Checmical Requiremetns of materials Question 1

[jgibbs22]

Hey everyone:

Just needed some clarificaiton. On the Secotion II, Part A material callouts. In the table with Checmical requirements for the various specficiations, what does it mean when there is a "..." under that checmical column??

Also, are single values listed the MAXIMIM amount of that element that is allowed under that specfiication? Is there any wiggle room above or below??

Thanks.

Jason

 

[metengr]

Not specified or reported.

 

[jgibbs22]

So does that mean you could have a percentage of that specific elem,ent and it does not matter, it still meets the specs?

 

[SJones]

If no supplementary requirements have been imposed by the purchaser, then the material would meet the specification. Whether it does or does not matter is another question.

Steve Jones
Materials & Corrosion Engineer

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

 

[jgibbs22]

Thank you for the responses! so as a follow up.... if I am using PMI to identify an unkwon material, and I get a list of element concentrations, couldn't the material then meet a whole range of ASTM materials and I still would have to guess? One example I am dealing with is a PMI resulted in a SA182 Grade 310H. Everything matched up on the table to the requirements of the specification, except there was 0.09% Mo concentration reported, but the table lists "..." So is it possible the material is actually something other than 310H?

 

[Guest102023]

I hope you are aware that PMI is NOT chemical analysis. It is an alloy sorting tool. In your situation PMI would be valid to disqualify the material with 100% certainty, but confirmation comes with a confidence level that is not 100%.

While PMI is useful for the Cr-Mo and stainless steels in refinery, it does not measure carbon, which is crucial to ID low-carbon grades (for just one example). Also, any element below 0.1% may or may not be present, and even if it is, the second digit is a random number.