Also, at TVRM we did boiler washes every thirty-days to remove minerals/sludge buildup. BOTH water level gauges were also cleaned and flushed. Anti-scaling and anti-foaming chemicals were added to the tender water supply every operating day.
At TVRM, SAFETY was paramount, and still is. 
Working as a STEAM fireman/engineer, you quickly develop a healthy respect for the potential "rolling bomb" that is a steam locomotive! 
Another significant threat is mineral deposition on the sheet, primarily from poor water chemistry.
Depends on what you mean by "significant." I could find no referenes to scale buildup leading to a boiler explosion in any of the period trade journals available on-line; I don't even believe it's mentioned in any of the ICS courses I have. In fact, the only reference I can find to scale leading to a boiler explosion was in the opinion of an appellate case. Not too "significant" in my book. 99% of boiler explosions were caused by low water.
Boiler washes and blowdowns really eliminate the risk of scale-buildup explosions.
...lack of water is not the only reason for crown sheet failures. Another significant threat is mineral deposition on the sheet, primarily from poor water chemistry. The insulating effect of scale deposits on the crown sheet can raise the normal operating temperature of the sheet close to or at the failure temperature of the metal. As little as 1/8-inch of a silica-based deposit can reduce heat transfer by as much as 30%. So, maintenance of water level, while essential, is no assurance that you will not have a crown sheet meltdown.
Possible...but HIGHLY unlikely.
If steam locomotive boilers are maintained in compliance with the rules, then there will not be any crown sheet failures due to scale. Between the water treatment program used and the required monthly boiler wash, not enough scale can build up to get anywhere close to causing this kind of failure.
Every steam locomotive operator has a water treatment program developed to chemically treat the water used in the boiler. The "witches brew" of chemicals used include oxygen scavengers, PH controllers, anti-foaming agents and anti-scaling compounds.
Also, the action of thermic siphons and circulators provides a lot of water movement over the crown sheet. Water literally fountains up and out of the siphons due to the thermal action on the water which takes place within the siphon. Combine that with the fact that a lot of the actual steam generation takes place right on the crown sheet and you have a situation where scale build-up on the crown is highly unlikely because there is so much water circulation and movement there.
A steam locomotive maintenance facility would have to be grossly negligent to allow enough scale to build up on the crown to cause a failure. As Steve pointed out above, I am also not aware of any crown sheet failures that could be blamed on scale build-up. However, there are hundreds that were caused by low water.
That's the truth. This is an interesting video (Part 1 of 2) that shows exactly how violent it is inside a boiler. When you're used to looking at the glass, it's hard to believe.
Good film clips
I remembered seeing these a number of years ago when attending Steam Boiler School in Cincinnati, Ohio. They also had clear view steam traps, as well as different type control valves, so a person could actually see what is going on inside equipment, and boilers. They also did a water treatment program, and showing the class how Total Dissolved Solids (TDS) effected the boiler/steam production operation. What Rich Melvin said earlier about scale causing a boiler explosion, was right. When we would do our yearly preventative maintenance on our plant boilers, we'd hook up temperary circulating piping between the mud drum on the bottom,and steam drum on the top, and circulate 5.5 acid solution to clean the scale, then run a neutralizing solution thru the boiler tube circuit, before turning it over to the metals inspection dept. When entering the steam drum on the top you could always tell, if the TDS had been run at a high rate for any length of time, before doing periodic mud drum blow downs, and adjusting the continuous blow down from the steam drum on top. This post has been an eye opener. I talked today with 2 of my personal friends, who both went to work at 14 years old in 1942 for the C&O, WW2 was taking a large part of the railroaders off to serve. They both were engineers on the C&O and were very versed with these disasters, as well as telling me about the "close to happening", that they were directly involved in firing and running steam locomotives for the C&O, + all of the extra training that the engine crews endured, after those explosions! When they both retired they received a 50 year service Pin. Just How many employees can do something like that today?
Another significant threat is mineral deposition on the sheet, primarily from poor water chemistry.
Depends on what you mean by "significant." I could find no referenes to scale buildup leading to a boiler explosion in any of the period trade journals available on-line; I don't even believe it's mentioned in any of the ICS courses I have. In fact, the only reference I can find to scale leading to a boiler explosion was in the opinion of an appellate case. Not too "significant" in my book. 99% of boiler explosions were caused by low water.
