Here is a revival of the previous thread, " They don't know what they don't know. " http://www.rypn.org/forums/viewtopic.php?f=1&t=35525
The power plant outage is complete, at least my part, so here we go...

Frankly, while it was a lively discussion, some of the comments turned into personal attacks, and that really turned me off. Let's start with a clean slate.

Essentially, when operating a carbon steel boiler, the pH of the boiler water should be controlled in the pH 10 range. The reason for this is to minimize the general corrosion rate of the carbon steel.

The traditional method of obtaining this water condition is by the use of Alkaline chemicals; Carbonates, which become hydroxides, Hydroxides themselves, which are potentially caustic in their concentrated form, and phosphates, which come in various sources and forms, and shift forms, based upon concentration.

The underlying and potentially most critical problem with using the Alkalies is that it is possible to have over concentration. The result of this is damage to tensile stressed steel. The concentrated alkali forms expansive crystals in the micro-cracks of the stressed metal. Riveted seams, staybolts and pipe threaded joints which allow weeping and seepage admit the alkaline water. Heat and evaporation, and / or crevice conditions concentrate the alkali into extremely high, caustic concentrations. The alkali crystals continue to grow and expand. The micro cracks become larger flaws and weakened points in the pressure vessel. Cracks formed along features like rivet joints eventually join up into major crack weakened areas. There have been many boiler failures over the years, due to this Caustic Corrosion Cracking.

This is the reason for needing daily or more frequent sampling and analysis on alkaline treated boilers. ASME and ABMA have established recommendations and upper limits on Phenolphthalein alkalinity ( P Alk ). To this I will add that it is well within capabilities to achieve the desired pH range while maintaining a conservative margin for safety against approaching the recommended limits of P Alkalinity.

The more modern approach, as demonstrated over 50 years of experience in utilities, industrial and marine applications, is the use of amine treatment. The amine cannot concentrate to produce a pH over about 10.2. It cannot go into the caustic range, even if boiled to dryness. It simply boils away with the steam. The big advantage is that it is self regulating and does not require daily chemistry checks to prevent Caustic Stress Corrosion.

It is recommended to monitor and regulate Total Dissolved Solids using a simple hand-held conductivity meter. The increase in TDS will depend upon incoming water quality and boiler loading. The treatment is fed proportionally with the boiler fill and makeup. As the boiler ' cycles up ', the TDS will increase. A really dirty boiler just starting on the treatment program will probably need to be blown down to maintain 2,500 Parts Per Million TDS ( or about 3,000 microsiemens, formerly known as MHOS of conductivity ). As a boiler becomes cleaner and conditioned, good dry steaming will be produced up to 3,500 PPM TDS or higher.

The comment has often been made, you cannot have ' one size fits all '. Agreed, the routine monitoring of TDS is what customizes the fit to the conditions.

Previous discussion included oxygen control and protection of boiler metal. Similarly, the traditional methods use various forms of sulfite as a chemical oxygen scavenger. The amount of sulfite required, using cold feedwater, means that a large quantity must be fed in attempt to maintain an active sulfite inventory in the boiler. As a reminder, sulfite and it's decomposition product, sulfate, are highly electrically conductive. They contribute disproportionally high to TDS and the tendency for foaming. All boiler water becomes an electrolyte, due to the concentration of salts and minerals. The use of sulfite also contributes toward mixed-metals galvanic corrosion. Being a sulfur salt, sulfite makes ordinarily soft and fluid scale and sediment ( calcium carbonate ) into a gypsum cement ( calcium sulfate ), which is a hard and tenaciously adherent scale.

The approach with the amine treatments is to contain a water soluble organic filming agent, typically poly acrylate. This forms a 2 or 3 molecule thin film on the clean boiler metal. Think of it as a wax job that goes wherever the water goes. Combined with the Magnetite Hydroxide produced by the amine, it protects where Apexior cannot be applied.

1. The polymer physically isolates the steel from oxygen and corrosive salts in the water.

2. The polymer electrically insulates against galvanic corrosion.

3. The thin and smooth organic film promotes nucleate ( many small bubbles ) boiling that is the most effective form of liquid convection, heat transfer and steam production.

The allegations of amine treatments presenting a health hazard are just that, a lot of hand waving and empty accusations with no substance in fact. I will state that amine treatment has been 100 percent adopted by the navy in both fossil and nuclear applications. Now think about all the submarine crews that have been in a closed environment with this treatment for 60 days or longer at a time. The turbine steam exhaust condensers have ' air ejectors ' which exhaust into the engine room. Any treatment decomposition products ( oxygen, carbon dioxide, nitrogen ) gets exhausted here. This gets circulated throughout the boat. That is 10's of thousands of people over the years, and no one has experienced any illness from it.

This is not a commercial or info-mercial. I want to advise my rail brethren of comparisons in technologies, programs and advances in technologies that result in superior performance and cost savings. Just because folks are running steam power does not mean that we have to be stuck in 1890 on boiler and engine preservation. If a superior bearing, lubrication or anti-wear material is available, it gets tried and adopted. No reason to make boiler chemistry an emotional issue, when other industries have 50 years of success with new technologies.

