Rotork IQ70 MOV Issue Resolution(and some questions)

Dear all,

Sharing this for benefit of all. We had a recent issue at site and it was rectified.

What Happened?

  • We have the following Rotork IQ70 at our Ammonia plant.
  • The valve was taken off service for overhaul in outage. The valve stem was removed. During this activity the main AC supply was disconnected and battery was also drained(we didn't now).
  • When the valve was installed back on the field, and following observation were made:
  • When the valve was closed remotely, the valve closed but ‘’fully closed status’’ came earlier on the remote HMI than the actual position. However, the valve kept on moving till closed.
  • When valve was given open command, the valve kept on opening and did not stop on the actual open position and was eventually tripped on overload of motor.
  • It became clear that actuator limits where disturbed.
  • Secondly, the Display screen was not installed on the card so we could not see the limits.

Actions Taken?

  1. Since we did not have the Display screen on the installed card(Pic1) we changed the card with a new one.
  2. The new card display was not clear and letters were missing(Pic2). It was un-readable.
  3. We checked the ribbon cables and connections and they were Okay.
  4. We had another card available, and we installed that. Even in this card we had distorted display screen but not as much as previous one(Pic3)
  5. However, We referred to the manual/online videos and figured out the text and set the limits of MOV.

Operational check was done and MOV was declared OKAY.

Points to Ponder?

I wonder why the display on the screens was not proper? They were new cards! and we store than at temperature of 24 degree C in a dry environment. Anyone can shed light on this?

I asked ROTORK and their comments were:

‘’It is not uncommon for the LCD Display segments to become faulty with age. It is not due to any connections and just simply faulty LCD display”

‘’I believe that the limits may have been altered during the overhaul and when the actuator was fitted back on to the valve it may have been in a different position than before. That is why it is always important to reset the limits if you remove it from a valve’’


Also, how can we ensure health of such electronic cards when in storage? We don't have a test jig for every card available at our warehouse. Should we replace the cards with new ones in storage if storage has been for over some certain number of years? What do you guys think?

Learning:

  • Always ensure that MOV battery is healthy. Replace after every 3 years.
  • Whenever MOV is removed from field to workshop for overhaul or work on Valve, you need to reset the limits of MOV.
  • Sometimes spares can also not be relied upon!
 

Attachments

Rotork used to have simple but excellent controls on their valves.

A spare part with a faulty display tends to suggest damage in storage;
if no obvious signs I would reject Rotork's poor explanation and demand replacement without charge.
 
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