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Dear mates,

In the refining industry speaking of PMI, it is justifiable to have a gun that includes the determination of C, in other words when a PMI gun would be needed, for what specific uses.
Any comments, suggestions, opinions, etc., are welcome and grateful.


If you predominately work with steels that only really differ in C then a portable OE would make sense.
I used to be able to do C by a spark test with a grinding wheel, but that take a lot of experience.
Remember that PMI is the field verification of alloy type, it is not a chemistry determination.
If the alloys of interest can be sorted using other elements then C may not be needed (Cr, Mn, Ni for ex).

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube


If your "gun" is XRF, it will not provide a quantitative analysis for carbon. At least one portable optical emission tool can provide carbon analysis. We checked that machine analysis with at least 10 samples with LECO carbon and the accuracy of the OE unit was verified. Argon shielding was used.


Some of the new LIBS guns will do light elements such as C, I have seen them separate stainless grades with various C and Ti levels.
Now all that I need is N.....

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube


PMI identifies alloys using approximate analysis and applying a statistical algorithm against an internal alloy database. It is not chemical analysis. It is ideal for identifying all that undocumented piping in your refinery's lower 40, sorting scrap, or confirming your welder did not weld that P91 pipe with E7018.

PMI's major shortcoming is inability to measure carbon, so it cannot tell the difference between two carbon steels.

Unfortunately it has been sold as 'chemical analysis', mostly by inspection companies, for whom it is a great moneymaker.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."


Dear Joss10,

PMI equipment are being used in the oil and gas sector since decades. They normally work on XRF which cannot detect any non-metal.

Now-a-days, latest machines based on OES are able to detect everything it seems, but I am old school and would rely solely on chemical analysis.




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