Stress at bolt hole location 1

[amith014]

Hi all,

Am doing FE analysis of plate heat exchanger.

The FE results are showing high result at the bolt holes location, which is local stress, but that is still higher than the allowable stresss(1.5Sm).

Can I avoid the stress at that location.
If so what is the exact reason to avoid the stress at bolt hole locations.

Please help

 

[TGS4]

How is it that you have determined that the allowable stress is 1.5Sm? How re you interpreting the FE results? Division 2?

 

[amith014]

yes, using div 2

 

[TGS4]

Please answer my questions:

HOW have you determined that the allowable is 1.5Sm?

HOW are you interpreting the FE results?

You need to provide significant more details to get a useful answer.

 

[amith014]

According to ASME stress categories the local stress should be less than the 1.5*allowable stress.

The stress which is observed at bolt hole location is clearly local stress.

To interpret the stress at the bolt hole locations, i dont have any exact calculation right now.

if you suggest something regarding this, it will verymuch helpful for me.

thanks

 

[corus]

Surely the stress due to a local discontinuity (such as a hole) is classed as peak, and hence has no limits other than those imposed by fatigue damage with regard to the number of expected cycles. Nominal stresses around the hole (disregarding the peak stress component) would be limited to Sm, 1.5Sm, or whatever, depending on the classification.

corus

 

[TGS4]

As corus has stated, the classification of stresses around a hole are not straight-forward. However, I believe that you have fundamentally misunderstood the requirements of ASME Section VIII, Division 2.

What edition of Division 2 are you using? What FEA software? Do you know what it means to linearize stresses? Have you read (and understood) WRC-429? Please search the archives here for numerous discussions on stress linearization and stress classification.

In my opinion, you are in over your head, and need some mentorship by an engineer who has significant experience applying finite element analysis results to pressure vessels.