Thanks for real information - I think a lot of the emotional stuff is based on a lack of good technical information from the usual suspects in the sales end of things.

Moving along: if amines are used, are you saying here that it is not necessary to also use alkiline or oxygen scavenging addatives? I'm still not clear on what amine teatments do and don't do.

Thanks for all your information.

dave

Dave, Thanks for your response, direct and simple.

Not to get into anyone's proprietary formulations, but to bring to the ' open ', some of the formulary elements that may be included in a modern treatment;

DEHA - is an oxygen scavenger and passivating agent. from the Association of Water Technologists http://www.awt.org/certification/quiz4.pdf



While this is an highly appropriate choice, it works best where the feedwater is above 185 F. In the steam railway enviornment, we have cold, oxygen saturated water. Does that preclude using DEHA ? No, just be advised and adapt. The treatment will degrade over a 24 to 48 hours of exposure to oxygen. This is true in an open tank or a boiler in cold wet layup. The treatment is best applied when tender or tank water will be fed into a boiler within a day. A well known steam operation gravity feeds treatment directly into the injector supply lines. Sounds good to me.

Some excursion RR operators supplement ' out of the bottle ' treatments by the addition of Tri Sodium Phosphate ( TSP ). This boosts the pH and is compatible with another common formulary ingredient, Phosphonate. This is an organically bound form of phosphate. The iron-friendly properties of phosphate are legendary. The phosphonate delivers this in a pH moderated form, the chief advantage is that it is stable, slower acting and less hazardous to handle, compared to dry TSP.

Pure mountain spring water has it's advantages; low mineral content and TDS. However, in a ' down and dirty ' practical sense for carbon steel systems, pure water tends to be aggressive or " hungry " and corrosive. Let's add something to stabilize the water; phosphate is a good and iron-friendly thing in moderation, a few PPM.

Not everyone needs this supplement. It depends upon the water source. One size does not fit all. Have a knowledgeable consultant, one who has your best interest in mind. Look over his ( M/F ) shoulder and ask questions. It is only a ' Black Box ' if you let it be so.

For routine steaming operations, it is not necessary to add an additional or supplementary oxygen scavenger to the ' out of the bottle ' treatment. For weekend operations with cold or in-between transitional layup, cooling down from Sunday evening to Saturday morning, I highly recommend Nitrogen Blanketing. No oxygen in the boiler, no rusting and pitting, no degradation of the treatment already in the boiler water. Much less expense and trouble compared to letting the air in. Simple and easy.

How do the amine treatments work ? The pH boost by the amine and metal surface protection were previously described. To describe the cleaning process, I will make an analogy; It is like popping old shingles off a roof. The metal oxides and scale are bound to the solid boiler metal by thin films of oxide and mineral scale. The treatment has an affinity for solid metal. It is electrostatically a cathode ( + charge ) looking for an anode. The treatment itself becomes the anode ( - charge ).

When the bonds are broken, simple physics and mechanics takes over. The large particles, flakes and chunks fall to the bottom. The molecular size particles stay in solution / suspension. Honest answer; it is so small and there are so many variables, that it may be a combination of solution and colloidal suspension ( think chocolate milk ).

For a boiler that is just starting a cleanup treatment program, there will be a big load of large chunks. I have cleaned six wheelbarrows at a time of scale and crud out of 1, 000 gallon boilers upon first cleaning. As the treatment / cleaning process progresses, the debris becomes finer less in volume, eventually there is almost no solid debris. Instead of boiler solids, we have everything in solution or colloidal suspension which easily flows out the bottom blowdown.

Hopefully, some of your questions are answered, Dave.

As always, as a railfan, I enjoy visiting RYPN, and keeping up with developments. It seems I have often been a change agent. It can be an exciting life for a techno geek, as it draws fire from the status quo and skeptics of all varieties. This happens to be my technical and professional specialty, and the Ry preservation movement should be availed of the current knowledge and technology.

Well, yes and no........

I know TSP as a cleanser. Easy to see how it can raise PH, not enough of a chemist to know it is "friendly" to carbon steel. So......does this mean that if you use an "out of the bottle" amine based treatment (which you mention also raises PH) but the PH doesn't get to the 10-11 range, including a bit of TSP would be a good idea relative to other methods?

You don't make it clear of the DHEA is integral in the amine-based formulas or if that is another potential addative. Perhaps there are many recipes for amine based formulae, maybe all are essentially similar.....since the recipes are considered proprietary we don't actually know what we might be buying. This leads us back into the need to test and treat accordingly.......

So, how would we investigate different amine based treatments and choose the best alternative for our particular circumstances? Or, can we purchase amines, TSP, and DHEA for our own mixing and juggle them against test results?

Not speaking for anybody but myself here, but the extent of my ignorance is too high to make complete sense out of your responses. I think you ned to start from a more basic level about just what's in these commercial products and how they differ.

dave

0-6-0, have found this current thread quite informative. A couple of questions for you:

You mention the Sunday night to Saturday morning wet layup as being best handled with a nitrogen blanket over the treated water in the boiler. Boiler pressure has to be reduced to zero before the nitrogen can be introduced? Any small "steam leaks" above the water level would allow the nitrogen to escape, so it would have to be monitored during the week and more gas added if necessary, yes? How expensive is the amount of nitrogen needed for the average small to medium sized locomotive boiler?

