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Letdown station
6

Letdown station

Letdown station

(OP)
Hi
I am Utility Shift team leader and we have steam letdown station but one of the valves stuck opened and can not isolate it to hand over attemperator valve to maintenance , my question is Is there any technique to isolate the valve online ?

RE: Letdown station

inlet/outlet and bypass valves?

RE: Letdown station

(OP)
The line is 18 inch , the valve is the main valve and there is no bypass

RE: Letdown station

If there is no bypass then a process developer/designer considered that process should not operate in case of CV malfunction, correct? Why do you believe that developer/designer's reasons are not valid more? Why should a process be operated not as intended for?

Do you have an option to switch superheated steam to atmosphere and close CV's inlet valve?

RE: Letdown station

Sameh,

How is anyone supposed to answer this when you have provided no sketch or drawing to show what the issue / valve is, but sometimes there is no option other than go back down the line and find an isolation vale and the de-pressurise the header and remove / replace the valve.

If the original designers wanted to save money by not putting in suitable isolation, then this is consequence.

But give us a bit of a clue please.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Letdown station

(OP)
Thanks for helping

RE: Letdown station

Safety FIRST, Profit Second.
Tell your Operations Manager he has find some other less suicidal challenge to get his promotion.

RE: Letdown station

(OP)
It is not like that, plant is running and this job need total shutdown so we are searching for another solution to avoid total shutdown, our turn around will be in 2025!

RE: Letdown station

What's wrong with the isolation valve?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Letdown station

(OP)
Full respect to all but this is the first time to me in thus forum, anyway the isolation vlave is not fully closed and want to remove upstream CV (attemperator) for maintenace but could not isolate it due to this passing

RE: Letdown station

(OP)
Thanks Pierreick

RE: Letdown station

Concentrate on the valve.

What type?
Is it closed and just passing or??
Are there no sealant injection points?
If a ball valve can you vent the ball enough to prevent passing of steam?
Have you stroked it a few times?
Any details?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Letdown station

(OP)
Hi littleinch
The valve type is gate valve
The valve is passing
Opened and closed many times but no improvment same passing
No seal injection point
This valve want to close it to remove upstream CV for repairing and no isolation for it , it is live with MPS header , need to avoid total shutdown

RE: Letdown station

(OP)
Hot tapping i beleive for small pipe not for large , our size is 18 inch !

RE: Letdown station

Tried Furmanite?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Letdown station

(OP)
Is furmanite can isolate gate valve and remove the valve later ? After repair the defcted valve

RE: Letdown station

@Sameh Elsayyad
Why do you ask instead of googling a bit?
Traditionally limited from 4” (ND 100 mm) to 12” (ND 300 mm) pipe, this method is now available for larger diameter pipes, from 14” (ND 350 mm) to 46” (ND 1150 mm). ... HTP stops are effective at temperatures up to 370ºC (700ºF) and pressure ratings up to 1480 psi (102 bar).
https://furmanitehk.com/wp-content/uploads/2020/11...

RE: Letdown station

(OP)
Flow is superheated steam
Temp 235 c
Pressure 10.5 bar
Pipe material : CS

RE: Letdown station

(OP)
Thanks

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