I have that book and was active in the hobby for decades. The problem with that book is that is has been reprinted many times without any technical corrections. I once had a conversation with a modeler who knew that builder. What few know, is that that boiler failed a few years later, and was replaced with a conventional boiler. All involved with that book are long dead and it should be treated with caution as a modern reference.

Maintenance costs, any thing that makes the parts last longer with less labor to replace corroded parts is going to be a winner. Labor costs from the "glory days" of steam engines look very inexpensive these days.

But it's academic, not likely to be any "new built" steam locos anytime soon.

Several mainline steam locomotives are currently under construction, including at least one in the US.

Not to mention some already built, that have experienced the problems with welded construction to original drawings, and improper interpretation of older specifications.'

We can agree to disagree on the boiler built for 5550.

Well, I do of course wish anyone replicating a "heritage" boiler using the same materials used 50 plus years ago the best of luck.

BUT, if I was to undertake the challenge of making a long lasting and cost effective steam locomotive boiler for use in 2030 and beyond I would begin with an exhaustive survey of modern materials. There have been remarkable improvements in materials science since "mainline" steam locomotives stopped being "built new" in the late 1940's.

Perhaps the "steels" available for constructing steam boilers in the late 1940's are the "best that will ever be", but I doubt it.

Cheers, Kevin.

.

Didn't steel for steam locomotive boilers have a tensile strength of 55,000 lbs. Which means it isn't as hard as a steel of a higher tensile strength. Didn't they call it flange steel, indicating that it was easier to bend/flange. Boilers expand and contract and are affected by the changes in boiler pressure and temperature. Stainless steel, like high strength steel, has a higher ultimate tensile strength which indicates that the steel is less ductile than steel used to manufacture steam locomotive boilers. In the late steam era, they used high strength alloy steel in manufacturing side and main rods. And they came to the conclusion that if a rod had been dropped on a concrete floor, it would ultimately fail in service.

I get the impression that what Kevin meant was the 'commodity' maintenance of a large number of boilers in minimum time at minimum cost, as motive power that would generate the greatest revenue as cheaply as possible. We're unlikely to ever return to those days, or see them even in the poorest foreign nations.

But...

There have, in fact, been careful studies of both more 'improved' materials and fabrication techniques for 'heritage' boilers (which can be built regardless of cheapest cost, and with careful attention to spec and fabrication details). That includes, for example, a modern equivalent to the Alco normalizing facility for the largest prospective boiler size, and the use of techniques like properly-shielded and blown laser keyhole welding as a substitute for submerged-arc welding of boiler seams.

Now I'm going to give you the same advice I gave Robby Peartree regarding standards. The ASME boiler-code meetings for 'Power Boilers', which specifically includes all the data of the recently-reintroduced code for 'locomotive boilers', are open to anyone, and I very strongly recommend that you attend one or more of these (Locomotive Boilers meets only every other Boiler Code Week, but you can easily check schedule and details long in advance) and ask what alternatives, and what demonstrations, and what applied materials science, would be appropriate for eventual approval for and inclusion into the Code. It can be done, but only on the actual, provable merits.

PM me if you need contact information for this part of ASME.

FWIW,
I have been informed by some of my welder friends, the Chloride Stress Corrosion Cracking is a problem with welded SS boilers and pressure vessels. This becomes an increased issue when you add higher temperatures and chlorinated city water. The failures don't occur slowly as is the case with carbon steel, the joints fail quite rapidly and without a clear sign of impending failure.

Development of steam boilers for mobile applications (RR locomotives) essentially stopped in the 1940's.

Stationary power plant boilers have lots of latitude for space and weight.

Yes stainless steel boilers are not in the code today....

Things get added to codes all the time (after appropriate testing and consensus), the NEC electric code adds stuff every 5 years or so as new technologies come "on board" like GFCIs (impossible with 1940's vacuum tubes) or the new arc fault circuit breakers.



With all due respect to welders (My Grandfather was one) stress corrosion from exposure to chlorides is a well known problem (I made the mistake once of using plastic fittings on a room temperature bleach line, the bleach got into the micro cracks in the plastic and the whole thing fell apart).

There are many many flavors of stainless steel and new ones are still being investigated. Stainless steel pressure pipe fitting for nasty chemicals are still in wide usage (pressure pipe for fluids that are not a "fired pressure vessel").

A NASA report from 1969;

https://ntrs.nasa.gov/api/citations/196 ... 028850.pdf

They knew all about stress corrosion cracking (SCC), a bunch of folks have looked at it and it is not an impossible "nut" to crack. Just need to pick the right "flavor" of stainless steel for the expected operating conditions.




Thank you, that was what I meant. If railroads where to somehow replace all the diesel locos with steam locos I suspect there would be a lot of new innovation in mobile boiler technology and stainless steel might be a part of that.

Where I work we are "3D Printing Invar" for structures that need to be strong and stable.

