This topic contains 10 replies, has 5 voices, and was last updated by 
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Posts
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SP6 has anybody dropped this valve online by keeping switch valve towards other drum. My question is do we suspect switch valve will pass
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AnonymousSwitch valve passing probability is very less. however, one shall keep vigil.
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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. -
I agree with Mike. Too dangerous.
Question: Why do you need to remove SP-6?
Regards
CG -
AnonymousTHANKS 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. -
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 -
AnonymousGood 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. -
AnonymousWhat is SP 6? You mean off line drum Feed Valve or Drain Value?
I can ans to you.
Regards
santhosh -
AnonymousWhat is SP 6? You mean off line drum Feed Valve or Drain Value?
I can ans to you.
Regards
santhosh -
Anonymoussantosh
yes SP6 is feed valve to drum which is downstream of switch valve
regards
u.karthik -
AnonymousDear 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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