Positioner type 3730-5 Smart Valve Positioner with diagnostic functions Presented By: Mr. Gourishankar Saharan Product management Jens Bargon / V42
Product overview P Process V Valves l Control Valves Positioner and Accessories
Control Valves & FF Smart Positioners Control Valves are the work horses in every process plant They are subject to wear and tear and therefore an important target for asset management and predictive maintenance procedures Smart positioners with integrated diagnostic functions and FOUNDATION TM Fieldbus technology deliver optimal solution
Control Valves & FF Smart Positioners Typical valve failures Eroded seat and plug internal leakage Erosion of valve body finally external leakage Leaking stuffing box external leakage Increased / decreased friction higher / lower hysteresis Closing (Zero) point shifting deposits on sealing edge Change in opening / closing breakaway torque (e.g. ball valves) Poor control performance External leakages in the pneumatic supply
What is diagnosis? Usually the term diagnostic diagnostic is used in the medicine and means interpretation of symptoms with the target to get information about the actual status or reasons of a malfunction. 1 step: condition monitoring measuring different process parameters Deliver symptoms of expected or existing malfunctions 2 step: diagnosis interpretation of the process parameters By experienced service personal Better: via software, based on experienced algorithms 3 step: maintenance requirements / measures constructive steps Service-> Keep the working condition Recondition-> Restore the working condition
Where do the diagnostic messages appear? Type 3730-5
Condensed state acc. to NAMUR recommendation NE 107 Classified status messages (forms & colors): good maintenance required / demanded failure function check out of specification Internal device failure GOOD_MAINT_REQ Working at full capacity Perhaps not enough air Classification by End User No message/diagnostic active Shifting working range close Perhaps bias reduced TEST Highest rated message determines the condensed state
Condensed state acc. to NAMUR recommendation NE 107
Condensed state acc. to NAMUR recommendation NE 107 So far the DI function block of the positioner type 3730-5 is used to read in the condensed state into the host Condensed state configuration Examples: M/s. Bayer, China. Plant is in Caojing and has nearly 11.000 FF devices with around 3000 of positioner type 3730-5 running well in the plant also using the positioner diagnosis.
Condensed state acc. to NAMUR recommendation NE 107 In future devices and systems are working according to Specification FF 912 Field Diagnostic Profile (required for devices tested with ITK6.0) Source: FF-912 chapter 1.3
Monitoring functions during the running process General requirements Diagnostics should be realized without any additional sensor systems The valve is in controlled operation and the process may not be to interrupted! Histograms allow to evaluate the valve travel [x], the set point deviation [e] and the valve cycle counter as an automatic function without any setup in the background The valve signature function allows to detect possible changes in friction to detect possible changes in the supply pressure e or maybe leakages ages in the pneumatic supply The Final position trend monitoring function allows to detect a fluctuating or creeping zero point due to seat & plug wear or material between seat and plug Dynamic Stress factor to monitor the stuffing box Partial Stroke Test for on/off applications Leakage sensor to detect inner leakages between seat & plug
Cycle counter details The operator needs to differentiate the stuffing box! The corresponding values are based on experiences in the SAMSON development department! Self-adjusting Adjustable packing Bellows seal Other adjustable threshold Dynamic stress factor [%] The rate of wear of the selected stuffing box will be calculated New: 0% Statistical defect 100% Above 90% a message will be generated Long-term histogram
Cycle counter in practice Parex Process The pump around valve sees every two minutes new process conditions, when the Rotary Valve has been switched and two new column beds are connected to each other. The process requires a fast and precise response of the control valve controlling the flow to the adsorption chambers, leading to a high number of cycles. Source: UOP LLC 25 East Algonquin Road, Des Plaines, IL 60017-5017
Cycle counter in practice Parex Process Valve requirements Optimized pneumatic Hook-up to achieve high accuracy for small steps (0.5 %) as well as large steps (50 100%) Consequence after some years The stuffing box has reached the tolerable number of cycles (dynamic stressfactor > 90%) and needs replacement at the next service interval Result: Cost optimizatoion i t i due to smart Predictive Maintenance Step response 0,3% Step response 50%
Partial Stroke Test Especially for on/off applications (critical ball or butterfly valves, maybe safety related) Partial Stroke Test without disrupting plant operation (e.g.: 100% to 90% and backwards to the operation point) Prevent the valve from becoming stuck Starting time scheduled or manually Step or ramp function (adjustable ramp to prevent overshoot) Configurable test abortion conditions Condensed/test status acc. to NE 107 Documentable & reliable Goal: maximize the time between full proof tests -> Cost optimization Full Stroke Test over the entire travel range is always required! PFD SIL threshold PFD 1 = λ 2 test intervall without PST test tintervall with PST 6 12 18 24 DU T PR months
Partial Stroke Test examples 1 2 1. Ramp with low friction No noticeable problems 2. Ramp with increased breakaway torque Slightly overshooting 3. Ramp with high breakaway torque Extreme overshooting could cause problems for the running process! Therefore cancellation conditions travel & drive signal y 3
FF specification work for end user benefit Fieldbus FOUNDATION has added d end user requirements into their specifications for interoperable use of diagnostic functions FF-912 Field Diagnostic Profile according to NAMUR recommendation NE 107 Self-Monitoring and Diagnosis of Field Devices FF-906 Positioner Transducer Block parameters for diagnosis test CYCLE_CNTR, CYCLE_CNTR_LIM, VST_MODE Partial Stroke or Full Stroke Test PST_BREAKOUT_TIME, TIME PST_RAMP_RATE, RATE
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