Pipe Thickness Calculation based on ASME B31.3

Internal Design gage Pressure (P, Psig)
Pipe Outside Dia. (D,inch) Piping Table
Nominal Pipe Thickness (wt,inch)
Allowable Stress of Pipe (S,Psig)
Quality Factor (E)
Weld Joint Strength Reduction Factor (W)
Coefficient (Y)
Corrosion Allowance (c, inch)
Mill Tolerance (M, %)
Result
Cal_Min.Req. Thickness(tm_3a, inch)
Cal_Min. Pipe Thickness(tm_3b, inch)
Cal_Thickness inc. mill tolerance(tw, inch)
Min. Actual Thickness taking into account Mill Tolerance (wtt, inch)
Sizing Equations, "ASME B31.3, 2012"

t m=
P * D / 2 *( S * E * W + P * Y)
+ c    (3a)

t m=
P * (d + 2* c) / 2 *[ S * E * W - P * (1 - Y)]
+ c    (3b)

Where:
tm = minimum required thickness, including mechanical, corrosion, and erosion allowances
c = Corrosion Allowance
D = outside diameter of pipe as listed in tables of standards or specifications or as measured
d = inside diameter of pipe (without allowance) = D - 2 * wt * m - 2 * c
E = Longitudinal Weld Joint quality factor from Table A-1A or A-1B
P = internal design gage pressure
S = stress value for material from Table A-1
W = weld joint strength reduction factor in accordance with para. 302.3.5(e)
Y = coefficient from Table 304.1.1, valid for t < D/6 and for materials shown.

The value of Y may be interpolated for intermediate temperatures. For t ≥ D/6,
Y=
d + 2*c / D+d+2*c


M = Mill Tolerance,Mill tolerance and Piping Stress Analysis

STEPs
1 ) tm=Max (tm_3a, tm_3b)

2 ) tw=
tm / (1-M/100)


3 ) wtt=wt * (1-M/100)

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