How to seal ducts and pipes, which penetrate the air tightness layer

We all know how important it is, to have a continuous air tightness layer installed. But did you know that every penetration through this layer creates a potential risk for lowering the air tightness performance?

I constantly come across with functional and also less-than-ideal solutions for sealing such penetrations. Bad examples can be found easy enough on the internet, that´s why I´m focused to show viable solutions for the air tight sealing around ducts and pipes.  

Option 1 - Sealing with standard air tight tape

Option 2 - Using of collar (if makeable)

Option 3 - special Flextape