Level Transmitter Diaphragm Material

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srzambre Associate Join Date: Oct 2007 Posts: 29 Good Answers: 1	Level Transmitter Diaphragm Material 03/26/2010 5:53 AM
	For a Level Transmitter with remote seals installed on a Caustic Soda Evaporator Tank, what Diaphragm Material is most suitable? Please note that on HIGH side Caustic Soda Concentration is 48% and temp is @ 140 Deg C and LOW side is connected to top of the tank where Saturated Steam with 13 Bar pressure is present. (High Temp. and Caustic Vapours may be present at low side) Present diaphragm material was Nickel on both high & low sides, but LOW side has developed a HOLE in it. What about Hastalloy-C on this application? Any ideas? Reagrds, __________________ Best Regards, srzambre.
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Anonymous Poster	#1 Re: Level Transmitter Diaphragm Material 03/26/2010 11:45 PM
	316L ss will be sufficient for this application
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srzambre Associate Join Date: Oct 2007 Posts: 29 Good Answers: 1	#3 In reply to #1 Re: Level Transmitter Diaphragm Material 03/27/2010 8:44 PM
	No.... SS316L is not suitable for Caustic Application. __________________ Best Regards, srzambre.
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Carl_E Power-User Join Date: Nov 2009 Posts: 335 Good Answers: 63	#2 Re: Level Transmitter Diaphragm Material 03/27/2010 8:06 AM
	Tough call. I'd be wary of 316SS at those elevated temperatures and concentrations. Marcello Picciotti's article in Chemical Engineering Progress warns against 316 at temperatures above 100°C due to stress corrosion cracking http://www.allbusiness.com/management/4110394-1.html Nickel 200 has been the standard for hot caustic. DeRenzo's Corrosion Resistant Materials Handbook (4th Ed) has a table (pg 665) listing Hastelloy B-2 & Inconel 625 with very low 0-150um/yr corrosion rates in 50% boiling NaOH. I wonder if the use of nickel with whatever its life isn't the cost of doing business, and that there isn't anything much better
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srzambre Associate Join Date: Oct 2007 Posts: 29 Good Answers: 1	#4 In reply to #2 Re: Level Transmitter Diaphragm Material 03/27/2010 8:48 PM
	Hi Carl, Thanks for informative feedback. Any idea's for Hastalloy C-276? Transmitter with Nickel Diaphragm will be a special order I guess.... __________________ Best Regards, srzambre.
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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	#5 Re: Level Transmitter Diaphragm Material 04/06/2010 8:22 AM
	PTFE-coated 'anything', 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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Anonymous Poster (1); Carl_E (1); PWSlack (1); srzambre (2)

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