730 Old Boiler Dissection

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Glenn Brooks
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Re: 730 Old Boiler Dissec

Post by Glenn Brooks » Tue Oct 01, 2019 10:25 pm

Carl,

We owned sailboats and commercial fishing boats for 45 years. I just don’t see galvanic corrosion being an issue in live steam boilers. Fresh water is just not a significant conductor. But it is a big deal in boats immersed in salt water, as salt water is an excellent- indeed the principle conductor of stray electric current. And generally insignificant for boats in fresh water. Also, many salt water marinas are considered extremely “hot” because of mucho stray electric current from dock side leakage, and, other improperly wired boats. In these circumstances electric current exacerbates galvanic corrosion - greatly.

Now, a more significant concern in boilers is steel oxidation caused by excessively aerated water. Indeed this may be the most significant cause of your crown sheet failure. Steel oxidation, E.G. Rust, is basically caused by steel immersed in water, oxygen and heat - the exact optimum conditions we experience when making steam. Firing with the flat crown sheet, aerated water, and particularly, repeatedly operation with low water in the boiler, would burn out the crown sheet across its width in no time - just as we observe in the photos.

A quick story: last year, I talked to the fellow who owns and operates the Folsom Valley Railroad - a 12” gauge commercial miniature train operation in City of Folsom’s park, just outside Sacramento. http://folsomvalleyrailway.com/history

He operates 7 days a week, year round- so constantly firing one of his two steam locomotives. Two years ago he had a new code boiler built and installed on Cricket- Eric Thomson’s old Loco. A beautiful Ottaway.
3C29D28C-F38D-48B1-87B0-7DB93275369F.jpeg
Anyway, after two years, the crown sheet in the boiler failed. After extensive technical analysis, including an on-site inspection and operating audit by a water quality lab, he determined the boiler failure was caused by excessive oxygen mixing in his water supply. He used to use a traditional elevated round water tank to fill his tender two or three times each day. You can see part of it in the snapshot. Lower the pipe, fill the tender- very cool theming for the customers to watch. Anyway, this gravity feed water tank aerated his water supply and killed his boiler.

Now he fills the tender from a hose, laid quietly on the bottom of the tender- so that no, or at least minimal aeration can occur, and religiously uses water treatment with each fill up.

Pretty clearly, your other big problem is sedimentation that precipitates out of hard water. So, probably the prior owner never used water treatment - resulting in the excessive white scale buildup in your water legs.

I think it would be real informative to see what the staybolts look like, underneath the scaling.

Anyway, go with the rounded crown sheet and kill the O2 and you’ll be ahead of the game!

Good luck,
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

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rkcarguy
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Re: 730 Old Boiler Dissection

Post by rkcarguy » 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.

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Marty_Knox
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Re: 730 Old Boiler Dissection

Post by Marty_Knox » Wed Oct 02, 2019 5:42 pm

Fender wrote:
Sat Sep 28, 2019 9:04 pm
As far as condemning limits, I seem to remember that a loss of 40% of the original thickness indicates that replacement is warranted. I suppose you’d need to consider the original factor of safety too. Maybe Marty can correct me on this?
FRA regulation (CFR49:230.33) states: Wasted sheets shall not be repaired by weld build up if the wasted sheet has been reduced to less than 60 percent of the minimum required thickness as required by this part.
In other words, if you've lost more than 40% of the original thickness the sheet needs to be replaced.

Soot n' Cinders
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Re: 730 Old Boiler Dissection

Post by Soot n' Cinders » Wed Oct 02, 2019 6:30 pm

With all this talk of issues from excessive aeration, would it be worthwhile for us to add oxygen scavenger to our boiler treatment regimens? I use LSB already but from what I understand, there is nothing for oxygen in there. Just a pH buffer and some chemicals to keep solids in suspension.
-Tristan

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rkcarguy
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Re: 730 Old Boiler Dissection

Post by rkcarguy » Thu Oct 03, 2019 4:35 pm

I think its most important to just use good water, drain and dry the boiler after each use, and maintain the proper PH. I know in many applications a "basic" PH is preferred but I don't remember the target #.

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Fender
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Re: 730 Old Boiler Dissection

Post by Fender » Thu Oct 03, 2019 5:07 pm

rkcarguy wrote:
Thu Oct 03, 2019 4:35 pm
I think its most important to just use good water, drain and dry the boiler after each use, and maintain the proper PH. I know in many applications a "basic" PH is preferred but I don't remember the target #.
My information is that a pH of 9-10 is best for a steel boiler with copper flues, and 10-11 for an all-steel boiler. High pH will pretty much eliminate corrosion. Oxygen content can have a significant effect. I’ve heard of boilers failing in just a couple of years when water with excessive oxygen (or chlorine) was used. If an oxygen scavenger such as sodium sulfite is used, remember that a little goes a long way. Too much will cause foaming.
I agree that drying the boiler between runs is also important.
Dan Watson

Glenn Brooks
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Re: 730 Old Boiler Dissectio

Post by Glenn Brooks » Thu Oct 03, 2019 7:50 pm

I remember a recent thread on aeration here on Chaski from a few months ago - or was it last winter???? Can’t remember. It contains some good detail about this same topic.

anyway because of that thread, I did some background research on local PH and oxygen scavengers - trying to figure out what and if I should use anything to attack oxygen and treat the water.

