Pressure Vessel - Selection of Material and Manufacturing Process
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Transcript of Pressure Vessel - Selection of Material and Manufacturing Process
Selection of material and process.
07010042 R.Jyoti Swaroop07010044 Prudhvi Teja07010045 Pramod J
pR
tt
= pR/t
2a
Design requirementsFunction: contain pressure, pObjective: maximum safetyConstraints: (a) Must yield before break
(b) Must leak before break (c) t small: Reduces mass and cost (d) Shape : Cylindrical (e) Inner Radius and Height of cylinder is
constantFree Variables : Material
M1 = KIc/ys
ys
pRt
M2 = (KIc)2/ys
M3 = ys
Yield-before-break
Condition for Thickness
Leak-before-break
Thin wall, strong
the stress required to active crack propagation
c
Ic
aY
K
Leak-before-fail criterion (leaks can be detected over lifetime)
KIc
Y t
Pressure vessel for HOT ISOSTATIC PRESSING
Material and shape constraintsPressure - 100 MPaYield strength > 100 MPaInner Radius = 0.5 mHeight of Cylinder = 1 m
The leak-before-break criteria Minimum Thickness and strong
M2 = (KIc)2/ysM3 = ys
Yield-before-break (Less preference)M1 = KIc/ys
From charts Steels would be best option and ys = 500 MPa
Calculation of parametersTaking safe factor = 2
Surface area, A = 2πRoh = 3.8 m2
Volume = π (Ro2-Ri
2)h = 0.8 m3
Slender thickness = t/√A = 0.1Weight = ρV = 6400 kg
Ro = Ri + t = 0.7m
Design Constraints for manufacturing processConstraint Value
Material Steel
Sectional thickness, t 200 mm
Density, ρ 8000 kg/m3
Melting Temperature, Tm 1600 K
Surface area, A 3.8 m2
Volume 0.8 m3
Weight 6400 kg
Slender thickness (=t/√A) 0.108
Mean precision ± 1.0 mm
Batch Size, N 10
Shortlisted process
What about the mass constraint???
Processes and commentsProcess Comments
Machining Machine from solid (rolled or forged) billet.Much material discarded, but a reliable product. Hence, not economical.
Hot working Steel forged to thick-walled tube, and finished by machining end faces, ports, etc. Preferred route for economy of material use.
Casting Cast cylindrical tube, finished by machining end-faces and ports. Casting – defects a major problem.
Fabrication Weld previously-shaped plates. Not suitable for HIP. (Useful for larger vessels like nuclear pressure vessels).