Insulation 3E Plus

[cheme112]

Does anyone know how to determine insulation thickness by using 3E Plus Software? I am using the software to determine insulation thickness requirement for 150# steam and I am specifying calculation type "heat loss per hour", ambient temp. Wind velocity, process temperature, pipe size and material of insulation with 0.1 Aluminum jacket.
The program generates a table with insulation thicknesses, surface temp. deg. F, heat loss (BTU/HR*FT) and % efficiently. but what is the ideal thickness? All the generated results are below surface temp of 140F, and efficiency is between 91% and 98%.
For example at efficiency of 94% heat loss is 73.3 BTU/HR*FT, surface temperature is 68F and insulation thickness is 2" for 2" NPS.
@ efficiency of 95% heat loss is 65 BTU/HR*FT and surface temperature is 65F and insulation thickness is 2.5" for 2" NPS, and it goes on.

 

[georgeverghese]

Usually, piping and vessel insulation thickness is set by economic considerations, if insulation OD surface temp requirements per HSE guidelines are met. If you plot a graph of CAPEX + OPEX vs insulation thickness, you'd usually obtain a min point in the curve, which is your selected thickness.

To get the CAPEX, ask an insulation installation contractor for materials and field labor cost for unit costs per linear metre insulation for various thicknesses for the line sizes you have.
To get the OPEX , assume a payback period (usually between 3-5years for miscellaneous items like this), and calculate the cost of the energy lost to atm per linear metre at this insulation thickness over this payback period. The cost of the energy lost would be a function of the marginal unit cost of heat generation at your facility.