I then called our local water district water quality person. He informed me our water supply in the Pacific NorthWest, and perhaps all of the west coast, differs greatly from most of the rest of the country. Here in the PNW we have mountain snow melt- surface reservoir water delivery for our water supply. Typically the rest of the country pumps water from deep aquifer limestone formations. Hence the Midwest and east coast usually have high concentrations of dissolved minerals and sometimes off the chart PH. So in those areas you would need water treatment. Our spring snow pack melt contains very little mineralization and a reasonably neutral PH. I think it’s around 9-10, or thereabouts. So no treatment is required. Locally, the water quality guy hasn’t seen any mineralization in local boilers in over 20 years.

Two critical points, the water quality guy said anyone can test for PH with a pet store Aquarium test kit- it’s cheap and easy.

Second key point, once you know the PH and mineral content, it generally doesn’t change over the one term....you can treat each tank consistently, without having to test all the time.

Lastly, I tracked down whomever produces LSB 4000 water treatment, and the 6000 product. They confirmed the product DOES NOT scavage oxygen. There’s nothing in it to treat excessive aeration, only water hardness, e.g. mineralization.

So regarding oxygenation, I adopted two methods to reduce excessive aeration:

1)VENT THE BOILER WHEN FIRING - first vent your boiler during firing- heated water drives off the oxygen, so crack the pop off value during initial steam up, and the oxygen from inside the boiler water will vent and not get recycled through the tubes and water chambers, (thanks to Russ Noe NP317 for this tip)

2) FILL THE TENDER WITH A SLOW RUNNING HOSE: gently let water flow into the tender tank, from the bottom - So as to not disturb the surface of the water in the tank while filling. And DO NOT SQUIRT OR DUMP large quantities of water into the tender. Also do not fill up from a gravity feed water tank; dumping water through a trough, or hose nozzle aerates the flow just as a mountain stream would do. (Grateful to the Folsom Valley Railroad for this technique).

I think also, one could mix in sodium sulfite as Fender suggested. However, I don’t know where to find small quantities (yet) and haven’t researched what PPM, really PPG (parts per gallon) to use. Also I haven’t a clew how many actual gallons my tender holds. I guess I should measure the tender and find out- one of these days....

Cheers,
Glenn
Moderator - Grand Scale Forum

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

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Fender
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Re: 730 Old Boiler Dissection

Post by Fender » Thu Oct 03, 2019 8:52 pm

A neutral pH value would be 7. Ideally the boiler water should be a higher pH, in the basic range.
If you google "sodium sulfite anhydrous" you will find several mail-order suppliers that sell a one-pound jar for less than $10. I use just a few ounces dissolved in a pint of boiling hot water, which will go a long way in removing the oxygen. You don't want to use too much of it.
Pool supply stores sell liquid chemicals to raise pH, and test strips are available to test the water. I prefer the strips that have multiple color swatches, because they are more accurate in the high pH range.
Glenn is right about the water quality varying. Here in TN/GA, water tends to have a very low pH, sometimes only 4-5. Hardness varies a lot, depending on whether it is ground water (from a well) or surface water (typically from a river or reservoir).
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Greg_Lewis
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Re: 730 Old Boiler Dissection

Post by Greg_Lewis » Thu Oct 03, 2019 9:30 pm

Fender wrote:
Thu Oct 03, 2019 8:52 pm
If you google "sodium sulfite anhydrous" you will find several mail-order suppliers that sell a one-pound jar for less than $10.
Here's one source that will sell from 10 grams to 50 lbs.: http://stores.photoformulary.com/sodium ... anhydrous/
Greg Lewis, Prop.
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Soot n' Cinders
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Re: 730 Old Boiler Dissection

Post by Soot n' Cinders » Thu Oct 03, 2019 10:17 pm

Fender wrote:
Thu Oct 03, 2019 8:52 pm
A neutral pH value would be 7. Ideally the boiler water should be a higher pH, in the basic range.
If you google "sodium sulfite anhydrous" you will find several mail-order suppliers that sell a one-pound jar for less than $10. I use just a few ounces dissolved in a pint of boiling hot water, which will go a long way in removing the oxygen. You don't want to use too much of it.
Pool supply stores sell liquid chemicals to raise pH, and test strips are available to test the water. I prefer the strips that have multiple color swatches, because they are more accurate in the high pH range.
Glenn is right about the water quality varying. Here in TN/GA, water tends to have a very low pH, sometimes only 4-5. Hardness varies a lot, depending on whether it is ground water (from a well) or surface water (typically from a river or reservoir).
As someone who works in the pool industry, dont get the liquid chemicals. Too easy to splash and they will definitely give you chemical burns. Get dry pH increaser, or a box of Arm & Hammer washing soda. Both are sodium carbonate which will form sodium hydroxide, or lye, when mixed with water. The washing soda is cheaper, but harder to find. Both are way safer than the liquid chemicals, especially if they spill in your toolbox or truck.
And water quality definitely varies a lot. Here in GA, our water is usually around 6.8 and only about 8-12ppm hardness. But our water here comes out of the Etowah River. Definitely way better than some of the well water in TN, Ive seen plenty of orange toilets in TN from the iron rich water.
-Tristan

