Manufacture of a flange with a groove

We can manufacture a flange from 60 to 300 mm with a groove out of a glass tube made of BORO 3.3.
This has two advantages: firstly there is no welding between the tube and the flange. Secondly, these flanges can be manufactured out of all diameters of standard tubes, regardless of their wall thickness.
For example: DN100, made of a tube with a diameter of 120mm and a wall thickness of 9mm.
For the diameter DN300, which is not a standard dimension, the quick release clamp made of INOX can be delivered as well.