PetroStreet

How can optimum thickness for hot and cold service piping be calculated?

Things to consider while deciding for insulation thickness are
1) Cost of heat which is being wasted at any given thickness of insulation: Obviously more the insulation is thick less would be the heat loss, however
2) Cost of of insulation increases proportional to the square of the thickness.
3) overall heat transfer coefficient (hi) of the insulation: higher the heat transfer coefficient the thicker would insulation get for the same heat loss.
now keeping these things in view the optimum thickness would the one which would give minimum overall initial investment and maximum energy savings.

I've attached two graphs for the better understanding of what Imran is saying.

1) Is there any Specific Formula for calculating Insulation thickness.?

2) Can i see some sample calculation for determining "Piping Insulation thickness"?

Regards

Selection/Calculation of insulation & its thickness is described in brief detail below. This is a guideline intended to set a path for you to pursue. This is on top of what has already been said above.

Insulations are specified for piping & equipment due to any one or a combination of below mentioned reasons.
1) To conserve energy (Insulation is specified not to exceed a certain heat loss)
1a) To provide best economic configuration possible
2) For personnel protection (Insulation is specified to bring surface temperature to a preset value, 60 Deg.C for most companies)
3) For fire proofing

Calculation of thickness for 1 & 2 is described below
Below is only for cylindrical shapes like pipes,
Nomenclature:
q' => Heat loss per unit length
n => Total number of layers
j => given component
r => Inside radius
T => Temperature
h => Film coefficient
k => Thermal Conductivity
Subscription "s" => Surface
Subscription "e" => Environment
Subscription "f" => Piping fluid
Subscription "i" => Inside of the pipe
As you can see the solution will be iterative.
Environment side film coefficient depends whether the pipe is in air, water, soil and on top of it specific prevailing conditions in that medium etc. These are available in literature.

Most companies have there own insulation standards and process engineer does not have to do this calculation for every single pipe and literature is full of material that effectively converts this exercise into a selection. Table-1 given below provides the guidelines on selection of insulation material and Table-2 gives a typical selection of insulation thickness for most applications. For your specific problem you can take free advice of our experts thru services tab.

Table-1 Table-2

Thank you so much for providing this useful information . Certainly that helped a lot.

If you can provide the references of the above mentioned Tables(Table 1 and Table 2), that would be great?

Regards

LUDWIG, E. E. (2001). Applied Process Design for Chemical and Petrochemical Plants (3rd ed.)