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urgent advise needed

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This topic contains 10 replies, has 5 voices, and was last updated by  Anonymous 7 years, 8 months ago.

  • Author
    Posts
  • #1740

    hurtado
    Participant

    SP6 has anybody dropped this valve online by keeping switch valve towards other drum. My question is do we suspect switch valve will pass

  • #4536

    Anonymous

    Switch valve passing probability is very less. however, one shall keep vigil.

  • #4535

    Mike Kimbrell
    Participant

    Karthik,
    I would not attempt to remove the SP-6 valve on one drum while operating the other drum in the pair. Cokers use double block with steam pressure above process pressure in-between the two valves to provide isolation for routine coke removal. Removing the SP-6 valve for maintenance requires positive isolation. Using the swithch valve only with the unit still operating has very high risks of hot hydrocarbons being released to the atmosphere. I would not remove the SP-6 valve if the unit was in hot circulation either.
    To remove the SP-6 valve, my recommendation is to remove hydrocarbon from the heater and purge the heater and the transfer line with steam. You can then depressure and isolate the feed system and then perform maintenance on the SP-6 valve.

  • #4534

    Claus Graf
    Participant

    I agree with Mike. Too dangerous.
     
    Question: Why do you need to remove SP-6?
     
    Regards
     
    CG

  • #4533

    Anonymous

    THANKS ALL FOR YOUR REPLY.
    We are facing lot of problem while opening and closing of the valve during feed in and feed out in to that drum .Also while opening/closing it take high torque to operate this MOV.There must be lot of coke deposit in the seat body and bellow of the SP6 probably and making the motor to exert high torque.We have reached a stage where we fear motor may get damaged so we are to remove the SP6 and replace with another spare SP6.
    I agree with all your views becuase we dont know whether switch valve may pass or not.

  • #4532

    Claus Graf
    Participant

    This happened at a coker I worked a few years ago.
     
    One of the overhead vapor valves (Ball 24″ MOV) got stuck. After operating a few more days the unit was shut down and the valve removed and taken apart, only to find that it was clean.
     
    The solution was to change the reduction gears (ratio) between the motor and the valve. (to increase the torque on the valve)
     
    Hope this helps
     
    CG

  • #4531

    Anonymous

    Good News is that we have successfully changed the SP6 valve by putting the block in hot circulation and by gods grace the switch valve holded it was not passing no leak.
    Thanks for all your inputs.

  • #4526

    Anonymous

    What is SP 6? You mean off line drum Feed Valve or Drain Value?
    I can ans to you.
     
    Regards
    santhosh

  • #4525

    Anonymous

    What is SP 6? You mean off line drum Feed Valve or Drain Value?
    I can ans to you.
     
    Regards
    santhosh

  • #4523

    Anonymous

    santosh
     
    yes SP6 is feed valve to drum which is downstream of switch valve
     
    regards
    u.karthik

  • #4521

    Anonymous

    Dear karthik, we had also faced same problem in our coker history, to avoid choking of SP6  increse the purge steam presurre of SP6  and also keep open the body purge steam R/O bypass valve  in onlne drum .  because steam goes through  R/o is very less and it will lead to coking in sp 6. after done it  now a days we dont have any problem with sp6 since long time

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