Do any members of the forum have actual documentation of a locomotive boiler suffering a crown sheet failure due to the feeding of water into the boiler from an injector, inspirator or properly funtioning feed water heating device after a low water situation has occured?

From time to time the old notion "Never put water into a boiler that has low water or the crown sheet will shatter" comes up and I am concerned that in the face of rational thought this poor idea, as I see it, continues to be passed down. I have never been able to to produce any information the supports this scenario in locomotive service (not stationary or marine). I wonder if we are putting our industry in danger by perpetuating this wive's tale? The first thing I would instruct a new fireman to do in a situation where he thinks the water is too low is to start getting water into the boiler, FAST! As I understand it, crown sheets fail when they are overheated due to low water. I have never seen evidence of one failing from "cold water".

Can't answer it from the aspect of a Steam operator, but from experience in Blacksmithing, if you quench (quickly cool) metal faster then it can create the crystals than it becomes very brittle if it doesn't shatter in the bucket. This is the reason why knives and chisels can be sharpened but chip when abused. ( before the question is asked, flexible blades only have the cutting edge quick quenched while the rest is cooled slower)

First question I would have to ask is, where do the injectors add the water? If it is at the bottom and submerged then the warming action of the steam feed and mixing through the boiler's volume, then it is highly unlikely, but if the water is injected directly onto the crownsheet then that would set-up the correct environment for quick quench.

Rich C.

I think you will get a lot of flack on this one. Many years ago there was an incident on a CPR passenger train that left Toronto racing along with no water in the glass and the fireman (said not to have been a very bright man) put the injector on and blew the two of them to Kingdom Come! I was taught that a full glass and an empty glass look very similar and only the practiced eye can tell the difference and be able to detect water. That is the biggest reason not to carry water too high. Also, make sure water is always moving in the glass. If it is still, it is a false reading.

My Old Man taught me what to do when first getting on an engine. "Put your lunch bucket on the seat. Don't bother putting it inside yet." He then went on to explain how to "prove" the water level by closing/opening mountains and blowing the glass properly. "If you cannot get water in the bottom nut of the glass, do NOT put the injector on. Pick up your lunch bucket and head for home!" In other words, let some shopman fix things since they left it that way for you. "If all is well, put your lunch bucket in the seat box and get her ready."

Years ago, the Chicago & NorthWestern had a roundhouse on the south side of Milwaukee. An old "Zulu" 2-8-0 was used to provide heat in the winter. I rode by the house a few times on the North Shore and meant to get over there one day and try to photograph the Consolidation which, unfortunately, I never got around to doing. As I heard the story, the watchman apparently fell asleep one night and when he woke up, he saw the water in the glass was gone and hit the injector. End of watchman, 2-8-0 and a good portion of the old roundhouse! This was really a shame because when the C&NW decided to start its steam program a few years later, the 2-8-0 would have provided more tractive effort than Ten-Wheeler #1385.

Les

There is a very good discussion of this going on right now on the Smokstak (traction and stationary engine forum). http://www.smokstak.com/forum/showthread.php?t=115438. The general consensus is to drop the fire (if possible) and clear all people from the area until the boiler can cool. You may wind up with a destroyed firebox, but that's cheaper than the mortal hazard a crown sheet failure would cause.

Michael Seitz
Missoula MT

We've all heard this story, the engine crests the hill and water sloshes, or somebody hits the gun. It certainly seems logical enough, red hot steel gets quenched.

But let's play devil's advocate here... Take this story: "he watchman apparently fell asleep one night and when he woke up, he saw the water in the glass was gone and hit the injector. End of watchman..."

So how do we know he turned on the gun? Obviously he didn't testify at the investigation. If the gun was blown to bits, hard to tell if it was on or off. Maybe he was peacefully sleeping on the seatbox when the crown sheet finally overheated enough to let go?

There's more to this question than you think at first glance.

I believe that this type of response is at the heart of Brendan’s question. Think about it, if the boilers had exploded and the crews were killed, how can anyone know if the injector was being started at all, the explosion happened at the moment the injector was started, and if it did, that that wasn’t just the time that the crown sheet became weak enough to fail anyway? Or is that a detail that is routinely added to one of these stories because “everybody knows” that that’s what happens?

Oil burners aren’t the issue since the fire can be extinguished with the flick of the wrist. A good sized coal burner with a rip-roaring fire can take a good five minutes to dump. Is that five minutes better spent with the injector running and the train stopped, by which time there may be water in the glass again, or with the crew frantically shaking the grates (into the ashpan, where it will still be heating the boiler) while the pops are up, dropping the water level further every second?

Locomotives normally do not feed water anywhere near the crown sheet. Isn't that to allow for circulation and keep the cooler water off of the crown sheet? Cool water would head to the mud ring, right?

