Dear Jouko,

I tried to understand why you involved Step 7, which is used only in case the value of A is falling to the left of the applicable temperature line in Figures of ASME II D. Do you suspect that might be a curve (applicable to 290 F for example) to the left of the curve specified for "up to 300 F"?- or I totally failed to understand the reason?

In my opinion the reason for specifying the curve applicable "up to 300F" is the fact the modulus of elasticity value is considered as constant up to that value (and the value is 29*10^6 psi for curve CS-2, for example). So in my interpretation, indeed that curve is "up to 300F" and must be considered as applicable for cases when the vertical line "A' intersects that curve and T<=300F.
For the actual cases when A is to the left of the curves. B should be taken as B=A*E/2 (comparing the equations in step 6 and step 7).
By the way, for A=0.176E-04 and E=29E06 psi, the value indicated in table CS-2 is 0.250E3 (which is an approximation of AE/2) but CS-2 figure indicates a value of 2500 (at least in 2019 edn).