In another reference from the Puffing Billy blog, they mentioned finding a lens-joint failure that had been 'concreted over' to mask the effect of the leak, leading to extensive reconstruction. As part of that, they decided to incorporate short flexible sections in the main steamlines from the header to the cylinders, mentioning this was a historic area of trouble for that type of locomotive.

This used what was described as double-wall braided construction (with no mention of what was 'between' the two braided faces) with the braids welded to standard fittings at either end. This had proceeded as far as partial installation in the last mention (in January 2016, as far as I saw).

How successful has that been, what are the non-obvious potential problems with it, and are there applications of the idea to American practice, for example in fabricating more effective piping to boosters?

They work.

We at the Wabash, Frisco and Pacific Railroad have been using them for delivery lines from the throttle to the cylinders. In that size, it's a bit tricky to form copper tubes and expect them to come apart next time you need them to.

We use stainless hose. I need to go back and look at my order history. I suggest getting the ones with the unions on one end so that they are easy to install and remove.

-Mike Walsh

Noting that the Wabash, Frisco and Pacific Railroad is a 12" operation in Missouri.

Hope this discussion takes off some more. I know in other areas of industry they have used couplings that were slightly flexible in high pressure use. I am not a steam fitter or work in that kind of industry anymore. With the poor condition and cost of casting steam delivery pipes have always wondered if used in the connections if that might simplify replacement in this kind of use? Of course we have seen some fabricated delivery pipes made and if I recall, hear they work fine? As rebuilds go further and further into having to replace worn castings would this type of flexible fitting be of any use? I am thinking more of small flexible fittings to use almost as unions rather than long runs. Maybe just finding the right shop to fab the delivery pipes is the way to go? Just wondering out loud, not purporting that it is the way of the future.

The picture of the burst steam pipe from hotel laundry is scary. The people working in laundry would not know what hit them if they were near by.

Regards, John.

Several years ago, I noticed that Tweetsie RR had used flexible braided hose between the turret and injector starting valves on WP&Y 190. They were not insulated, though I suppose you could wrap flexible hose same as pipe. Don't know if they're still using the braided hose or not.

The hose only failed after 13 years in service. If you put a hose in service like that, it would seem prudent to replace it periodically. You can't leave it in there forever...it will fail sooner or later, no matter what the rating is.

David Wardale used flexible "accordion" couplings in the main steam pipes on the modified SAR 4-8-4 #3450, aka the Red Devil. These held up fairly well but eventually failed in service. IIRC, he determined that there were significant pressure pulses in the main steam pipes coinciding with steam admission to the cylinders, and this fatigued the couplings eventually causing them to crack.

Thank you for the input. I can finally put that "flexible coupling" idea to rest. Regards, John.

This is what the Puffing Billy did when using the flexible piece. I suspect they would change it at some standardized interval. Notice it is not the entire piece, but just a small part.

The Na class are small locomotives doing a big job in daily revenue service. Few of us work ours so hard and often..... the useful life of this alteration will let itself be known in due course - I hope it lasts long enough to be a cost effective problem solver.

Now, got to go back and read the archived blogs.

Here's a photo and some more info on the Red Devil application:



"26 Class no. 3450; main steam pipe with axial bellow-type expansion compensator. The steam pipes were not bent according to the drawing and consequently exited the smokebox higher up than as designed, hence the patch visible in the correctly positioned hole in this newly rolled smokebox shell. The expansion compensators proved unable to withstand the service conditions and had eventually to be replaced by plain sections of pipe."

(from Wardale's book: The Red Devil and Other Tales from the Age of Steam")