this is regarding heat loss

Learn to add details to your question. Whats delta T? Where are you installing in?

Ambient temp? Which make?

If you are already using/ deciding to use, the product carries a detailed spec. sheet indicating graph the heat losses, learn to go through these first.

the ambient temp outside the wall is 40degree celsious and inside the wall is 1250 to 1300 degree. I am talking about strip cleaning furnace in galvanizing line.I am doing some study on energy saving in furnaces. so i would like to know about the same.

I am doing some study on energy saving in furnaces. so i would like to know about the same.

Your Insulation Material - You really have to check the spec.sheets of different suppliers.

Normally Rock wool high temperature & density are utilized and cladded with 24 swg. Galvanized Sheets .

The rule of thumb for Insulation is, "if you can keep the palm of your hand and comfortably stand" - thats 90% good insulation.

For energy conservation of furnaces :

1 . Modulating Air / Gas Ratio Burners.

2 . Pre-heating Combustion Air with Recuperators.

3 . Good Insulation.

4 . Balanced Zero furnace pressure.

Not +ve else hot air will blow out. Not -Ve else cold air will be sucked in.

5 . No cracks/openings at doors & joints.

6 . Monthly Flue Gas Analysis & Burner Tuning as required.

7 . Gas Flow & Temperature hourly Strip/Circular Chart Recording.

8 . Air pressure switches on all Blowers.

Further details: NAMCO HandBook.

You can conduct studies on the same through stimulation programs , energy saving is itself big topic

Dear Vijay

Checkout this website and down load the course ware of Energy auditors/Managers http://www.energymanagertraining.com/new_index.php.There is a chapter on Furnaces.