On Jul 25, 2:03*am, Clive wrote:

Priming is normal for any engine with an over full boiler,

Priming might be "inevitable" if you over-fill the boiler, but it's
never "normal".

Look at the sad tale of 532 Blue Peter, if you want to see how bad
priming can get.

On Jul 25, 6:27*am, harry wrote:

No-one in their right mind is going to lose sight of the water level.

A wise idea - mostly because it's very hard to tell if a gauge glass
is full of water or steam, once you've lost sight of the level -
especially on the LMS, where the gauge cocks were linked to a single
handle, so you couldn't blow one at a time.

On Mon, 25 Jul 2011 02:53:44 -0700, Andy Dingley wrote:

On Jul 25, 6:27Â*am, harry wrote:

No-one in their right mind is going to lose sight of the water level.

A wise idea - mostly because it's very hard to tell if a gauge glass is
full of water or steam, once you've lost sight of the level - especially
on the LMS, where the gauge cocks were linked to a single handle, so you
couldn't blow one at a time.

Of course, in the earlies (or, indeed, up until the 1860s in many places)
it was a bit harder, as there weren't gauge glasses. Recommended procedure,
I have read, was to tap on the boiler side with a mallet (or similar) to
check whether it 'rang' at a given level. If it did, then that bit was above
water (the same method was used for whisky stills until well on in the
19th century - no reason for introducing that except it's a nice factoid :-)

With the small, domeless boilers of early years, the surging inherent in
primitive locomotives, the rocking and swaying inevitable on short rails
(3'ish, in most cases under early locomotives) and the horrible prospects
if a flue tube became uncovered for any length of time, priming must have
been near-universal on the pioneer locomotives, at least at the start of
a run (when there must have been a severe temptation to over-fill the
boiler rather than risk getting stuck away from any chance of refill/
suffering feed pump failure).

--
From the Model M of Andy Breen, speaking only for himself

On Mon, 25 Jul 2011 02:52:31 -0700, Andy Dingley wrote:

On Jul 25, 2:03Â*am, Clive wrote:

Priming is normal for any engine with an over full boiler,

Priming might be "inevitable" if you over-fill the boiler, but it's
never "normal".

Look at the sad tale of 532 Blue Peter, if you want to see how bad
priming can get.

Going back to the earlies, the /extremely/ large clearances at the ends
of the cylinders on the two surviving Hedley (Wylam) machines could
be a recognition (possibly by Trevithick, given that the cylinder patterns
are very like ones in his stationary engines, and the cylinders may
in fact be cast from the patters made for the 1805 Gateshead engine)
that they were going to prime.
In the Wylam application, of course, it would have been even more important
to have this clearance as the cylinders were mounted externally (rather
than within the boiler, as the cylinder design suggests they were intended
to be fitted) so condensation would be an issue - and there were no drain
cocks on those (vertical) cylinders...

--
From the Model M of Andy Breen, speaking only for himself

In message
,
harry writes
Priming is never "normal". If you'd ever seen it you'd know why.
Significant priming would wreck the superheater (if fitted) and damage
the steam engine.
No-one in their right mind is going to lose sight of the water level.
You keep an eye on the chimney, at the first sight of priming you turn
off the injectors and the priming stops almost immediately, no damage
and security in not letting the boiler get to low, allowing
concentration on proper firing and fire management with just the
occasional look at the sight glasses.
--
Clive

In message
,
Matty F writes
Why is there such a steep taper on the thread on the plugs?
Wouldn't that make the whole plug fall out more easily?
The lead plugs I remember had a very large pitch but weren't tapered,
though the ones around the boiler to assist in washout were.
--
Clive

On Jul 24, 9:40*pm, Andy Breen wrote:
On Sun, 24 Jul 2011 12:07:53 -0700, harry wrote:
On Jul 24, 2:14*pm, Andy Breen wrote:
Surely the biggest factor would be the reliance of the
Trevithick/Hackworth /Stephenson line of locomotive on exhaust steam
blast to stimulate the fire and draw it through the flue/tubes? In a
stationary engine the only limitation on chimney height is cost and
structual limits of materials, and in marine applications uptakes can
be carried high - and there's likely to be significant air movement
over the top of the uptake anyway. If neither of these suffice, then
there's more space available to provide forced draught (either in a
closed-stokehold or open-stokehold arrangement) than there is in the
limited loading gauge of a locomotive.

Forced (or induced) draught becomes an issue in "economic" style
boilers, ie ones where there is high resistance to combustion gas flow
due to multiple small firetubes. *In early boiler where there was just a
furnace tube the resistance was low so natural draught would suffice.

