Fireman, Don't Let Your Crown Sheet Go Dry.....

So ust plain untreaated water is used, not treated with chemical(s) to help remove deposits?  How long does this take, several hours or just  how long until water runs clear?  You mention clean inside boiler, do you mean just lettiing water do the work or acessing the actual inside with cleaning tools?

"very small men with no fear of claustophobis!!"

Anyway thanks Hotwater for you valuable insight and answers.

When you read around all the uh, -- extracurriculars here --    very interesting thread. Thanks to all the pros for the education.

Yes...the pros are very enjoyable...as for the rest...well I'd say spare us the diatribe and fish elsewhere.

Mr. Moderator....

If the replies to my topic continue to arrive in unabated numbers, perhaps we should  initiate a new section of the OGR Forum called "Boiler Explosions".

Bad Order Hal

Good grief, NO!  Discussing this subject once is enough.

This subject is a critical one when dealing with a life threatening event. 

I remember at the state fair in Ohio 4 years ago a steam tractor boiler blew killing a few people because of a stuck safety pressure release valve. 

So with the picture below of a cross section of a typical steam engine, you can see the water over the crown sheet as per thread discussed. 

What procedure is taken if the crew thinks there may be an event of low water?

Drop the fires, release the safety steam valve? then ?

There is no way to manually "release the safety steam valve"! Besides, the safety valves are NOT designed to prevent a boiler explosion anyway.

The best thing to do is, drop the fire and get the he%% off and FAR out of the way!!!

Aside from the very first report of a boiler explosion, where it was alleged the fireman or engineer tied down the safety valve because it was "noisy," no boiler explosion in recent times was caused by a "stuck safety valve."

Again...they're caused by LOW WATER.

Steve,

You are correct! The initial report was a the safety valve was stuck causing the explosion but after a thorough investigation it was stated:

The Medina County Sheriff's final report states its conclusion simply: "It is obvious from physical examination, photographs, and testing, along with computer generated stress analysis conducted on the stay bolts and crown sheet fastening points, that ninety plus years of corrosion and erosion had taken its toll on this boiler." If Medina Sheriff Neil F. Hassinger was trying to quell further discussion on what caused the July 29 explosion with this statement, he doubtless failed to that end.

Primarily, this is because of strong sentiment in many circles that even a weak boiler, if properly tended and its water level kept up, will not fail in the cataclysmic fashion as experienced in Medina. 

If I remember correctly, the report on the steam traction incident stated the crown sheet had eroded to less than 3/16" (or maybe it was 3/32") in the area where the stays pulled from the sheet. There were also notes about the stays being eroded and loose in the sheet as well. Basically it was an accident waiting to happen. These engines, although they operate well below the PSI a locomotive runs at, still contains HUGE amounts of energy in hot water.

The steam tractor explosion was July 29th, 2001 Medina County Fairgrounds, Medina Ohio.  If any of you guys are interested in attending a 2014 Steam School here they are Illinois May 17-18, Iowa May 3-4, Minnesota June 14-15, Penn May 17-18, Virginia April 12-13, Wisconsin  Sept 26-28. If you are interested in improving your intelligence on steam engine/steam boiler operation, and proper maintenance  of both. Google Farm Collector.com and you can find all of the necessary info and where abouts to attend, you might even catch me at one or 2 symposiums teaching a class or 2.

One of the most entertaining threads in ages !  Congrats, gentlemen,  OTOH, crown sheets, stay bolts, boiler washes, injectors, eccentric cranks.....YOY !   Gonna grab my trusty SD7, and never look back !

Lots of folks think boiler explosion occur because of malfunctioning safety valves.

Even if stuck closed, the boiler can safely handle several times it's maximum allowable working pressure (MAWP). Our engine's MAWP is 190 psi. The gauge goes to 300 psi. We would obviously notice the problem once the engine got to about 200 psi (our safeties should blow around 195/197), and actions would be taken to reduce pressure and resolve the problem with the safety valves (there are always at least two, for redundancy). We cannot operate if the safety valves aren't functioning properly.

So again, it's low water that's the problem, not over-pressure--when there's no water over the crown sheet, it cannot transfer the heat from the fire to that water, so the steel absorbs it, until it becomes ductile. With 190 psi (in our case) pushing down on every square inch of that crownsheet, it could rupture. The liquid water in the boiler is 160 degrees F HIGHER than the boiling point--but it cannot turn to steam when it's contained in the boiler under pressure (see, e.g., Ideal Gas Law). Once it's released to atmospheric presssure, however, it tranforms instantly from X gallons of water to (X *1,700) gallons of steam. That's the explosion.

If you've ever seen a blowdown, you can get some idea of that power. Lots of people think we're "venting steam" when we blow down. In fact, we're releasing water--and it explodes instantly to steam when it hits atmospheric pressure.

As for what I'd do if I noticed a possible low water event would be to instantly shut off my fire, start the injector, have the engineer start his, leave the engine and try to clear the area of people.

Good overall explanation. However, in my opinion, I would NEVER put the injector on because if indeed a portion of the crown sheet is already bare, or almost bare, the water being inputed by the injector could instantly flash to steam upon water hitting that portion of the crown sheet.

