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Parent - - By ssbn727 (*****) Date 12-03-2009 19:14 Edited 12-03-2009 19:44
You are correct Bill! ;) Then again, I'll ask you to read page 15 in the January 2005 AWS Inspection Trends article for clarification as well as an explanation regarding FP XRF-RPMI's limitation to certain grades of CS. OES method does not have such limitations... Nonetheless they are both considered PMI instruments... So the appropriate method would be chosen for the given application ,and as both methods can be easily rented, there's no need for such a high initial investment in using either technology for a specific application as well.

Respectfully,
Henry
Parent - - By spots (**) Date 12-03-2009 19:59
If I have read this thread correctly it seems that you could get a rough idea of chemical composition with an XRF instrument, nail down the carbon content with the OES method, and then verify additional properties with destructive testing (tensile, charpy, etc.).

Pull a sample.

How does this particular grade differ from other more garden variety materials? Alloying? manufacturing processes? both?
Parent - By ssbn727 (*****) Date 12-03-2009 20:28
Both:

http://steel.keytometals.com/Articles/Art61.htm

Niobium/Columbium is an important element to look for from what I've read so far... There could be others as well which can determine the difference between this grade from your "Garden Variety" grades of CS. ;)

Respectfully,
Henry
Parent - - By 3.2 Inspector (***) Date 12-03-2009 20:34
You will get an idea of certain alloying elements with an XRF.
Just for fun, call jrw159 and ask him to do a XRF test on a CS :)

3.2
Parent - - By jrw159 (*****) Date 12-03-2009 20:54
There is a mode called "Teach match" that one can use. One would take a piece of "known" LTCS and shoot it. The info is stored and then one can shoot an unknown piece and verify if it is or is not the same.

jrw159
Parent - By 3.2 Inspector (***) Date 12-03-2009 21:00
How can the XRF instrument store information, which it never received?

3.2
Parent - - By kipman (***) Date 12-03-2009 21:16
John,
I am familiar with this function and I recommend extreme caution.  XRF cannot identify low atomic number elements.  If you shoot a piece of carbon steel, you can indeed store into the memory what the device sees.  However, it is missing information (for example carbon content).  You could then shoot another piece of carbon steel, and the stored reading may indeed match.  However, and here's the problem, it's not measuring carbon content and so it could tell you that another type of carbon steel is a match.  So the second piece of steel could possibly be an exact match, but it is also possible that it is not.
Regards,
Mankenberg
Parent - - By jrw159 (*****) Date 12-03-2009 21:33
Kipman,
   Thank you for that info. I was not told this when I spoke with an Atlas tech/rep. I can indeed see the reasoning in what you are saying.

jrw159 :-)
Parent - - By 3.2 Inspector (***) Date 12-03-2009 21:37
Instead of being so busy rating my posts with 1 diamant, you should have noticed the post where I mentioned that an XRF can't detect anything below atom #22 :)

3.2
Parent - - By ssbn727 (*****) Date 12-03-2009 22:28
OES can! ;)

Henry
Parent - - By 3.2 Inspector (***) Date 12-03-2009 22:29
no more medicin for you today Henry...

3.2
Parent - By ssbn727 (*****) Date 12-03-2009 22:50
I wish I could say that is true, but unfortunately I must take more after 9PM EST and two more times after that! However, thank you for your concern. ;)

Respectfully,
Henry
Parent - - By jrw159 (*****) Date 12-04-2009 01:55
First off the diamond (yeah that is how you spell it here) rating is bogus since one can rate there own posts. Second I don't give most of your post's the light of day anymore because you are in left field fighting a battle that does not need to exist.

I will for sure admit my "LIMITED" experience and knowledge in this area. I am trying to learn but when someone comes off with some good knowledge in a piss poor way it does not stick.

I will for sure, right now, admit that I have been mistaken and misinformed when it comes to the capabilities of a PMI gun.

So thank you Kipman, Henry, the several reps and techs I spoke with and yes even you 3.2.

jrw159
Parent - - By ssbn727 (*****) Date 12-04-2009 03:15
Hi John!

I wouldn't say that you're misinformed at all... It's just that the XRF method of PMI is mostly limited to detecting most elements without being able to isolate carbon, yet some can determine certain specific grades of CS up to the most common grades say 20 to 25 different grades with about a 95% accuracy which is not so bad and yet in comparison to OES, it's very limited...

Having said that, the OES method of PMI can detect and isolate carbon and measure it much more precisely than an XRF PMI instrument can because all the XRF gun can do is to acknowledge that it is present without any capability of isolating and therefore being able to measure with any sort of accuracy - CAPECHE???

An OES PMI gun can accurately measure the carbon content in the material being analyzed, so it all boils down to which method is being used in order to accurately measure the carbon content in an unknown piece of material ,and then there are different types of OES portable PMI systems as well where some do not require some sort of sampling at all and others that do require some sort of lifting of a very minute sample of the material in question yet smaller than something that one would be required to cut out.

So you're not incorrect all together when it comes to PMI! I hope this clarifies somewhat the differences between the two portable methods of PMI being used currently out in the field.

On another note; Isn't it kind of late concerning yourself now with how you rate with the diamond system 3.? I mean if it really did concern you that much wouldn't you show it in the way you respond to most people in here? Just some food for thought, because I certainly will not debate this nor discuss this with you any further since I'm only offering you a different prespective for you to consider - that's all.

Respectfully,
Henry
Parent - - By Richman (**) Date 12-05-2009 13:28
Thus anyone had already the idea what is the best instrument or equipment to be used in verifying LTCS or low temperature carbon steel materials for piping and fittings?
Parent - By ssbn727 (*****) Date 12-05-2009 18:24
I believe it's rather obvious that Optical Emission Spectroscopy is the appropriate method since it does measure actual carbon content, and depending in which specific model one chooses... One may or may not need to use a very minute sampling inorder to get accurate results from these OES type Portable PMI systems. ;)

I would suggest to contact one of the few companies that either manufacture the equipment in order to either purchase or rent the appropriate model OES system for you specific application... The Manufacturers usually have a list of inspection agency's that either offer this type of inspection service, or if you know someone who is properly trained and qualified with the equipment, then you could possibly rent one of these units from one of their distributors or suppliers as well... Whichever route you decide to go, you need to contact the companies in the list I posted previously regarding the OES Portable PMI equipment manufacturers and inspection agency offering this service also.

Respectfully,
Henry
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