Never would have seen that coming when I started out in engineering.

https://www.youtube.com/watch?v=dCGTi_5tYj8 (I do not work for or have any affiliation with these folks)

Invar (tm) (aka invariable metal) is an alloy of steel and nickel that remarkably does not change it's size when it's temperature changes (not appreciably being a size change of ~ .0000001 inch per degree of temp change). Was discovered by a German Watch Maker about 150 years ago. Was very expensive, but it is getting more affordable all the time.

Imagine a 3D printed Invar boiler were the dimensions only change by a few thousandths of an inch over the length of the boiler when it goes from cold to hot, get rid of a lot of the stresses that way.

Cheers, Kevin.

Invar is cheap. The only thing 'difficult' was determining the original alloy proportions and trace constituents to make it work.

A far better achievement was Elinvar (not only dimensionally invariant, but elasticity invariant) which of course was made famous by the Hamilton Watch Company. It was used in railroad-watch hairsprings. I don't have a reference at hand for the research program that developed this, but there is a very long laundry list of constituents, some of which have to be precise to tenths of a percent.

Interestingly, the early batches discolored weirdly when heat-treated, and were artificially 'blued' (so they look like conventional hairsprings). Later the alloy was refined again to give that silver 'nonmagnetic' look...

The thing about stainless that is not susceptible to chloride SCC is that the stock tends to be expensive, and the fabrication would likely require expensive multiple annealing and possibly hot working. That said, simple proper water treatment will knock down chloride ion right in the tender tank, and there are interesting alloys that might be suitable for a one-time, 40-year boiler shell and firebox wrapper, if 'cost is no object'. The catch is that a boiler made of far less expensive and more easily worked material, which will be compliant with the current ASME locomotive-boiler code, will have equivalent effective life if treated correctly and given proper water treatment. And there is no prospective waiver for an exemption from the 1472-day inspection requirements, inside and out, that would involve difficult and costly removal of the tubes (which could only with difficulty and risk be safe-ended, so there's new stock if you use special alloy) and replacement of the tubesheets (which can't really be annealed in place, and cannot tolerate any developed cracks either from initial installation, stress during operation, or stress being removed).

In my opinion, a great deal of the 'difficulty' with metal corrosion in a boiler involves the 'nooks and crannies' of conventional riveted seam construction. If you weld the joints, conduct suitable NDT such as condinuous radiography as in nuclear-reactor vessel fabrication, and then grind and polish the welds, it would be difficult for corrosion to develop as it does in, for example, improperly-caulked areas between lapped plates.

The most chilling thing I've read here since I joined was that idea that you could 3D-print a boiler. I assume you're working with the system used to produce those contest rocket nozzles a few years ago, which involves a sintered or HIP-compacted form of 'printed' metallic microspheres treated with a lower-temperature (but still high-melting-point' matrix. I don't like the idea of stressing a large fabrication made that way both thermally and under pressure loading, with in places some very sharp thermal gradients across joins (for example in the outer wrapper where the front tubeplate or Chapelon preheater head abuts the smokebox) with that kind of composite material, particularly if it can only imperfectly be Magnafluxed.

Indeed, garden variety Invar that fell off the back of a "Sanford and Son" pickup truck is inexpensive.

When you need Invar with a pedigree (accurate chemical analysis showing the constituents and trace junk materials) the price goes way up and you may or may not get it in the next 5 years.

We have a stash of "Super Invar" stashed away from those "one out of 50" mill runs that were exactly TCE=0.000000000.

We have to trace all of our materials back to the original mill production run with ALL the paper work.... The Invar costs $100, the pedigree costs $10,000....

The 3D printed Invar we are doing at this time is a structural application for an precise mechanism. It involves Invar power sintered together into a structural form using a laser in a "layer by layer" approach.

Not a pressure vessel, but I could see it producing pressure vessels in the future.

You guys are a little behind the times. Stainless steel has been successfully used in the nuclear industry since its conception. Nuclear reactors generate far more heat, pressure, and corrosion than any steam locomotive ever could. It has obviously been proven to be an extremely dependable and safe metal under extreme conditions.

There is also no evidence that ordinary steel (such as that used in steam locomotives) is better, safer, or stronger than stainless steel. I find it hard to believe stainless tanks that are used under the most extreme pressures, heat, and corrosion are unfit for something as simple as a steam locomotive boiler. Certifying a stainless steel locomotive boiler (which, from my research, is just as safe if not safer since it is not corroding like steel) should be a simple process and one that any manufacturer of stainless steel tanks should be able to do. A few links on this topic if you have time.

https://blog.thepipingmart.com/metals/h ... -overview/

https://www.cnclathing.com/guide/metal- ... cnclathing

Found this interesting site regarding many studies of steam boilers

https://www.nationalboard.org/Index.asp ... 164&ID=412

.

That's what so many here appeared to be saying about getting Locomotive Boilers back in the codes at all.

As I said to him: Go to Boiler Code Week, talk to the people on the ESC, see what they say. Those are the first step to getting better alloys accepted for purpose.

Nine-nines anything is terrifically expensive; audit trail through the whole production far more so. (Bet is wasn't to that purity after you fabricated it, though... ;-})