Originally introduced in warships as a source of short-term "sprint" power,
IIRC (late 1870s, I think. Iris-class rings a bell here but I'm not going to
go and pull Brown off the shelf to check..). Had the added advantage of
allowing fuel saving the rest of the time by reducing the weight of machinery
needed for sprint power. Got adopted widely (over-widely, and over-ambitiously)
in warships after CALLIOPE sustained 110% of 1-hour power for 23 hours
while escaping the typhoon at Apia in 1889 - she had a very good set of
boilers and engines by Maudsley (and a very good chief engineer).
As you say, the advantages were restricted to boilers with a more restricted
draught path than the old large flues (where forced draught would simply
have sucked the fire straight through [1]) - warship use of forced draught,
and subsequent civil maritime use - followed the introduction of multitubular
fire-tube boilers in place of the old flue type, and snowballed with the
appearance of water-tube boilers (Bellevilles, and such..).
For a bit of uk.r topicality, the multitubular fire-tube boilers were
referred to at the time as "locomotive" boilers, even though - with the
grate in a large flue - they were unlike anything used in main-line locomotives
after the 1850s (apart from some L&Y 0-8-0s in the 1900s, I think...).

[1] which happened later, where boilers were over-forced. To a spectacular
degree at times, such as in WW1 battlecruisers.

To carry this off topic digression on a little further, an interesting
development of the '20s and '30s was what Brown Boveri & Cie marketed
as the Velox boiler. The idea was to make a more compact boiler where
the airflow could be managed to match the combustion conditions. The
concept added a blower to the fresh-air side of the boiler (nothing
too special there), but then had the clever idea of powering the
blower by means of a turbine in the exhaust stream, rather like a
turbocharger. These were large machines, so the turbomachinery in
each case was multi-stage axial equipment. BBC then made the (for the
time) radical step of taking such a device, increasing the pressure
ratio by adding a few stages to the turbomachinery and getting rid of
the boiler itself, just leaving the fire on its own. The resulting
machine was installed in Neuchatel in 1939 and became the world's
first gas turbine (the Neuchatel machine itself remaining in service
as a back-up generator until about 10 years ago).

Robin

On Jul 24, 11:37*am, Jeremy Double wrote:
On 23/07/2011 23:28, The Real Doctor wrote:

On Jul 18, 8:26 am, Jeremy *wrote:

It also gains them another 80 degrees or so of temperature difference
between the heat source and heat sink, which significantly increases the
maximum possible efficiency of the heat engine, according to the second
law of thermodynamics.

Enthalpy change from superheated steam at 10bar/500C to saturated
water at 1bar/100C: 3052.1 - 417.5 = 2634.6 kJ/kg.

Enthalpy change from superheated steam at 10bar/500C to saturated
water at 0.05bar/32.9C: 3052.1 - 137.8 = 2914.3 kJ/kg.

Extra enthalpy available: 2914.3 - 2634.6 = 279.7 kJ/kg ~ 10%.

Yes, and looking at the Carnot cycle efficiency (i.e. using the second
law of thermodynamics rather than the first law), using your figures:

Theoretical maximum efficiency = 1-(Tc/Th)

For 33 deg C sink temperatu efficiency = 1-(306/773)= 61%
For 100 dec C sink temperatu efficiency = 1-(373/773)= 52%

But this (500°C) isn't the temperature of the heat source, it is the
temperature of the steam at the hottest part of the cycle. The heat
source (combustion products) is more likely to be at around the 2000°C
mark. This is one of the major sources of thermodynamic loss in a
steam cycle, largely corrected for in the GT combined cycle.

Robin

On Jul 25, 1:55*pm, bob wrote:
On Jul 24, 9:40*pm, Andy Breen wrote:









On Sun, 24 Jul 2011 12:07:53 -0700, harry wrote:
On Jul 24, 2:14*pm, Andy Breen wrote:
Surely the biggest factor would be the reliance of the
Trevithick/Hackworth /Stephenson line of locomotive on exhaust steam
blast to stimulate the fire and draw it through the flue/tubes? In a
stationary engine the only limitation on chimney height is cost and
structual limits of materials, and in marine applications uptakes can
be carried high - and there's likely to be significant air movement
over the top of the uptake anyway. If neither of these suffice, then
there's more space available to provide forced draught (either in a
closed-stokehold or open-stokehold arrangement) than there is in the
limited loading gauge of a locomotive.

