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ASTM A480 & ASTM A693 -13 vs -16 rev interpretation

ASTM A480 & ASTM A693 -13 vs -16 rev interpretation

ASTM A480 & ASTM A693 -13 vs -16 rev interpretation

Chemical requirements of UNS17400 per ASTM A693 changed such that previously (rev -13) a limit of Ta+Nb of 0.15-0.45 was the acceptable amount. In the newest revision (-16) they have removed tantalum entirely and list only Niobium 0.15-0.45. In a theoretical context of Ta=0.00... these two are equivalent.

However, per ASTM A480 6.2.2 the fact that Tantalum is no longer a listed requirement means that material with trace amounts don't have to have it measured or reported and even if it is reported is not basis for rejection. So in a theoretical case where Nb=0.450... and Ta=0.001 this is satisfactory to revision -16 but not -13 (>0.45). The likelihood of this seems minute but on the other hand ASTM provides no rationale in the summary of changes of the revision.

Furthermore, some other standards that use the same material have not been revised (yet) to include this change (e.g. A564)

Any thoughts?

RE: ASTM A480 & ASTM A693 -13 vs -16 rev interpretation

Welcome to how the ASTM folks work and think versus ASME B&PV Code committes.

RE: ASTM A480 & ASTM A693 -13 vs -16 rev interpretation

My job is effectively trying to reverse engineer people's thought processes and some of these make my head spin.

In another ASTM standard I'm reviewing for changes the phrase "rule of thumb" is used... in a technical standard?

RE: ASTM A480 & ASTM A693 -13 vs -16 rev interpretation

I have been in these discussions, and the reason is that the Ta content is very small so to be inconsequential.
The other thing is that anything 0.004% Ta and lower should be reported as 0.00%.
Because of this the material meets all revisions of the spec.

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P.E. Metallurgy, Plymouth Tube

RE: ASTM A480 & ASTM A693 -13 vs -16 rev interpretation


Thanks for the input; I suspected something similar was the case but I don't know where they got those limits to begin with...observation?

I have a cert here with Ta at .010 (ASTM A564, not A693) which I'm not saying is significant. The three certs I've seen lately at least report to 3 decimal places though. The two others I looked at were .001 and .000.

I'm not necessarily concerned about the material other than having a divergence in the standards. Can I currently say the 17-4 specced to ASTM A693-16 matches chemically to the 17-4 in F899-12b? This part isn't entirely trivial.

RE: ASTM A480 & ASTM A693 -13 vs -16 rev interpretation

People may be reporting three places, but I believe that the standard for this requires two places.
Please double check but I am fairly sure.
In the ASTM world the current spec rules, people cannot require you to meet a specific revision other than the latest.
These changes were made with the intent of not changing the requirements.
All that really matters is the properties, are they OK? of course they are.

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

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