 # Calculate Boiler Tube thickness?

Can you calculate tube thickness is one of question must be answered by mechanical engineer who involve in design steam boiler. Basically the calculation of tube thickness is really simple but if we don’t know, it will be difficult off course.

Basically you only need knowledge about the theory of longitudinal stress in cylindrical part and circumferential stress cylindrical part as my previous post. The following below is formula to calculate tube thickness because of these stresses:

tL = P D / 2 SL (equation 1)
tC = P D / 4 SC (equation 2)

where:
tL = tube thickness because of longitudinal stress
tC = tube thickness because of circumferential stress
P = design pressure
D = inside diameter
SC = circumferential stress
SL = longitudinal stress

From the equation above, thickness because of longitudinal stress is always greater than thickness because of circumferential stress. Therefore you can simply choose the equation 1 to calculate tube thickness.

However, if the tube is used in boiler plant, the calculation should refer to ASME BPV Code Section I Part PG 27.2.1 as following formula:

t = (P D / 2 S) + 0.005D + e + Ca

where:
t = minimum required tube thickness
P = maximum allowable working pressure
D = outside diameter
S = maximum allowable stress value at certain temperature in each material, the table can be found in ASME BPV Code Section IID.
e = thickness factor for expanded tube ends
Ca = Corrosion allowance.

To make easy to calculate tube thickness, I had made a spreadsheet of tubethickness calculation, you just enter input data such as pressure, outside diameter, e, Ca and S value.

So if you get question “can you calculate tube thickness?” just answer it, I can do it for 5 minutes only, he…he… but if you have already ASME BPV Code Section IID to find S value.

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