i need help..i am new to this so bear with me. I have a square lid covering an opening in a pressure vessel (5 psi). The lid is made out of crs. There is a screw in the center of the 31"X17" plate, pushing plate down. How to determine plate thinkness needed and and force required to hold down lid? also the lid weighs alot so i need help to design torsion spring to assist in lifting lid (but i need an idea to push lid closed again)... sorry i dont do this type of design so i am lost.
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pressure lid forces (design) 4
- Thread starter angelique
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Angelique,
31in x 17in x 5lbf/in^2 = 2600lb.
This is the force you need to hold that lid down, and yo need a generous safety factor on top of that. This sounds like a job for someone who is experienced with pressure vessels, or at least someone working under the supervision of a pressure vessel expert.
This is a dangerous job to try on your own.
JHG
31in x 17in x 5lbf/in^2 = 2600lb.
This is the force you need to hold that lid down, and yo need a generous safety factor on top of that. This sounds like a job for someone who is experienced with pressure vessels, or at least someone working under the supervision of a pressure vessel expert.
This is a dangerous job to try on your own.
JHG
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Sound like a "Quick Opening Door" which requires special considerations. Check out:
Show these pictures to the non-engineer, if he needs a reason to hire somebody experienced with PV design.
Show these pictures to the non-engineer, if he needs a reason to hire somebody experienced with PV design.
Angelique,
I am not an engineer. I am an engineering technologist certified in Ontario, Canada. I think I can do the calculation, but if I get anything wrong, there will be several hundred pounds of steel hurtling through the air.
If it were me doing this design, I would not start the task until it was understood that a pressure vessel engineer with a PEng was going to check everything. I would want to chat with him ahead of time, just so I would know exactly what he wants to see.
I would forget about the screw pushing down in the middle. You need a gasket. A set of bolts around the outside is the optimal design. The bolts require careful engineering. If the thing absolutely has to open easily, I would work out some kind of latching mechanism. If the thing is latched rather than bolted, I would ponder what would happen if someone released the latches while the system was pressurized.
There is a neat book that has been recommended elsewhere on this website...
Why Buildings Fall Down
by Mario Salvadori (and someone else)
You can probably find this through Google.
There a nifty chapter on how someone installed a tank improperly, it exploded, rupturing a gas line directly overhead. A few minutes later, the gas exploded, causing extensive damage to the building, although, fortunately, no people killed.
I hope your co-worker is reasonable. Pressure vessels and office politics are a bad combination.
JHG
I am not an engineer. I am an engineering technologist certified in Ontario, Canada. I think I can do the calculation, but if I get anything wrong, there will be several hundred pounds of steel hurtling through the air.
If it were me doing this design, I would not start the task until it was understood that a pressure vessel engineer with a PEng was going to check everything. I would want to chat with him ahead of time, just so I would know exactly what he wants to see.
I would forget about the screw pushing down in the middle. You need a gasket. A set of bolts around the outside is the optimal design. The bolts require careful engineering. If the thing absolutely has to open easily, I would work out some kind of latching mechanism. If the thing is latched rather than bolted, I would ponder what would happen if someone released the latches while the system was pressurized.
There is a neat book that has been recommended elsewhere on this website...
Why Buildings Fall Down
by Mario Salvadori (and someone else)
You can probably find this through Google.
There a nifty chapter on how someone installed a tank improperly, it exploded, rupturing a gas line directly overhead. A few minutes later, the gas exploded, causing extensive damage to the building, although, fortunately, no people killed.
I hope your co-worker is reasonable. Pressure vessels and office politics are a bad combination.
JHG
I cannot agree more to what is stated about looking for help on the design.
Said that, I would add that it is possible to use your central point load model, and it is indeed used in pressurised vessels, the big difference is that I would make the door open to the side. This door will be very heavy, thus, most times this kind of doors are opened to the side to avoid lifting the weight. Some vertical vessels open them to the top, but they use an hydraulic jack to open the door. I dont think a spring will work.
About the design of the door itself, the design should include not only the plate, but also an arm, which will hold the weight and provide the central point load to the plate, and a thick frame, against which the door will close, and to which arm will be hinged on one side and fastened on the other, perhaps through a bolt. This frame will be welded to the vessel. The exact calculus for these pieces should be done by someone with experience with pressure vessels, and who can see the actual vessel.
Once the welding procedure is finished, you should fill the whole thing with water (to avoid a blast in case there is a failure), and pressurize it to 1.5 times the operating pressure, and see if nothing leaks. You MUST use a relief valve and a relief fuse setted at 1.1 times the operating pressure.
Another point to add. These kind of doors are used to load and unload steamers, very fast. However if you do need a manhole to inspect a vessel and will not be used often, a bolted design, that opens to the interior will be a better and safer approach.
sancat
Said that, I would add that it is possible to use your central point load model, and it is indeed used in pressurised vessels, the big difference is that I would make the door open to the side. This door will be very heavy, thus, most times this kind of doors are opened to the side to avoid lifting the weight. Some vertical vessels open them to the top, but they use an hydraulic jack to open the door. I dont think a spring will work.
About the design of the door itself, the design should include not only the plate, but also an arm, which will hold the weight and provide the central point load to the plate, and a thick frame, against which the door will close, and to which arm will be hinged on one side and fastened on the other, perhaps through a bolt. This frame will be welded to the vessel. The exact calculus for these pieces should be done by someone with experience with pressure vessels, and who can see the actual vessel.
Once the welding procedure is finished, you should fill the whole thing with water (to avoid a blast in case there is a failure), and pressurize it to 1.5 times the operating pressure, and see if nothing leaks. You MUST use a relief valve and a relief fuse setted at 1.1 times the operating pressure.
Another point to add. These kind of doors are used to load and unload steamers, very fast. However if you do need a manhole to inspect a vessel and will not be used often, a bolted design, that opens to the interior will be a better and safer approach.
sancat
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