Boiler washes and blowdowns really eliminate the risk of scale-buildup explosions.
So what is your point here? Are you saying if only one guy out of 100 is killed because of crown sheet failure due to scale build-up you're OK with that? Of course it's a threat-I don't know if it's 1, 5 or 20%. What's the difference? I'm raising an important subject regarding potential crown sheet failures. Additionally, there is no way of knowing if some deposit failures were mistakenly attributed to low water. These things do happen.
On the subject of water turbulence washing away or inhibiting scale deposition-no this is completely incorrect, as is the notion that boiling from the crown sheet surface will also inhibit deposition. In the world of stationary watertube boilers where boiler water is flowing through the tubes by way of convection and the steam drum sees a great deal of turbulence, scale deposition is the single greatest cause of tube failures from overheating, especially in central utility boilers. The deposition occurs right at the water and steel interface where the heat transfer is greatest and is independent of water turbulence. The crown sheet in a steam locomotive is essentially the same as a generating tube in a stationary boiler which sees the hottest part of the flame and is most susceptible to deposits.
While blowdown does remove accumulated sludge from the bottom of the boiler and limit total solids when done on a regular schedule, it's effect on scale deposition at the heat transfer surface is minimal at best. Many locomotives used unsoftened water as make-up and relied entirely on chemical treatment to remove the scale forming salts as sludge. Hence the need for effective blowdown. But even the chemical sludge can form insulating deposits causing failures. Boiler washes will not remove adherent scale deposits only loose and some dried-on sludges. Scale deposition would require mechanical or acid cleaning. To dismiss the potential effects of scale deposits on crown sheet failure, is in my view, rather silly.
Your posts to me, and others, are rather silly, since you've clearly never fired a steam boiler, and you are clearly talking from a perspective of zero knowledge on the subject. But...
Carry on! We are all enjoying your "catalyzing" action here! 
How much more useless and incorrect drivel must be endured before he gets banned?? 
Unfortunately, I don't think you can get banned for being an ill-informed neophyte, who is uninformed on the subject to which he claims expertise, and who passes his incorrect personal opinions on as fact.
Your posts to me, and others, are rather silly, since you've clearly never fired a steam boiler, and you are clearly talking from a perspective of zero knowledge on the subject. But...
Carry on! We are all enjoying your "catalyzing" action here!
No need to fire a steam boiler-you can do that for me. You have zip for a reply answer so who is the one talking from zero knowledge? Holy crow, you guys are like 5 year olds, with all this name calling. Now I understand why he's firing a boiler.
While blowdown does remove accumulated sludge from the bottom of the boiler and limit total solids when done on a regular schedule, it's effect on scale deposition at the heat transfer surface is minimal at best. Many locomotives used unsoftened water as make-up and relied entirely on chemical treatment to remove the scale forming salts as sludge. Hence the need for effective blowdown. But even the chemical sludge can form insulating deposits causing failures. Boiler washes will not remove adherent scale deposits only loose and some dried-on sludges. Scale deposition would require mechanical or acid cleaning. To dismiss the potential effects of scale deposits on crown sheet failure, is in my view, rather silly.
Our engine worked in a limestone quarry for many year after her service during WWII. She took water directly from the pit. ZERO boiler treatment.
That engine survives (and runs) today because of the coating of lime scale that protected its heating surfaces.
Your incorrect opinion and lack of knowledge on the subject really do amuse me. I'm certainly glad we don't have folks like you coming out to "help" us.
Jealous?
I gotta hand it to you Skyhook...you are trying to dig yourself out from the mess you created.
But the hole just gets deeper...
GOLLY FELLAS...
All I did was post the Topic, but beyond that, I had no idea that it would result in such an avalanche of replies, many of which are so controversial.
Please just remember me as Bad Order Hal, who innocently brought up the subject of crown sheet failures, without knowing much about the subject.
BAD ORDER HAL
Hal, every once in a while a thread just sort of takes on a life of its own. This is one of 'em.
