I am building a panel press to glue 4? x 8? sheets of ½? plywood to a
core material. For proper bonding the glue requires a pressure of 7
PSI. To exert uniform pressure on the plywood I thought to make a 4? x
8? flat matrix (= pressure plate) out of several parallel running 8?
long rectangular structural steel tubes and weld four 4? long steel
tubes perpendicular on top of the 8? tubes.

I plan to attach a hydraulic assembly to four ?load transfer points?
located on the inner two of the 4? tubes with each point exerting a
pressure of 3,700 Kg for a total of 14,800 kg (7 PSI x 32 x 144). Each
one of the four points would be in the center of an imaginary line
running from the center of the 4x8 matrix to the four corners. This
way I hope to transfer the hydraulic pressure in a rather uniform way
to the 4? members, on to the 8? members and on to the plywood panel.

Instead of covering the surface of the matrix with a 4x8 sheet metal I
thought to rely on the structural properties of the plywood panel to
give me ultimately a rather uniform pressure of 7 PSI at the glue
line.

I plan to over dimension the load bearing 4? members so that a little
deflection could be ignored. I think this would make the dimensioning
of the 8? members easier.

I need the necessary formulas to assess the optimum dimensioning of
the structural steel tubing and an example calculation. In addition I
would certainly appreciate very much any good recommendation.

This is not a simple problem that beam formulas would solve. I would
like to take your $100 and solve some formulas that mean nothing, but
what would come closer is a finite element analysis. Maybe someone
will answer and prove me wrong. I don't understand why you don't want
to use a 4x8 piece of plate. Granted it will cost more, but you are
already spending quite a bit of money on this project and it is
certainly worth doing right. I would probably use a 4x8 sheet of 3/4
inch plate.

Thank you redhoos-ga for your quick response. I agree with you that a
plate is the easiest - and in fact on the other side of the press I
have already a plate. I need to go with tubing because on the plywood
panels are already some fixtures installed which stick out. Bummer! I
don't know how to solve "finite level analysis" problems nor do I have
the software for it. Never-the-less you lived up to your image on
Google-Answer for great knowledge, responsiveness and fairness. Thank
you!

You scared me there for a second, I thought you were going to say that
I was "fair and balanced".