ASME DIv. 1 vs Div. 2 Flange Stress Factor?

[Mechanimal]

Hi I have an excel program to do Appendix 2 flange calculations. I have read that Div. 2 2010 includes external loading into its calculations and I would like to integrate that into my spreadsheet. Most equations are the same but I have noticed that V = flange stress factor / factor / hub factor for integral type flanges is different from Div. 1 and Div. 2. I appears that the Div. 2 committee has just run a curve fit to try to simplify the Div. 1 calculations for V, can someone confirm this? Also Div. 2 limits V for h/ho values of 0.1 to 2 which is not in Div. 1 does this matter?

 

[vpl]

ASME Section VIII Division 1 and Division 2 are two different Code divisions with different assumptions and requirements. You either design by Division 1 or do the detailed analysis by Division 2. You don't combine them.

This thread explains some of the basic philosophy differences: thread794-63572

also thread794-281698

Patricia Lougheed

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[Mechanimal]

True but in this case they both use the taylor forge method for calculating flange dimensions.

 

[Mechanimal]

Anyone?

 

[PVPguy]

Yes, I can confirm that as part of the effort to remove graphical approaches from the code and make it more computer program friendly, they curve fit the old equations with new ones. The accuracy of the new equations is within about 3% across to full range of the variables, so if you compare calcs using both the old and new approaches, then you will get some small differences. But in the big scheme of things, about the same. Although other parts of Div1 and Div2 flange analysis are now different, the calculation of the flange factors is still "identical", while taking a different form. The new equations offer no improvement over the old ones (other than being more succinct).

 

[PVPguy]

Oh yes, and the h/ho limits are just the limits over which the curve fit is accurate.

 

[Mechanimal]

Thanks,

I did compare the two but noticed outside the h/ho range there was a large difference between the Div. 1 and 2 equations. Within the range they are fairly close as you have noted.