Help, Auto welding open shapes

Hi,
is there a way to auto weld vertices based on distance in open shapes like this?


It’s a single object with open areas, vertices needed to weld are really close to each other in compare to others.
Remove doubles is not working in this case.

Remove doubles is not working in this case.
Why does it not work ? Have you adjusted the merge distance

Oh, turns out I was increasing it in the wrong place( i thought it was “double threshhold” ), now it works. Thanks anyway.