After all that thread repair & hydro, I belatedly took the jacket off of the boiler to inspect the wrap. Well.

The car that this boiler is in was assembled in the late '60s, and it ran up until about 1987. People who remember it running say that it was a pretty smart performer. A hydro test held between 750 and 800 psi for several days straight without dropping.

But - it has no wire winding. Everything I've read says that plain steel fire-tube boilers blow up at steam car pressures. What is the deal? Is it made out of plate that's strong enough for this kind of duty? There's only one seam in the drum, and the welds are pretty heroic-looking all around. It weighs 375 lb dry.

Has anyone ever seen one done like this?

Kelly

Kelly
You have hydro it above the required 150% of its working pressure.
The top and bottom plate look to be 3/8 of an inch thick from the photo. That’s the minimum ASME thickness for any boiler under 42 inches in diameter. That’s OK
I don’t like the vertical weld ( Im not talking about the welding) Just the fact that its not a seamless shell. Some auto engine re-builders have equipment that can measure the thickness of the drum plate by reading through it.
You may want to put a dial indicator up against the center section of the shell and hydro it again and see how much the boiler expands and that it returns to zero at no pressure. Or just have it wound with wire.
The weld of the top and bottom plates is a standard ASME code procedure WP 16-1 (a)
See photo.

Rolly

Top and bottom plates appear to be 1/4". The bottom one looks larger because it seems to have a ring shrunken onto it (I can't detect a seam) that is about 0.43" tall and 0.19" thick. So if the boiler were placed flat on the floor, that outer edge ring would hit the ground before the tube ends would. Hard to understand.

When the weather gets warm again I'll try the dial indicator test.

Kelly
The ring on the bottom plate is a good idea. The burner would go up against it or just inside the ring. This makes for a tight seal and would keep the burner from shifting side to side.

Rolly

It has been suggested that this boiler may have built by Richard Mann, in the 60s or 70s, to an Ottaway pattern. Apparently some differences of opinion arose around that time about the value of winding.

I don't have any doubt about that value - the boiler is being wound. One wrap is in place, two more to come. Thanks so much to Tom Marshall and Mike May for their advice and help. And thanks Rolly for your thoughts, too.

Kelly

One further follow-up. At the 1977 Pacific Northwest Steam Meet in The Dalles, the owner of a non-condensing car spoke on his restoration. The report of the meet in The Steam Automobile, 1978 v19 #4, included these two sentences:

It has a Mann boiler and burner. The boiler is made to Navy specifications, so is not wire wound, but is tested to 2000 pounds.

In case someone is researching in the future...

Kelly