That would certainly seem to be the proper course of action. (The REAL proper course of action is to keep water in the glass in the first place, but given the circumstance of low water...) Even if you don't blow yourself to bits by turning on the injector, if the crown sheet has been exposed there's obviously potential for damage and at that point you would want to have it inspected prior to resuming service. I think most would agree that's the best approach.

However, this discussion is interesting, even if only from a theoretical point of view.

Here's another question to toss into the mix. There are two versions that seem a lot alike.

1) Water out of sight, turned on the injector, water hit the red hot crown sheet and it bursts. Often this is on an engine that's not moving.
2) Water out of sight, engine crested a hill, water sloshed over the red hot crown sheet and it bursts.

So my question is whether or not these two are essentially the same. The second has the potential for a lot more water contacting it at once, as opposed to the slower action of an injector filling the boiler. On the other hand, the water already in the boiler should all be hot already, as opposed to the "cold" water from an injector. (Just how cold is it at that point anyway?)

I'm also pretty certain there are documented instances of this occurring, but then again I don't have any actual reports at hand stating that.

I'm also guessing that is the second has been documented to occur, it would be easy for somebody to assume that the first would also occur, even if that's not actually correct.

BTW - I'm not talking about the momentary exposure that sometimes occurs when cresting a hill or with heavy braking. I'm guessing every fireman on a mountain railroad has seen that on occasion, you look at the glass and it's empty for an instant. Then the water bobs back up in the glass and your heart starts beating again.

The place to find out for real is here, ICC Accident Investigations. Lots of interesting reading. Personally, I don't recall reading an investigation that concluded that starting the injector was the cause of the explosion. There are plenty of reports where inspection of the remains showed where the firebox was burned several inches to a foot or more below the crown, indicating that there hadn’t been water in the glass for a long, long, long time, way more than the time it takes to slosh the crown sheet dry cresting the summit.

I've debated this with several folks over the years, and I take the position that it's an old wives tale; that if they can even prove that the injector was opened, that it was simply a coincidence, and the boiler was going to rupture anyway. The two arguments that are always made are:

1. The rising water level touching the red hot steel "flashes to steam" and causes the explosion. Well, does it? Is there any reason that this raises the pressure any higher than it already is?

2. Quenching the red hot steel causes it to crack. Except, I don't think that boiler steel has enough carbon content to really get appreciably harder, and I've never seen a piece of mild steel crack when quenched. Anyway, adding water to one side of the sheet isn't going to quench it all the way through, considering the heat source on the other side, so at best it would be a situation like the boundary zone where a blacksmith only quenches the end of a hot tool. I would like to see an investigation report that shows evidence of cooling cracks in the damaged boiler sheets.

Old timer's wisdom doesn't count... those are the old wives who were telling the tale. Remember, these guys just worked for a living... they didn't own the locomotive, and could always get a job elsewhere if they got fired. Reminds me of one of the guys talking about the fire drills they had at the propane fueling racks they used to have at the bus garages... the boss is saying do this, do that, and my buddy interrupted him and basically said, "When that fire alarm rings, don't come lookin' for me. I'm gonna be that little dot on the horizon, runnin' down North Avenue."

This is an interesting topic. I have often read about the idea that adding cold water to overheated boilers causes explosions. The idea of dropping cold water on a red hot crown sheet sounds dire, but that is not what is actually happening. If the crown sheet is red hot, it seems to me that an explosion is already imminent.

With added water, it is introduced mid-height along the boiler sides toward the front. This will be lower than the level raising concerns for the crown sheet. So from that forward, submerged point of water introduction, I would think it would draw down a lot of heat quickly without directly affecting the crown sheet.

But, as a question, say the crown sheet was uncovered and rapidly heating, but not yet red. Could adding water induce an explosion?

Say the crown sheet was actually red hot. Would adding water pull it back from the brink by the chill down; or would it suddenly make the boiler weak enough to explode?

Concerning the watchman and the C&NW roundhouse in south Milwaukee, please note that I said "As I heard the story....." Maybe that's not what actually happened. If anyone has the story of the accident investigation, I'd be glad to hear it.

Les

That's the first thing I thought as well. I have read plenty of transportation incident reports over the years (admittedly, mostly aviation losses) and they're really hesitant to say specifically that "Smedlap hit the X lever instead of the Y lever, and bam, no more Smedlap..."
Conjecture is one thing, but I think the most dangerous preface to any sentence ever has to be, "I heard that..."

It's been my experience, reading the ICC accident reports, that they are very reluctant to say specifically, "Mr. X failed to do this." Instead, they lay out all the facts, than draw the conclusion that the railroad needs better training procedures. They leave it to the railroad to deal with Mr. X.