Bolting per VIII Div. 3

[FC2008]

Hi,

KD-621 in VIII Div.3 states that:

- The average primary stress intensity based on the root diameter should not exceed:
1/1,8 * S_y.

- The primary-plus-secondary membrane stress intensity:
0,75 * S_y

- The primary-plus-secondary membrane plus bending stress intensity:
S_y

Say that I am looking at the bolts on a flange.
The axial force due to pressure is the only force acting on the cross-section of the bolts.

Am I then right in saying that the average primary stress intensity is this force divided by the area of the root diameter?

Is there a secondary membrane stress in this problem?

thanks

 

[tetraz]

If you are sure that you don't have anything on the bolted connection except pressure, then you are right (for a flange, for example, you may have local loads, flange deformation due to thermal effects or gasket relaxation, etc.).
The secondary stresses, as far as I know, are due (mainly...) to thermal effects.

Hope this helps and this is correct.

Regards,
Andrea