Corrosion in NPT threads vs pure Acetic Acid
Corrosion in NPT threads vs pure Acetic Acid
(OP)
On a pilot plant to be built in short time we have lot of vessels with NPT female instr conn`s. Fluid is 100% liquid acetic acid. We suspect -in time- that NPT thread will corrode with the result that instr can`t be taken from the vessel and the vessel is ruined and we get a major claim. How good idea is use of NPT and this fluid. Is there any one who can advise.
thanks in advance!
Note1:Design p&T in range of max 20 barg & 250C and 2 barg & 150C type vessels.
Note2: Due to small sizing of vessels flanges wont`t work.
thanks in advance!
Note1:Design p&T in range of max 20 barg & 250C and 2 barg & 150C type vessels.
Note2: Due to small sizing of vessels flanges wont`t work.





RE: Corrosion in NPT threads vs pure Acetic Acid
Don
Kansas City
RE: Corrosion in NPT threads vs pure Acetic Acid
I forgot to mention that all material, vessels and instrumentation and tubing /piping is already AISI 316 including bite ring fittings.
rgds
Henjo
RE: Corrosion in NPT threads vs pure Acetic Acid
Half couplings welded to the shell?
If so, you can have them made from billet or high pressure fittings, giving you an arbitrarily thick wall... e.g., thick enough to be bored out and tapped to a larger size should repair be necessary.
If they're already made, and thin, just use a lot of teflon tape... and older pipefitters.
Mike Halloran
Pembroke Pines, FL, USA
RE: Corrosion in NPT threads vs pure Acetic Acid
rgds
Henjo
RE: Corrosion in NPT threads vs pure Acetic Acid
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You have to use an anti-seize or ptfe tape or _some_ kind of pipe thread sealant on pipe threads in order to prevent galling on assembly. Enough of the sealant usually remains to allow disassembly by ordinary means.
An MSDS has this to say:
"Corrosivity:
Highly corrosive in presence of stainless steel(304).
Slightly corrosive in presence of aluminum, of copper.
Non-corrosive in presence of stainless steel(316)."
So I'm not sure that I understand your concern, unless you're worried that you may have some misidentifed 304 stainless in the system.
Mike Halloran
Pembroke Pines, FL, USA
RE: Corrosion in NPT threads vs pure Acetic Acid
I can recall no problem with the threads other than they are extremely hard to break if required. Any new make require the use of Teflon tape or paste.