Serviceability Criteria on ASME VIII div. 2 par. 5 1

[Anthony Aponte]

Good afternoon,

I am currently working on a FEA of a rectangular vessel. Idea is validate it by ASME VIII div.2 par 5 using elastic plastic approach. I allready done this activity so combination, safety rate to apply are clear.

No problem on convergence: that means vessel is ok considering stress point of view.

My concern are the Serviceability Criteria: which combination has to be considered here? Just an example of the problem: vessel has design pressure of 10 bar but I evaluated stress with 24 bar because safety rate required by ASME is 2.4.

Now, if need to check the deflection of the wall I have to check it with 24 bars or only with 10 bars? This time, with flat shell, difference is enormous so I need your opinion or the code point of view, if any.

Thanks for your help.

Best regard

 

[TGS4]

You check the serviceability criteria at the design loads.

 

[Anthony Aponte]

Hi TGS4,

with design conditions are you referring to the real design condition of the equipment ( 10 bar ) I think, right? So under deformation check no amplification factors ( 24 bars ) has to be considered.

Frankly speaking I agree with you but there is a part in the code that appears not so in line: they says to refer to table 5.5 and there amplification coefficients are indicated. The extract is attached.

Escuse me if I ask the question 2 times: you opinion coming from experience or I miss some paragraphs in code where is indicated to proceed like this?

Thanks for you answer and for you time.

Sincerely AA

 

[TGS4]

The paragraph that you are referring to in your image is 5.2.4.3(b). Yes, that refers to Table 5.5, but you will see that there is a line in there that is titled "Serviceability". This line points you to the UDS and then references you back to 5.2.4.3(b). The key note in sub-paragraph (b) is the term "design loads". These are the loads without a load factor. Or, if you would like to think of it this way - it's with β=1.0.

My opinion comes from the fact that I am a member of the ASME Code Committee responsible for Part 5, and I teach a technical training course on the topic of Part 5.

 

[Anthony Aponte]

Thanks for explanation TGS4, my doubts are closed. I seen you are from Becht Engineering: I read so much articles from you... Nice to meet you.