730 Old Boiler Dissection

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Glenn Brooks
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Re: 730 Old Boiler Dissection

Post by Glenn Brooks » Sat Oct 05, 2019 5:44 pm

Dave, seems to me the flat top crown sheet boiler design is a major cause of this boiler’s demise. As once the Water level drops to the crown sheet , the whole crown sheet will become actively exposed to oxidation e.g. rusting and corrosion. Next factor could be excessive aeration of the water supply, then an active electrolyte ( see all the sediment in the water legs -this was in an active solution at!Some point triggering more Rapid corrosion ) and finally add in High heat from pressurized steam, and you have the perfect recipe for rapid crown sheet oxidation. Think about a sauce pan cooking on the stove boiling out all its contents. The whole bottom surface of the pan becomes scorched and damaged when the water gets too low. The damage always occurs on the side opposite the fire.

More importantly, the most active oxidation occurs at the water steam interface. This is why you see stay bolts corroding away at the water interface in the boiler where steam is generated.

Somehow because of these factors at the crown sheet, the boiler just ate itself up. That’s my theory anyway.

Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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ccvstmr
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Re: 730 Old Boiler Dissection

Post by ccvstmr » Sat Oct 05, 2019 6:29 pm

Fender wrote:
Mon Sep 30, 2019 3:37 pm
Glenn Brooks wrote:
Mon Sep 30, 2019 2:54 pm
One thing that struck me about this boiler design is that the builder looks to have built the crown sheet flat on top, with very sharp radius corners. My two boilers, a code boiler in 1950, the other, a riveted boiler from early 1900’s both have round crown sheets - no flat top surfaces, and very smooth, large radii edges - almost circular in design. Certainly elipitcal. They both are in excellent condition, current ultrasound shows almost no reduction in sheet thickness. The picture is the 1900’s boiler.

I am wondering if the flat crown sheet contributed to this boilers early demise. Also wondering if the steel formulation was not appropriate for boiler construction...

Glenn
Some very interesting points. At this point, the type of steel used is probably unknown. Was pressure vessel quality steel (such as SA516) used, or something else? Did the radius of the curves and type of steel used contribute to the deterioration in the corners? What boiler water treatments were done, and were they effective?
From the quantity of scale or rust in the firebox sides, my guess is that ineffective or little water treatment and cleaning of the boiler is the biggest factor in the thinning of the sheets.
Sorry Dan, guess I never got back to addressing your questions. So, let me try and make that up now considering each of the points made...

1) steel(s)...correct, don't know what kind of steel was used to fabricate the original boiler. Flat sheets were MOST LIKELY cold rolled steel the builder got from his place of employment. Most likely NOT boiler rated. The DOM tube for the boiler barrel...no idea where that came from. Don't believe DOM tubing is "certified" boiler material either. Suspect the original builder figured...if/when the boiler failed, he would build a replacement. Didn't matter how much time was on the boiler or other factors contributing to an early(?) boiler failure.

2) firebox radius curves...photos of the cut apart boiler show the radius. Too tight? Can't answer that. The larger the radius, the less stress put on the steel to form the curve. Will simply ask...does stressing the steel open the "pores" on the outside radius of the bend? This is hard to tell in the photos since the saw cut thru the welds around the stay bolts and might give a false impression of fire side steel decay.

3) water treatments...don't know if water treatment (if any) was used by the builder until the locomotive was purchased. Once under my ownership, various types of treatment were used. For several years, used LSB8000. LSB was not intended for pH control. After reading some comments about the LSB material used in West Coast locos, switched to TSP...tri-sodium phosphate to get the pH up. Did this for several years before being introduced to a granular commercial boiler compound from Aquaserve. Wish I could get MORE info on this compound. The A/S compound was used in conjunction with the TSP until the boiler failure. Was this the "best" water treatment program to use? Can only go back to the fact that the boiler lasted 23 years of moderate to somewhat heavy use. Was the service time good or bad? And could that time have been extended with alternate treatment practices? Can't answer that. Will address the internal boiler residue in another post.

4) cleaning/flushing...was not performed. As bad as this might have been...out of sight, out of mind. When looking across the front mud ring thru the blow down valves...the mud ring was clear. Would later find out...that was NOT a true indication of what was going on at the front of the boiler barrel or the remaining water legs. Will add...if the crown sheet had survived, it was only a matter of time before the firebox water legs burned thru, bulged, or other.

Thanx for the questions, comments. Moving on... 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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ccvstmr
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Re: 730 Old Boiler Dissection

Post by ccvstmr » Sat Oct 05, 2019 6:43 pm

rkcarguy wrote:
Wed Oct 02, 2019 12:35 pm
What about thickening the crown sheet, or potentially fire brick the fire box top and sides to eliminate that? Even if it means having to fit an extra tube or two into the boiler to make up for the lost heat transfer area of the top of the firebox to the boiler? Because it's directly above the fire it's going to be the hottest spot by far.
RK...original Rutland boiler was built with a "square" firebox. Had a total of (17) flues with turbulators. Steamed well. No complaints there. The new boiler was fabricated with a key hole firebox. Total number of flues was now (28). Turbulators were installed once again. Believe the firebox side sheet were thicker than the original boiler. In addition, the (2) halves of the fire box were slightly crowned where (from the forming operation) and welded along the center line.

