I am analysing a piping system according to B31.3-2010 using Caesar-II version 5.20. All the static load cases I created is in a single calculation file and are intended to evaluate the following stresses:

1. Check the code stress following the rules in Chapter-II.

Item 1.1 Evaluate the Displacement Stress per section 302.3.5(d) equation 1a - "Allowable Displacement Stress Range, Sa = f(1.25Sc + 0.25Sh)". In this case, the stress type is "EXP" in Caesar-II spreadsheet.

2. Check the code stresses following the alternative rules in Appendix-P. I am aware of the code statement used in section P300(a) "...satisfied EITHER the requirement of Chapter-II OR the requirement of this Appendix". My purpose is to check the piping stresses in both rules of Chapter-II and Appendix-P.

Item 2.1 Evaluate the Operating Stress per equation (P1a) - "Allowable operating stress, Soa = 1.5(Sc + Sh)". In this case, the stress type is "OPE" in Caesar-II spreadsheet.

Item 2.2 Evaluate the Operating Stress Range per equation (P1b) - "Allowable operating stress, Sea = 1.25f(Sc + Sh)". In this case, the stress type is "OPE" in Caesar-II spreadsheet.

In the configuration setting, I activated the "Implement code case 178" and "0.75 Sustained SIF multiplier" for code compliance to current B31.3-2010; and also activated the alternative code rule Appendix-P. The piping material is A106-Grade B, with both Sc and Sh equals 137.9 MPa.

Now, here are the allowable stress errors I am getting after generating the stress summary report in Caesar-II.

-For item 1.1 above, the Allowable Displacement Stress Range, Sa = 345 MPa instead of 207 MPa.
-For item 2.1 above, the Allowable Operating Stress, Soa = 345 Mpa instead of 414 MPa.

The Allowable Operating Stress Range, Sea = 345 MPa is correct for item 2.2 above.

And if I changed the configuration setting and deactivated the use of Appendix-P, the stress report gives the correct Allowable Displacement Stress Range, Sa = 207 MPa for item 1.1 above.

Is there any "special" setting in Caesar-II in order to provide the correct allowable stresses for these situations in a single calculation file? Or two calculation files are necessary-one using Chapter-II alone, the other using Appendix-P.

Many thanks.

Moreover:

Should it be that if the stress type is "EXP", the allowable displacement stress range Sa will still use the default rule of Chapter-II even if the Alternative rule of Appendix-P is active - which is applicable only for "OPE" stress types?

First let me note that the current release of CAESAR II employs B31.3 - 2008 and 2008 rules in Appx. P are a little different.
CAESAR II defaults to equation (1b). If you want to see the more conservative allowable expansion stress range (1a), you must set that request in the Config file or special execution file. And, if you wish to use (1a), then I am uncertain of your interest in Appx. P as the intent of Appx. P is to avoid referencing the sustained stress in the expansion limit. You are already avoiding that reference by using (1a).
2008 code uses f in both the operating stress check and the operating stress range check. For A106 B, you can set f=1.2 (using the radio button in the allowable stress definition); that should line everything up for you.

Dear Dave Diehl:
In the model , How to know use 1a or 1b?
as you say, the default in CAESARII is (1b), but since the APPENDIX P is there, How to know we should make special setting for the line?

thanks!

The Code intent is to meet (1b). But (1b) includes the calculated longitudinal stress due to sustained loads (SL). If you do not want to calculate SL, you can simply assume SL is the maximum allowed of SH (the basic allowable stress at temperature). Replace SL with SH in (1b) and you get (1a). A good approach for a slide rule. But (1a) may cause "unnecessary" flexibility redesign as it is more conservative.
Now, when you throw Appx. P into the mix, I figure CAESAR II will replace the limit on expansion stress range found in EITHER (1a) OR (1b) with the limit found in Appx. P: (P1a) in 2008 or (P1b) in 2010.

Hello Dave,

When to use the appendix P? When applying the appendix P the allowable reaches up to the ultimate tensile stress. Is it recommended to use operating allowable up to tensile strength?

Appendix P is intended to address the changing stress due to sustained loads as the pipe moves (and lifts off supports) to its operating position. Read the opening paragraph of Appendix P.
You can use Appendix P whenever you wish but Appendix P requires more evaluation (expansion stress range, sustained stress and operating stresses).
The math in Appendix P will get you to two times yield. And that can be OK.