ASME VIII Div.1 Annex 2 Bolting Cross-Sectional Area: “nominal stress area” ??

[Henzy1977]

ASME VIII Div.1 Annex 2 2-3 (Notation) specifies the following definition for Am1/Am2: “total cross‐sectional area of bolts at root of thread or section of least diameter under stress”.

I have a to verify a body-bonnet connection of a valve with Annex 2 and the connection is performed using Socket Head Cap Screws. Can I use the ISO value of the “nominal stress area” instead of the root of thread area?

Is it possible to say that for screws ( e.g. Hex Type ) the least diameter under stress can be the nominal stress area even if it’s value is bigger than the root area?

Thanks

 

[Christine74]

No, not as far as I'm aware. Appendix 2 calculations require you to use the root area of the bolt, not the effective tensile area.

If possible, you may want to consider using larger diameter or higher strength bolts. Another way to increase the root area is to specify fine thread (UNF) bolts.


-Christine

 

[MGZmechanical]

I think in ASME VIII and EN 13445 (pressure vessels) you must always use the root area of bolting.

Best regards