Does pentane normally corrode aluminum? 1

[IFRs]

In general, dDoes pentane normally corrode aluminum or is aluminum normally resistant to and compatible with pentane?
Where would I go for a good answer?

 

[MortenA]

I dont think pentane does - but you have to consider if Hg is present.

--- Best regards, Morten Andersen

 

[EdStainless]

No pure HCs will, but there are lots of trace impurities in them that can cause corrosion.


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P.E. Metallurgy, consulting work welcomed

 

[IFRs]

Thanks for the info. How much Hg would it take to cause trouble? I can probably get a sample analyzed.

This pentane comes in warm off a refinery stream via pipeline into some floating roof tanks. The aluminun non-contact skin-and-tube floating roofs experienced severe widespread pitting corrosion, mostly below the liquid surface. It is not clear if the corrosion was from a prior brackish water hydrotest or exposure to pentane after the hydrotest. The IFR underside was rinsed after hydro but I'm sure some salty residue was left. It was assumed that any residue would be washed off by the product movements, or removed from oxygen exposure by the pentane. I'm getting samples sent to a lab. Any suggestions for a lab near Houston?

 

[MortenA]

Hg forms an amalgate with Al one that can erode away i think. Im not an expert but try to google the issue. It seems to be a problem mostly in cryogenic distillation where the Hg will concentrate and can cause corrosion in the HX.

--- Best regards, Morten Andersen

 

[dik]

Thanks... I didn't know that it was the gift that keeps on giving (from Wiki):

"The net result is similar to the mercury electrodes often used in electrochemistry, except instead of providing electrons from an electrical supply they are provided by the aluminium which becomes oxidized in the process. The reaction that occurs at the surface of the amalgam may actually be a hydrogenation rather than a reduction.

The presence of water in the solution is reportedly necessary; the electron rich amalgam will oxidize aluminium and reduce H+ from water, creating aluminium hydroxide (Al(OH)3) and hydrogen gas (H2).[contradictory] The electrons from the aluminium reduce mercuric Hg2+ ion[clarification needed] to metallic mercury. The metallic mercury can then form an amalgam with the exposed aluminium metal. The amalgamated aluminium then is oxidized by water, converting the aluminium to aluminium hydroxide and releasing free metallic mercury. The generated mercury then cycles through these last two steps until the aluminium metal supply is exhausted.[4]"


Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[IFRs]

Thanks, I'll check for the presence of Hg