Forced (or induced) draught becomes an issue in "economic" style
boilers, ie ones where there is high resistance to combustion gas flow
due to multiple small firetubes. *In early boiler where there was just a
furnace tube the resistance was low so natural draught would suffice.

Originally introduced in warships as a source of short-term "sprint" power,
IIRC (late 1870s, I think. Iris-class rings a bell here but I'm not going to
go and pull Brown off the shelf to check..). Had the added advantage of
allowing fuel saving the rest of the time by reducing the weight of machinery
needed for sprint power. Got adopted widely (over-widely, and over-ambitiously)
in warships after CALLIOPE sustained 110% of 1-hour power for 23 hours
while escaping the typhoon at Apia in 1889 - she had a very good set of
boilers and engines by Maudsley (and a very good chief engineer).
As you say, the advantages were restricted to boilers with a more restricted
draught path than the old large flues (where forced draught would simply
have sucked the fire straight through [1]) - warship use of forced draught,
and subsequent civil maritime use - followed the introduction of multitubular
fire-tube boilers in place of the old flue type, and snowballed with the
appearance of water-tube boilers (Bellevilles, and such..).
For a bit of uk.r topicality, the multitubular fire-tube boilers were
referred to at the time as "locomotive" boilers, even though - with the
grate in a large flue - they were unlike anything used in main-line locomotives
after the 1850s (apart from some L&Y 0-8-0s in the 1900s, I think...).

[1] which happened later, where boilers were over-forced. To a spectacular
degree at times, such as in WW1 battlecruisers.

To carry this off topic digression on a little further, an interesting
development of the '20s and '30s was what Brown Boveri & Cie marketed
as the Velox boiler. *The idea was to make a more compact boiler where
the airflow could be managed to match the combustion conditions. *

The idea of the Velox as an inspiration for gas turbines is an
interesting one, but the gas turbine (in theory at least) goes back to
the 18th century. They didn't need the Velox boiler to inspire them.

The resulting
machine was installed in Neuchatel in 1939 and became the world's
first gas turbine

Neuchatel wasn't the first gas turbine. There were a number in service
in the US before this, running with blast furnace gas.

On Jul 15, 9:44*am, fred wrote:
In article
,
harry writes

Assuming you are in the UK and not Zimbabwe.

Any regular who takes an interest in what is contributed here will know

to ignore Harry.

On Jul 25, 10:53*am, Andy Dingley wrote:
On Jul 25, 6:27*am, harry wrote:

No-one in their right mind is going to lose sight of the water level.

A wise idea - mostly because it's very hard to tell if a gauge glass
is full of water or steam, once you've lost sight of the level -
especially on the LMS, where the gauge cocks were linked to a single
handle, so you couldn't blow one at a time.

Tch. You don't know anything do you? i don't know why you come
spouting all this book crap from a position of total ignorance.

If you look at a guage glass it has diagonal stripes behind it.

If the glass is full of water they are refracted to the horizontal as
seen through te sight glass.
If the glass is full of steam, they remain diagonal.
So you know whether the water level is above or below the glass.

But you don't know by how much. But at least you can take the correct
action to rectify the situation.

There are three cocks to every guage glass.
Steam side and water side to isolate the fitting if the glass breaks
and drain to blow down each leg separately so as to prevent blockages
and rings forming on the glass.
There are min. two gauge glasses on ever boiler for redundancy/
camparison reasons
They are all fitted with safety glasses too.

On Jul 25, 11:24*am, Andy Breen wrote:
On Mon, 25 Jul 2011 02:52:31 -0700, Andy Dingley wrote:
On Jul 25, 2:03*am, Clive wrote:

Priming is normal for any engine with an over full boiler,

Priming might be "inevitable" if you over-fill the boiler, but it's
never "normal".

Look at the sad tale of 532 Blue Peter, if you want to see how bad
priming can get.

Going back to the earlies, the /extremely/ large clearances at the ends
of the cylinders on the two surviving Hedley (Wylam) machines could
be a recognition (possibly by Trevithick, given that the cylinder patterns
are very like ones in his stationary engines, and the cylinders may
in fact be cast from the patters made for the 1805 Gateshead engine)
that they were going to prime.
In the Wylam application, of course, it would have been even more important
to have this clearance as the cylinders were mounted externally (rather
than within the boiler, as the cylinder design suggests they were intended
to be fitted) so condensation would be an issue - and there were no drain
cocks on those (vertical) cylinders...


If you ever saw a boiler priming, it would frighten the **** out of
you. Priming is to be avoided at all costs. and it's not all about
water in cylinders either.

