In most of the photos, the boiler failed at the front of the engine. The steam behind the pipes could not make it's way out fast enough, so the pipes and their

In most of the photos, the boiler failed at the front of the engine. The steam behind the pipes could not make it's way out fast enough, so the pipes and their supporting frame were forced out the front. In the photos where the boiler failed in the middle, they just get bowed out from the pressure. Something the article mentioned was running out of water. As you said, the metal overheats and gets soft because water isn't there to absorb the heat by being turned into steam. So you get either an internal leak or explosion (depending on severity). The Union Pacific has "Big Boy" 4014 running again. It is traveling with three tenders with water and fuel (but mostly water), because the infrastructure isn't there any more for steam locomotives to refill along the tracks. https://www.youtube.com/watch?v=jvP59TCMePI https://www.youtube.com/watch?v=jvP59TCMePI