The stainless steel arch was modified (shortened the height) to maintain proper clearance between the arch and the crown sheet. Material removed from the height, was used to elongate the horizontal section of the arch. Arch length was 2/3 to 3/4 the length of the firebox. "Side wings" were welded on the underside of the arch to form an inverted scoop to force hot gases towards the back of the firebox.

Hard to say where the hottest spot in the firebox was located as the arch shields direct flame impingement from most of the crown sheet. A thicker crown sheet? S'pose that's possible, but would creates more welded seams in the firebox. Just my 2 cents....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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ccvstmr
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Re: 730 Old Boiler Dissection

Post by ccvstmr » Sat Oct 05, 2019 7:06 pm

A number of readers/contributors have commented about water aeration. Allow me to describe the water system at my local club.

Two buildings with a combined roof area of approx. 1400 sq. ft. are used to collect rain water. This water flows to an intermediate stainless steel collection tank of some 50 gallons where it is then transferred via a sump pump to a 2100 gallon stainless steel holding tank. The tank was originally used as some kind of silo in a food processing plant.

A pool pump with pressure switch is used to pump water to (2) hoses in the steaming bay area for filling boilers and tenders and (3) trackside stainless steel water tanks with float valves to admit water for topping off. The entire system is pressurized. As soon as a float valve opens or a hose end valve is opened...the pump kicks on to maintain distribution piping at a 40'ish psi pressure. A couple times a year, a gallon of bleach is poured into the system and pumped into the main holding tank for organic material growth control. One of the club boiler specialist members didn't see 1 gallon in 2100 gallons as being detrimental to boilers.

As described, there's a number of points where the water gets stirred and oxygen mixed into the water supply. How the water is dispensed into a tender or boiler...may be trivial compared to the water distribution system. Mentioned in another thread, when prepping the loco for operation, usually wait until the safety valves lift (to check operation) and disperse whatever oxygen might be in the boiler.

Starting with the new boiler, have been adding granular sodium sulfite to my tender water for oxygen scavenging. The stuff isn't that expensive as noted elsewhere in the thread. The idea of using this was two-fold. 1st...the component for oxygen scavenging. Although I've heard...unless the water can be at rest for a while with the chemical...a tender on-demand treatment might not provide much scavenging value. 2nd...the sodium component helps with pH control in addition to whatever might be in the granular boiler treatment when trying to reach pH's greater than 9.

As info...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 » Sat Oct 05, 2019 8:30 pm

Carl,
This has been a most detailed and informative “autopsy” of your old boiler, and I appreciate the effort you have put into this. Kudos to you!
Dan Watson

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NP317
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Re: 730 Old Boiler Dissection

Post by NP317 » Sat Oct 05, 2019 10:04 pm

Carl:
Thank you for your efforts to share your experience.
Priceless.
RussN

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BigDumbDinosaur
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Re: 730 Old Boiler Dissection

Post by BigDumbDinosaur » Sun Oct 06, 2019 2:22 pm

I'll second the others. Although I don't do steam railroading, I do have an interest in what is going on inside a boiler, and found this "autopsy" an interesting read.
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Fender
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Re: 730 Old Boiler Dissection

Post by Fender » Sun Oct 06, 2019 4:50 pm

I’m in the process of building a boiler for a new project, and plan to incorporate some of the features discussed in this thread, as well as some others I have learned about. High on the list: washouts on all corners of the fire box, as well as above the crown sheet, rounded corners and top of the crown sheet, and water legs at least 5/8” wide. Also, a removable steam dome, so that the inside of the rear tube sheet is accessible for cleaning. This, in addition to controlling the pH of feedwater and using an oxygen scavenger. I’ve had good reports on the LSB product so will use that too. Of course, having washouts in the boiler doesn’t help unless you “wash the boiler”!
Dan Watson

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ccvstmr
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Re: 730 Old Boiler Dissection

Post by ccvstmr » Sun Oct 06, 2019 6:59 pm

Dan, Russ and BDD...

Appreciate your comments. Glad to know the information and experiences (?) provided in this thread, are helping fellow live steamers!

Learned at work many years ago, it's sometimes better to know what NOT to do...than to know what to do! Used to say some of the specifications I helped draft were "specifically vague". We might not have known exactly what we wanted...but we knew enough to know with certainty what we didn't want...THAT'S EXPERIENCE!

Another time when my sarcasm was being peaked...was when management wanted us to do these 360 reviews...where colleagues, customers (engineers in the plants) and suppliers were to provide feedback regarding my knowledge, experience, performance, etc. Naturally, I twisted this around a bit. And provided the following as a revised 360 review:
Q: How did you get so good at your work?
A: Made a lot of mistakes.
Q: Why did you make a lot of mistakes?
A: How else do think I got the experience!

