PubKeg Tapping Issues

[globe]

I got a really great deal on a keg of mead from a local meadery. I have a corny system so I bought a Sanke tapper and corny adapter pieces. That all went together fine. This is a plastic keg and the coupler is plastic is as well. When screw in the tap and lock it down the tap slowly unscrews and pops off. Right now i have some card board and boxes wedging it in so it will not unscrew. Am I doing something wrong or is the plastic just too slick to grip onto the tap? Has anyone ever seen this? This is my first experience with sanke, and I am just assuming a metal keg would be fine, but lots of places use these pub kegs so they must be ok.

 

[barnaclebob]

Sanke taps look like they are only tapered for part of the rotation and it shoudl eventually sit on a flat part. Are you sure you are twisting the the tap all the way before trying to lock it down? You should be twisting all the way to some stops.