nozzle local stress analysis by Annex G of PD5500 in PvElite

[mohamad3010]

hi every one. i am working on designing of a PD5500 - 2012 pressure vessel by PvElite 2014-sp2 software. after opening Nozzle input/Analysis menu, i select in calculation method bar, PD:5500 item. now my question is:
if the nozzles on vessel doesn't have reinforcing pads (integrated type):
i. should i consider membrane stress intensity factor alone for nozzle (1.2 f) or i must check only membrane+bending stresses (2.25 f) for nozzle local stress analysis by PD5500?
should i check the Print membrane stress at nozzle Edge box for analysis of nozzle by Annex G of PD or not?
Link
thanks in advance for your help.

 

[mechanical2014]

Should i consider membrane stress intensity factor alone for nozzle (1.2 f): YES.
or i must check only membrane+bending stresses (2.25 f) for nozzle local stress analysis by PD5500 : YES
Should i check the Print membrane stress at nozzle Edge box for analysis of nozzle by Annex G of PD or not : YES

 

[mohamad3010]

hi mechanical2014. many thanks for answer.

A.3.3.2 paragraph in PD 5500 - 2012 says:
A.3.3.2 Nozzles and openings subject to pressure and externally applied loads
For these limits to apply the nozzle or opening has to be reinforced in
accordance with 3.5.4.
The maximum stress intensity adjacent to the nozzle or opening due to internal
pressure shall be obtained from G.2.5 in the case of spherical shells, or from
G.2.3.6 for cylindrical shells.
Under the design combined load the stress intensity due to the sum of
membrane and bending stresses shall not exceed 2.25f.

our consultant based on above paragraph and example W.3.2.3 of pd 5500, interprets that there is no need for considering membrane stress intensity (1.2f) separately. so based on your answer, his interpretation is incorrect. i am right?
thanks in advance for your help.

 

[mechanical2014]

Yes, your consultant is correct. But i saw the values of allowable vs actual membrane stress in your attachment (That too with factor 1 only)and this caught my attention. Code is using word "as appropriate" and i think it fits the bill.

 

[MrPDes]

The reason why you don't need to calculate the membrane stress at the edge of the nozzle is because there is no way of calculating the membrane stress due to pressure loading (PD 5500 only provides a method of calculating the stress at the tip of the crotch corner). Therefore for some reason PD 5500 allows you to skip this membrane stress assessment.

I think that if you did voluntarily wish to calculate the local membrane stress (1.2f) then the local membrane pressure stress could be calulated using the method in ASME VIII-1 Appendix 1-10.

Of course to remain compliant with PD5500 you would still need to use the crotch corner stress and allowable stress of 2.25f for the membrane+bending assessment.

 

[mohamad3010]

thanks a lot MrPDes for these valuable information.