Hi,

I notice in Codecalc WRC107 they have now included a 'stress summations' box in which the software shows resultant vessel stress and a 'passed' or 'failed' result. This is great as in a glance the engineer can see whether the vessel stress is acceptable, or can they?

I have 2 questions as follows:
1. I do not think these results (stress summations) include for secondary membrane and bending stresses which are also shown in the results as per previous Codecalc releases. From my understanding these membrane and bending stresses are limited to 1.5S (ASME VIII Div.2) and I have seen many results where Codecalc shows the vessel stress to be acceptable but these stresses seem too high.
I appreciate how the loads are produced is a factor and so for this question I assume that loads are both thermally and mechanically produced.

2. Where does it show the membrane pressure stress results? I am sure this used to be shown in previous versions of Codecalc? And is this pressure stress included in the resultant stress?

Please review and let me know some thoughts.
Thanks

Hello Alan,

1. The stress summation does include the secondary stresses. If you have thermal expansion piping loads acting on the nozzle the resulting stresses will be categorized as secondary stresses.

2. The pressure stress is listed as "Circ. Pm" and "Long. Pm". They are listed as the primary membrane stresses.

Refer to the attached screen shot,

Hi Mandeep,

Thanks for your reply and apologies for taking so long to respond.

The results you attached are shown if the inputs are entered as sustained loads. However these results are not shown if the loads are entered as expansion loads. Hence it is now up to the user to interpret the results.

You indicate that the 'stress summation' includes secondary stress results, what about the secondary stresses themselves and their limits? Could you please show me an example of these?

Thanks for your help
Regards
Alan

Alan,

If you just have secondary loads and no sustained loads then the program does not perform the stress summation. In that case put a small number for any sustained force/moment. Typically, you would have sustained loads.

In the attached screen shot, the Long Q (Exp) are the stresses resulting from secondary loads in this case thermal expansion loads.