Steam & Excursion > Hydro Testing Blowouts

During a Hydro Test, how common is it to have a, for lack of a better term, a "blowout" during the test?
I know that minor leaks are often discovered, but has there ever been a major failure during testing? If so, please explain some of the big problems encountered.

Thanks!

R.R. Conway

RRBadTrack Wrote:
-------------------------------------------------------
> During a Hydro Test, how common is it to have a,
> for lack of a better term, a "blowout" during the
> test?
> I know that minor leaks are often discovered, but
> has there ever been a major failure during
> testing? If so, please explain some of the big
> problems encountered.
>
> Thanks!
>
> R.R. Conway

The only one such "event" that I am aware of, happened to SP&S #700. Many years ago, while the locomotive was still in the park, the "group" decided to conduct a hydro after working on the boiler for some time (years?). However, one person in the "group" wanted to "one-up" the SP 4449 crew, and hydro the poor 700 at just a few pounds ABOVE the 375 PSI that the 4449 was always hydro tested at. Obviously, the "group" on the 700 failed to take into account that the SP&S 700 was NOT a 300 PSI working pressure boiler!!!!!!!  Cold water from a nearby fire hydrant,t and GREATLY over pressure, resulted in dozens of staybolts being pulled out along the Fireman's side of the firebox side sheet.

And am supprised that they put water in it with that attitude might have thinned the group out a little and it would have bee no more.

BAB Wrote:
-------------------------------------------------------
> And am supprised that they put water in it with
> that attitude might have thinned the group out a
> little and it would have bee no more.

Remember, it was just a hydro test, and thus would NOT result in a "boiler explosion" with killing results.

The compressability of water is near zero!

Out

I would suspect that they would have had specifications to work from with the 700.

Thanks for the information.

R.R.

I've heard of a few other incidents like this through the years.  Most have the common denominator of the leader of the group coming from the "live steam" hobby where they hydro test boilers to as much as 100% above MWP, not knowing any better and thinking they "know it all" because they built a 7-1/2" gauge Little Engines 4-4-0. 

RRBadTrack Wrote:
-------------------------------------------------------
> I would suspect that they would have had
> specifications to work from with the 700.
>
> Thanks for the information.
>
> R.R.

Well, any "specifications" sure didn't seem to matter, did it?

CFR230.36 has a healthy fine for such things, course there's the other part with the healthy fine for improper boiler
washes and look how far that went!!

Out

A major boiler failure during a hydro is not the same type of event as a boiler failure when under steam.

The amount of stored energy in the boiler during a hydro is a tiny fraction of the energy stored in the boiler when it is under steam. It might make a good "BANG!" when the staybolts let go and water will spray out of the failed area for a while, but that's about it.

Water is the SAFEST testing material.

Unlike gasses, as soon a  minor 'tear' ocurrs, the pressure drops-off immediately.
it is important to get virtually every bit of 'air' out of the system, because it compresses and can aggravate pressuring.
If it is a solid water test, and a failure ocurrs, its mostly an event that gets the 'testers' a little wet.

If you had a fire hose under a static pressure ( not continuously pumped) --- and you chopped the filled hose with an axe, it would simply sag as the pressure immediately  & instantaneously is relieved.

Gas testing , involves making the tested vessel into a BOMB!
Years ago, while at a NewYork Air factory school, we toured their factory, and saw the explosion pit where they tested AB-style Auliary Reservoirs, ( actually the Auxiliary Reservoir consists of two compartments, separated by a domed, plate divider) to destruction under compressed air pressure.  We saw the lighted test pit, but we did NOT get to witness the explosion ---- darn!

One of the main functions of the loco test is to 'stretch' the staybolts of the firebox. Some are equipped with telltale holes...some are short stays with holes drilled a couple of inches into each end of the rigid bolts. Flannery Flexibles have a ball and socket fit
at the outer-ends of the bolts. The other end, is threaded into the side sheets.  
The firebox is made of 3/8" thick steel,
so at. 
12-treads to the inch, that leaves  ( math wizards, please) how many, threads 'holding' in the side sheets?

