Triflic Acid Compatible Materials of Construction (Or Information on Full 316L S/S Safety Valve)

[BenjaminM]

I am looking for chemical compatibility information for Triflic Acid.

I have an old handling guide which states to use only 316L S/S and Teflon. It goes further to state Hastelloy C has similar chemical resistance to 316L S/S. We are relatively certain Kalrez is functional.

Triflic Acid is not listed in my Compass Publications Chemical Resistance Guides. I have scoured my other sources and the internet to no avail.

The driving force for this is I am looking for a 1/4" safety valve for a portable container in which we handle this product in. I have yet to find a safety valve that is 100% 316L S/S wetted parts with Teflon or Kalrez.

Thank you.

 

[moltenmetal]

Trifluoromethane sulphonic acid is nasty stuff. It's basically a proton-spitter- a superacid.

I don't have any materials compatibility data to share with you. But if the portable container is sub-ASME, such that you can use a proportional relief valve, have a look at both Swagelok and Circle Seal. They both use elastomeric components but if you've got the money and Kalrez (FFKM) is an option, they should work for you.

 

[BenjaminM]

moltenmetal,

Thank you for the quick response. I actually already have some pricing from Swagelok. The pot is an ASME stamped container, but as you stated the Swagelok are proportional relief valves, not code stamped safety valves.

In our case the container is rated at 185 psi, and we will operate it at 10 psi with nitrogen. We are not able to exceed 100 psi if we wanted to.

I am estimating I need 10 SCFM emergency venting for a fire case. Lowering the set point to 150 psi, the Swagelok proportional relief valve will provide will provide this rate and it increases to around 50 SCFM at the MAWP of 185.

I am not familiar with Circle Seal. Let me look into them further.

Thank you again.

 

[moltenmetal]

Circle Seal don't make ASME relief devices either.

Sub C-sized ASME relief valves are very expensive and long delivery. They do exist, but they're like finding a needle in a haystack. Definitely hard, and not worth the bother.

Your cheapest and safest option in this case will be a rupture disk. ASME certified rupture disks are available from numerous vendors and small ones are definitely available. Since you will never challenge the disk except during a fire, you eliminate the risk of leakage or of back-migration of moisture into your triflic acid.

 

[BenjaminM]

moltenmetal,

It looks like Circle Seal actually may have an ASME safety valve. Their M5100 line is presented as such in their catalog. I am awaiting details from the local distributor.

I have not yet started investigating the use of a rupture disc for this process, but it very well may be ideal.

 

[moltenmetal]

It will be a fraction of the price of the ASME relief valve. If Circle Seal offers one, it will be very expensive indeed.

 

[BenjaminM]

Just following up,

I was not able to locate a 1/4" or 1/2" rupture disc with a burst pressure less than 300 psi.

While speaking to a sales rep about the disc though, he recommended I look at Leser.

The final price was about $750 for a full 316L S/S safety valve, 1/2". Metal on metal seal. ASME stamp.

Thank you again!