Introduction to Pressure Vessel Safety Awareness Tutorial
Safety  Accidents  Investigations  Inspections  Training  Instructions
Pressure Vessel Force and PressureWhat is force? Force can be described in pounds or tons. We intuitively think of force in weight which is a fair description. Is there a difference between 10psi and 1000psi? Yes, there is a 100times difference in pounds. This becomes very important when a pressure vessel contains steam, air, volatile gases, compressible gas/fluid, or substances that have internal energy such that when exposed to the atmosphere the substance expands violently. Steam is a good example where there is an expansion process of 1604times [saturated steam]. Question: Imagine a vessel with a 1foot diameter cover that is fastened to a pressure vessel and there is 10psi pushing outward against the cover. How much force is being applied to the cover? A) 10psi B) 10,000pounds C) 1,131pounds D) 101pounds Answer C) 1130pounds. That is over 1/2ton of force with only 10psi. The point here is 10psi can be as deadly as 1000psi. Finally, we can never under estimate the care needed in keeping pressure vessels in top condition. Force = 10psi x p r ^{2 }[don’t forget to convert ] Lets try another question. A tank is 50foot tall with atmospheric [exposed to the outside air] pressure at the top and it contains water. How much pressure [psi] is at the bottom of the tank? A.) 0psi B.) 22psi C.) 25psi D.) 53psi Answer B) 22psi. Gradually, as we come down the tank wall the pressure increases; therefore, the thickness of the tank wall would have to increase in order to retain the water. p = g x 50feet [don’t forget to convert & g = 62.4 lbs../ft^{3} ]
