Steel grade designation

[Viekku]

Hi all!
I wonder what letter S (without any number) means after grade name in A516 Grade 60S?

 

[metengr]

Typically, there is no alpha suffix designation after the ASTM A 516 Grade minimum tensile strength level.

 

[EdStainless]

If there was a number following the 'S' it would refer to a supplemental requirement.

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P.E. Metallurgy, Plymouth Tube