Pattern in Valve

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pme Active Contributor Join Date: Oct 2012 Location: India Posts: 16	Pattern in Valve 11/23/2012 5:52 AM
	All, What is the real difference between short and long pattern for valves (practical) Short pattern valves are generally avoided. What is the reason for this. Thanks __________________ Achieve anything in Life just by Hard Working alongwith Smartness
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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	#1 Re: pattern in valve 11/23/2012 7:06 AM
	One cannot lag the pipeline properly if the valve handle is under the lagging. Also, a valve handle that is under the lagging is rather difficult to operate... __________________ "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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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	#2 Re: pattern in valve 11/23/2012 7:44 AM
	Valves for cryogenic service are generally long-pattern. The reason is twofold: It enables the handle to continue to be available for use despite the usual football-sized chunk of atmospheric-moisture-ice that inevitably builds up around them, and It reduces the risk of the operative getting frostbite while operating it. __________________ "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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pritam Guru Join Date: Aug 2008 Location: City of destiny, INDIA Posts: 775 Good Answers: 67	#4 In reply to #2 Re: pattern in valve 11/25/2012 8:45 AM
	GA. One more reason for its use in cryogenic service is: - It enables the handle to continue to be available for use despite the thick layer of insulation (some times up to 250 mm) to reduce heat in-leak which causes vaporization loss in cryogens.
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lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#3 Re: pattern in valve 11/23/2012 10:00 AM
	The master standard for face-to-face dimensions is ISO 5752. From: The Function of Ball Valves Used in the Oil & Gas ... - PDH Center
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lyn (1); pritam (1); PWSlack (2)

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