"Better to keep your mouth shut and appear stupid than to open it and remove all doubt." - Samuel Langhorne Clemens
While blowdown does remove accumulated sludge from the bottom of the boiler and limit total solids when done on a regular schedule, it's effect on scale deposition at the heat transfer surface is minimal at best. Many locomotives used unsoftened water as make-up and relied entirely on chemical treatment to remove the scale forming salts as sludge. Hence the need for effective blowdown. But even the chemical sludge can form insulating deposits causing failures. Boiler washes will not remove adherent scale deposits only loose and some dried-on sludges. Scale deposition would require mechanical or acid cleaning. To dismiss the potential effects of scale deposits on crown sheet failure, is in my view, rather silly.
Our engine worked in a limestone quarry for many year after her service during WWII. She took water directly from the pit. ZERO boiler treatment.
That engine survives (and runs) today because of the coating of lime scale that protected its heating surfaces.
Your incorrect opinion and lack of knowledge on the subject really do amuse me. I'm certainly glad we don't have folks like you coming out to "help" us.
Some people appear to look very small (and lack knowledge), but that's only because they are flying so high. I think that's what is going on here. I know you feel threatened intellectually by what I am saying, because no one has ever caused you to question your doxie. You'll be OK, I promise.
Firetube boilers like locomotives will never have tube failures due to scale overheating from limescale because the tubes are not seeing live flame like the crown sheet. These are two different situations. Limescale does protect the tubes from oxygen pitting it is true, but also reduces fuel efficiency-and good boiler operators always try to prevent scale buildup of any kind, and deal with oxygen pitting chemically. And that my fireman, is a fact.
HEY NICK,
Mr. Clemens was also quoted as saying:
"The reports of my death have been greatly exaggerated."
Bad Order Hal
I gotta hand it to you Skyhook...you are trying to dig yourself out from the mess you created.
But the hole just gets deeper...
I don't see it that way, Rich, sorry about that. There are a lot of different subjects going on here and I'm not locked in to one thing. I know there are a lot of people on here who may not like what I have to say so there is a lot of name calling and personal attacks like children will do-I just let that go and respond as I see fit. It is getting like a mob mentality around here, isn't it? (LOL)
Man, I don't know from nothing when it comes to crown sheets, and maybe less about a real steam engine.....I do know about bed sheets, though.
But, none the less, this is one of the most interesting threads I have followed in a long time. Keep it coming. The more information the better, deep hole dug and all.
Greg
GOLLY FELLAS...
All I did was post the Topic, but beyond that, I had no idea that it would result in such an avalanche of replies, many of which are so controversial.
Please just remember me as Bad Order Hal, who innocently brought up the subject of crown sheet failures, without knowing much about the subject.
BAD ORDER HAL
Hal, anyone who builds Van der Graaf generators, gets an A in my book, pal.
thanks to Bad Order Hal I now have a 'working' knowledge of how quickly tragedy can
arrive when working around steam.
My great grandfather had a loco explode due to it running dry. that was in 1900 when
the virgin timber was being logged.
Again, thanks Hal for putting forth such an explosive subject for us to grit on!!!
HEY SKYHOOK and RUFUS:
Awwww shucks, fellas...such unabashed adulation is makin' me blush!
bad order
I think that I saw that one in the Frankenstein Movie back in the late 40's. Was it a Lima/Alco/or Baldwin? Very interesting to say the least.......
YO BRANDY,
That was my home-made Bonetti Machine (now dismantled) with a maximum potential of 300,000 volts of electrostatic charge, by hand-cranking the counter-rotating 25" acrylic discs.
The Frankenstein movies used Tesla Coils, which were high-voltage, high-frequency continuously discharging machines, totally different from Van de Graaff, Wimshurst, Bonetti, and all other types of electrostatic generators which were one-shot devices.
Lima? Alco? Baldwin? Those were steam locomotive manufacturers, my son.
BAD ORDER
I gotta hand it to you Skyhook...you are trying to dig yourself out from the mess you created.
But the hole just gets deeper...
By now that hole must getting pretty warm. He can't be far from the mantle by now.
You wish to treat all threats equally. The chances of a boiler explosion occuring because of scale buildup is basically nil in today's world (and also back "in the day"). I worry a lot more about derailing at a switch or making sure I oiled the eccentric straps than I do about scale buildup causing my boiler to explode.
