In a pharmaceutical plant, a copper pipe (kc=400W/mK) with inner diameter of 20mm and wall thickness of 2.5mm is used for carrying liquid oxygen to a storage tank. The liquid oxygen flowing in the pipe has an average temperature of 2200C and a convection heat transfer coefficient of 120W/m2K. The condition surrounding the pipe has an ambient air temperature of 20C and a combined heat transfer coefficient of 20W/m2K. If the dew point is 10C, determine the thickness of the insulation (kins= 0.05W/mK ) around the copper pipe to avoid condensation on the outer surface. Assume thermal contact resistance is negligible