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Boiler Explosions https://www.rypn.org/forums/viewtopic.php?f=1&t=1996	Page 1 of 1

Author:	RLM [ Mon Aug 06, 2001 10:20 pm ]
Post subject:	Boiler Explosions
FYI, sometimes a boiler in an ill maintained state will not fail in such a spectacular way as will a well maintained one. A good example of this was the Gettysburg accident. That was not a boiler explosion at all, but more of a "controlled" release of steam. The rear tube sheet knuckle and front part of the crown sheet was so riddled with stress corrosion that when the sheets overheated, they opened up at the cracks (and the open staybolt holes)and released the steam pressure in more of a gradual manner. If the boiled was well maintained this wouldn't have happened and we would have had the classic boiler ripped from frame scenario.

Author:	R. Hahn [ Tue Aug 07, 2001 8:42 am ]
Post subject:	Re: Boiler Explosions
The way the Gettysburg locomotive failed was by design, not accident. The engine (and I believe most Canadian engines)had alternating rows of two different types of ridged stays. By their basic design one type would fail before the other, allowing only a partial crown sheet failure. Sort of a last ditch type of fusable plug as the contents of the boiler empty onto the fire through dozens of 1" holes. While you have a destroyed crown sheet, you don't launch the boiler. Roger > FYI, sometimes a boiler in an ill maintained > state will not fail in such a spectacular > way as will a well maintained one. A good > example of this was the Gettysburg accident. > That was not a boiler explosion at all, but > more of a "controlled" release of > steam. The rear tube sheet knuckle and front > part of the crown sheet was so riddled with > stress corrosion that when the sheets > overheated, they opened up at the cracks > (and the open staybolt holes)and released > the steam pressure in more of a gradual > manner. > If the boiled was well maintained this > wouldn't have happened and we would have had > the classic boiler ripped from frame > scenario. Belpaire@aol.com

Author:	HKA [ Tue Aug 07, 2001 8:13 pm ]
Post subject:	Re: Boiler Explosions
Does this mean that I should stop maintaining my boiler?

Author:	RLM [ Tue Aug 07, 2001 9:29 pm ]
Post subject:	Re: Boiler Explosions
I will agree that the placement of the button head stays helped, but they are not the only reason the boiler didn't explode. Canadian locomotives with this design could and did explode. My point was that because of the very poor condition of the firebox, the boiler was "able to relieve itself" somewhat. The cracks in the sheets became small tears and openings compared to a sheet in good condition that would have torn open wide and all at once dropping the pressure quick enough to cause the water to flash over.

Author:	RLM [ Tue Aug 07, 2001 9:32 pm ]
Post subject:	Re: Boiler Explosions
You know what I mean Kelly. See my previous post.

Author:	Pete [ Tue Aug 07, 2001 10:10 pm ]
Post subject:	Re: Boiler Explosions
FWIW, extracted from the NTSB report on Gettysburg: "In accordance with Canadian Pacific policy, the crown stays . . . were alternating rows of straight-threaded and button-head crown stays. The first five rows [from the knuckle] were straight-thread crown stays followed by rows of button-head crown stays. The boiler had been made that way so that if the crownsheet failed because it was not covered by water, it would be pushed off the straight-thread crown stays first. Consequently, although the crownsheet would buckle, it would be retained for a time by the button-head crown stays. Thus . . . the failure would occur progressively and in stages, rather than [be] instantaneous and catastrophic. Other than being designed to make a failure progressive . . . the boiler did not have any low-water protection devices."

Author:	RLM [ Wed Aug 08, 2001 9:58 pm ]
Post subject:	Re: Boiler Explosions
Pete, As I have said before, I agree that the design certainly helped as the sheet was only beginning to pull away from the first row of button stays. The point I'm trying to make is that a lot of pressure was relieved through the stress corrosion tears in addition to the staybolt holes. If the sheets were in good condition, there would been more time for the sheet to pull off of the button head stays. The sheet had already pulled off of full penetration welded and taper head bolts (taper head bolts are designed to do about the same thing as button heads) so depending on the conditions at the time, the button heads would have started to fail also. My original post was meant as an example only and in no way was I trying say that an ill maintained boiler was the way to go. You will be just as dead when a crappy boiler explodes as compared to a well maintained one, it's just that a well maintained one MIGHT last a little longer.

Author:	Pete [ Thu Aug 09, 2001 12:53 pm ]
Post subject:	Re: Boiler Explosions
The story of what happened seemed to be drifting into urban legend territory, so I was just quoting the horse's mouth rather than taking a position. I have absolutely no patience for those who think regulations are more of a hindrance than a help. After all, if everyone (i.e. the operating companies as well as the "museums" and tourist lines) were doing what they were supposed to to, the the FRA et al. would be out of business. If you can't take care of it properly, then you have no business operating it (the generic "you" here, not necessarily you personally). I'm waiting for an air brake disaster, which will be caused by similar sloppy, cheating maintenance.

