Dear Sir Jakub Good after noon Sir.
Sir I just want to share about the Mesh element applied Compound then Mesh the Element then apply loading using surface traction is not possible. See below snap shot:
However when applying BC, it is possible to select, see snap shot below:
It’s not just about compound parts. The Surface Traction load can’t be applied to edges. But you can use the Normal Shell Edge Load here instead.
Noted and Thank you Sir Jakub for your great advise 
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it seems normal shell edge loads can not be applied at condition of several faces with share common edge as in the example given. It has three faces and one edge shares due to intersection, model required to be separated by offset and connecting them with tie constraint or contact type tied.
probably, a feature such as Edge Traction is needed due to above limitation, so it can be simplified the task and become useful.
Dear Sir Jakub, Good day to you. Thank you for your great advice!
Just experimenting as an alternative, I also try to convert my uniform load (KN/m) to Pressure load (MPa) and able to implement pressure load on top of the flange. However I would like to inform Sir, that selecting just (one) element is not possible. I try to attempt all of the available selection command but selecting one element is not possible. Many Thanks Sir and appreciate any advice regarding this matter.
Best Regards and have a great day,
jess
Click the More button and select Element there. You will be able to pick individual elements this way.
