Hi all. I have a question about draining boilers to do washes, ect. How do any of you that work on boilers do your cooling down to flush or drain them. I ask this because i work at a museum where if we have to do a boiler wash or just drain the boiler, we can let it cool down for a few days before draining. Obviously some out there dont have this option. For instance, i was taught to never run the injectors for longer than it takes for boiler pressure to drop more than 5 pounds. The time this takes would of course depend on how well the boiler can keeep up with steam demands. How hard is it on a boiler to run an injector for 5 minutes while the locomotive is not working, this would cause a loss in pressure much greater than 5 pounds. How bad are the stresses on the sheets and barrel cooling it this fast. Please do not take my comments the wrong way. I am not critisizing anyones methods. However i have not been trained ( due to out practice of waiting a few days to do a wash after shutdown) on how quickly a boilers temperature and pressure can be reduced and cause only minimal stress. Also, whick is easier on the boiler, blowing it dry while still warm (no fire), or cooling it with cool water. Thanks in advance for all comments.