Order of internal pressure resistance to expect from laboratory glassware? I have a need to use more pressure differential than can be afforded by vacuum vs atmospheric pressure alone, and so I've come to consider using pressurised laboratory glassware for part of my setup.

I've made a little bit of research here on stack-exchange and on google and the general information I've gathered is that the physical shape of laboratory glassware and reaction vessel lends better to resisting external pressure (when we use them with internal vacuum), than to resisting internal pressure, though I'm left wondering what to expect to be doable in terms of pressurising glassware.

I have two pieces of glassware I'm considering using on the pressurised end of my setup: One is a 5,000mL flat bottom flask and the other is a 20,000mL flat bottom flask. Both are borosilicate glass, neither are perfect (they both have one or two tiny air bubbles in the glass at places) but both have shown very good resistance while being used with internal vacuum.

Is it realistic to expect them to be fine while adding an internal pressure up to 3 Bars? (I would put the glassware inside of a big metal cylinder for safety in case of "explosion")

What will be the best Resistance vs Glassware Shape / Glassware Volume / Temperature / etc. ?

Does anyone have any tips on the topic?
Put the flask in a metal container, with a large (at least three times the volume of the flask, for 3 atm pressure) bladder or sylphon (metal bellows) in the supply to the inner flask. Pressurize the outer metal container with air or inert gas.

The absolute pressure in the reaction vessel should be the same as the outer vessel (unless the reactants outgas rapidly), but there would be no differential pressure difference, ergo, no additional stress on the glass. 

Or just conduct the whole experiment in a hyperbaric chamber... not a wimpy 0.1 atm plastic bubble, but something like this 10 atm unit, with margin for error. ;-)