In present work, the factors involved in the heat transfer processes in structures of offshore production units submitted to thermal radiation due to the Flare system will be exposed. An experimental apparatus is suggested for the evaluation of the temperature distribution in a heated tube under cross flow of air through a wind tunnel installed at PUC-Rios s university. Convection heat transfer occurs on the surface of the heated pipe to the fluid which is in cross flow, and the local or average heat convection coefficient, h, is important for verifying heat transfer rates in tests where such configuration is present. Theoretical analyzes for calculating this coefficient are evaluated for different Reynolds number values and related to Nusselt number.