Well, here is an example of a crochet flange in the true sense of flange, i.e., making your product stronger, as you say, not just an added edging:

Are you familiar with the TSC (turning single crochet)? Until I began working on a shawl a few months ago, I had not even heard of such a thing, though a lot of you here probably have. My patterns is made up of DCs. However, a TSC is used to replace a DC (turning chain 3) at the beginning of a row. It is more stable than a CH 3 and looks more like a DC at the beginning of the row.

Here is how it is done:

SC in the first stitch.
Then insert your hook under the vertical bar and work a second SC on top of the first SC to bring it to DC height.

This is a wonderful technique. I'll never use a CH 3 for turning again unless there is some necessity to do so.