[Nezil]

Mine were also screwed in, and were hex head screws with a rubber o-ring attached. I too was concerned about leaks, so I wrapped the threads with a lot of thread sealant tape (for plumbing) and that seemed to work. In the latter time of using the charge pipe I had WMI so I was using the bungs for their intended purpose.

I have a feeling that the screws shipped with the unit aren't tapered thread, which is why they never tighten properly. Whoever buys the FTP pipe that I'm selling will get both the stock FTP screws and some proper tapered plugs as well. If I were installing again today, I'd buy some tapered plugs and install them. I'll post a link to plugs when I find them; they shouldn't be expensive.