sm8 97

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PROBLEM (8.97) A cylindrical tank of inner diameter d and wall thickness t has butt welded
helical seam forming an angle
φ
with the longitudinal axis, as shown in Fig. P8.97. The allowable
normal stress in the weld equals w
σ
. Determine the largest internal pressure p that can be applied in the
tank, using Mohr’s circle.
Given: d = 2r = 1.6 ft, t = 8 mm,
φ
= 55o , w
σ
= 10 ksi
SOLUTION
55
2o
t
ta
pr
t
σ
σσθ ===
2
ta
p
r
t
σσ ==
τ
13
()
24
avg t a t
σ
σσ σ =+=
y’
11
()
24
ta
Rt
σ
σσ =−=
'cos70o
wx avg
R σσσ == −
31
cos70
44
tt
σσ =−
0.664 0.664
t
p
r
t
σ ==
Introducing the data:
3(1.6 12)
10(10 ) 0.664 0.008
p
×
=, 6.28
p
ksi
=
110o
x’
C
σavg
R
σ
σa
σ
O
t
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