Currently I'm dealing with underground pipeline analysis. The thing is that the pipe is thermally insulated. I model the pipe specifying the insulation thickness by direct input into the dialog box and also assign cladding thickness. Insulation thickness=25mm and cladding thickness=5mm. To check the effect of thermal insulation I also ran for the case without including thermal insulation and cladding thickness. The results show that the stresses decrease significantly when I apply thermal insulation and cladding. Can anyone tell me if direct input of thermal insulation and cladding is correct way of handling and that the results are reliable?