Appendix P & the allowable for Expansion Stress

It just came to my notice that on activating App P, the allowable for Expansion Stress range are affected.

This should not have happened as I can't figure out any relation b/w App P & the allowable for Expansion Stress Range.

Does anyone can please throw some light on this?

Additionally, if App P is activated, the allowable are reduced by 15%.However, for the material in my case A106 Gr B, ratio b/w min specified yield strength to min specfied tensile strength is 0.58 (doesn't exceed 0.8)but still the allowable are reduced. Checking on the help file,it states that the checkbox for "reduction of ope allowable for App P" is kept activated by default for 31.3 & it reduces the allowable only if the codition as specified by code are met.But still its doing it.
The B31.3 code edition I'm referring to is 2010 & Caesar version is Caesar V6.10.

Compare equation P1a with with equation 1b (which is the c2 default).

I don't believe that "when applicable" phrase should be there in the "help". If you check the checkbox, the 15% reduction is applied.

Rich,
I figured out the whole thing. The allowable in "Exp" are in fact "Operating Stress Range" allowable ( as per equ P1b).

Can we have an added option in future wherein we can check Expansion Stress range alongwith "operating stress ranges" separately when the App P is activated. Also, it should be called "operating stress range" as per App P rather "expanion stress range" when App P is activated; to avoid any confusion between the two?

I quote from the help file for App P allowable reduction "The software selects this check box by default for the B31.3 code. When selected, CAESAR II performs this reduction, when applicable."

I interpreted " when applicable" as the software will reduce the allowable only & only if it meets the conditions of smys/st more than 0.8.It doesn't direct the user not to deactivate it if its not applicable.

I guess most of the users will interpret it my way.

The "help" is indeed misleading. This will be corrected.

On the "range" issue, you select the "stress type" of the load case, either OPE or EXP. This determines not only how the stress is computed but also how the allowable is computed. You can define both cases when App_P is active.

Regarding the "range" of OPE and EXP load cases when App_P is active, this doesn't to be working independently in Caesar-II. If you activate the App_P, the allow of "EXP" stress type load case is always overridden by the App_P's OPE allow stress range.

Rich,

What I want is the freedom to evaluate expansion stress with the allowable as stated in equ 1a of 302.3.5 of B31.3.

I made cases as follows (hope this is what you meant in your post)

L4-(Ope) W+T+P+H
L5-(Sus) W+P+H
L6-(ope) L4-L5-----------ope stress range
L7-(Exp) L4-L5-----------exp stress range

The problem is the allowable for L4 & L6 are same which is incorrect since the code requires to calculate the allowble for L4 as per equ P1a & for L6 as per equ P1b of App P.

Now, the exp stress allowable for L7 is not as per equ 1a of 302.3.5 but rather as per equ P1b of App P.

This means the software can't calculate the allowable for exp stress range as per equ 1a but treats it as "operating" stress range & uses the allowable as per P1b of App P.

So both cases can be defined but there is an issue with the selection of the correct allowable.

Rich/Dave,

Any help on this?

If Appx. P is active and you call the case (EXP), (P1b) is used; if you call it (OPE), (P1a) is used.

"Range" calc's use (P1b) and "state" calc's use (P1a). (EXP) is range anmd (OPE) is state.

Can you confirm?

I think that it is important to clarify what is Operating Stress Range and what are the differences between Operating Stress Range and Expansion Stress Range.
As I previously suggest, Operating Stress Range can contain also Primary Stresses. Thanks in advance for the one that will put light on this.

Regards,

Yes,Dave..That is what I found & suggested in the earlier post.But the problem starts when one wants to have a look at "expansion" stress range (not "ope"stress range) which is not shown when App P is activated.

Dan..I believe some primary stresses exist in both the stress ranges - operating as well as expansion.Correct me if I'm wrong!!!!

I am uncertain of your question here.
If you use Appx. P, then the expansion stress range evaluation found in 302.3.5(d) is REPLACED in its entirety by P302.3.5(d).
If you are using Appx. P in C2, then any appropriate range calculation (with or without primary components) should be labeled (EXP) and any appropriate operating stress state should be labeled (OPE). Then C2 will use (P1b) as the (EXP) limit and (P1a) for the (OPE) limit.
What we have always been doing in C2 with the typical "L1-L2 (EXP)" is just a type of range calculation. Before Appx. P, we assumed the highest SL in setting the (EXP) limit in (1b). That ratcheting check in (1b) (the "-SL" term) is replaced by the (OPE) check found in Appx. P's (P1a).

Dave,

Let me make it more clear.

The issues on Activating App P are:

- The range case is called "exp" which is confusing when you report it to client b/c the allowable are as per equ P1(b)& not the usual equ 1a.It will be apt to term it as operating stress range in load case rather than expansion stress range.

-I would like to have at my disposal the option to check expansion stress range as per equ 1a (the normal without App P check) even when App P is activated.This can be achieved by calling one load case as ope stress range & other the normal Exp.

Appx. P is either active or inactive. That's how it functions in C2 now.
If you want to use (1a) then do not turn on Appx. P.
In accordance with B31.3 you either use (1a) [or (1b)] from the base Code, or, you use (P1a) and (P1b) from Appx. P. Mixing them [referencing (1a) & (P1a)] is not indicated by the Code.
The intent in Appx. P is to get around the nonlinear issues in setting SL in (1a). You can either use C2's conservative approach (worst SL) in the single (1a) evaluation or run the two checks in Appx. P.

Dear Dave & Friends,

Since, Appendix-P is particularly to check the stresses & Stress range in Operating condition due to the effect of Non-Linear & Liner support of piping system.Is this effect to expansion stress check case also?

