As is well known

it is necessary to make correction for tube surface temperature measured by pyrometer. Because the reflected radiation has much effect on this temperature

the geometric factor considering the reflected radiation is an important quantity in the temperature correction. This paper presents a new method for calculation of geometric factor F. Based on local angle coefficient

the geometric factor F is obtained by calculating the average angle coefficient in the circle of vision field. As an example

the geometric factors for the Topsφes converter and the Lummus cracking furnace have been calculated

and by comparison of the calculated values of geometric factors for the Topsφes converter with those suggested good agreement between them has been found. Based on the presented geometric factor in this paper

the corrected values for the measured temperature by pyrometer agrees with measured temperature by armor thermocouple.