Steam & Excursion > PRR K4S 1361

Is there any news on the progress of the restoration?

WauhopM Wrote:
-------------------------------------------------------
> Is there any news on the progress of the
> restoration?

No.

Yes...
However, money is allocated as it becomes available.
A whole new firebox and outer wrapper had to be increased 
in material thicknesses, etc, in order to comply with the 
4:1 safety design ratio.  A boiler shell must be built using the
mathematical equivalent of 4-times the intended operating 
boiler pressure. K4s were built an proportioned for 205 psi
operating pressure.  That affects such things as weight on drivers and 
diameters of the pistons, and cykinder bores.

The 4-times 'safety ratio' came from the PRR's influence over the ICC,
as they upgraded the ICC law , to become effective in 1910.  PRR's 
'reality' was not the risk of boiler shell-related bolier explosions.
[ after 1900, virtually ALL boiler explosions are the result of engine
crews allowing the boiler water to drop below the top sheet of the 
firebox.  

When the water no longer cools the 'crown sheet' the re-heated, and softened 
sheets pull off of the threads of the supporting stay-bolts, allowing all 
the 400-degree water to instantly flash into a steam-explosion...

So, today's new firebox complies, mathematically, with the 4:1 safety factor,
as laid out on the new boiler drawings to be submitted to ASME and the FRA,
as the loco is placed in service.  So, YES, there has been A LOT of positive progress
on 1361's status.

Money flows are the main determinate to continued progress towards completion.
Your material monetary contributions are crucial to further progress.
So, if you want prigress, what are you doing personally to advance financing.

What the record shows as your contributions, I will match your future donations 2:1,
to advance the completion of 1361.

​W.
 

I'm trying to make editorial corrections, however, attempts to bring up 
the original typing, only brings up a blank screen..

the editing facility of this antique software, is in need of improvement.
Sorry about obvious grammatical errors; but, so far we're stuck.

W.

I have no details on the restoration status but here's a photo of how it looked at the museum in Altoona 25 days ago.  The tender looks sharp.

---

I wonder if the top of the Crown sheet still looks like something out of Architectural Digest?

Out 

The whole back 'cube shape' is 100% new construction, 
Belpaire firebox's outer wrapper sheets.

At the time they were designed, economically feasible electric stick
welding was 25 years in the future.  New fireboxes have about a 5-year 
life-span before they start cracking in tte lower corners --- a result of 
years' of thermal-cycling between low-temp sitting-around temperatures 
and Train-service firebox temps of 3,000F firebox flame temperatures.

As PRR entered the 20thcentury, their intent was to build 1,000 boilers,
with light-construction Belpaire fireboxes.   When corner-cracking  justified 
it, PRR had new fireboxes ready to go, for quick change-outs.

( Theoretically, in their planned renewal policies, PRR shops would have replaced
the 3/8" -thick steel inner furnace, And they would fit a new furnace into the re-used
outer wrapper structure,.... and they would have many, upgraded spares, ready 
for installation.  Stick-welding came along and allowed much quicker repairs,
without having to renew the whole firebox.  So the 'new firebox' scheme was
only used for a couple of years.)
 
They intended to build 500 K4 class 4-6-2s and 500 L1 class 2-8-2 locos.
The actual numbers slightly varied.  At the time they were designed, It was
easier to apply new fireboxes using hot rivets,  because there existed no way
to repair corner cracking with the tools and methods available in the 1910-era,
when they were designed.

By about 1927, economical, DC welding technology was perfected and applied 
in heavy repair shops.  When stick-welding was accepted, it obviated the need
for all new fireboxes --- every 5 years, across the whole fleet.

In the 1930's, new fireboxes were used after about 20-years of service.
A big economic savings, over the life of the 1000-boiler fleet.

At the time of design & construction of 1361, the 'new' boiler construction requirements 
of the 1910 revision of the ICC boiler construction rules (4:1 minimum Factor of Safety)
had not taken place, yet.

The 'new' Rules required that new boilers had to be designed as if
the operating pressures were 4-times the actual operating pressures.
The origin of the "4:1 factor of safety", as required by the new Regs.
So, PRR's new boilers would have a operating pressure of 205 psi.
And a safety-factor of 4:1would have been a structure built to operate 
at 820 psi.  All the sheets, the shell and staybolt spacing was to be designed 
using arithmetic numbers of 820 psi steam pressure.

