I normally work with pipes but this is more of a vessel related and I do not have PV Elite to check what it does. I hope that a vessel designers would answer.

Not one of the standards are clear. I have a question how to understand ASME Factor B graph/table together with UG-28.

If we assume the following:
Graph and table: CS-2
A value: 0.0034 (or any value that intersects 300 F line)
Temperature: 299 F

Round dimensional values used
Do: 98.5"
t: 1"
L 40"

In the graph there is a note for the 300 F line Upto 300 F. In UG-28 Step 4 it says "Move vertically to an intersection with the material/temperature line for the design temperature." Table has no word UpTo. Design temperature is below 300 F. There is no line 200 F or similar below 290 F but there is that UpTo so it is valid for all temperatures below and including 300 F.

Step 4 last sentence: For values of A falling to the left of the material/temperature line, see step 7. This is 100% clear if the A value would be less than 0.176 10^-4 which is the lowest A value.

If I use Step 7 formula the maximum allowable external pressure is around 900 psi. Using the 300F graph max pressure is about 210 psi. That is a serious difference. Material values will not change between 299 to 300 F that much.

Please consider above and let me know if Step 7 formula should be used or 300 F line where A crosses the line. I tried to look at code cases but I could not find a solution. Literature I found is silent.

Thanks