How can I calculate an assymetric box header.
(Air cooler return header)
Which is the correct method acc. ASME VIII. Div 1. App. 13., A ???.
+----+
I.......I
I.......I
I.......I
+-...-+ plate with holes
I.......I
+----+

Any answer???

Dear Gabor,

ASME App. 13 can be applied to rectangular (or oval) header boxes with or without holes.

You also mentioned that it is an asymmetric box header, is the cross-sectional area changing along length? The App. 13 in ASME only addresses non-circular vessels with uniform cross-sectional area.