The doubt is that while to issue client as a stress report / output, the Expansion cases allowable shall to follow the equ. 1a of 302.3.5 31.3 2010 OR any version w/out Liberal case & wth Liberal case Eq 1b of 302.3.5 not the Eq P1b, please correct me if I am wrong.

SJ also mentioned that here CAESAR taking eq P1B as a allowable for the Expansion stress range.

APPENDIX-- P tells as below.

Eq P1a - Operating stress.
Eq P1b - Operating stress range.----> Not Expansion stress range.


Dear Rich ,

Posted 55389 by you.

""If you check the checkbox, the 15% reduction is applied"".

I found in Code this statement & theory, but in CAESAR where is this "check box"?

As per our practice we normally Tick TRUE in Sif & stresses at Confi. set up. I do not found any "check box" for reduction 15%.

Dear Dave,

I understand "Range" (P1b), but may I know what is "STATE" for P1a?

SND,

Turn on the "Appendix P" option, then notice the "Allowable Stress" dialog in the input when the B31.3 Code is selected. This checkbox appears at the bottom (added in v.6.10).

Dear Richard

Thanks, we are also using Version 6.1,

I found the check box above the "Fatigue Curves" tab.


Regards
SND

Dear All,

I agree with SJ and SND. CAESAR-II only checks the load case type whether it is OPE or EXP, but not any RANGE type.

I checked and finally this is the conclusion

APP-P .. ON

OPE load case(irrespective of STRESS or RANGE Type)-- P(1A) eq is using.
EXP LOAD CASE --- P(1B) eq is using.


From My side, IF APP-P ON..

OPE STRESS TYPE-- P1(A) (CAESAR is also using P1(A))

OPE STRESS RANGE TYPE -- P1(B) [CAESAR is using using P1(A)]-- This is the main problem for the users I think.

EXP STRESS RANGE TYPE -- P1(B) (CAESAR is using using P1(B)

pls correct me , if iam wrong.

I agree with DAVE, :In accordance with B31.3 you either use (1a) [or (1b)] from the base Code, or, you use (P1a) and (P1b) from Appx. P. Mixing them [referencing (1a) & (P1a)] is not indicated by the Code."

SJ & SND, can u conform ??

Dear Durga,

I read carefully what DAVE said in his post, he is right.

I also checked with seniors.It is confirmed.

Regards
SND

Dear SND,
Even I agree with Dave, but ur doubt made me confusion regarding ope stress RANGE using p1a not p1b, what abt this? Can u pls clarify.

Dear SND, SJ

DAVE WORDS -- "If you are using Appx. P in CAESAR II, then any appropriate range calculation (with or without primary components) should be labeled (EXP) and any appropriate operating stress state should be labeled (OPE). Then CAESAR II will use (P1b) as the (EXP) limit and (P1a) for the (OPE) limit".
so from the above sentence ; L6 case is not possible.. any stress range should be labled as EXP OR OCC.

L4-(Ope) W+T+P+H
L5-(Sus) W+P+H
L6-(ope) L4-L5-----------ope stress range
L7-(Exp) L4-L5-----------exp stress range

Please correct me if iam wrong...

Dear Durga,

In my opinion, you are correct, also DAVE has mentioned in the same way. L6 (OPE) is not considering.

The confusing word for us in Code is about operating stress range, instead of that either to use as "Expansion Stress Range".

So, if use APPENDIX-P, do not club up with 1(a) & 1(b) with P1(a) & P1(b).

I do not have experience for the cold lines like negative temp.what APPENDIX-P is taking on that cases. Anyway for Hot temperature it is correct.

Add if any other ur thoughts.

Regards
SMD

That is what I conveyed.

Whenever you activate App P,then the "Exp" stress range is in fact "operating stress" range calculated as per P1b.

Rich/Dave

The reason I wanted the freedom to check Exp stresses as per eq 1a is I wanted to use App P for a project in order to avoid checking for lift-off cases as this is taken care of in App P operating stresses.

Since the client wanted us to check the Exp stresses without the "Liberal" stresses so I wished that was allowed in Caesar to check both the stress ranges Operating as well as Expansion.

Moreover, don't you feel the word "Exp" is a bit confusiong in case of App P as it is "Operating" stress range!!!

Your thoughts on this!!

Dear SJ,

We are also using the APPENDIX-P for the same purpose for not making separate file what we generally did previous time for Lift up check.

Your requirement is also correct,may be Rich can help this matter.

Regards
SND

Dear SJ, SND
May be not possible, as Dave said. because CAESAR follows code requirements, in later code versions if it is mentioned like what SJ said, then this option comes into picture.
Now the only option what we are doing is creating 2files.

Dear Richard sir,
Good morning.

From ur post: I don't believe that "when applicable" phrase should be there in the "help". If you check the checkbox, the 15% reduction is applied

These are the some common doubts of CAESAR-II users.. can you please clarify.

1.From CODE : 15% reduction is applied for Sy/S-tensile EXCEEDS 0.8. So user has to check that ratio, and he is the responsible for ON or OFF (tick OR not to tick) based on the ratio. Is this statement correct or not?

2.If my above statement is correct, then Why CAESAR is taking DEFAULT is ALWAYS ON. Based on that ratio WHY CAESAR is not taking automatically. Please correct me if iam wrong.

You are correct, that phrase "when applicable" will be removed from the next publication of the documentation.

1) Yes, the user is responsible for setting this checkbox.

2) The CAESAR II material database does not have St for most materials, therefore the program can't make this decision. Checking the box by default (as the "help text" states) is conservative. Not checking the box (without knowledge of the Sy/St ratio) would be non-conservative.

Thank you Richard.