SA-335 has hardness specified for pipe materials below
9.3 Pipe of Grades P91, P92, P911, P122, and P36 shall
have a hardness not exceeding 250 HB/265 HV [25 HRC].
Hardness of P23 shall not exceed 220 HB (RB 97).
Why? Because ASME imposed hardness to ensure proper microstructure and heat treatment as an additional quality check for B&PV Code application whereas, the ASTM committee did not believe this was necessary. Another of the differences between standards committees.
To answer your second question, yes, you can impose the above for information purposes for A-335.