Displacement change vs Code change

Hello,

In my model, when I only change the code from NC to B31.1, the displacments vary about 15%. It makes sense?

Carter

Caesar database reflect the codes. So if in one code a material have a expansion coefficient and in other code have other expansion coefficient, you will see a difference when you change the code.

Regards,

The material of all pipes is SA-106B. The thermal expansion coefficients of the two codes should be same.

Carter

Check the modulus of elasticity too. Is one analysis using E_h and one usinh E_c?

And are they using the same initial / minimum / ambient temperature?

Check this.

This was changed in 5.2. Did you received the COADE notification regarding the updated material database?

Regards,

Check the modulus of elasticity too. Is one analysis using E_h and one usinh E_c?
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Steve Perry


Hello Steve,

This is a good point.

I have checked both codes, ASME Sec III, NC 3000, nuclear class 2 piping and ASME B31.1 regarding Ec and Eh. These requirements are same.

I applied this issue to other model by changing the code from B31.1 to NC, same thing happened.

Some opinions from COADE?

Carter

Narrow down the system/scope of the issue.

First, type in all the material properties, then you take the database and the Codes out of the mix with regard to material properties.

If you're just chasing displacments, then your looking for why [K]{x}={f} yields a different {x} vector when you change the Piping Code. {f} should be the same, and the solution technique is the same, so that leaves a difference in [K].

[K] can be different if the "bend flexibilities" are different between two Codes. Eliminate the bends (use square corners) and see if that resolves the differences.

CAESAR II Error Notification - Material Database - Incorrect Values

The expansion coefficients in the CAESAR II material database for ASME NC and ND materials have been incorrectly specified since Version 3.24. The database contained the “instantaneous coefficient of expansion” (Column A of Table TE-1 in Section II Part D) instead of the “mean coefficient of expansion” (Column B of Table TE-1). (The “instantaneous values” result in more expansion than the mean values for temperatures greater than 70F and thus should have produced conservative results in most cases.) A corrected material database for CAESAR II Version 5.20 can be obtained from this link

Hello Dan,

Thanks for your points.

Where is the corrected database link? I'd like to compare the results with the new data.

Carter

link: http://www.coade.com/uploads/caesar/cmat_520.zip

Once you have this file, unzip the archive and copy “cmat.bin” to your \system directory for Version 5.20. Note that the location of \system depends on your particular Operating System.

For Windows XP: “C:\Documents and Settings\All Users\Application Data\COADE, Inc\CAESAR II\5.20\System”
For Windows Vista and 7: “C:\Program Data\ COADE, Inc\CAESAR II\5.20\System”


Hope this help.

Best regards,

Hello Dan,

I replaced the file and run the model, the results of NC code are same as the ones of B31.1 code. Thanks again.

Carter

You're welcome.

Note that, for example, B31.3 and B31.1 have different coefficient of expansion for the same material.
How come? What is the story of this? I do not know.

Regards,