So, when stretched, the expectation is that the telltale hole weeps water during the hydro test.  The Flannerys' lengthy tell tale hole extend the entire length of the bolt and must penetrate the spherical head by one-third it's diameter.  The entire interior of the telltale hole is copper plated, to aid in conductivity.  The hole is plugged with Flannery Pourous Plugs to keep cinders and unburned coal out of the holes.

Flannerys are tested under hydro pressure, to stretch any tears in the thread area...... however, the hole must be verified to be open its entire length...... A Flannery 'hole tester' tester is a battery-operated continuity tester... when the tiny tip of the test probe makes contact with the copper plating at the bottom of the hole, the lighted bulb verifies that the hole is OPEN it's entire depth.
The tester's circuit is completed by a ground wire screwed into a convenient, nearby staybolt hole.

The tester DOES NOT 'test' the the staybolt, it verifies only that the hole is open.  If the hole is plugged, so that the light cannot be lit, the bolt must be considered 'a broken bolt', and must fall within the allowed number of 'broken bolts', for the loco to remain service.


So, hydro testing is the safest way to test boilers, failure of a large joint, simply results in a minor flood, but no disastrous rupture, or explosion...  

Hydro-test leaks are common, but certain kinds of leaks must be remedied, but not all leaks.

​W.

Edits don't work, at this time ........
 



Edited 3 time(s). Last edit at 04/10/17 17:12 by wcamp1472.

Wes--at 12 tpi a 3/8" sheet will have (12x.375) or 4 1/2 threads.

Threaded staybolt's  supporting area...
Also, consider the number of square inches of firebox steel that applies loading pressure to the threads.....'times' the PSI, per square inch  ( of the area supported by each bolt)....

So, as you ca see, there's not much holding the sheet---- only the the treads, themselves, and they're not that deep.
Ye, stybolts are 'driven', or peeled-over on the firebox side, some practices added a single-pass 'seal weld' aronun the staybolt.
I believe that in today's world, non-threaded bolts areall welded in the firebox,, using proper hole prep dimensions, etc.

I'm told the 'seal' weld's intent is to provide a continuous metal connection between the bolt and the sheet for more even thermal conductivity and distribution between the two mtetals, sheet & bolt, not necessarily adding any structural benefits.......
The bolt, being thicker, has less are for cooling bythe water, than the comparative generous cooling area provided by the flat sheets.....

Also, most tears occur at the firebox end of the bolt ---- the outer ends of rigid bolts are threaded into the  1" thick wrapper sheets, or are the Flannery bolts with spherical heads floating in a suitable socket, or base seat, typically bored to a 45-degree seat angle...which may or may not have replaceable caps ( for breakage/replacement ease....).

Interestingly, crown stays typically do not have the deep tell tales, and have the advantage of their greater length to freely flex along that length..  By freely flex I mean that the rigidly screwed bolts into the sheets, have minimal 'racking' thrusts imparted by the bolt shank onto the threaded areas.  The threaded ends can remain at right angles to thier sheets ( bolts remain straight for short distances) as the bolt shanks gently cuve into a gentle, S-like shape..... that's important since the majority of the firebox is surrounded by much colder water, and side sheet expansion is considerable, but not nearly as severe as the temperatures that the crown sheet experiences.  That crown metal is very close to its softening temperature during, long, hot grade ascents....a crown sheet can drop off the supporting stays in a matter of a few, careless, seconds.

Crownsheet-failures and the resultant explosion of the EXPANDING GAS ---- STEAM,  causes immense damage to the surrounding area as well as destroying the boiler and instantaneously killing the crew members....

Ben Kantner always liked smaller fireboxes, [ account of the smaller amount of movement of the sheet ---- less square footage] , during the thermal-cycling of the fire temperatures in the fireboxes] compared to the more modern approach with immense length crown sheets, and long side sheets.  

He especially appreciated the modest fireboxes of the Canadian Pacific G5-class, 4-6-2s, of the late 1940's construction era.  
They had very clever methods of minimizing the damage in the event of the greater portion of the crown suddenly giving-way under low water conditions....

They supported some regions of the crown using several rows of straight-threaded crown stays.....under the softened-steel
( low-water event) of the crown sheet, the softened threads of the sheet could expand and slip down, and off the ends of the stays,,,... that led to an immense steam cloud inside the firebox, instantaneously extinishing the fire, in a few microseconds, but the rest of the crown was still supported by conventional, inverted-taper, threaded stays.  

