I do not think pit fire alone can cause damage to the coke drum structure. However there are other possibilities of major fire on the structure.
 
We have fire water monitors installed at first level of the structure to fight pit fires and hose reels at each platform of the structure. However we consider this insufficient to protect the structure in case of a big fire and are exploring various possible ways to protect the structure in case of a major fire. We are considering a deluge system for the structure, elevated fire monitors with high capacity on sides of the styructure, etc. We are also considering fire wall installation along the side of escape route from the structure.