One of my users ran into an interesting issue. For a number of materials in B31.3, the allowable stresses have different values based on wall thickness ranges.

The example we ran into is material number 168 - A312 321 Stainless Steel. For thickness less than 3/8" the basic allowable at 70F is 20,000psi and goes down from there. For thickness above 3/8", the allowable at 70F is 16700 and goes down from there.

When selecting this material in Caesar, the 20,000 allowable is the basis and it does not appear to adjust based on the wall thickness.

It was largely a matter of chance that the user happend to look up the allowables in the code since he was not strongly familiar with the material and caught the discrepancy.

I've tried a couple of different ways and orders of inputing the material and wall thickness and I have not been able to find a way to trigger to lower allowables.

I've searched through the forum and haven't come across a post addressing this and the documentation hasn't proven any more enlightening.

Thanks,

The CAESAR II Material database does not include all of the materials from any particular code. Rather we went through and picked what we thought were the most common materials.

As you noted, occasionally there is a material with two entries for allowable stresses, based on a thickness range. At the present time, the database only contains one of these entires, typically the thinner one. Additionally (at this time), even if you added the other entry, CAESAR II is not able to make the selection based on wall thickness.

Currently, the best way out of this dilema is to add another entry to the database with a slightly different name, perhaps A312-321THK, where THK indicates "thicker wall". This way the user can select either entry based on the wall thickness.

That's good to know. I am aware that CAESAR II doesn't contain all the materials and I have had to add materials myself to the database on a number of occasions. So that is something I know to look for.

It is somewhat disconcerting in this case since the material was covered by the database, but not in the thickness of interest. It would probably be wise in such cases to indicate that in the material description, so the user is aware of the limitation.