I thought you'd point that out! In actuality, this is probably a myth. Back in the 1800s, the Pennsy set up an engine with an injector directly over the crown sheet, and let the crownsheet overheat. Then they sprayed water from the injector (remotely operated, of course) onto the red-hot crownshet in an atempt to get it to explode on purpose. They were unsuccessful.

I'll see if I can find that article--it was posted to RYPN a while ago, in a thread on that very subject.

EDIT: He's the article:

And here the RYPN thread, which is very interesting reading.

I have always heard that if there is any suspicion of low water, do NOT try to add water to the boiler. Dump the fire and get out over the water deck of the tender.

With regard to boiler washes, NYC policy on "mainline power" was to perform a boiler wash every 15 days.

Finally, I read somewhere that a fireman noticed how water treatment pellets were very good at cleaning grease from his hands, so he took some home to his wife with instructions to add one when she washed his overalls. After the wash, she could not find the overalls at all, just some shiny buttons! (I don't know whether this is true or not, but it makes enjoyable reading!)

INJECTOR QUESTION:

I know that water has to be admitted to the boiler at a pressure exceeding boiler pressure...how is this done?

With a high-pressure water pump from tender to boiler?  Is this the "injector"?

Also, why does the firebox grate slope down and forward?

Thanks, steam guys! 

BAD ORDER HAROLD

Feedwater pumps and injectors are different.

I personally think the injector is a simply amazing piece of engineering--it takes steam out of the boiler, at, say, 200 psi, mixes it with water, and shoots it past a check valve in the boiler which is being held shut at that very same 200 psi. Mechanical engineers at the time thought it was akin to perpetual motion; like someone being able to raise himself off the ground by pulling up on his own boot straps.

The key lies not only in the "pressure head" of the steam that is pushing the water, but the addition of the "velocity head" of the water's movement which provides just enough extra force to get past the boiler check valve.

The neat thing is, Henri Giffard, the injector's inventor, was a quite-famous aerialist at the time--the 1850s. He invented the device in 1858 as an efficient way to power balloons!

(If you want more info, the book "Practice and Theory of the Injector" is pretty good for the price).

HW can tell you about FW pumps--I've never run one.

There is no way this topic can get any better.....

but everyday, it does just that.

Gets better and better. Thank you gentlemen.

quote:

(If you want more info, the book "Practice and Theory of the Injector" is pretty good for the price).

Save yourself some money and read the following. Keep in mind that this is a big pdf file. It takes some time to load, but, you won't be disappointed.

Locomotive Boiler Feeding Devices

All the Steam questions you were afraid to ask but wanted to know....

Since we are talking Feed water pumps ... what do they do and what is the difference in the Elesco and Worthington type? Any reason why there were mounted to the top of the smoke box?

DEAR CNGW,

As the member who introduced the topic (without knowing much about it), I feel good, but surprised, that the thread expanded as much as it did!

All contributors are very knowledgeable about the dangers of low water in locomotive boilers, and many have contributed interesting and informative stories of those dangers.

I'm proud to have been the "kickoff" of this great thread!

Bad Order Hal

Well, as noted, the steam tractor explosion was not at the Ohio State Fair, but on the

Medina Co. Fairgrounds, where they have one or more train shows annually, and is

some distance northeast of the state fairgrounds in Columbus.  Because of that

accident, a farm tractor show in Greenville, (western Ohio), (it was a county fairgrounds, so I presume the county acted) banned all the steam

tractors, and those enthusiasts acquired their own grounds a few miles north, so

they could continue to display and operate.  There was a major steam tractor

show on another grounds in eastern Indiana, Portland, but I don't know if that still goes on.

Not bad, but pretty basic. If you want to immerse yourself in Injector theory, the book I recommend is better (I have both). Of course, the mathematics in it make my head spin.

And here is your answer to feedwater pumps and more (again a big file, wait for it).

Feedwater Heating Equipment

Feed water pumps are exactly what they sound like - a pump to mechanically force what into the boiler.  Elesco and Worthington I believe are the brand names of feed water heaters. 

A feed water pump can work just like a steam powered piston air compressor, the steam piston is connected to the air piston and the greater pressure available in the steam piston can force the air to be compressed.  for a feed water piston pump the steam piston would have to be larger than the water piston.  More commonly available was an axle driven pump, which obviously would not work if the loco was standing still.

A feed water heater uses the heat from the locomotive exhaust to preheat the water before it is injected into the boiler.  this is a huge efficiency boost for the engine.  you are taking leftover heat the you have already paid for and increasing the water inlet temperature, reducing the amount of additional heat needed to raise the pressure and phase change from liquid to vapor.  The visible portion is located above the smoke box because that's were the exhaust is.

Utility scale boiler plants still do the same basic thing only they call the feedwater heater an economizer.

Hope this helps

And yes, in eastern Indiana, we have two steam/tractor shows, one here in Fort Wayne that's usually held the same weekend as the FWRRHS open house (the show gounds are right around the corner from the 765...) and one in Portland IN. the following weekend. Usually they are the 3rd and 4th weekends in August, IIRC.

Wow, I just discovered this thread this evening and it has taken me an hour to get through it, like a good book you can't put down. It got even better when what's his name dropped out.

.....

Dennis