I have always thought (theoretically, have not tried it) that keeping a locomotive boiler warm on "house hot water" supplied by a stationary boiler, would be one good way to keep the boiler expanded and keep stresses to a minimum. I'm thinking 180-200 degrees water temp, circulated through a couple of connections and a pump.

How would this technique fit in with your layup recommendations? Is it really overkill to think about connecting a loco boiler to a stationary hot water source? Has anyone tried this yet?

Thanks for your considered and detailed discussion of this subject; it is very interesting.

Howard P.

Yes it has, Howard, with varying success. Golden Spike NHS had a system set up to do just that for Jupiter and 119, with the source for the hot water located on a floor below the level of the boilers. Result was the boilers were warm and dry and the heaters warm and waterlogged in the morning. Back to the drawing board......

SLM / Sulzer / whatever they are today built a preheater and circulator for their new generation rack and adhesion locomotives that could actually be activated through the telephone line a day in advance of a trip to get the boiler and water hot, or keep it that way during longer than overnight breaks in service. The very efficient insulation on their boilers maintained heat and steam overnight with no help.

I've wondered of a thermostat in the belly and a furnace type burner shoved through the firedoor couldn't do the same.

dave

At the risk of going off topic here, would not the burner in firedoor be considered a flame in the firebox for the purposes of service day calculation? One other advantage to the hot water standby is preservation of service days. No pressure but a burner flame in firedoor--- does that count?

An immersion thermostat could be set for 190 deg and that should make sure there's no boiler pressure. Then everything is nicely expanded and ready for lighting off.

Howard P.

Service day = any calendar day in which there is a fire in the firebox and pressure on the gage (in simplest terms and plain language). So, cooking fire to keep her warm without pressure costs you no days...but how many of us use up the in service days before we die on the calendar anyhow?

dave

[An immersion thermostat could be set for 190 deg and that should make sure there's no boiler pressure. Then everything is nicely expanded and ready for lighting off.

Howard P.[/quote]


Howard,
A simple electric waterheater with a circulating pump will keep the boiler water at the 190. An industrial heater will do the job easier however most of those need 440V. Residential heaters are 110 or 220 and work just fine. heating and circulating the water does not trigger a service day.

BobK

Thanks again. I think my problem with a market comprised of several products that all make the same claim but by also claiming due to proprietary formulations they can't reveal what you are actually buying makes it difficult to compare the products to determine which might best serve you based on your particular conditions. It isn't evil....it just makes intelligent shopping difficult, which leads (in this day and age of rampant corporate shenanigans) to an immediate sense of distrust. One would imagine that copywrights and patents would protect formulae. So, it's about transparency and understanding based on even more transparency.........leading to the ability to make good choices.

Appreciate the references you provide. I think water treatment has been made to seem more mysteriously complex than it really is and by learning to break it down and look at it its essential logic will be revealed, eventually.......at least i hope so.

dave

I'm certainly not a chemist, but was involved in water treatment in 3 large steam generation plants.

In the older two, TSP was added along with Sulfite to the Dearator as a pretreatment. TSP helped to reduce any traces of hardness after the Zeolite softeners and kept solids in a suspended slurry so that they could be readily blown down. The Sulfite worked along with the Dearator to eliminate Oxygen.

I like the idea of a boiler, natural gas or oil fired -whichever is cheaper to operate- to circulate water through a locomotive boiler during the week. Although diesel, a shortline I know pretty well uses a similar system during the winter on its Geeps; heated coolant in through the 'Y' between the radiators, out through the drain valve. On a steam locomotive, a valve in the steam dome could let the water in, with the return out through the blowdown. Being counterflow, a circulation pump would be needed.

As far as nitrogen goes, we have a process here in my plant that uses 80 SCFH of nitrogen, produced by a nitrogen generator. Even though this piece of piece of process equipment only runs five or six shifts a week, we run an air compressor 24/7 to keep the nitrogen generator charged. Its also a maintennce intensive unit, to say nothing of keeping plant air up all the time. Depending on how much a cold boiler leaks, you may be using a lot of nitrogen-

With respect to pH, we have another process that requires full-time pH monitoring and correction; we also do our own waste water treatment. I have a few suggestions on where to buy test equipment and supplies, if anyone wants to PM me.

EDM

This is a very informative thread, but just to add a bit:

I understand that Monticello uses the nitrogen blanket layup procedure on Southern 401. I'd be interested to see their experience as compared to 060's.

Also, what about water in the tender? Fill it up before you lay up, or wait until fire-up to test the water and treat accordingly?

For water you treat in the tender, how long does it take for the various chemicals to become effective? Do you have to agitate the water to get even distribution of the stuff, whatever brand it may be?

For a historical perspective, here are a series of telegrams outlining a new wet storage regimen to be used with CNR 6167 in 1962.

http://www.trainweb.org/j.dimech/6167/bc1962.html