At the time, no boilers were constructed to the new standards, and many 
loco orders had already been placed, with boilers designed at lower factors of safety.
It was the dawn of the adoption of superheating and the very beneficial performance 
standard increases.   Builders & RRs appealed to the ICC for a slower implementation 
period, of 10- years, or more of gradually increasing construction standards -- 
before the 4:1 Standards were mandatory.  The ICC relented, and the 4:1 standard
was allowed to increase over a lengthened 'adoption period'
1361 was built during that allowed 'lower' safety factor period.

( Its important to note that the 4:1 design standards applies to the boiler 
   shell, only.  That would be the cylindrical sections, and includes the outer
   wrapper of the firebox, and the firebox, staybolt-supported, and the firebox sheets
   are 3/8" thick.  Staybolt spacing would be determined using the 820 psi pressure
   'assumptions' , regarding number and spacing of firebox staybolts).
  
   The inner firebox, 'furnace', is constructed of 3/8" steel supported by rows of staybolts.  
   For 4:1 safety requirements, staybolts  are mounted more closedly together,
    than used on the original firebox of the era before WW1.
   The closest theoretical staybolt-spacing, limits maximum boiler design presure to 310psi.  
   
   The "new" wrapper and firebox fitted to 1361 meet the spacing and quantity of
    staybolts required by the 4:1 safety design standard.  Operating pressure
     remains at 205 psi.)

In the meantime, WW1 came along, about 1917/18, and the mandated 10-year
adoption period was relaxed by the ICC...so that assembly lines could keep up
with new loco poduction demands... Remember, that the efficiencies of superheating 
led to greater numbers of new production locomotives.  Superheating doubled 
the distances that a tender-full of water could go...

Electric stick-welding made firebox repairs much easier and quicker, so 1361
arrived at the 1950's with its original, firebox from its 1914 design-date, with
a lower factor of safety than 4:1.... WW2 further delayed the mandatory date 
for 4:1 compliance, on the older locos.  PRR had thousands of locos built to 
lower 'factors of safety', so that many were scrapped, as the 1940s and 1950s 
approached. 

So, 1361, now has a fully-compliant firebox built to the 4:1 safety requirements..
Or soon will-have, when they install the new firebox up, inside the new boiler shell.

​W.

( Ross and I visited 1361, at very near the same date as the photo above
was taken.  Thanks for posting).
   


 



Edited 6 time(s). Last edit at 08/30/24 12:51 by wcamp1472.

Thanks all for updates and information. 👍

Regards

Posted from iPhone

Are there advantages to the Belpaire firebox over the more commonly used design? Thanks in advance for any info.

Markus V.
“The Fort” in Indiana

Posted from iPhone



Edited 1 time(s). Last edit at 08/29/24 14:01 by Goalieman.

The original design used 3/8" thick steel for both the innner and outer
firebox sheets.   Conventional 'wagon-top' boilers use 1" thick boiler sheets,
like used for the boiler shell.

PRR's original intent &  design was less costly, across a whole fleet of engines.
And in their original intent, whole fireboxes were replaced, so quality control
was very easy to keep under observation.

PRR had intended to install an entire firebox, because at that early date firebox
repairs took weeks to complete. So PRR intended to apply a whole fresh firebox,
that could be added in 2 days. So the subject loco could be more quickly returned
to service.

The removed firebox section was fitted with new internal sheets, new staybolts, etc.
, and was returned to the pool of ready-to-go fireboxes.

With the advent, and wide use of stick-welding technology, PRR no longer needed to
remove the whole firebox, simply  to make repairs to cracks and installl patches in the
firebox sheets --- mostly in the lower corners, where expansion/contraction distances
were the greatest.  The hot firebox sheets expand and contract from their centers..
.. into the corners.

So, for a whole fleet, change-outs of Belpaires made a lot of sense;
but, 'wagon-top' boilers were better, especially after repairs ---
cracks and patches--became easier with advances in stick-welding and
other metal working techniques, that became common in the 20th centrury.

However, whole fireboxes eventually need to be replaced, so even conventional
wagon-top boilers get replaced fireboxes.  The otiginal metal gets too thin in places,
and eventually the firebox must be replaced.

Recently when I saw 1361, in Altoona, I forgot to get the thickness of the newly
fabricated outer firebox sheets... I'd be interested to know what that is.
My guess is that the new outer-wrapper is made of much thicker steel sheets,
than the original.

The firebox will still have to be 3/8" steel ---- it's the thickest that the cooler, water-side 
can keep the 'hot-side' of the sheets from melting!  

Anything of thicker steel, softens and melts, under a sustained, stong draft.

​W.



Edited 8 time(s). Last edit at 08/30/24 11:51 by wcamp1472.

