Pressure Vessels No handwriting please unless its very very

Pressure Vessels

(No handwriting please) unless it\'s very very clear

(Step by Step preferred)

As a Design Engineer you need to design a large vertical cylindrical pressure vessel to hold wastes from a manufacturing process. In your effort to make your bid more competitive you have to devise a way to reduce construction cost by placing a metal plate over the top of the pressure vessel rather than to weld on a circular top. To ensure that the top does not lift off the vessel when it is pressurised you need to add large weights on top of the metal sheet. The vessel is made of steel with the yield strength of Sy = 240 MPa. Assume a safety factor of 2, total corrosion allowance C = 3.0 mm and welded joint efficiency of 0.85. Take inner diameter as 3 m and internal pressure alter loading the waste = 2.0 MPa. Calculate the following; Wall thickness of the pressure vessel Suitable weight on the top of the lid neglecting lid weight Check whether thickness is sufficient or not

Solution

a)

Hoop stress = P*d/(2t)

P = 2 MPa

Taking safety factor of 2, we need to design for P = 2*2 = 4 MPa

240 = 4*3/(2*t)

Thickness t = 0.025 m = 25 mm

Taking 3 mm corrosion allowance, we get thickness t = 25+3 = 28 mm

b)

Force = Pressure*Area

= 4*(3.14/4*3^2)

= 28.26 MN

Considering joint efficiency of 0.85, weight needed = 28.26/0.85 = 33.247 MN

c)

Since we have taken factor of safety of 2 into account, thickness is sufficient.