Author:	Dick [ Thu Aug 09, 2001 1:16 pm ]
Post subject:	Re: Boiler Explosions
> I have absolutely no patience for those who > think regulations are more of a hindrance > than a help. After all, if everyone (i.e. > the operating companies as well as the > "museums" and tourist lines) were > doing what they were supposed to to, the the > FRA et al. would be out of business. Having experience with federal OSHA and EPA, and hearing countless horror stories of how they've created unnecessary disaster in so many places with no common sense to their regs, I can't agree! Not long ago the EPA declared the Platte River in Nebraska as "polluted" with overheating from the sun, and tried to require the state to do something about it!

Author:	RLM [ Thu Aug 09, 2001 8:40 pm ]
Post subject:	Re: Boiler Explosions
Pete, I was involved in the initial inspection of the engine and had the opportunity to see for myself the condition of the boiler. Although I agree with the official report, I was able to see "minor details" that were not included, none of which would have changed the end result. For the record, I am pro FRA and I like the new CFR, but it's just unfortunite that it took this incident to wake people up.

Author:	Pete [ Thu Aug 09, 2001 11:01 pm ]
Post subject:	Re: Boiler Explosions
Yes, I've had similar experiences. The one that comes to mind at the moment is the boiler inpspector who: 1) had "never seen such a large fire tube boiler" before; 2) was completely baffled by flexible staybolts; 3) couldn't conceive of the fact that flush flexible staybolts had only seal welds around the cup; and 4) didn't know how to read the drawings we showed him on nthe subject (out of the ICS books). And yes it does take a Gettysburg and a steam tractor to re-educate the regulators. Our govenrmental system was set up to be re-active rather than repressively active. Bureaucrats are an animal unto themselves.

Author:	Dave [ Fri Aug 10, 2001 6:32 am ]
Post subject:	inspectors?
Our state inspectors in GA are also responsible for elevators, amusement park rides, and some other more common technologies and are usually baffled by what is simple to us. The inspection on GOAT was beating on the rivet heads to see if they were loose and checking to see whether we had a code safety valve. I offered the inspector a copy of the non destructive test results along with the stress calculations but they were turned down. I offered to do a hydrostatic test during the inspection but the response was "what is a hydrostatic test?" Even inspected boilers can be unsafe. Those of us that are standing next to them need to assure ourselves that we aren't riding a bomb. Dave irondave@bellsouth.net

Author:	John Stewart [ Fri Aug 10, 2001 8:45 am ]
Post subject:	Gettysburg and gauge glass bore.
I keep a copy of that report at home; It makes sobering reading every year or two. Especially since I did spend quite a bit of time (and wished that I could have spent more) on sister engine 1201 back in the '80s. One question that I had was the problem of the bore in the gauge glass; 1/8". That's about 10% of the surface area that a 1/16th wall thickness gauge glass would have. Now, 1/8" bore is not that much smaller than my small 1:16 scale models have. Would that greatly reduced flow of water have added to the plugging problems that the gauge glass experienced? BTW - I have been going through the CFR 230 since most of my steaming happens in the USA. It is a good document. Thanks; John Stewart Ottawa, Canada. > I was involved in the initial inspection of > the engine and had the opportunity to see > for myself the condition of the boiler. > Although I agree with the official report, I > was able to see "minor details" > that were not included, none of which would > have changed the end result. > For the record, I am pro FRA and I like the > new CFR, but it's just unfortunite that it > took this incident to wake people up. john.stewart@crc.ca

Author:	Chester [ Fri Aug 10, 2001 8:47 am ]
Post subject:	Re: inspectors?
Those > of us that are standing next to them need to > assure ourselves that we aren't riding a > bomb. > Dave If a fellow isn't experienced & confident enough of his boiler and the work he's done on it to know he's not "riding a bomb" before the inspector is called, he shouldn't be doing this stuff in the first place. The inspector is just another level of reassurance for the operator; he should justify the confidence one already has, not be the sole provider for it. I know my boilers better than most modern inspectors, it is MY duty to know that I have it in safe condition, the inspection simply confirms (or rejects) it.

Author:	RLM [ Fri Aug 10, 2001 9:03 pm ]
Post subject:	Re: Gettysburg and gauge glass bore.
Although I don't remember the pressure rating of the tubular glass, (my wife says I can't remember anything!) I know it was intended for high pressure service. Two problems with the glass was 1, it was filthy and very hard to see the water, 2, with such a small opening, the water level was hard to read.(even after it was cleaned up) I also remember that the lower glass valve opening was somewhere around 75% restricted. I don't recall if that restriction was smaller than the 1/8" glass opening, but regardless, the water would have been very sluggish in the glass. The main problem with the glass in my opinion was the restrictions in the valves. If the glass was properly maintained, the correct water level would have been displayed although it would likely be a little sluggish. I hope that helps.

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