I came across a locomotive recently that was built in the mid 1920s that was equipped with a lap seam boiler. I thought that seemed a bit late for a US manufactured locomotive to built in such a way. Thinking back, I've seen many much older engines with butt strap boilers. After discussing it with some friends, I'm even more curious now.

When were lap seam locomotive boilers really phased out?

Is the there a point at which locomotive manufacturers no longer offered lap seams?... and if so when did the various companies stop production of them?

Was this locomotive built for a common carrier or an industrial user?

I once heard that if an industrial user insisted on a lap-seam boiler it would be built even if this was after the change for common carrier use.

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I thought that the 19 "teens" boiler replacement was related to wrought iron boiler rather than lap seams.

The V&T took their wrought iron boilered Central Pacific built locomotive, Dayton, No 17, mounted a snow plow and declared it a piece of maintenance of way equipment (exempt from the wrought iron boiler rule). It was later sold to a movie studio, and continued in movie operation... still with the wrought iron boiler... now at the Nevada State Railroad Museum in Carson City...

The Rio Grande replaced the iron boilers on the smaller power in the 1912-1916 era. Some of the smallest 2-8-0's and 4-6-0's were deemed too small to reboiler and were scrapped.

The Rio Grande had some 2-8-0's built in 1887 with steel lap seem boilers that stayed in service with their original boilers. These were in the class C-17. All of this class was scrapped in the early 1930's with the exception of the one sold to the RGS as their #42. It got a new boiler somewhere in time.

The former F&CC engines ran with their lap seam steel boilers. Some got re boilered or at least were given reinforcement straps to the lap seam.

The steel lap seam boilers were only rated for 145 lbs. The iron boilers were also rated for 145 lbs., but under the 1911 boiler law, they could nor meet the factor of safety requirements. The engines that got re-boilered or got seam reinforcements were rated at 160 lbs.

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The short answer is the D&RG built "piles" of them. There is a picture out there of Alamosa shop taken in the mid-teens with about 10 boilers lined up to be applied to some class of 2-8-0. I would assume that Burnham made the boilers, but Alamosa had the ability to make boiler sheets too.

With the exception of the few steel lap seam boilers that the D&RG kept in service, every T-12, C-16 & C-19 that survived past 1920 had a new boiler applied. That's a lot of boilers.

Some interesting tid-bits have surfaced here. Thanks for the info.

The engine in question was a 50-something ton Hiesler.... the larger size with the diamond frame not the I-beam frame, built 1923. So, while not "very small" it was an industrial engine.

I would still be curious about records from builders if they can be found. Baldwin, Lima, ALCO, Porter, Vulcan... When was the last lap seam locomotive for domestic use built? What is the newest surviving lap seam locomotive?

Surprised that Union Iron Works built a lap seam for a 50 ton locomotive in 1923. Glover used outside contractors to build the boilers for their lokies, but they were predominantly small and light - lap seams common. Production there stopped at the beginning of the depression. I've laid hands on a 1925 porter 32 ton logger with a lap seam boiler.