Re: flat hatch

["Gary R. Boucher" <protek@shreve.net>]

A tank head is the curved end of a tank.  A propane tank is welded from a
rolled piece of steel that has two tank heads one at each end.  Tank heads
are made by certain companies that have the expertise to heat steel and use
a rolling device to obtain the desired shape.  You can order them from
certain materials (steels) and in certain geometries like hemispherical,
elliptical, semi elliptical etc.  A flat plate having 62+ thousand pounds
of total force on it is not wise and would have to be very thick.  A curved
hatch, if curved in the correct manner, will support way more total
pressure with a fraction of the weight.  I have seen several people on here
that have large flat plate sections to submersibles.  It takes a good
structural engineer to tell you exactly how thick it would have to be but
all of these approaches are counter productive.  Flat plates have bending
torques.  I got my tank heads from Baker Tankhead in the Dallas/Ft. Worth
area.  I assume they are still in business.

Gary Boucher