The ASME section viii division 1 provides two equations for calculating the thickness of the cylindrical shell for the thin walled pressure vessel. But before going to the ASME section 8 div. 1 equations and their application for our example, refer the input data and the pressure vessel sizing calculation example for better understanding this part of the tutorial.
Pressure Vessel Cylindrical Shell Thickness Calculation
Internal pressure for the pressure vessel, P=75 Pa = 0.000075 MPa (Refer Part-1)
Inside radius of the thin walled pressure vessel, Ri=1350 mm (Refer part-2)
Corrosion allowance, C=0.02 mm (Assumed)
So, the inside radius after adjusting the corrosion allowance, Ri1=Ri-C=1349.98 mm
Weld efficiency of the seams, E=85%=0.85 (Assumed)
Material for the pressure vessel shell=AISI 304 SS
Allowable stress for AISI 304SS, S = 103 MPa
Liquid to be stored inside the pressure vessel= Water
The required equations from ASME Sec. Eight Div.1 are,
- Minimum required thickness at the longitudinal seam welds,
- Minimum required thickness at the circular seam welds,
All the symbols are explained in the input section above.
And, the minimum required design thickness for the vessel shell will be tr=Maximum of (Eq.1, Eq.2)+C ………………………………………..Eq.3
By using the input data to the Eq.1, we get,
ta= 0.001156465 mm
By using the input data to the Eq.2, we get,
tb= 0.000578232 mm
Now, from the Eq.3, we get,
Minimum required design shell thickness, tr= 0.021156465 mm
For the pressure vessel design tutorial example, we have initially assumed the shell thickness, t = 6mm (refer Part-2)
And, as t>tb so our assumed shell thickness is safe for the application example.
That’s it for shell thickness, I will discuss the maximum allowable pressure calculation according to the ASME Section viii division i codes.
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