Part 5 - The Basics of Shell and Tube Heat Exchanger

Calculating Shell minimum thickness - ASME VIII Div 1, UG-27

Author

Syed Mohd Idrus
October 07, 2023

Calculating shell minimum thickness, tmin

Reference: ASME VIII Div 1, UG-27

tmin = Pds (rs) / (SE - 0.6Pds)

tmin = minimum thickness (mm)

Pds = Shellside Design Pressure (MPa)

rs = Shell Internal Radius (mm)

C = Internal Corrossion Allowance (mm)

S = Allowable Stress (MPa) - refer ASME section II, part D, Table 1A

E = Joint efficiency, refer UW-12

Before moving further, please ensure that you have understood 10/13 rule and Allowable Stress. Here are two articles if you have not read them already.

INPUT

Lets say that i have a design data as per below;

Pds = 3.4 (MPa)

ID = 1140, rs = 1140/2 = 570 (mm)

C = 3 (mm)

Shell material = SA 387-11 Cl 2, Design Temp = 410 deg C,

For SA387-11 Cl 2 refer to line 12

UTS = 515Mpa, YS = 310 (refer ASME Sec II Table 1A)

UTS and YS

UTS/3.5 = 147.14, YS(2/3) = 206.7Mpa (refer Understanding Allowable Stress )

S = 147.14 (MPa), as per ASME Sec II Table 1A, for SA 387-11 Cl 2 @ 410 degC, Take S = 148Mpa.

S (Allowable stress at 410 degC)

E = 1

Plug in the formulae, you will get;

tmin = 13.3 (mm)

trequired = tmin + C = 13.35 + 3 = 16.3mm

tselected = T selected is the plate thickness available from the plate manufacturer. It will be thicker than T required, in this case the thickness selected is 20mm

Next stop - Understanding Maximum Allowable Working Pressure.

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