Load cases for stress range

Hi

I have ambient temp. 25 deg.
Line temp. 180 deg(T1).
Min. Temo. 10 deg(T2).


Are these load cases correct.
1. W+T1+P1 OPE
2. W+T2+P1 OPE
3. W+P1 SUS
4. L2-L1 EXP.--Stress range case

For completeness, I would also check:

5) L1-L3 EXP
6) L2-L3 EXP

Hi Nikhil,

How are you ?
L4 will give u max stress range in piping sysytem due max displacements, and try to add Richard specified load cases also for completeness.

All the Best!

Thanks& Regards,
Rakesh.

According to ASME B31.3, Can load case 2(minimum temp) be used for generating force and moment?

Best regards!

Hi Miangun,

Only native load cases give the real result for F, M, and D. Further You can search it using search facilities on above right with keyword native.

Nikhil,

The code specifies different allowables for different types of stresses eg load induced or displacement induced.

The minimum load cases required for your system involves the physical problem that your system describes.

Say for example, it is a piping system involving few heat exchanger outlets which are going to a vessel.

To properly formulate the load cases, you need to study the P&ID throughly and also talk to your process engineer to understand what is happening in the system ie the different temperature and pressure scenario that the system can see. This may include start up, multiple operation etc.You will also have to see for notes in P&ID and Line list if two phase flow ,high velocity flow ( >0.5 Mach for eg)or high sound power level is possible or not.Such discussions will tell you the no. of Ts and Ps involved.
Also for the number of operating scenario, you will need to discuss the no. of expected cycles.

Next, you will have to find out for significant differential movements between the structures supporting the pipes.

Requirements for Wind and seismic ( inertial and displacement induced) , which is something , your project Pipe stress document will tell , is also something that has to be studied.Seismic movements may involve in or out of phase movements between structures.

Only then will you know the necessary and sufficient no. of Load cases that are required.

Your system may have different ambient conditions at different parts of the year and hence, you may have to check for differnt ambient temperatures.

Hope this helps.

thanks, anindya stress

I have made a mistake in editing, The question is that
According to ASME B31.3, Can load case 2(minimum temp) be used for checking nozzle loads?

Best regards!