Valves Flashcards
What is the first thing that you should do prior to working on a valve?
Communicate with operations to determine the function of the valve and any affects of valve movement.
Why is it important to completely read through a job plan prior to starting to work?
An understanding of hazards and an inventory of any tools or spare parts required should be obtained before starting the work.
Where would you find safety critical procedures?
OMS - Standard Operating Procedures.
How do you determine whetehr you have a smart or analog device?
Name plate, model number.
WHat type of test devices are needed for analog vs smart devices?
4-20mA source or Hart communicator.
How do you know what the bench set is of an actuator?
Manufacturer’s label.
When would you need to adjust the bench set of an actuator?
When the process pressure may overcome the spring pressure of the actuator. Process change or trim change.
What is important to look for when coupling a valve to an actuator?
Mounting, fail open vs. fail close, bench set.
How do you tell if a valve is fail open or fail close?
Air on top (fail open) or air on the bottom (fail closed).rotation for 90 degree valves.
What is the difference between a dual acting and a spring return valve.
Dual acting valves are driven by air both open and closed. Spring return are only driven one direction with air.
What potential failures might be found when trouble shooting a control valve?
Control wiring damage, blown fuse, leaking seals, leaking gaskets, broken spring, valve corrosion, positioner mechanical failure, IP failure, worn trim…
How would you troubleshoot a valve?
Remove valve from service. Inspect, check voltage, check pressure, stroke valve with amperage source.If neccesary, obtain parts and inspect internals.
When all calibration is complete and the valve still leaks by, what is left to check?
Valve internals. Process pressure.
Where would you find information for replacement parts?
Manufacturer’s manuals.
How do you isolate a valve from the process without causing an upset?
If possible, work with operations to by-pass the control valve.