Respected Engineers,

I need to pass a quartz tube (deigned like this https://ibb.co/WndSG9z) through a Flange (https://ibb.co/tHnZLp9) that is connected to a vacuum reactor. I designed the tube according the outer diameter of the Flange (https://ibb.co/tHnZLp9) but the tube cannot pass through because the inner diameter is smaller (https://ibb.co/k1Vygrb) and also it is used as a connector and not for passing tube through it.
I hope the honorable engineers can give some advice for this engineering problem. thank you
All type of advice will be highly appreciated