Asbestos insulation - first year chem eng problem

[bruceflea]

how good an insulator is asbestos? (thermal conductivity 0.15 W/ m K). I am trying to determine the thickness of insulation required to reduce the heat loss of a spherical container by half. The answer I calculated it to be is 0.2cm which to me doesn't seem right (too small?) but having no experience with asbestos, it may be correct?

 

[Astronuc]

Here is a table of thermal conducitivties, which includes metals (good thermal conducitivity) and insulators (poor (or low) thermal conductivity).

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/thrcn.html

See also discussion on thermal conductivity
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatra.html#c2