In the calculation report the allowable stresses in Case 1(OPE) W+T1+P1, are 0. Why? For other cases it is okay. The pipe material is A106B. Its density is 0.00783 kg/cu cm. Inside the pipes flows flue gas. density of the flue gas is small.
I have clicked two times on box called allovable stresses. On the left side of the input sheet, there are Code 31.3, SC 137.892.... Box called Eff is emty, so are the boxes F1 to F9

Additional information. The pressure is 10bar and temp is 15 C.

Because you have not read or do not understand the code you are working to. You do not understand by default there is no required code operating case stresses.

There is an optional method shown in the 2004 book but it is not a required code case.

Buy a copy of B31.3 2004 and read it...

B31.3 2004 requires the following loads to be evaluated... displacements, sustained loads, and occasional loads (combined with sustained loads). Note there is no required analysis for operating loads which are combinations of perhaps all 3 of the above load types. I repeat “There is an optional method for calculating operating loads/stresses shown in the 2004 book but it is not a required code case.”

V5.0 of CAESAR II may have the optional calculation of operating stresses available but again this is not required by the code it is merely an acceptable alternative.

eek.

eek 10^6

B31.3 uses stress to evaluate two distinct and separate modes of failure - collapse and fatigue. Operating stress does not measure either of these.

Almost everybody asks this question at one time or another.

Yes I got smarter by reading manulas. They are huge! I understand that I need only SUS W+P
But I have a simular system, pressure is 20 bars. In SUS there is only W, P is missing? Why? As I understand W is weigth and P pressure.

Sounds like someone was messing with your load cases. Try the [Recommend] button and see what the resulting load cases are.

eek 10^12

I notice from your profile you are a student.
So i think it is best if you declare if possible if you are,
a)learning on a college course (Caesar??)
b)Working on a live project.

The responces of this forum will be vastly different depending on your situation.

This is because Engineers(Ahem) have a moral duty to be 'competant' and using Caesar like a magic wand is every Stress analist's worst nightmare. The incorrect application of pipe stress analysis on a live project can lead to devistating concequences.
However, Trying to learn the mystic art of pipe stress analysis by any means possible is a good thing! you will find very few yes/no answers on this forum.

My suggestion is if you are a college student working on ghost projects for an assignment then the people of Coade are totally dedicated to the correct application of Caesar and will help you were possible.

If you are working on a live project, then put your pen down, and ask an experianced engineer/Consultancy for help and guidance.

I have been involved in Caesar Calculations/Stress analysis for nearly 5 years and i am only just feeling comfortable in perfoming stress analysis 'Solo' on normal piping systems.

Also use the search facillity (Coade should put that button in a flashing box !!!)most of the questions i have wanted to ask have been posted previously.

eek 10^24

Hello VVV,

Learning basic structural design and analysis of piping systems is not easy. This is a specialized area of engineering that is not taught in undergraduate school. You can help yourself by reading and asking questions. While you are learning, your work should be reviewed by a mentor.

Reading the Codes may not tell you everthing that you need to know - BUT you do need to read the Codes and become VERY familiar with them. There are two current books that you should seek, read and become one with:

Process Piping: The Complete Guide to ASME B31.3. Second Edition. Charles Becht IV. ASME Press
http://members.asme.org/catalog/
http://www.asme.org/pubs/asmepress/

The Fourth edition of the CASTI Guidebook to ASME B31.3 - Process Piping will cover the new 2004 ASME B31.3 code book that was recently released in June 2005. The authors are Glynn Woods and Roy Baguley.

http://www.casti.ca/books_ebooks/B31_3.html

Be a good student.

Regards, John.