Question

A vertical vessel has an internal radius of 48”. The material's allowable stress is 12,000 psi. The MAWP of the vessel is 120 psig. The welds are “double welded” and the nameplate mentions spot radiography. The top of this shell section is 4„ from the top of the vessel, and the bottom of this shell section is 52‟ from the top of the vessel. Determine the required thickness.

Answer 1

Answer:-

Thickness expression ( t ) = PDi / 2fJ - P

Where Di is the internal diameter

P is the design pressure

f is the allowable stress value

J is the joint efficiency factor

P= 120 + 5% of 120

=1.05*120 psig

for the double welded spot radiography , value of J is 0.85

t = (1.05*120)*(2*48*0.0254 m ) / ( 2*12000*0.85 - 1.05*120)

t = 15.15 mm

As the value of corrosion allowance is not given it means the material is non ferrous and stainless steel .

so t' = t + C

where c is the corrosion allowance

C = 0

t' =15.15 mm

standard thickness (ts) would be 16 mm