Load cases

Hi experts,

I am new to pipe stress analysis ( and piping too). I wonder why piping codes divide loads into many load cases instead of using 1 combination load (includes all GRTP, earthquake, wind, etc).

because my senior wants to know the general stresses (shear, hoop, longitudinal, total,...=> tension or compression to evaluate the dangerous points) from CAESAR II (he is familiar with ANSYS, SOLIDWORKS,...But doesn't know anything about this software too). So I have to explain him that this software calculates stresses according to codes and bases on the codes to asses the critical points.

But he would ask about why the codes divide loads like that, the purpose?

Please help me. I will be very appreciated. Thanks

In my opinion, taking into consideration the engineering background of your senior, an acceptable start is being familiar with ASME SECTION VIII, DIVISION 2, PART 5 DESIGN BY ANALYSIS REQUIREMENTS.

An up-to-date and practical reference book on piping engineering and stress analysis is Peng's book "Pipe Stress Engineering" 079180285X.
This book emphasizes the main concepts you are looking for.

Piping Codes to differ in primary, secundary stress and also sustained, operating, ocassional load cases.
For all load cases are different allowable stress limits.

Read this earlier post, which is a Sticky Topic near the top of the list.

Dear all,

Thanks for your kind help. I have read those threads and had some understanding. But I have one more question need to be clarified ^^

If my material(plastic) is not in software's library, and my customer cant provide it. All I have is Yield strength and Ultimate strength of that material (at room temperature). How can I get the allowable stress at room temperature.

Currently, I use 2/3 of Sy (according to 1 document on the internet). But in "pipe stress engineering - Peng", says the allowable is equal to Ultimate strength/safety factor, and the safety factor for B31.3 is 3 so I am being very confused.

I know you are busy but hope you can spend a little time to help

Thanks

You should read B31.3 code again, para 3.02.3