4 in NPT S/S or Bronze hex socket pipe plug

[picocg]

Looking for a line on a 1 1/2 inch and 4 inch NPT stainless or bronze hexagon socket pipe plugs. Largest I could find are 1 inch steel.

 

[rconner]

I am just curious why must socket be "hexagon"?

 

[picocg]

rconner

To make the plug difficult to remove without the proper tool when attempted by intruders from a local high arctic community. The plug must be flush with the steel deck of a barge hence the socket. I'm open to a different socket config.