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LME by Hg
2

LME by Hg

LME by Hg

(OP)
In order to protect a BAHX (aka "cold box") from LME, we have started measuring Hg in the inlet gas.

Question 1) What's the minimimum amount of Hg that will cause LME?  is there a published threshold value?

Question 2)What's the most effective non-destructive test (non-intrusive) to detect Hg in such equipment (completely insulated)?

Thanks,

Corgas

RE: LME by Hg

1) That which will condense liquid mercury under the operating conditions

2) Surely, trying to detect mercury is not an ALARP measure.  If you have a susceptible material and liquid mercury will drop out, you have two options: change the material, or remove the mercury upstream

For aluminium, there will also be an amalgam corrosion risk if water is present.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04
 

RE: LME by Hg

It depends on the alloys involved and the stress levels.
In general if there is free Hg then you have an issue.

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Plymouth Tube

RE: LME by Hg

(OP)
Mr. Jones,

even in the ppb range will cause LME?

Thanks,

RE: LME by Hg

(OP)
enmax : Thanks for the info.

It all comes down to this : Based on the Hg coming in with the gas, when do we need one of those fancy Hg removal systems in order to protect BAHXs?

RE: LME by Hg

I saw an on-platform separation vessel that had Hg in the bottom of it.  An operator opened a valve and drained a little to show me.  It was a Monel valve.  When they replaced it later that day (after I pointed it out to an engineer) we took the valve apart and it crumbled in our hands.

Steve, thanks for the presentation.

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Plymouth Tube

RE: LME by Hg

(OP)
Thanks everyone for your input.

Corgas

RE: LME by Hg

If you even think you have Hg (in Al equipment) ,I reccommend precautions. As I remember a "carbon" filter was effective (sorry I can't be more specific).

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