Goalieman Wrote:
-------------------------------------------------------
> Are there advantages to the Belpaire firebox over
> the more commonly used design?

It simplified the boiler's internal construction, at least in the PRR's opinion.

pennsy3750 Wrote:
-------------------------------------------------------
> Goalieman Wrote:
> --------------------------------------------------
> -----
> > Are there advantages to the Belpaire firebox
> over
> > the more commonly used design?
>
> It simplified the boiler's internal construction,
> at least in the PRR's opinion.

Thanks pennsy3750!

Posted from iPhone

Goalieman Wrote:
-------------------------------------------------------
> pennsy3750 Wrote:
> --------------------------------------------------
> -----
> > Goalieman Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > Are there advantages to the Belpaire firebox
> > over
> > > the more commonly used design?
> >
> > It simplified the boiler's internal
> construction,
> > at least in the PRR's opinion.
>
> Thanks pennsy3750!

Yes, as all the staybolts are generally the same length, i.e. no VERY long radial flexible staybolts.

Fine but the jungle of bracing above the Crown was really interesting, those door sheet
brackets were quite an item.

Out 

HotWater Wrote:
-------------------------------------------------------
> Goalieman Wrote:
> --------------------------------------------------
> -----
> > pennsy3750 Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > Goalieman Wrote:
> > >
> >
> --------------------------------------------------
>
> >
> > > -----
> > > > Are there advantages to the Belpaire
> firebox
> > > over
> > > > the more commonly used design?
> > >
> > > It simplified the boiler's internal
> > construction,
> > > at least in the PRR's opinion.
> >
> > Thanks pennsy3750!
>
> Yes, as all the staybolts are generally the same
> length, i.e. no VERY long radial flexible
> staybolts.

Thanks HW!

Posted from iPhone

ALMOST ....
Above the crown sheet there are two rows of cross-stays
that tie the top portions, above the crown sheet, together. 

Remember, that PRR's fireboxes, inner and outer, are made of 3/8" steel, 
and full bracing is required.

I suspect that 1361's new design uses substantially thicker 
'wrapper-sheets' outside of the firebox, proper.

Firebox sheets exposed to direct flames are kept 'cool'
by water circulating over them.... but, thicker steel in the 
firebox sheets couldn't be kept from softening and partially
melting, when exposed to 3,000 F flames and firebed,
of necessity, 3/8" steel is the thickest that fireboxes can be.
Its why, in today's world,  water-tube boilers are the common standard..
They can be up to 500psi ratings..

Before 1900, fireboxes & boilers were structurally weaker and there were no 
industry standards for minimum thickness of materials. or no uniform,
industry-wide quality standards for manufactured steel sheets.
There was no ASME, at that time.... so, there were boiler failures,
and explosions due to defects in design and matetials used in early 
boiler structures.

As the early 20th century progressed, material quality improved, 
uniform standards were becoming accepted, and "structural integrity"
increased.   With the ICC's tightened inspection laws of 1910, over the 
earlier ICC rules,  new boiler explosions due to structural issues
disappeared.  But there were still a lot of 'old' dangerous boilers in use
every day!

The most common boiler explosions were invariably caused by low 
water over the crown sheets.  When the softened, overheated crown
sheet had an 'area-failure',  a large portion gave-way, and a full-boiler
of water at near 400F instantaneously flashed into steam, making a rocket,
and throwing the boiler into the air and down the tracks.
Boiler explosions happened into the 1950s.... C&O crews blew-up a 1600,
Allegheny, 2-6-6-6,  about 1953.  The D&H crews blew up a relatively 
young 4-6-6-4 Challenger,  due to "low water"

And Gettysburg RR "dropped" a crown sheet, loco 1278, in Pennsylvania,
on June 17, 1995!   Some 20th centrury loco explosions have FLATTENED 
small towns across America...

EVERY ONE of those firebox explosions was caused by the crews allowing 
the water level to drop dangerously low, allowing the 3,000 F fire to soften,
& the unprotected steel began to glow, red-hot until it was pushed-off the 
stay bolts by the hundreds of tons of boiler presstue.... remember that pressures 
are rated in square INCHES, but firebox sheets involve  lots of 
square FEET.  A square foot is 144 square Inches... ( at 250/300 psi?)
That can add up to immense areas exposed to lots of pressure.
Mulitply 144 X 300 psi.....( and that's for ONE square-foot..)

Explosions happen very quickly, when the hot steel becomes softened...
​Our next boiler explosion will be our LAST....
This shit is DANGEROUS!

​W.

 



Edited 6 time(s). Last edit at 08/31/24 18:43 by wcamp1472.