Possible british naval item?

[Depotman]

I've got absolutely no idea what this is! It's made of brass and "15" is the only mark on it. It's 45mm dia. Depotman

 

[Depotman]

'Bumping' this one - no ideas anyone?!! Depotman

 

[kiwieod]

I don't think its any kind of storage container as once its done up theres no room for anything in it.possibly the top part with 15 on it is some sort of guage and the other part is to protect it
maybe its an apprentice machinist piece to show his skills,or maybe somebody just made it for fun

 

[reccetrooper]

Maybe a plug and a cap from piping or machinery that just happen to share the same thread size and have been stored together.

 

[Depotman]

Thanks for your thoughts - I actually have two of these, both identical and the screw-in plugs are both cast and then machined. Regards, Depotman