pipe thread sealants suitable for low pH solutions

[gloriag]

Can anyone suggest a suitable thread sealant for the following application: stainless steel piping carrying a low pH (1.6 - 1.8) acid cleaner.

 

[SlideRuleEra]

How about teflon tape, such as this

http://www.cleanfit.com/literature_pdfs/Teflon_Yellow_3-Wrap.pdf

http://www.SlideRuleEra.net

 

[TBP]

Teflon tape is likely the best way to go, as per SlideRuleEra's post. If it's not suitable for some reason, you could try Xpando. Xpando will seal just about any threaded joint, but the downsides are a 24 hour cure-time, and extreme difficulty in getting the joints apart for modifications or maintenance. Anything with a long cure time can be a problem in that production people want things back in service 15 minutes ago, and often just won't wait.

 

[flyfisher42]

Xpando is not recommended for ph<2

 

[TBP]

You may very well be right flyfisher42 - I try to avoid xpando, since I come from a maintenance background. I tend to think of it as the pipe dope of "last resort". Construction & installation folks use it more often, as they typically have the time to wait for it to cure, and won't likely be the ones coming back to work on the system.

 

[unclesyd]

Here is one of many pipe dopes (SAFE-T-LOK) we have found quite satisfactory for low PH fluids. We tend to use it prior to the required cure times as mention above, but we still get very good results.

http://www.saftlok.com/stl/sealant.htm

Stumbled on this will looking for the SAFE-T-LOK. I wonder it the cap will stick on like the others.

http://www.loctite.com/int_henkel/loctite_us/index.cfm?pageid=444&layout=1

 

[unclesyd]

Be careful.
Forgot to add that Xpando is a variation on the Oxychloride Cements and contains a goodly percentage of Chloride Ions. This has caused problems with SS pipe especially if the PH gets below 4. We used it on several systems but never on any Austenitic SS.

 

[TBP]

Good to know, unclesyd - I'll keep the chloride factor mind. We've got a can of Xpando sitting around for dire situations, but try really hard not to use it.