Can one of the many talented steam experts here either point me to a good online resource, or write something up describing the various ways locomotive boilers are made?

I'm not talking about fire tube versus water tube, etc. I want to know the differences in lap seam boilers versus all the other types up to modern welded boilers and the advantages and disadvantages of each. (I know, I don't want much. :-) )

In addition, what are the reasons and issues with boilers that change their diameter along their length? In particular boilers like the heisler at Travel Town that has a pronounced cone shape about half-way back along its length. I would think that would make it weaker than a straight shell. So why do that?

thanks,

Brandi

How much time you got?

Try Hugh Odom's ULTIMATE STEAM PAGES which contain links to things with links to other links to just about anything on the web steam related.

The SteamTech list recently had a discussion of Brotan boilers and flash boilers for locomotives (as well as toilet jokes) so you have to be willing to seperate the wheat from the chaff if you go there.

Model live steamers sites probably contain a lot of information about designing and building small replicas of various types of boilers, but i only work on 12" to the foot, so somebody else maybe can point you in those directions.

Happy hunting.

dave

Dear Brandi:
An excellent book is "The Steam Locomotive in America" by Alfred Bruce. It has a section on boilers and fireboxes (as well as section on every other part of a steam locomotive.
A quick answer to your first question is strength. Properly designed and constructed, the seam on a welded boiler is stronger than a riveted butt seam which is stronger (and less prone to cracking) than a riveted lap seam. A riveted lap seam is the weakest type of seam and hasn't been widely used on locomotives since the early 1900s'. The welded boiler is the most modern type of construction used in locomotive boilers. Welded boilers are also less expensive to manufacture, which is why most boilers built today are welded (a few historic/replica riveted boilers have been made both here and in England).
The diameter of a straight riveted boiler with muliple courses decreases slightly at each circumferencial seam because one fits inside the other, reducing the diameter by the thickness of the primary course. Typically, a straight welded boiler will be a constant diameter. Occationally and for a variety of reasons, boilers are designed with tapered or "conical" courses. Often these"conical" courses are not a true cone but rather are straight on the bottom. These "conical" courses are designed to be as strong as the other courses.
I hope this helps.
J.David

Let me summarize the previous post and other material I've read to see if I'm understanding.

You have 3 basic types of shells: The lap seam, the butt seam, and the welded.

The lap seam is made by rolling the steel sheet and then overlapping the ends and riveting the sheet to itself?

The butt seam is made by rolling the steel sheet and butting the edges together and then riveting a plate to both pieces?

The welded boiler is made the same way as the butt seam, but the edges are welded to each other?

In a butt seam, subsequent courses telescope into the previous course and are riveted to each other?

Can you have more than one course in a lap seam boiler?

In a welded boiler, do the subsequent courses telescope or are they butt welded too?

Thanks,

Brandi

You really need to look at pictures or hardware to understand how many interesting variations there are in boiler construction. I think the explainations are sometimes confusing rather than enlightening. I have seen pictures of where more than one technique was used in the same boiler, and where different techniques were used in repairing a damaged boiler. Mark Ray at Tennessee Valley has joined a welded partial course to a riveted existing course in a locomotive currently under restoration, and with his qualifications, can give you much better information than me.

Best wishes. BTW, why are you exploring this?

dave

Our company Wasatch Railroad Contractors currently employees one of our nations foremost experts in terms of boiler construction both past and present. He is currently writing a posting that will better answer this question and provide some very beneficial information. As a past boiler inspector and having well over 25 years in the boiler industry, I marvel at the information that is contained in this man’s head. He is a true asset to our industry.

Stay tuned for a much more in-depth response later this evening! May I also add that you are always more than welcome to ask us a Technical Question by visiting our web page at www.wasatch-rr-contractors.com.

John E. Rimmasch

Just curiosity really. Started looking at some boilers with no lagging and jacketing, and started thinking.

Brandi

Dear Brandi,
Mr. Rimmasch, President of our Company---Wasatch Railroad Contractors, has asked me to comment on your questions. However, it appears that Dave Conrad and Dave Lathrop have done an excellent job of providing you with fine references and accurate insights on those points you are researching.
The welded boiler is far superior to a riveted one in several aspects such as first cost, weight, strength, corrosion, ease of repair and in one very important area, that of caustic embrittlement. Riveted boilers were quite prone to this problem due to the many opportunities for minor leaks in the joined plates, this leakage concentrated chemicals from the water and in conjunction with inherent stress promoted intercrystaline cracking, ultimately causing failure of the plate and sometimes catatrophic failure of the boiler itself. The advent of an all welded boiler removed this problem due to lack of points for leakage. Caustic embrittlement is still with us, but found now in other forms much less dangerous.
Another problem with riveted boilers is referred to as "grooving",better know today as stress corrosion. Where plates are lapped, as in circumferential seams, the joint is sometimes subject to bending while in service, minute as it may be, it results in premature thinning of the plate in a narrow area along the edge of the plate. This then creates an oppotunity for crack development, and again if not detected can result in a significant failure. This again, in most instances, is eliminated in a welded boiler.
Riveted boilers are a fascinating piece of engineering, consider building a pressure vessel using plates, pins, drilled holes and nothing else(except the required tooling), not knowing what was done in the past it would be considered outlandish today.
It might be mentioned that corner joints in high pressure boilers(over 15psi) are required to be full penetration welds rather than fillet welds, just a point of clarification.
As a point of interest, from my studies it appears that there were roughly 110 all welded locomotive boilers built before the end of steam in this country, the first being for the D&H in 1937. The drawings of how this boiler was constructed can be found in the 1941(and later editions) Locomtive Cyclopedia.
Respectfully,

Dave -

Thanks very much for your comments. Our museum has what I believe is the only "as-built" welded boiler locomotive still in existance from that era; Chesapeake & Ohio 2-8-4 #2789. There are some others locomotives from the steam era with welded boilers still around too, but I believe that these were locomotives rebuilt with welded boilers (by the AT&SF and perhaps others). Of course, there are a number of more recently constructed or rebuilt locomotives that have new welded boilers in this post-steam era period.

For the record, Kanawha #2789 was built for the C&O by ALCO in 1947. Unfortunately, its four sister engines built at the same time (numbers 2785 - 2788) were all scrapped.

Les Beckman (Hoosier Valley Railroad Museum/North Judson, Indiana)

Which begs the question; are the QJ boilers welded? Anyone know?

Thanks,

Bob

I was told by someone who would know that the QJ's are welded and were done up very well. I was curious too about the workmanship. Was told the workmanship was very good on the boilers, but some of the other welding was atrocious. This would be for appliances, running boards ect. 2nd hand info so take it with a grain of salt. 2nd hand info mixed with my interpitation is subject to error.

I too find boiler construction interesting and remarkable. Almost more interesting is looking boiler repairs done on these now parked engines. Some of the repairs done to the UP Big Boy now indoors in Green Bay, Wi is facinating. Some looks like it was done after a couple of cases of beer was drunk up on a friday nite, while other repairs are steller in comparison. My favorite locomotives to look at for horendous repairs are the two Quincy and Torch Lake engines sitting outside in the harsh enviroment of Michigans UP, {by Hancock, Mi}. The orignal construction methods are a science in themselves, but some of these repairs are from yet another world. Meaning the world of no money, no parts and we need to keep this thing running. Start looking at park engines and start noticing the repairs on the boilers, running gear and frames, it is a lot of fun, as well as educational. Cheers, John.