Question 10.5: A vessel has the following design data: design pressure P =2...
A vessel has the following design data: design pressure P =2500 psi; design temperature=250 °F; a spiral-wound metal, fiber-filled stainless-steel gasket with inside diameter 13.75 in. and width N =1.0 in. The gasket factors are m =3.0 and y=10,000. Bolts are SA-325 Grade 1 with S_{a} =S_{b} =19,200 psi. Is the gasket sufficiently wide to keep from crushing out?
Determine the effective gasket seating width as follows:
N =1.0 in., b_{0} = N/2=0.5 in., b = 0.5 \sqrt{b_{0}} = 0.3535in., effective gasket diameter
G = 13.75 + (2 × 1)−(2 × 0.3535)
G = 15.043in.
The gasket loadings are as follows:
H=0.785 G^{2} P=0.785(15.043)^{2}(2500)= 444,100
H_{ p } = 2bπGmP = 2(0.3535)π(15.043)(3)(2500)
= 250,600
W_{ m 1}=H+H_{ p } = 444,100 + 250,600 = 694,700
W_{ m 2} = πbGy = π(0.3535)(15.043)(10,000)
= 167,100.
Since S_{ a }=S_{ b } =19,200 psi, W_{ m 1} sets the bolting area A_{ m } as
A_{ m }=\frac{694,700}{19,200}=36.182 \text { in. }^{2}A_{b} =actual bolt area=36.8 in.^{2} for sixteen 2-in. diameter bolts. The minimum gasket width is
N_{\min }=\frac{36.8(19,200)}{2(10,000) \pi(15.043)}= 0.748in. versus 1in.actual.
A 1 in. wide gasket is sufficient to prevent crushing.