Around the perimeter of the bend to set the flange into. It give me just a little space to bend over the flange, not much. Do I need to solder it to make it air tight. How do I solder the bend onto the flange without affecting the lead bend which is embedded several inches of concrete.

Hi Arunee...

No need to solder here... just peen the edge over and you should be all set.

What material is the flange made of? Let me know...

Mark