Positive Material Identification
Positive Material Identification
(OP)
Hi all,
I work in Power Plant with 3 Gas Turbine "GE7EA" and 1 Steam Turbine (Fuji) totaling 304MW and I'm beginning a activity to identify the material's chemical composition, espeficaly the parts (capital parts) that have "coating".
I'd like to know if anyone have experience about PMI [b]without removal the coating (Is it possible?). I'm concerned in damaging the parts if I remove the coating (few parts are new e other are repaired.
Any feedback will be very appreciated.
Emir Martins
Termonorte S.A.
+55 (69) 8115-8147
I work in Power Plant with 3 Gas Turbine "GE7EA" and 1 Steam Turbine (Fuji) totaling 304MW and I'm beginning a activity to identify the material's chemical composition, espeficaly the parts (capital parts) that have "coating".
I'd like to know if anyone have experience about PMI [b]without removal the coating (Is it possible?). I'm concerned in damaging the parts if I remove the coating (few parts are new e other are repaired.
Any feedback will be very appreciated.
Emir Martins
Termonorte S.A.
+55 (69) 8115-8147





RE: Positive Material Identification
The XRF alloy analyzers used for PMI have an interaction volume that they sample from. I've found that thin samples, for instance, will pick up a little excess iron from the table that I test them on. In the end, it comes down to interpretation. PMI is not an exact measurement of chemistry, it is just there to make sure that some dummy in receiving didn't swap the carbon steel barstock with the stainless barstock.
If you want a perfect chemical analysis, its going to be a destructive test, and you will have to remove the coating.
RE: Positive Material Identification
The manufacturer of the turbines and generator casings will give you exact chemical/alloy requirements for their pressure casings.
RE: Positive Material Identification
If you really want to know what they are you have to destroy a part to find out.
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P.E. Metallurgy, Plymouth Tube
RE: Positive Material Identification
RE: Positive Material Identification
"Even,if you are a minority of one, truth is the truth."
Mahatma Gandhi.
RE: Positive Material Identification
All other field testing and such needs to be done knowing that there are no codes or rules.
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P.E. Metallurgy, Plymouth Tube
RE: Positive Material Identification
First of all, I'd like to thank all feedback received (were very useful).
The Capital Parts that we want to test are Nozzles, Buckets, Liners, Transition Pieces, etc. and we have materials' "spec" of, practically, all parts (GE's Manual) and, in gerneral, these Capital Parts use GT-33 coating.
So, we'd like just check (to make sure) if the material the parts that we buy (or send to repair) are the same.
Best Regards,
RE: Positive Material Identification
RE: Positive Material Identification
I thank (understood) your comments and our supplier knows about "material spec" but, as I said early, this (to check always the parts when arrive in the company) is a recommendation (order) of our Insurance.
The Insurance wants to make sure (for warranty effect) that we are assembling the parts according spec GE.
RE: Positive Material Identification
Trying to check after the part has been made is too late. You need to know that he is verifying all of the properties, not just composition.
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P.E. Metallurgy, Plymouth Tube
RE: Positive Material Identification
Really, the suppliers knows about all "spec" recommended by GE and we already visit few workshops them and we can check that the services are performed according OEM. Anyway, as we purchase pieces of several suppliers (including GE), we need to check the parts when arrive in the company (insurance requirement).
What about other properties, we don't have conditions of to test in site and we need to trust in supplier (tests report, etc.).
RE: Positive Material Identification
"Even,if you are a minority of one, truth is the truth."
Mahatma Gandhi.
RE: Positive Material Identification
In fact they should be interested in helping audit the supply chain.
The first thing that dig into at a audit is how thoroughly they audit their suppliers. Good procedures and double checks are all that you can rely on. Checking at the end is loosing game.
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P.E. Metallurgy, Plymouth Tube
RE: Positive Material Identification
Ok I appreciate and respect your opinions.
However, don't believe that to be this way because we are trying minimize any problem of this source. We believe that this tool (PMI) help us to "monitor" our suppliers and supervise us too, and make sure the pieces are being assembled according to the OEM.
The time is being used in this activity is "very small" close to the time required to repair the machine if happen a problem of the material.
One more time, I'd like to thank all and say that this is our opinion about this matter.