the flow direction of high pressure globe valve

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Anonymous Poster	the flow direction of high pressure globe valve 04/09/2009 2:14 PM
	I am a local operator of a power plant. We are building three gas turbines and one steam turbine. While I check P&ID I found most of globe valves installed opposite of the flow direction in HSRG and the Feed water system. They are mostly from CCI and some from Severn. Three of CCI globe valves are located at the inlet side of the Economizers and six of CCI globe valves are in the feed water system. They are all installed opposite of the flow direction. Why?
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Curious George Active Contributor Join Date: Apr 2009 Location: IL., USA Posts: 24 Good Answers: 1	#1 Re: the flow direction of high pressure globe valve 04/09/2009 4:32 PM
	"They are all installed opposite of the flow direction. Why?" I do not understand what you are asking? I have not seen a Globe valve that is not bidirectional. Are you wanting to know why they are all on the inlet side vs. outlet side? __________________ Half of everything in life is counter-intuitive,,, I'm not sure about the other half yet...
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woodygb Power-User Join Date: Mar 2009 Location: United Kingdom Posts: 308 Good Answers: 28	#2 Re: the flow direction of high pressure globe valve 04/09/2009 5:26 PM
	For low temperature applications, globe and angle valves are ordinarily installed so that pressure is under the disk. This promotes easy operation, helps protect the packing, and eliminates a certain amount of erosive action to the seat and disk faces. For high temperature steam service, globe valves are installed so that pressure is above the disk. Otherwise, the stem will contract upon cooling and tend to lift the disk off the seat.
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ducon Guru Join Date: Dec 2006 Location: Hop around Toronto, New York & Karachi Posts: 1876 Good Answers: 19	#3 In reply to #2 Re: the flow direction of high pressure globe valve 04/13/2009 9:28 PM
	Yes true but still does not answer his " WHY"? __________________ I not only use all the brains that I have, but all that I can borrow. Woodrow Wilson
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#4 In reply to #3 Re: the flow direction of high pressure globe valve 04/14/2009 3:24 AM
	<...Otherwise, the stem will contract upon cooling and tend to lift the disk off the seat....> Really? __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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ducon Guru Join Date: Dec 2006 Location: Hop around Toronto, New York & Karachi Posts: 1876 Good Answers: 19	#5 Re: the flow direction of high pressure globe valve 04/14/2009 9:16 AM
	They are all installed opposite of the flow direction. Honestly i tell you about my case just last year. We installed the steam distribution header with an inlet from a Steam Boiler and 2 nos similar make 8" Globe Valve(from China) for outlets with Arrow(on body embosed) pointing upwards. When we started Valve #1 passed steam BUT Valve #2 DID NOT. After all checking we took off the Valve to find "The arrow -direction was WRONGLY embossed ". We inverted the Globe Valve now with the arrow down and it started working.Being a China origin anything is expected but till date we wonder if they recast arrows on the body again after they cast the valves? They are all installed opposite of the flow direction. Why? After my experience on the "No flow" I am also curious as to this "Why"? __________________ I not only use all the brains that I have, but all that I can borrow. Woodrow Wilson
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Curious George Active Contributor Join Date: Apr 2009 Location: IL., USA Posts: 24 Good Answers: 1	#6 Re: the flow direction of high pressure globe valve 04/15/2009 1:09 PM
	Ah, now I understand. I was confusing globe and gate valves. Apparently, the arrow mentioned is not intended to indicate flow in all applications, just orientation. After a little searching, I found this: Globe Valve Direction of Flow For low temperature applications, globe and angle valves are ordinarily installed so that pressure is under the disk. This promotes easy operation, helps protect the packing, and eliminates a certain amount of erosive action to the seat and disk faces. For high temperature steam service, globe valves are installed so that pressure is above the disk. Otherwise, the stem will contract upon cooling and tend to lift the disk off the seat. from: http://www.tpub.com/content/doe/h1018v2/css/h1018v2_38.htm __________________ Half of everything in life is counter-intuitive,,, I'm not sure about the other half yet...
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Curious George (2); ducon (2); PWSlack (1); woodygb (1)

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