Table A.2 of NACE MR0175 / ISO 15156, Part 3: 2016 edition (Austenitic SS’s in “sour” services) 2

[NGiLuzzu]

I’m not sure on how the table in object should be read.

Do both the 2nd and the 3rd rows refer to “Austenitic stainless steel from materials type described in A.2”?
So those materials should be used for service fluids with:
- chlorides concentrations ≤ 50 mg/l
or
- H2S partial pressures ≤ 100 kPa and temperatures ≤ +60°C.

Is this the right interpretation of the table?
(The graphical format doesn’t assist in a good understanding…) :-(

Please see also thread338-415235 about similar issues.


THANKS in advance to All,
’NGL

 

[SJones]

Your interpretation is correct - it is an 'either or' application.

Steve Jones
Corrosion Management Consultant

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

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

If you want the 'and' option you look at table A.8 for the highly alloyed grades.
And the remarks often do not help make things more clear.

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

 

[NGiLuzzu]

Thank you Steve, thank you Ed!!

I’m not looking for more corrosion resistant alloys, I’m only trying to understand the limits for austenitic stainless steels and, as I said before, the graphical format of the table (especially the solid border lines of each and every cell) doesn’t help; I believe that, for clarity sake, the cells of the first column referring to the same materials (2nd and 3rd; 4th through 9th) should have been merged into one…​

By the way, how should I consider cast grades (CF8M ≈ J92900, CF8 ≈ J92600, CF8C≈ J92910, etc.) when they are not centrifugal castings used as seal rings and gaskets (Table A.5) , but sand castings for direct pressure containment (e.g.: valve bodies) instead?​

Shall they be assimilated to the group of “Austenitic stainless steel from materials type described in A.2” in general, as they’re note individually mentioned?​

How about the low carbon cast grades (CF3M ≈ J92800, CF3 ≈ J92700, etc.)?​

Best Regards,​

'NGL​

 

[SJones]

The table isn't that difficult as it is written - each row is discrete to the division of the first column in which it resides. If it is merged then it definitely will be difficult

If the item being dealt with does not satisfy the specific application description in the table title, then the default option is to use the "any equipment or component" table. Table D.1 can be used to identify which UNS number is associated with which table.



Steve Jones
Corrosion Management Consultant

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

All answers are personal opinions only and are in no way connected with any employer.

 

[NGiLuzzu]

Thank You again, Steve!

I got your points, they sound consistent and result useful to me; but, sorry, I have to disagree about typographical readability: I remain convinced that it would be clearer if the proper cells were merged into one… more or less like in the attached cutout picture:​

Anyway, I still can’t understand how Table D.1 could help in identifing which UNS number is associated with which table.​

Table D.1 just provides ”a link between the UNS numbers used in the tables of Annex A and the chemical compositions of the alloys to which they refer”, but some cast grades (e.g.: J92900, J92600) are mentioned only here and in Table A.5 - Environmental and materials limits for austenitic stainless steels used as seal rings and gaskets. What if they are used as different components?​

Moreover, other grades are mentioned in Table D.1 only (e.g.: J92800) or not mentioned at all in the whole standard (e.g.: J92910, J92700).​

I understand, me too, that those cases should fall within Table A.2 - Environmental and materials limits for austenitic stainless steels used for any equipment or components , in the first general category of “Austenitic stainless steel from materials type described in A.2”: I just wanted to be sure about this (one never can tell, it's always easy to ignore or forget some little sub-sub-clause or note under a table of the standard) ;-)​

Best Regards,​

’NGL​

 

[SJones]

As a native UK English speaker, it looks reasonably straightforward to me: one looks up the UNS number and identifies which table(s) address the requirements, one then refers to the appropriate part of the table dealing with that alloy. In your example, you are not dealing with S31603, nor S20910, thus you are dealing with an austenitic stainless steel from A.2. Again, if the specific application of the item does not concur with the table title, then it defaults to any equipment or component.

Steve Jones
Corrosion Management Consultant

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

All answers are personal opinions only and are in no way connected with any employer.