730 Old Boiler Dissection

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makinsmoke
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Re: 730 Old Boiler Dissection

Post by makinsmoke »

If you are running a lye solution in your boiler should you be concerned about sitting behind the Loco when it pops off?

Lye in the eyes seems problematic.
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Fender
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Re: 730 Old Boiler Dissection

Post by Fender »

Sodium hydroxide is a chemical commonly used for pH adjustment. I’ve even seen it on the list of ingredients for eye drops! But you only need a small amount in the boiler water to raise the pH to the desired level. True enough, in concentrated form it is quite toxic.
Dan Watson
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Glenn Brooks
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Re: 730 Old Boiler Dissection

Post by Glenn Brooks »

Carl,

have you been able to clean up the staybolts? I am curious how thick was the calcium build up around the shafts, and if you observed much staybolt deterioration ?

BTw this is a really valuable thread for me. Very informative to actually see these effects - processes we all worry about but never really get to observe.

Thanks
Glenn
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rkcarguy
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Re: 730 Old Boiler Dissection

Post by rkcarguy »

makinsmoke wrote: Tue Oct 08, 2019 9:28 am If you are running a lye solution in your boiler should you be concerned about sitting behind the Loco when it pops off?

Lye in the eyes seems problematic.
"Earl fell off his tender and died, what happened?"

I agree, safety factor of these additives you'll likely be breathing in as you operate your steamer?
This thread and the cut open boiler are extremely valuable, one should be able to take some, or all of the precautions when fabricating their boiler and using their steamer and hopefully have their boiler last much longer.
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Fender
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Re: 730 Old Boiler Dissection

Post by Fender »

rkcarguy wrote: I agree, safety factor of these additives you'll likely be breathing in as you operate your steamer?
Well, you don’t think it’s safe in small quantities in a boiler, but it is ok in eye drops? Look, concentrated NaOH is very caustic (aka Caustic Soda) but isn’t a big deal in the minute quantities used for boiler treatment. Also, it isn’t present in the steam unless the boiler is foaming. If one uses reasonable care in mixing, it’s perfectly safe. Much more to be concerned about with coal and oil smoke from the stack.
Dan Watson
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NP317
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Re: 730 Old Boiler Dissection

Post by NP317 »

Think:
Distilled. Water vapor only.
That's what is getting in your face, unless major priming or foaming is going on.
So don't let that happen...
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Re: 730 Old Boiler Dissection

Post by ccvstmr »

Glenn Brooks wrote: Tue Oct 08, 2019 11:11 am Carl, have you been able to clean up the staybolts? I am curious how thick was the calcium build up around the shafts, and if you observed much staybolt deterioration ?

BTw this is a really valuable thread for me. Very informative to actually see these effects - processes we all worry about but never really get to observe. Thanks Glenn
To Stay, or Not To Stay

Noted a couple weeks ago I'd get measurements on boiler shell thicknesses. Decided to measure some stay bolts at the same time for Glenn and anyone else interested.

Let's start with the stay bolts. Saving the fireman's side of the boiler for a display, the engineer's side boiler was further cut crosswise into several sections. The firebox was not exactly cut in half. Looking at the photo, the left piece appears smaller than the right. This was just a matter of foreshortening. Measured a couple stays WITH deposits...and knocked the deposits off to measure the remaining stay. Here's what I got...

xxIMG_2119.jpg

Can't say what the diameter of the original stays were...5/16"? ...1/2"? With (1) remaining stay at 0.365"...if I was a better person, would say all stays probably started at 1/2" diameter. The residue build up was substantial. What remained of the stay even more concerning...but not as much concern as the following boiler measurements...

xxIMG_1574.jpg

The boiler barrel and all other flat surfaces with the exception of the crown sheet exhibited what I would say was minimal degradation. Suspect the DOM boiler barrel was nominally 0.250" thick (or whatever mill tolerances allowed). Where numbers exceeded this value...there might have been a burr remaining from the band saw cut or some residue on the surface.

The rear flue sheet which was replaced in 2005 when the boiler was re-flued...might have been 5/16" boiler plate.

Of greater concern, was the flue sheet. 0.034" at the front, to 0.101" in the middle, to 0.118" at the rear. Discussing these numeric values, and someone might have mentioned this in an earlier post that...due to the violent nature of boiling water to make steam over the crown sheet, this reaction MIGHT have a tendency to erode the crown sheet. Therefore, perhaps the erosion was more so on the water side than the fire side.

Will add...believe the 1st firebox arch was installed by the builder when he converted the Rutland to propane fuel firing (sorry, don't know the year that happened). Upon my purchase and replacing the builders home-made burners with commercial rose-bud or slotted cap burners (Sept. 2002)...a new stainless steel arch was installed. With the arch "protecting" the front 1/2 to 2/3rds of the crown sheet from direct flame/heat impingement... why would the crown sheet decay so badly towards the front (realize this might be a rhetorical question)? Once again, more questions than answers. But this was an interesting idea.

Carl B.
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rkcarguy
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Re: 730 Old Boiler Dissection

Post by rkcarguy »

The upper portion of the tube sheet is pretty much gone. It corresponds with being the hottest area of the boiler. Could be a good case for making the crown and tube sheets on the firebox end much thicker in future builds, even if one has to add a few more tubes to offset the loss in heat conduction?
ccvstmr
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Re: 730 Old Boiler Dissection

Post by ccvstmr »

rkcarguy wrote: Sat Oct 12, 2019 1:26 pm The upper portion of the tube sheet is pretty much gone. It corresponds with being the hottest area of the boiler. Could be a good case for making the crown and tube sheets on the firebox end much thicker in future builds, even if one has to add a few more tubes to offset the loss in heat conduction?
Sorry rk, guess you and I are not seeing the same thing. Perhaps you're seeing the opening where the flue was.

