Making Decisions with Insulation

Chemical and Process Engineering Resources

Nov 08 2010 12:30 PM | Chris Haslego

in Heat Transfer

Economics

Economic thickness of insulation is a well documented calculation procedure. The calculations typically take in the entire scope of the installation including plant depreciation to wind speed. Data charts for calculating the economic thickness of insulation are widely available. Below are links to economic thickness tables that have been adapted from Perry's Chemical Engineers' Handbook:

Table 1: Economic Indoor Insulation Thickness (American Units)

Table 2: Economic Indoor Insulation Thickness (Metric Units)

Table 3: Economic Outdoor Insulation Thickness (American Units)

Table 4: Economic Outdoor Insulation Thickness (Metric Units)

Example of Economic Thickness Calculation

Using the tables above, assuming a 6.0 in pipe at 500 ^Â°F in an indoor setting with an energy cost of $5.00/million Btu, what is the economic thickness?
Answer: Finding the corresponding block to 6.0 in pipe and $5.00/million Btu energy costs, we see temperatures of 250 ^Â°F, 600 ^Â°F, 650 ^Â°F, and 850 ^Â°F. Since our temperature does not meet 600 ^Â°F, we use the thickness before it. In this case, 250 ^Â°F or 1 1/2 inches of insulation. At 600 ^Â°F, we would increase to 2.0 inches of insulation.
Economic thickness charts from other sources will work in much the same way as this example.