Skin temperature

[sumon emam]

Some parameters of an atmospheric distillation heater are given below:

heater inlet temperature = 220° C

heater outlet temperature = 370° C

radiation zone temperature = 700° C

I want to know about the maximum skin temperature of the radiation tube of material P7 and P9 in the mentioned condition.

[chirukatta]

Tube skin temp of fired heaters not only depnds on temp,it also depends on process fluid and its properties..refer API standards.