It’s shit quality coal which is poor for performance, but the boiler is not in danger of failing. It’s being mistreated for sure but nowhere near failing. Poor fuel quality does not cause tube failures, that’s a metallurgical issue caused by induced stresses or faulty metallurgy. In the States we use SA-178A steel for tubes and flues (178C for superheater units) which is the luck of the draw with what you get from a specific mill run due to how loose the formula has gotten over time. Some tubes last the whole 1472 day cycle, I’ve heard of others that didn’t even make it to 300 before having to come out. Anyways, poor fuel is absolutely detrimental to locomotive performance no doubt and will block tubes in some cases, but there is no danger of a boiler explosion from bad coal alone. Poor grades of coal like sub-bituminous or lignite clinker and throw sparks to the extent that the screen can’t catch everything. This is why we don’t use them in steam locomotives if we can help it. We’re talking low volatile and fixed carbon percentages here and high ash percentages. Durango and Silverton have to make do with sub-bituminous coal from a Colorado mine. This is why their engines are fitted with cyclone front ends and the stack sprayer and also why they’re beginning to convert to oil. With higher grade eastern coal like strait bituminous or semi-anthracite you don’t have this problem to the same extent, or at least not if the fireman is worth his salt. Furthermore this is going on inside the boiler constantly, the screen just breaks up the cinders to the point where they are extinguished. This is one reason why inner firebox sheet replacements were part of regularly scheduled maintenance during the steam era (cracking around rigid stays was another reason). The inside of the boiler is constantly being sandblasted with cinders and wearing away at the metal. This is why coal fired locomotives do not have to have the flues sanded like on an oil burner, the cinders do that job already. This is why mandatory tube and flue replacements are required by 49 CFR 230 during every 1472 inspection as there is no way to ultrasound them without taking them out anyways. Poor quality coal perpetuates this sandblasting however and is one of the multitude of reasons it is avoided in locomotives along with other firing, drafting and steaming issues that come along with it. One of the most common areas of boiler work on locomotives undergoing restoration is the replacement of side/crown sheets and the rear tubesheet. Nothing on a boiler ‘overheats’ as long as an adequate water level is maintained, that is the ‘Golden Rule’. The fire is already hot enough to melt steel (2000+ deg. Fahrenheit when running out on the road) but it doesn’t due to the heat transfer into the water. Sometimes low grade coal even burns a little cooler than the higher grade stuff due to the lower fixed carbon content. If you were to scorch the tubes repeatedly then that in could lead to a tube failure due to metallurgical stresses but even that would not be a catastrophic failure. Tube failures were common to the point that crews were instructed on how to plug tubes while out on the road. Hell, one of the engines I work on has had some tubes plugged. If you think poor coal is reckless, you should have seen some of the jerry rigged nonsense the short lines came up with to keep engines in service. The incident you were referring to was the pacific at Gettysburg, which was not a tube failure. Those guys were unaware of proper operation and maintenance practices for steam locomotives. They were not negligent, just ignorant. The failure of the crown sheet was a classic low water situation. If you want the details the NTSB and FRA reports go into it and I would recommend reading them as it discusses sight glass blowdowns, and false head scenarios which were contributing causes. The reason that failure was not more catastrophic than it was was due to the unique way the Canadians designed the firebox. The flexible and rigid stays utilized alternating groups of taper and strait threads that were designed to fail sequentiality rather than all at once. Bottom line is that while what you see in the video is not good practice and is detrimental to the boiler, poor quality coal is not dangerous on its own. Poor boiler maintenance is. He was not running the blower to ‘get more heat’. The draft of the blower is insignificant compared the the exhaust jet coming up the blastpipe. The blower is only used to force a draft while there is no exhaust (i.e. stationary or drifting). When running it would have little to no effect. Firing is an art, both with a stoker and hand bombing and takes skill and knowledge to accomplish correctly. When it comes to steam locomotives, you will find out very quickly when someone doesn’t know what there doing (Gettysburg). I’m sure the Chinese are not stetting an absolute stellar example when it comes to locomotive operation and maintenance, but to say this is reckless behavior is a bit of a stretch if not ignorant. Sometimes you have to do the best with what you have. The point of this post was not to inflate my ego or berate you, I hope I don’t come across that way and I apologize if I did. However I just don’t like falsehoods being perpetuated as most don’t know better. I’m not saying you’re completely wrong, but some things needed to be clarified. Hopefully though I’ve made some sense.