The inverted taper of conventional crown stays, continue to support the softened, expanded holes in the crown sheet to only slip by a couple of threads....... so the CP safety Crown scheme, allowed very rapid pressure decreases, while controlling the release to over a few seconds.  Thus, avoiding a sudden, total collapse of the crown sheets, of earlier firebox fabrication practice.

The boiler explosion at the Gettysburg RR, in the 1990s, was just such a controlled event ---- had that boiler exploded in a conventional manner, the little hamlet where the disaster occurred would have been virtually flattened....
Had that been a true boiler explosion.....I speculate that would have been the END of full-sized steam on any American railroads.

Thank you, the designers in Montreal, we are all indebted to your wise solution -  I know of no other Canadian G5 -class engine ever having suuered the fate of the CPR #1278 class G5d, 1948
 
She rests quietly, in the Age of Steam roundhouse, Sugar Creek, Ohio.
The High Iron Compny ran many FINE excursions behind her.
And he astounded the CNJ professionals as she snaked the 18-car train out through multiple numbers of double-slip switches, as she nimbly powered her way out of Jersey Ciy, and never slipped, a bit....
( Big CNJ and Reading and B&O engines often stalled because of the extreme drag forces of many heavyweight passenger cars wedged in those double slips.... it never phased the mighty G5 over the next successive, long excursion trains that we dragged
out of the Communipaw Passenger station.....Still Standing, at Liberty State Park, NJ.  
We rattled had the fun of rattling those wonderful windows many times, now sitting silent..).

​W. 



Edited 2 time(s). Last edit at 04/11/17 15:23 by wcamp1472.

We dont at Train Mountain some other clubs might so not all do.
-------------------------------------------------------
> I've heard of a few other incidents like this
> through the years.  Most have the common
> denominator of the leader of the group coming from
> the "live steam" hobby where they hydro test
> boilers to as much as 100% above MWP, not knowing
> any better and thinking they "know it all" because
> they built a 7-1/2" gauge Little Engines 4-4-0. 

Thanks for all the good information.

R.R.

Once in a while, some fool Will decide that if a boiler is designed to be able to handle 4 times it's operating pressure, that it should be hydroed to that pressure. IOW, if it's a boiler that operates at 250 psi, why not hydro it to 1,000 psi to make sure?

I know of one who decided it would be a real good idea to test the superheater units to 1,800 psi. And did. Or tried to.

Thanks much for explaining Hydro tests. As one who will qualify to run steam at the Illinois Railway Museum this summer, I've been expanding my knowledge of steam engine machinery and testing procedure. I always thought the CP used "Fusible Plugs" to prevent a complete boiler explosion in the event of a crown sheet failure. They way "Fusible Plugs" were explained to me is that they were plugs in the actual crown sheet itself and made of lead. In the event of a crown sheet failure, the lead was supposed to melt out, blowing out the fire in the manner you describe. Very interesting info you present sir!!

wchogger

"Fusible Plugs"...

You raise important points about fusible Plugs.
They were a complement to low water alarms.  Low water alarms were mechanical devices, used primarily by roundhouse forces as reminders that engines kept hot, sitting for hours waiting for the 'call'.....

Early fusible plugs were made ofbrass with hollow center's, filled with a melt-out material. The lead-filled models  often failed in that the water rushing out the orifice, actually cools the rest of the metal remaining in the plug , with a small hole , blowing steam and water.   The later versions were modified by 'soldering' a brass plug in the hole, thus as the metal softens , the entire brass plug drops out, leaving a larger hole that does NOT tend to close-up.

Low water alarms were 'resettable', meaning that once triggered, the whistle could be changed to a loud hissing noise. The two best low water alarms were the Nathan and the Barco.  The Nathan used a long copper tube, outside the boiler, in the cool air.
The lower end of the copper tube, extends to a point about 3 inches above the crown sheet.  The copper tube remains filled with cold after, there being no open end.  If the water level in the boiler drops below the level of the opening of the sensing  tube.
As the copper tube filswith steam, it lengthens, eventually opening a valve that blows a sharp-sounding whistle in the cab.

