Combustible Liquid Splash Filling

[MementoMori]

Hello all,

My company is looking at putting in a new atmospheric aboveground storage tank for an organic monomer. The chemical is a Class II Liquid (100 F < FP < 140 F) and will be handled below its flash point.

The company has been receiving the chemical by rail and tanker, unloading with air pressure, and splash filling storage tanks for an extended amount of time. In reading the the relevant codes (NFPA 30, OSHA 1910.106) I have become aware of the potential danger of splash filling regarding static. I am particularly concerned about the potential for misting at the end of the unloading process as the line empties which may be flammable below the FP.

I anticipate pushback in proposing to modify the process. Perhaps with good reason since process changes seldom come without risk. A few concerns I have or that have been raised
-Back flow due to siphoning with a dip pipe or bottom fill connection. For a dip pipe, the antisiphon hole could become obstructed with polymer. Check valves can fail.
-Trapping pressure (from static head) in the fill line and having to disconnect hose connections at trailer. Would require a bleed system that could be prone to error.
-If unloading with air, the line will bubble compressed air through the bottom of the tank. This is still forming a fuel/oxygen mixture (my intuition is this would still be preferable to splash filling the whole time or a mist at the end.

Are my concerns about splash filling warranted in this case? Is anyone aware of accidents caused by splash filling specifically combustibles (not flammables)? I have seen a good bit for diesel but it is often coupled with switch loading from gasoline. It would make selling a change easier. Should the practice always and everywhere to be avoided? The codes do not seem to mandate bottom filling or a fill pipe for combustibles below their FP. Thank you for any input you may have.

 

[pierreick]

Hi shvet,
Sorry It's a paper version. Check the link I shared in my second reply to this post (June 25th).
Not sure the OP understands the risk associated with this material. Unfortunately, no PID shared.
Feel bad.
Pierre

 

[TiCl4]

I agree with Pierreick on this - your risk from O2 depletion is MUCH higher than from internal deflagration, both from a probability standpoint (you operate well below the flash point) and a risk standpoint (AA polymerization is near-explosive once it hits decomposition temperatures). Due to temperature-related autopolymerization, if you are ever at the flash point of AA, you have other problems, as it is likely near the onset of runaway. For example, our site has bulk glacial methacrylic acid, of which 104F is the maximum storage temperature. The onset of autopolymerization will occur in the 115-125F range even with perfectly good inhibitor. I suspect AA is similar, though I didn't see anything in the EBAM manual on this.

The only way I'd put an air/N2 mixing valve feed to a AA tank would be if you SIL-3 protection to ensure you NEVER feed pure N2 - requiring at least two separate O2 sensors, separate control networks, and separate final control elements for shutdown of feed if air feed is lost.

FYI you can "splash fill" from the top with no dip tube more safely than just dumping the material in at the top nozzle. Extend the fill nozzle a bit inside the tank and turn it to the wall at a 45 degree down angle. You can even contour the end of the pipe to a flattened fan shape, ensuring you terminate the pipe within a short distance of the wall. This will allow the AA liquid to hit and flow down the wall in a smooth sheet instead of free-falling and creating droplets.

 

[ProSafPlant1]

The Canadian Fire Codes are more restrictive than NFPA last time I checked on this detail - transfer of flammable or combustible liquids by compressed air or other non-inert gas pressure is prohibited.

Re combustible liquid mists see

attached

 

[pierreick]

Hi,
another document from Dow Chemicals.
Pierre

 

[MementoMori]

All, thank you for the replies. I did not mean to suggest that the principal hazard of acrylic acid handling was flammability. I will continue working through the material you have shared. Pierre, that last file is an earlier version of the BAMM handbook I mentioned earlier. ProSafPlant1 -- thanks for sharing that is precisely what I was looking for.