Personally, as a fireman, I'm WAY more concerned with water level than wondering about (essentially non-existent) scale. I'm also concerned about other things that can cause problems, like foaming, or priming. I guess that's why I can fire, and you wouldn't be allowed to--you cannot prioritize your "threats," and might perhaps be too fearful to do the job safely and responsibly.
Can't wait!
Everyone, please remember that when wrestling a pig in the mud, it is VERY frustrating, until you FINALLY understand that the pig is enjoying it!
To satisfy popular demand and for the continuing reading enjoyment of all you Steam Geeks out in OGR Land I will be submitting additional and exciting steam bulletins in the months to come. Stay tuned.
Gentlemen, I think it's official: VOX is back!
Rusty
Hey, Bad order, Yes I know of the Steam/Diesel Locomotive Manifacture's, as I was just having some fun. I did see the hand crank in the picture, but didn't know how that thing worked. Seems like there are some PO'd folks on this one for sure! My wife use to teach Science and Chemistry in school before retiring. I saw something that she was running for a class, that reminded me of old Dr. Frankenstein charging his Monster, but what ever. Have a nice day you guys, as I gotta Mow some friggin grass today!
Everyone, please remember that when wrestling a pig in the mud, it is VERY frustrating, until you FINALLY understand that the pig is enjoying it!
Hey, Warm Water, you've got me laughing so hard here I think I'm going to bust. I've got to get out of here and go play with some trains.
Everyone, please remember that when wrestling a pig in the mud, it is VERY frustrating, until you FINALLY understand that the pig is enjoying it!
Hilarious!
To satisfy popular demand and for the continuing reading enjoyment of all you Steam Geeks out in OGR Land I will be submitting additional and exciting steam bulletins in the months to come. Stay tuned.
Good grief...
Just remember...your posting privileges have been suspended before. It can happen again.
And since I am the only person who can change your display name, I wouldn't get any "Sultan of Steam" business cards printed.
Although I had the pleasure (once) of firing a tourist steamer on 100*+* September day (never again!) I was never enlightened about boiler washes, just make sure water was in sight glass and keep pressure at 160.
Rich said a "witches brew"of chemicals, but how is the procedure performed, how long, sequence, witch brew disposal etc. Please keep it simple for the great "unwashed" masses like me who armchair railroad, and smart enough to keep quiet and listen. From the real knowledgeable pros please (Hot Water, OGR Webmaster, smd4, and others) NOT skyhook depot.
Rich said a "witches brew"of chemicals, but how is the procedure performed, how long, sequence, witch brew disposal etc.
We use this company's products, notably OxyGon & ScaleGon (Hmmm looks like another familiar engine uses the same products). The OxyGon is an oxygen scavenger; the ScaleGon basically keeps the total disolved solids (TDS) in suspension, so they don't accumulate on surfaces before we drain the boiler. Which is, of course, how everything is "disposed of."
We mix them in certain proportions in a jar, and then and add them to our saddle tank when we operate the engine. We can test the boiler water for pH, etc., by collecting it by opening a tri-cock.
Rich said a "witches brew"of chemicals, but how is the procedure performed, how long, sequence, witch brew disposal etc. Please keep it simple for the great "unwashed" masses like me who armchair railroad, and smart enough to keep quiet and listen.
1) The FRA, and previously the ICC, REQUIRES that a locomotive boiler must be wash AT LEAST every 30 days. That involves, obviously reducing the pressure to zero, then opening ALL the "wash-out plugs", and then washing from the top downward the complete inside of the boiler, until all the discharge from each and every wash-out hole exhibits CLEAR WATER. During this process, all the in-cab valve connections to the water gauge glass/glasses are rodded/reamed out. All the wash-out plugs are then reinstalled, the boiler is refilled with hot water, and the fire is re-lighted.
2) Boiler water treatment chemicals are designed to keep the solids/minerals in suspension, i.e. prevent them from sticking to the interior sheets of the boiler/firebox. Thus, thus deposits can be blown out/down throughout the days trip (both the Engineer and Fireman have remote manual methods of opening their respective blown-down valves from inside the cab).
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