This is the door for real heavy duty application: ERET-Highspeeddoor ASE-S/120, designed for high windload, high frequency and large sizes. The door on the photo was installed in October 2013. It opens with an average speed of 1,0 m/sek (max speed 1,4 m/sek) and has a clear opening of 7,5 x 5 m. Inside the building is a steel melt. This cause significant windloads and agressive dust. As a result, you can see sediments of the dust on the panel.
A door approved for steel industry.