test parameters, such as minimum pressure and upper operating pressure.
    When a valve fails to move, adjust the speed, minimum pressure or pause time.
    Map the HART bit of FIELDVUE Instruments to HOST for getting SOV Health
    Check travel deviation or pressure deviation alert point to ensure correct configuration, this can be the cause of failure.
    Enable pressure mode to reduce stroke time of valve.
    Test more often than required to exercise valves if necessary.
    Baseline data from initial valve signature is PRICELESS!!!
  • 45. Business Results Achieved
    Testing valve On Line Improves Reliability and Plant Availability
    Trigger Data Available in case of “Safety Demand”
    Continuous Health Monitoring of Final Element
    SOV Integrity Check
    Predictive Maintenance
    Improved PST Flexibility
    Reduced Labor Cost
    Compliance to Regulatory Requirements
    Integration to Logic Solver Possible
  • 46. Summary
    Possible Issues on Final Element Testing
    Customer Needs and Requirements
    Field Issue and Concerns
    Possible Remedy – Digital solution
    Critical Evaluation of Solution
    Field Experience from Ras Gas
  • 47. Where To Get More Information
    IEC61508 – Functional Safety of Electrical / Electronic / Programmable Electronic Safety Related Systems
    IEC61511 – Functional Safety – Safety Instrumented Systems for Process Industry Sector
    ISA-TR84.00.02-2002 – Part 1 to 5
    Control System Safety Evaluation & Reliability – W M Goble
    Safety Integrity Level Selection – Ed Marszal and Eric Scharpf