Yet another Pressure Vessel with Polymers Design question

[b10m3ch]

Hello all,

I am in the preliminary phases of designing a bioreactor capable of withstanding pressurization up to 25 MPa ( i would like 50 but given some of my other design requirements i wont press my luck). I would like a safety factor of 3 so basically I am designing something to tolerate 75 MPa internal pressure. I know steel would be an obvious choice for this application but I would like to use a clear material high strength polymer if possible for movie recordings of that action within the vessel. The vessel will be exposed to pressure cycling (~10 hz max) and ambient temperatures of 37C, which are added points of complexity.

On the bright side the vessel will be a small cylinder (working volume ~ 5cm tall & 5 cm diameter).

I want to know if there are any new materials that are translucent but have structual properties to not just explode under these conditions. I am going to verify with FEA of course and do test pressurization prior to use but I would like to set myself up for success by getting my starting material right.

Thanks in advance.

 

[TGS4]

What do you mean by safety factor? Against what failure mode do you mean? Are you required, by statute, to follow any specific Code or Standard? Those pressures are getting you into ASME Section VIII, Division 3.

 

[b10m3ch]

This would be safety factor for failure. This would be a piece of research equipment, I would want to adhere to any given standard out of concerns for safety of myself and future users, though I am not required to follow any guideline.

 

[TGS4]

What kind of failure? Burst? Fatigue? Buckling? Creep? Other failure mode?

You are not required to follow any guideline, eh? Have you confirmed that with your local pressure equipment jurisdiction? Where in the world are you located?

 

[b10m3ch]

Sorry for not being specific. I would be most concerned with burst and creep failure. I am in the USA. Other science labs have designed similar pieces of equipment, made of steel. I want to switch materials and make a few other modifications. I would like this piece of equipment to be usable for years to come by others. I am on this forum to try and follow the appropriate standards and design a robust piece of equipment.

 

[btrueblood]

"The vessel will be exposed to pressure cycling (~10 hz max)"

10 Hz, at a full 3600 psi to 0 psi? How? I'd expect most of your bio mash to be expelled on the 2nd or 3rd cycle, due to foaming from dissolved gases.

No polymer I can think of will be translucent/clear at the thickness required, so start thinking glass instead. And with glass, it's not if the container will eventually fail, but when, so design a containment structure for your experiment (think bunker) where you can safely and remotely operate it until it breaks, then clean up the mess and replace the broken parts and go again.

 

[b10m3ch]

The cycling would probably be from 1000 psi to 0 at 1-5 hz. The larger pressures would be to simulate trauma. You have a point about pushing gas into the liquid media present. I will have to actually ensure the vessel is flooded. It sounds like I will be just making this out of steel. Anyone here familiar with Torlon® PAI. Cycling would be achieved having solenoid valve on the outlet and a piston.