Propane Tank Holder - Almost a disaster

Two years back we had a typical portable-grill propane tank leak after we disconnected the line from it. I made repeated attempts at re-sealing it via pushing the pin in and spring back, but it continued to leak. I ended up holding in the pin until all gas had escaped, then tossed it. The leak was very slow, enough to be smelled, and even heard if placed next to your ear. Had we stored the tank as we usually do, it would have built gasses in our outdoor storage compartment, then who knows what would have happened.

I wished there was a tight-seal screw-on metal cap available for those tanks for storage, after you started using them.