Why pay attention to the surface load of single-head tubes?

When communicating with customers about the technical parameters of the single-head tube, what we must determine is the specific size, power and working environment of the electric heating tube. Why do we pay so much attention to these parameters? On the one hand, we must know these to make non-standard customization. Production, on the other hand, is that we must use this to calculate the surface load of the heating tube. The surface load of the heating tube is extremely important for the electric heating tube.