I am looking to see if anyone has a 1956 copy of ASME Section II where they could look up and tell me the published allowable stresses for both A212A and A212B firebox steels.
I would also take something "in the vicinity" of 1956 as well.
According to the 1950 edition of section VIII the allowable up to 650°F was 16.25 ksi and 17.5 ksi, for SA-212 grade A and B, respectively. This is based on a design margin on ultimate of 4.