Question 16.6: Determine if the vessel described in Example 16.4 is adequat...
Determine if the vessel described in Example 16.4 is adequate to resist vortex shedding and ovalling vibration.
1) Determine the total dead load weight of the vessel:
Shell =\pi\left(31^{2}-30^{2}\right)(1200)(490 / 1728)=65,210 lb
Heads =\frac{4}{3} \pi\left(31^{3}-30^{3}\right)(490 / 1728)=3320 lb
Total weight =W=\overline{\overline{68,530 lb }}
2) Determine these properties:
w=\frac{W}{h}=\frac{68,530}{1200} =57.1 lb / in
E=30 \times 10^{6} psi
I=0.049\left(62^{4}-60^{4}\right)=89,000 \text { in. }T =0.0908 \sqrt{\frac{(57.1)(1200)^{4}}{\left(30 \times 10^{6}\right)(89,000)}} =0.6047
f_{ n }=\frac{1}{T}=\frac{1}{0.6047} =1.65 cps
\frac{H}{D}=\frac{(100)(12)}{(62)} =19.35
V_{ r } =40.33 ft / s
f_{ v }=\frac{0.2 V_{ r }}{D}=\frac{(0.2)(40.33)}{5.17} =1.56 cps
f_{ n }>f_{ v } : 1.65>1.56 (acceptable)
f_{ o }=\frac{683(1)}{(5.17)^{2}} =25.55 cps
f_{ o }>2 f_{ v } : 25.55>3.12 (acceptable)