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# thin walled cylinder

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An all welded vertical cylindrical tank 24m in diameter by 15m high is
designed for storage of molasses(SG=1.5).Determine the minimum thickness of
the shell plate if the allowable stress of the plate is 140MPa and the welding
efficiency was 80%. Allow 1.6m free board for air space in the tank. Round off

Mar 28, 2022

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It has been a while since I did these kind of calculations, but here is my stab at it :

140 MPa  = 140 x 106  N/m2

15 m - 1.6 m free board  = 13.4 m high

Volume of the cylinder of molasses = pi r2 h  = pi (12)2  * 13.4  = 1929.6 pi  m3

mass of this volume        1929.6 pi m3  ( 1.5)(1000 kg/m3)   = 2 894 400 pi kg

Find stress using    Fs = ma     using mass above   =  28 394 064 pi  N

Now find the thickness ( if 100% weld efficiency)

F = stress * area             where stress is  28 394 064 pi N     area = pi d t = pi 24 t  =  75.39822 t

140 x 10^6 N/m2  =  28 394 064 pi  N  * 75.398223 t  m2

solve for t = .0208155 m

Now factor in the 80% efficiency of the welds     .0208155 m / .8 = .02601 m   =   ~~ 3 cm     ( I think !    ~ EP  )

Mar 28, 2022