Over time, say 5 minutes, the steamin the copper tube condensesandthe coppertube refills with water.  All the recoveryprocedure presums tha the water level has been brought up by the injector, orthe pump.

The Barco style alarm use a float chamber to raise a float, closing the steam line to the warning whistle.  Again, there is a siphon pipe extending down to 3-inches above the crown sheet. If the siphon tube lower end gets exposed ( above the water level ), the water in the float chamber drains out, steam fills the float chamber, but does NOT raise the float bulb.  The 'bulb' only raises by floating on the surface of WATER.  The water level in the float chamber , again assuming that the low water condition is being remedied. Eventually, the water in the chamber, outside the boiler keeps the float n the top of the cooled water.

Over the road, the low water alarms CAN  be reseT, WITHOUT CONSEQUENCES.
There is no way to reset a blowing DROP plug while on the road.
So, it is possible that a low water event could have endangered the crown sheet, and the the crews can reset the alarm, and nobody knows that "a low water event" had occurred.
I am not sure why fusible plugs were never widely used on coal burners, but were commonly used on "oil burners".

When activated, the 'drop plug' blows water andsteam into the firebox. It does impair the draft rate of air through the firebox, burning of oil continues, but it is very hard to fire the oil burner, at all.  When, at the end of the trip, if a crew delivers an engine to the engine house with a drop plug blowing, it meant an 'automatic' 30-day suspension.

Union agreements often contain clauses giving 'hearing rights' to crews before suspension .  
The sloppy crews often would defer to 'self-discipline', ( taking off a month, non-paid, rather than going through a formal hearing.

So the discipline aspect of the fusible plugs was beneficial.  Especially since there was NO WAY to replace a 'blowing' drop-plug, while in the Road....

​W.
Im weary. We'll go band proof it, later
 

The incident involving the exSP steam locomotive getting into a low water situation on the KCS several years ago was instructive. Neither cab crew member tumbled to the fact the water was low. The locomotive was equipped with several fusible plugs, all of which did what they were designed to do and began blowing steam and water into the firebox.

They were still trying to fire the thing with the plugs open.
Not very smart. The locomotive was towed home and banned from that railroad ever after.

I still scratch my head at the story of the C&O allegheny that blew up near Hinton W.VA in 1953. According to witnesses the sound of the Nathan low water alarm could be heard for several minutes before the explosion actually occurred. Yet the engine and 10,400 tons behind it continued on until it exploded, killing 3 crew members. The resulting investigation concluded that the explosion was caused by a low water condition that led to a crown sheet failure.

"Chesapeake & Ohio .Railway locomotive No. 1642, hauling eastbound freight train Extra 1642 East, departed from Handley, W, Va., at 1:20 p.m., June 9, 1953, and proceeded without any known unusual incident to CW Cabin, near the city limit of Hinton, W. Va., a distance of 71.6 miles from Handley, where, about 5:25 p.m., the boiler of the locomotive exploded while the train was moving at an estimated speed of 20 miles per hour.


The train left Handley, W. Va., with 91 loaded, cars, adjusted tonnage 7510 tons. A stop was made at Thurmond, W. Va., 38.6 miles from Handley, at 2:55 p.m., where coal and water were taken, and a stop was made at Quinnimont, W. Va., 12 miles from Thurmond, at 4:12 p.m., where water was taken and cars were picked up. The train departed from Quinnimont, approximately 21 miles from the point of the accident, at 4:38 p.m. with consist of 123 loaded and 2 empty cars, 10,430 adjusted tons. The tonnage rating for the locomotive over this part of the division was 11,500 adjusted tons. Approaching the scene of the accident the track was undulating, but at the point of the explosion was level and. tangent. The weather was clear and dry. The positions of the three employees on the locomotive at time of the accident were not known.


At the point of the explosion, there were two tracks on the left side of the eastbound main, the westbound main and a switching lead, and on the right side New River ran approximately parallel with and about 55 feet from the eastbound main.


