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gabriel.rodel
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Globe Valves - Flow Direction

01/19/2009 4:24 AM

Hi guys, does anybody knows why the globe valve has a flow direction? Thanks..
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sb
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#1

Re: GLOBE VALVE FLOW DIRECTION

01/19/2009 5:16 AM

If you just look at the crossection of globe valves it will be clear, The inlet is sealed off from the chamber by the disc, So the acting inlet pressure is totally resisted by the disc/seat.

The gland seal of the operating stem etc are in the outlet chamber and hence in the low pressure zone. So the chances of leakage from the stem is lower.

This is especially critical since these are not ON-OFF valves like ball valves rather flow controol valves, so there is a chance of inlet being pressurised additionally when the outlet is throttled.

Additionally I feel the chances of valve malfunction in case of contaminants are slightly less.

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gabriel.rodel
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#2
In reply to #1

Re: GLOBE VALVE FLOW DIRECTION

01/19/2009 12:47 PM

Hi Sb.. Thanks a lot.. it helps me a lot.. regards..
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babybear
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#3
In reply to #1

Re: GLOBE VALVE FLOW DIRECTION

01/20/2009 3:36 AM

Hello sb,

GA to you for the explanation. Clear and to the point, especially if you have the valve in your hands!

Take care...............

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sb
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#7
In reply to #3

Re: GLOBE VALVE FLOW DIRECTION

01/20/2009 8:59 AM

Thanks but I don't understand your signature

If the mother is around (as is expected to be) - then it should be hear and run like hell, see and you forget (that you ever existed)

Take care is only OK portion

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babybear
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#10
In reply to #7

Re: GLOBE VALVE FLOW DIRECTION

01/20/2009 11:26 AM

Hello sb,

you are a bit of a deep thinker there sb?

What do you not understand about my signature prey sir? I have just modified it slightly to prevent any confusion between the two sayings, I have as my signature.

Take care............

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sb
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#12
In reply to #10

Re: GLOBE VALVE FLOW DIRECTION

01/20/2009 12:43 PM

Just this -

1- (baby bear + ofcourse the mother bear ) - hear and you can not forget - you have to run if I forget then clause 2 comes in being.

2- See you (two) and nothing of me is left out to remember - may be i will be in remembrance (in fact your avatar looks like polar bear isn't it ?)

Only portion apt is the take care...

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Morgan 23
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#4

Re: Globe Valves - Flow Direction

01/20/2009 6:36 AM

Flow direction is established so that flow enters the valve under the valve seat, that way the plug of the valve looks at the high pressure side of the process. Closing the valve isolates the packing from the upstream (high pressure) side, that allows one to close the valve, vent or drain the downstream side and remove and replace the valve packing without shutting down the entire process. This assumes, of course, that the process fluid is not lethal or otherwise dangerous. Safety measures must be taken to insure lock-out, tag-out procedures are incorporated in the repair to make sure no employee is put in dnager in the process. Face shields, and other safety equipment must be used as well as a complete written and practiced procedure to perform the work.
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yesyen
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#8
In reply to #4

Re: Globe Valves - Flow Direction

01/20/2009 9:06 AM

Well said, with enough precautions we used to repack critical valves even in harsh mediums like Ammonia, Chlorine etc. This one was the reservoir/receiver outlet valve.

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babybear
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#11
In reply to #4

Re: Globe Valves - Flow Direction

01/20/2009 11:30 AM

Hello Morgan 23:

GA to you sir!

Take care.............

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Abdel Halim Galala
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#5

Re: Globe Valves - Flow Direction

01/20/2009 7:15 AM

We used to use globe valve with flow direction from under seat to up towards the disc and this comply with the direction drawn on the valve body. But, I agree to use that valve with the opposite direction where the flow comes from up the seat to down, where in this case the pressure of fluid at upstream (when the valve is closed) will facilitate good tighten between disk and seat.

When the valve is partially open, I think the same friction loss will remain the same unless be proved by some experiment.

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sb
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#6

Re: Globe Valves - Flow Direction

01/20/2009 8:55 AM

Just to add to the comment made another two additional points

a) If the outlet is made inlet, the pressure acts on the backside of the disc. When the disc is partially disengadged from the seat, a full pressure (almost) is on its back.

In the end of the stem, usually a small washer shape (or a nut) will be there joining the stem to disc. In bottom to top flow, there is never a load on this washer since the shoulder of stem acts to operate the disc. However in case the pressure is from top to bottom , there is a possibility of this step breaking / washer/nut disengaging.

2) In my home globe valves (or equivalents) i am always able to attend to the leaking gland by just shutting out the valve but had this side beein pressurized, it wouldn't have been possible.

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yesyen
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#9
In reply to #6

Re: Globe Valves - Flow Direction

01/20/2009 9:24 AM

Good thinking, very fine points herein, very useful knowledge blocks which which would never come out from experts (thinkers) otherwise, thanks for CR4 for it service.

I have seen, occasionally, the globe valves used in reverse. I am trying to recollect. I'm not getting the rest but this one:

In steam condensers some valves connected to ejecting system were found (intentionally) in reverse as to avoid sucking air air through gland in closed condition.

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gabriel.rodel
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#13

Re: Globe Valves - Flow Direction

01/20/2009 2:08 PM

Hi guys.. thank you so much for the contributions..it's a great help..keep it up...cheers
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aivenyy
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#14

Re: Globe Valves - Flow Direction

03/03/2010 9:36 PM

globe valve is used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body. Please check here:

http://www.ecvv.com/product_directory/Globe-Valve.html

Globe valves can be arranged so that the disk closes against or in the same direction of fluid flow. When the disk closes against the direction of flow, the kinetic energy of the fluid impedes closing but aids opening of the valve. When the disk closes in the same direction of flow, the kinetic energy of the fluid aids closing but impedes opening. This characteristic is preferable to other designs when quick-acting stop valves are necessary.
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dhayanandhan
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#15

Re: Globe Valves - Flow Direction

04/27/2013 5:11 AM

Dear Mr. gabriel.rodel,

The answer for your question is YES. When the valve is fully closed, and there is NO LEAK, the gland side should not have any pressure, other than HYDRO STATIC COLUMN/HEAD pressure.

DHAYANANDHAN.S
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Users who posted comments:

Abdel Halim Galala (1); aivenyy (1); babybear (3); dhayanandhan (1); gabriel.rodel (2); Morgan 23 (1); sb (4); yesyen (2)

Previous in Forum: Hydraulic Cylinders - Multiple Stop Positions   Next in Forum: Average Life of Galvanized Pipe
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