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daves1459
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Re: 730 Old Boiler Dissection

Post by daves1459 » Fri Oct 04, 2019 8:26 pm

I've been reading this thread with great interest since it's beginning. There have been several explanations that I found very enlightening. BUT, can anyone explain or suggest why by far the greatest amount of rust or deterioration is on the crown sheet whether on the steam or fire side? If it were not for the deterioration of the crown sheet the rest of the boiler looks serviceable. In need of a cleaning, but still serviceable.

If water PH or lay up procedure were the problem wouldn't we expect entire firebox to be more eaten away then it is?

My current thinking is the rust inside of the firebox has to do with when the boiler is cold and sitting in an unheated engine house so subject to day to night temperature changes and condensation. But, the top side of the crown sheet being so badly corroded away makes me think the phenomenon may be occurring during firing while under steam. Could the water motion during boiling have washed the rust flakes over the sides into the water legs? If the crown sheet rusting was a result of the lay up would the rust flakes tend to remain stuck on the surface?

Is there something happening to a super heated crown sheet while boiling a shallow covering of water? Since the boiling is violent and there is a shallow covering of water maybe 1/2" deep or less could there be instant bare spots or? Could some sort of rapid heating and cooling accelerate the rusting process? I bet that during up and down hills sometimes the crown sheet is bare in the front and rear.

My first live steamer was a Little Engines 0-6-0 that I put steel boiler on with the firebox extended forward about three inches. I ran the wheels off it. After about 12 years I had the same failure as the subject boiler. I cut it open and it looked almost exactly like the subject boiler with one difference. It was a radial stay boiler and the front 2/3s of the stays were eaten off flush with the crown sheet and up about 1/2 inch. The rest of each stay was still in good shape and just hanging there like a stalactite.

Dave

wms6
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Re: 730 Old Boiler Dissection

Post by wms6 » Sat Oct 05, 2019 4:54 pm

ccvstmr wrote:
Tue Oct 01, 2019 2:59 pm
rkcarguy wrote:
Mon Sep 30, 2019 6:21 pm
I just realized something, so this boiler (the cut apart one) was originally steel tubes and they were replaced with copper.
Copper and Steel are a fair distance apart on the galvanic reaction chart, i.e. the steel will be consumed as the "anode" in the "battery". Heat speeds the process, and the crown sheets close proximity to the copper tubes (and all the brass fittings and valves at the control end) and increased heat would have made those copper and brass items the perfect cathodes to eat away the steel. Furthermore, the firebox side tube sheet would have experienced vertical water flow as the water was heated, which probably swirled at the top depositing additional "stuff" on that shelf of a crown sheet.
RK...good points. While I've heard only occasionally of some boiler operators installing sacrificial zinc or magnesium rods in their boiler...would think the hobby as a whole (generally speaking) is going to be in a big hurt!

Most steel boilers are now being build with copper flues. At some point as the boiler is mounted and piped, there's going to be a steel to brass/bronze interface for pipes or other boiler accessories. Does galvanic decay occur at such a rate steamers need to be overly concerned about? This is not something causing me to loose sleep (yet).

Here again, too many variables to take into consideration. I know some steamers that run 1x per month for 4 months during the Summer...with the boiler being drained between runs. Other steamers...running as much as 3x or 4x per month for as many running months as they can squeeze from early Spring to late Fall. Would almost believe...better care for a more frequently used boiler can outlast a boiler with less than desirable practices for an occasionally used boiler (have no data to substantiate that...but it could happen).

Internal water flow...having watched a local club member clean/de-scale a boiler with the steam dome removed...I can confirm the violent cyclonic water flow (rear to front) as the water is heated around the firebox, rises to the top, flows forward, cools and sinks to the bottom of the barrel to replace the water around the water legs. Not sure that flow could lift debris and deposit same on top of the crown sheet. Sorry, don't have that kind of background. In the Rutland boiler...if "sub standard steel" was used for the firebox, safe bet the same kind of steel was used for the girder stays implying lots of steel degradation.

Appreciate your thoughts on galvanic reactions. Carl B.
My dad's engine had it's first boiler cert in 1974 at LALS, steel with copper flues. It's still leak free and the bore scope shows things inside are looking great. It wasn't run much, just a few times a year. Water quality was always good and only the 1 blow down end of day. I'm going to add a couple of quick blow downs since I'll probably be running it more often.
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