The force of the explosion tore the boiler from the frame and cylinder connections and it was thrown upward and forward. The boiler struck on its front end on the rails of the eastbound track approximately 440 feet ahead of the point of the explosion, then rebounded. The back head, struck the track 639 feet ahead of the point of explosion where the boiler came to rest on its right side in reversed position with front end, on the adjacent westbound track and firebox on the switching track. The smoke box front was blown off and several super-heater units were blown out. The cab was blown 133 feet to rear and 58 feet to right of the point of explosion where it fell at the water edge of New River. Grates, grate bars, throttle lever, and other parts were scattered for distances up to approximately 772 feet from point of accident, some falling in New River, Many appurtenances were badly damaged and some parts could not be located. The track rails at point of explosion were indented by the trailing truck wheels and the two rear pairs of driving wheels and the westbound track was moved approximately 5-1/4. feet to the left. At the point where the front end of the boiler struck the track rails were broken and badly bent and a large hole was torn in the road bed. Where the back head of the boiler struck, the westbound track was moved 3 feet to the left. The locomotive running gear with tender attached came to rest with front end alongside the front end of the boiler with only trailing truck wheels derailed. All tender truck wheels were derailed and the front truck was off center. The tank was skewed, to the left with left front corner leaning approximately 10 degrees to the left. Nine cars were derailed and bunched, five were at approximately 90-degree angles with the rails four of which were on their sides.


The engineer, fireman, and head brakeman were killed. The engineer's body was found at the water's edge of New River, approximately 75 feet to rear of the cab. The fireman's body was found in the cab, and the brakeman's body was found in a ditch on the left side of the tracks near the point of the explosion.


DESCRIPTION OF LOCOMOTIVE


Locomotive 1642, 2-6-6-6 type, carrier's classification H-8 Allegheny, was built by the Lima Locomotive Works Inc., at Lima, Ohio, in December 1944. The four cylinders wore 22-1/2 x 33 inches the diameter of driving wheels 67 Inches with new tire's weight in working order 771,300 pounds, weight on driving wheels 507,900 pounds, and tractive effort 110,200 pounds. The locomotive was equipped with an Alco Typo H power reverse gear, American multiple front throttle, Standard H D stoker, Franklin No. 8-A Butterfly mechanically operated fire door, Baker valve gear, Worthington Type 6-1/2 S S A feed water pump, Nathan Type 4000-C special injector. The boiler was equipped with a Nathan Type B low water alarm and there were three Nicholson thermic syphons in the firebox. Locomotive had made 97,000 miles since last Class 3 repairs and 18,000 miles since last class 5 repairs. The rectangular east-steel water-bottom tender had capacity of 25,000 gallons of water and 25 tons of coal.


The boiler was of the three-course conical type with combustion chamber and wide radial-stayed firebox; builder's serial boiler number 8811. The inside diameter of the first course was 101-1/8 inches, second course 103-11/16 inches, and third course 106-5/16 inches, second course 103-11/16 inches, and third course 106-5/16 inches; thickness of first course 1-9/32 inches, second course 1-5/16 inches, and third boiler had 48 2-1/4 inch outside diameter flues and 278 3-1/2 inch outside diameter flues, 23 feet in length, and 71 Elesco Type E superheater Units. The working steam pressure of the boiler was 260 pounds per square inch.


The radial-stayed firebox was 180 inches long and 109 inches wide, and combustion chamber was 118 inches long. The firebox consisted of a one-piece crown and upper side sheets, lower one-fourth side sheets, door sheet, flue sheet, and inside throat sheet. Flue sheet and throat sheet were 9/16 inch thick and other' sheets were 3/8 inch thick, Flue sheet seam was riveted and door sheet seam was riveted across the top and welded down the sides. Other seams and patches in the firebox were butt welded. The crown sheet was 11-3/4 inches higher at the flue sheet than at the door sheet, The firebox was fitted with three thermic syphons. There was no syphon in the combustion chamber. New flue sheet and lower side sheets were applied on April 6, 1950,. at which time a patch was applied in bottom of combustion chamber, one-half section applied to left syphon, and patches applied to center syphon and, to diaphragm of connection sheet, Crown stays wore 1-1/8 inch diameter reduced body type, spaced approximately 4-1-16x4 inches Combustion chamber stays were 1 inch diameter, spaced approximately 4-1/6 x 14 inches. Fire box stays were 1 inch diameter, spaced approximately 4-1/8 x 14 inches. All stays were rigid except in the combustion chamber and breaking zones."

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