This is a very typical aviation application. Call http://www.skybolt.com/
and they can get you the part you need. Basically it is a machine thread
nutplate that you would rivit/pop rivit from the outside. You can use
countersunk pop rivits so that you have a flush finish for the gasket to
seal to.
Good luck
Bruce
"Rod McInnis" wrote in message
...


If you expect to use this access hole more than once, why not install a
deck
plate? You cut a 4" hole, install the deck plate collar using flat head
screws with nuts on the inside (you have a 4" hole to reach through to put
the nuts on). The deck plate then screws into the collar and seals with
an
O ring.

Only hard part is getting a 4" hole in stainless......


Rod