GIRTH FLANGE DESIGN (ASEM VIII DIV.1 APP.2 FIG.2-4 (5) 1

[bgchae]

I am gonint to design the girth flange design in case that g0 and g1 is equal.
I think that designed girth flange type is corresponding to FIG.2-4 (5) of ASME SEC.VIII DIV.1 App.2 when
g0 and g1 is equal and this girth flange neck will be connected to vessel wall by butt welding.

At this case, I like to know how long hub length shall be extended for FIG.2-4 (5) type of girth flange
because the hub length is extended to at least 1.5 go in general as per FIG.2-4 (6) of ASME SEC. VIII DIV.1.

My opinion is that there is no restriction for hub length of FIG. 2-4 (5) of ASME SEC.VIII DIV.1 except the radius "r" dimension
to be at least 0.25g1 but not less than 5 mm.
Therefore I am going to extend 100 mm the hub length of this girth flange and connect this girth flange with vessel wall by butt welding.
Please advise that this design is no problem with App.2 of ASME SEC VIII DIV.1.

 

[SnTMan]

bgchae, I am not sure the 1.5*g0 applies when g1 = g0, however I feel confident it is permitted. You don't mention other dimensions, but I assume for your case 100 mm = 1.5*g0, or g0 = 67 mm. However if g0 is much less than this an unecessarily long hub will run up the cost of your flange with no benefit. Have you run the flange with shorter hubs to see the effects?

Regards,

Mike

 

[bgchae]

Thanks SnTMAn.
My intention is to use shorter hub length than 1.5*g0 because the g0 and g1 is 132 mm and hub length is 100 mm to save the cost without any deviation of ASME Code.
The flange calculation is no problem as per App.2 of ASME Sec VIII. Div.1 but our concern is the dimension requirement of ASME Code.