Boilers and boiler treatment is one of those areas where there are many factors involved. There are numerous variables to consider when looking at water chemistry. And then when you're done running...what's the best/better way to bed down the locomotive? I'm still trying to find that best combination of methods that's realistic and practical (which reminds me...forgot to remove the safety valves after I got done running today). When the locomotive is stored 20 minutes from the house, it's not like I can drop everything to tend to the boiler.

All I can say to the Chaski community is...keep those questions, comments, personal experiences and photos (and more) coming. Your input IS invaluable! Stay tuned...there's still some more info to come. 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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ccvstmr
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Re: 730 Old Boiler Dissection

Post by ccvstmr » Mon Oct 07, 2019 9:42 am

Sedimental Journey

One of the puzzle pieces that I haven't described yet is in regards to the tan colored residue/sediment that's coating the boiler interior. I'll re-post the following photo...

IMG_1574.JPG

There is gentleman that frequents HDS Shop #2 to work on his model engineering project. We'll call him Tim ('cause that's what his name is). Tim is a retired chemist from BOC...British Oil Company (not to be confused with BP...British Petroleum). As long as the old boiler was still at HDS Shop #2, Tim performed a simple test on the boiler residue. I wasn't present when the test was performed (wish I was). As such the information was provided 3rd hand and then confirmed via email with Tim.

If Chaski readers remember some of their school chemistry, different elements and compounds have characteristic coloring. We all know iron oxide (rust) is reddish in color. Copper sulfate is blue-ish and so forth. Tim knew that "flaming" residues produce characteristic colors. He took a paper clip and burned off the plating to eliminate the contribution from the plating (most likely zinc) and then used the clip to hold a boiler residue sample and passed the sample over a flame.

Tim provided the following comment: behind the bright yellow sodium color was the characteristic orange red of calcium. This test is of course only qualitative but it is quite sensitive and will detect very low levels of an element. Tim went on to explain the resulting flame colors indicated the presence of both: 1) calcium and 2) phosphates.

Tim noted the calcium was typical of ground/well water. This comment caught my attention. While the boiler may have been fired with ground water for 5 years prior to my purchase, I used the club's collected rain water MOST of the time. The exception...when visiting other tracks where the local water supply was well water. During the last 17 years of boiler operation, the amount of well water used compared to rain water was considerably less. At a recent meet, ran into a guy with his own portable RO (reverse osmosis) filter system to remove well water minerals. He was kind enough to let me use his RO water during the meet. On the down side, it does take some time to pass enough water thru the RO membrane to produce any quantity of water. Want more water faster? Get a larger membrane canister.

Was not surprised about the phosphate finding. This made sense. I was treating the water with TSP...tri-sodium phosphate for pH control. Figured the "tri-sodium" would provide 3x the bang for the quantity of material used. In hindsight, might have been "over-phosphating" the boiler. There are other sodium compounds that can be used for pH control. Such as sodium sulfite which should help pH control in addition to providing whatever oxygen scavenging. However, oxygen scavenging in an "on-demand" basis from the tender might not produce adequate or desired results. Another possible compound is sodium-bicarbonate...otherwise known as baking soda. There's usually several leftover boxes in the laundry room my wife sets aside after using in the freezer for odor control.

Question now (in my mind)...what's a good way to control (read remove/reduce/eliminate) scale build up? Had been thinking about using CLR. While reviewing the CLR fine print, the manufacturer did NOT recommend use where copper was present. Whoops...took this to mean CLR was not suited for boilers with copper flues. There are other descaling solutions out there. With one-half of the old boiler left as is, the other boiler half was cut up. Will be easy-er, to try different descaling solutions. Any readers have any experience with descaling solution?

These findings provide an interesting look back at boiler water treatments. Although with several treatments used over the years, there's no way to say which, of any, was better than others. Good, bad or indifferent...it was too late to do anything for the old boiler. 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 » Mon Oct 07, 2019 10:03 am

Carl,
I use a diluted solution of NaOH (lye) to boost the pH. Used with care, it does work.
Dan Watson

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Re: 730 Old Boiler Dissection

Post by Soot n' Cinders » Mon Oct 07, 2019 1:23 pm

Fender wrote:
Mon Oct 07, 2019 10:03 am
Carl,
I use a diluted solution of NaOH (lye) to boost the pH. Used with care, it does work.
Same here. I put about a tablespoon of washing soda, sodium carbonate, directly into the boiler to buffer my ph. The soda will dissolve and form lye in the water and the excess creates a buffer that holds my boiler around 10.2pH.
One word of caution, do not put lye in anything galvanized. The zinc galvanizing will react with the lye to form zinc salts thus prematurely wearing out the galvanizing. My tender tank is galvanized steel and figure this out after finding weird residue in the tank. Didnt cause any damage yet but there was definitely a reaction.
-Tristan

Projects
-2.5" scale Class A 20 Ton Shay

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