And what you've written in the first post is not a warning bell for them?
Quote:
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.


They are just counting the stress- strain as elastic even the value of strain is in plastic domain, which is highly non-conservative. That's exactly what the graph tries to avoid and the reason for which such graph exists!

My best regards.