Question: how to calculate insulation of pipe?
Answer: Q/N = 80W/m. Pipe Dia is 12″ hence radius is 6″. Radius in meters : (6″ X 25.4)/1000 = 0.1524 meters. Extra margin must be taken on insulation thickness as sometimes conducting heat transfer through insulation may become higher than convective heat transfer due to air on outside wall of insulation.