Steam & Excursion > Question for the boiler experts

While doing research for an article I'm writting, I visited a railroad related construction site where, in 1875, the boiler of a two cylinder steam donkey exploded. I found this piece with a nice hammer welded, double ended clevis. The clevis is 3/4" square crosssection and 14" long and the one end is splayed open, as if taken apart by force. The long rod is 3/4" round and 30" long but broken off at one end so may have been much longer. The shortest of the three pieces is also broken off so I can't tell if it was a bolt or a spike/nail. Is there any possibility that these are stays or some part of the boiler that exploded?

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It looks like a part off a locomotive from just about anywhere if the boiler exploded.

CS

If it is off of the ‘donkey engine’, it looks like part of a a lever operating piece connected with the hoisting ‘gear’.
The donkey engine used a vertical boiler supplying a 2 cylinder steam engine...similar to a deck hoist used on ships.

Donkey engines were used in logging camps to drag logs off the slopes of the mountains to railway log loading areas, or sometimes to rivers and streams.

The lever might have been connected to a strap-brake operating around a shaft mounted drum.  It looks like the clevises were pivoting devices , at one time.  The donkey engines powered cable drums used to manage the whole log harvesting process.

The vertical boilers, if properly maintained, were very reliable and safe, they had an upper and lower tube sheet. The lower tube sheet was exposed to the flames..... ALL of the boiler water would have to have been gone to expose the unprotected lower sheet to the intense heat of the the fire.

i suspect that the failure was in a faulty seam of the rolled boiler...they often were constructed using simple lap seams and were riveted. Rivet holes are prone to cracking ( a factor is the dissolved calcium salts altering the steel molecular structures [ primarily at exposed seams and rivets] in hard water).  

Cracks can develop connecting to the rivet holes, and soon you have a zipper-like  string of broken steel “bridges”, hole-to-hole...
The seam can then separate & suddenly un-zip, and the boiler explodes.   Years and years of neglect, and near continuous operation, no inspections an no hydro tests, all combine to set up these disasters..

Those cracks around rivet holes are the major thing you look for when loco boilers have flues and tubes removed —- it ain’t about the tubes, which can be re-used multiple times, its about the critical internal inspection of the boiler’s (submerged) braces, the rivet holes of the shell seams, and the visible seams of the firebox, water-sides.

Those old, simple lap-seams became prohibited in loco boiler construction, in the late 1800s.

That’s my guess about the parts...

W.

not proofed, yet
 



Edited 2 time(s). Last edit at 11/25/18 06:04 by wcamp1472.

Wes,
  Thanks for the reply. Digging a little deeper, I see that it was the boiler of a two cylinder water pump. Not sure what that would look like or if it would still be a verticle boiler. I do know that the machinery being used was recondition equipment from an earlier job and since this was in 1875, I'll bet that the boiler was iron. These pieces that I have certainly appear to be iron and not steel. The initial newspaper report stated that the explosion was due to low water but then the coroner's inquest ruled that it was "An unavoidable accident".