Far as I could tell, the upper portion of rear flue sheet was still in good condition (was only 15 years old in a 23 year old boiler). Perhaps a couple more pix would explain what I saw. Note: the top flue was slit in half when the boiler was parted...

IMG_1579.JPG
IMG_1778.JPG

There wasn't any unused space in the rear tube sheet to add additional flues. So there was no way to add more flues. In fact, the guy that did the flue sheet replacement, told me he had to downsize (4) flues (2 on either side) that ended up too close to the firebox side sheets.

Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
I don't walk on water...I just learned where some of the stepping stones are!
I love mankind...it's some of the people I can't stand!
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Fender
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Re: 730 Old Boiler Dissection

Post by Fender »

One conundrum about boiler wasting in our models: why do live steam steel boilers (particularly fireboxes) waste away so much faster than full-size locomotive boilers? A typical live steamer has a firebox that is 0.25” thick when new, but a 1:1 firebox is anywhere from 0.375” to 0.500”. The life of the large firebox is often many decades (sometimes a century!) but 20-30 years is about the most to expect on a live steamer.
A big difference I see is the way the boilers are operated. The full-size boiler is usually only drained monthly, for the customary wash-out.
The rest of the time, it remains filled with boiled, mostly de-oxygenated water, except in winter. Also, the boiler water has a natural tendency increase in pH the longer it stays in the boiler.
The typical live steam boiler is refilled at the beginning of a session, steamed a day or two, then blown down, and rarely washed out. Each time it is refilled with water that is mostly oxygenated, with unknown (but often low/acidic) pH. Between firings, the boiler is stored in a “damp” condition.
I realize this is not true for all live steam boilers, but is nevertheless typical.
Dan Watson
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rkcarguy
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Re: 730 Old Boiler Dissection

Post by rkcarguy »

ccvstmr wrote: Sun Oct 13, 2019 5:57 pm
rkcarguy wrote: Sat Oct 12, 2019 1:26 pm The upper portion of the tube sheet is pretty much gone. It corresponds with being the hottest area of the boiler. Could be a good case for making the crown and tube sheets on the firebox end much thicker in future builds, even if one has to add a few more tubes to offset the loss in heat conduction?
Sorry rk, guess you and I are not seeing the same thing. Perhaps you're seeing the opening where the flue was.

Far as I could tell, the upper portion of rear flue sheet was still in good condition (was only 15 years old in a 23 year old boiler). Perhaps a couple more pix would explain what I saw. Note: the top flue was slit in half when the boiler was parted...


IMG_1579.JPG


IMG_1778.JPG


There wasn't any unused space in the rear tube sheet to add additional flues. So there was no way to add more flues. In fact, the guy that did the flue sheet replacement, told me he had to downsize (4) flues (2 on either side) that ended up too close to the firebox side sheets.

Carl B.
I was relating to the drawing with the dimensions added, but I guess that was the front of the crown sheet not the upper portion of the tube sheet.
If differential metals doesn't seem to be a problem, I wonder if the crown sheet could be made from something like 410 SS?
ccvstmr
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Re: 730 Old Boiler Dissection

Post by ccvstmr »

Fender wrote: Sun Oct 13, 2019 6:59 pm One conundrum about boiler wasting in our models: why do live steam steel boilers (particularly fireboxes) waste away so much faster than full-size locomotive boilers? A typical live steamer has a firebox that is 0.25” thick when new, but a 1:1 firebox is anywhere from 0.375” to 0.500”. The life of the large firebox is often many decades (sometimes a century!) but 20-30 years is about the most to expect on a live steamer.
A big difference I see is the way the boilers are operated. The full-size boiler is usually only drained monthly, for the customary wash-out.
The rest of the time, it remains filled with boiled, mostly de-oxygenated water, except in winter. Also, the boiler water has a natural tendency increase in pH the longer it stays in the boiler.
The typical live steam boiler is refilled at the beginning of a session, steamed a day or two, then blown down, and rarely washed out. Each time it is refilled with water that is mostly oxygenated, with unknown (but often low/acidic) pH. Between firings, the boiler is stored in a “damp” condition.
I realize this is not true for all live steam boilers, but is nevertheless typical.
Dan, that's as good as description of what can be going on as any. I'm not convinced dissolved oxygen content in the water is as big a factor as some make. However, believe one important factor was omitted in your discussion...fire up time.

Generally speaking, live steam boilers are brought up to pressure in 20-60 minutes...depending on the type of fuel and the size of the boiler. Real size locomotives took several hours to build a head of steam. Perhaps there's a thermal stress factor involved with our boilers causing "rapid" expansion (and contraction during cool down) of the firebox surfaces.

We tend to think of steels as being solid materials. But steel sheets have "grains" from the rolling process akin to wood. The problem could be made worse, when a steel sheet is formed to make bends. One side of the sheet is under compression, the other side under tension...is stretched... thereby opening the "pores" in the steel and exposing the insides of the material to water. Will point to the old 730 boiler photos of the firebox corners that show extreme degradation. If this is a problem, the affect could be reduced by forming the sheet "at right angles to the grain" vs "with the grain". This is pure speculation.

Perhaps we should slow down our fire-up rates. Here again, what's a good time frame? It's not practical to take half a day to reach pressure. And in the end...how much might that practice extend the boiler life? Not sure anyone can answer those questions. Interesting stuff though. Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
I don't walk on water...I just learned where some of the stepping stones are!
I love mankind...it's some of the people I can't stand!
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