Rectangular header box

[Kenneth Larsen]

Hi,
I am looking into a t.min calculation of an air cooled header box from ’64. It is a bended frame with welded side plates and a bolted cover plate. But I have a hard time figuring out how to handle it, been back and forth between Appendix 13 and UG-34.
I concluded that the sketches in Figure 13-2(a) is comparable to my left view, and therefor Appendix 13 is only for welded frames (plugsheet + tubesheet + top/bottom plate) and then side plate calculated as UG-34. Therefor I miss the option with a detachable cover plate in App-13.
How would you calculate an open frame header box with cover plate? (bended or welded corners).

 

[CuMo]

UG-34 equations (3) & (4) can help you determine the thickness of each rectangular plate individually.

You can also look into API 661 - Petroleum, Petrochemical, and Natural Gas Industries—Air-cooled Heat Exchangers

Also EN 13445-3
15 Pressure vessels of rectangular section

I think what might help you the most is:

PD 5500 Enquiry Case 133 - Flat unstayed ends of non-circular shape and associated flanges

Probably try to simplify the design to individual components rather than trying as a whole vessel.

Add some conservatism to the design - you can't go wrong.

 

[HTURKAK]

The length to width (42/12)>> 2 so , this could be modelled with portal frame having unit width . Thare are tables at structural handbooks . You may also look ROARK'S handbook . The with of flanges 2,5 in . so will not provide substantial fixity . The assumption of a portal frame 10,5 H/ 12in L with pin connection at supports would be OK and conservative enough.

- I would calculate with moment coefficients ( i attached an extract from the book Kleinlogel Rahmenformeln ) or Roarks formulas )

- Or better to model with FEM .

Appendix 13 is for rectangular headers etc. ( closed frames ).. and may mislead ..