Methyl Chloride Material compatibility

[EngBrandao]

Hi,

I would like to know what is the most suitable material with a fluid that consists a mixture of:

Methyl Chloride (ClCH3)
Hydrogen Acid (HCl)
Water (H2O)

If I guarantee that the system was free of water could use carbon steel, but eventually we will have a little water that possible generates Cl-.

Alloy 20 would be a good option, however it has copper in its composition and copper alloys are not compatible with Methyl Chloride.

Could someone, please help me. What kind of material should I specify?

Thank you.

 

[EdStainless]

The Cu in alloy 20 is nothing like a Cu alloy. It is a minor addition that aids in resisting attack in specific acids, H2SO4 particularly.

What in your maximum temperature?
That is the key to acid service.

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[EdStainless]

The maximum water solubility in MC is about 0.2%, but it is a function of temperature.
What other contaminates are there? Any trace metal ions? (Fe?) any Cl?

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[cloa]

He already (badly) said hydrochloric so it going to have chloride ions. Anyway he needs to specify the ranges of percentage of MethylChloride, hydrogen chloride and water in all plant conditions as well as temperature. EdStainless- did you mean is there chlorine gas?

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[moltenmetal]

Don't know where you're getting your information, but alloy 20 is not particularly HCl resistant.

Scrupulously dry methylchloride is a totally different animal than wet methychloride containing water and HCl. The problem is the water and HCl, and more precisely, how much HCl.

Is the HCl actually there, or just theorized to be present due to hydrolysis of methylchloride to methanol and HCl? The latter process, though possible, is extremely slow except at very elevated temperatures.

If the issue is really traces of Cl- rather than the presence of fairly concentrated HCl in water, you get a totally different suite of potential alloy options.

If temperatures are modest and conditions are really unknown, then there's Teflon-lined pipe, or better still, PFA-lined pipe.

 

[EdStainless]

on the mark, specifics will drive alloy selection.
Yes my concern is FeCl or free Cl, not chlorides.
In many cases Ni alloys will do well, but choosing between 600, B-2, and C-22 is a real challenge unless you know details.
Ti may be a better option if you want metal, but one of the grades with Pd would be better than a CP grade.

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