Steam can be travelling at over a hundred miles and hour down a steam
pipe.
Any water in there is going at the same speed. When it comes to a
bend or valve, it tends to keep right on going in a straight line. The
results can be devastating.

You need to research snifting valve too.
http://en.wikipedia.org/wiki/Snifting_valve

On Jul 25, 1:20*pm, Clive wrote:
In message
,
harry writesPriming is never "normal". If you'd ever seen it you'd know why.
Significant priming would wreck the superheater (if fitted) and damage
the steam engine.
No-one in their right mind is going to lose sight of the water level.

You keep an eye on the chimney, at the first sight of priming you turn
off the injectors and the priming stops almost immediately, no damage
and security in not letting the boiler get to low, allowing
concentration on proper firing and fire management with just the
occasional look at the sight glasses.
--
Clive

And how is watching the chimney (even if visible) going to warn you of
priming?

On Jul 25, 1:24*pm, Clive wrote:
In message
,
Matty F writesWhy is there such a steep taper on the thread on the plugs?
Wouldn't that make the whole plug fall out more easily?

The lead plugs I remember had a very large pitch but weren't tapered,
though the ones around the boiler to assist in washout were.
--
Clive

Pipe threads are tapered to assist in getting sealant into the thread.
Parallel threads need a washer and a seat.

On Jul 25, 8:04*pm, harry wrote:

You need to research snifting valve too.
http://en.wikipedia.org/wiki/Snifting_valve

Snifting has nothing to do with priming.

One of the few UK companies to use them was the LNER - including Blue
Peter, as mentioned alredy, the loco that suffered the worst priming
accident of recent years.

On Jul 25, 11:24*am, Andy Breen wrote:

Going back to the earlies, the /extremely/ large clearances at the ends
of the cylinders on the two surviving Hedley (Wylam) machines could
be a recognition (possibly by Trevithick, given that the cylinder patterns
are very like ones in his stationary engines, and the cylinders may
in fact be cast from the patters made for the 1805 Gateshead engine)
that they were going to prime.

I'd never considered this as a deliberate measure against damage from
priming, but it's an interesting idea. After all, in loco practice,
this large clearance still hung around until Churchward decided to
deliberately remove it, around 1900. For stationary engines, Stumpf
recognised it as a bad idea, after realising the importance of re-
compression at the end of stroke, for efficiency purposes.

On Mon, 25 Jul 2011 12:04:30 -0700, harry wrote:

On Jul 25, 11:24Â*am, Andy Breen wrote:
On Mon, 25 Jul 2011 02:52:31 -0700, Andy Dingley wrote:
On Jul 25, 2:03Â*am, Clive wrote:

Priming is normal for any engine with an over full boiler,

Priming might be "inevitable" if you over-fill the boiler, but it's
never "normal".

Look at the sad tale of 532 Blue Peter, if you want to see how bad
priming can get.

Going back to the earlies, the /extremely/ large clearances at the ends
of the cylinders on the two surviving Hedley (Wylam) machines could be
a recognition (possibly by Trevithick, given that the cylinder patterns
are very like ones in his stationary engines, and the cylinders may in
fact be cast from the patters made for the 1805 Gateshead engine) that
they were going to prime.
In the Wylam application, of course, it would have been even more
important to have this clearance as the cylinders were mounted
externally (rather than within the boiler, as the cylinder design
suggests they were intended to be fitted) so condensation would be an
issue - and there were no drain cocks on those (vertical) cylinders...


If you ever saw a boiler priming, it would frighten the **** out of you.
Priming is to be avoided at all costs. and it's not all about water in
cylinders either.

I'm not quite sure /how/ priming could be avoided in those early boilers
(in fact, contemporary accounts - and the rebuilds undergone by slightly
later locomotives such as "Rocket" - indicate that it was something they
struggled with, and really didn't start to get on top of until a few years
into the 1830s, with the introduction of haycock fireboxes and the like).
Bad as priming could be, it would still be a lesser evil than prolonged
exposure of a flue tube (one big flue, the collapse of which would be
- serious..). Again, this from such contemporary (or near-contemporary)
accounts as exist.

Steam can be travelling at over a hundred miles and hour down a steam
pipe.
Any water in there is going at the same speed. When it comes to a bend
or valve, it tends to keep right on going in a straight line. The
results can be devastating.

You need to research snifting valve too.
http://en.wikipedia.org/wiki/Snifting_valve

Yep. Sadly, they didn't have them then.


--
From the Model M of Andy Breen, speaking only for himself

On Mon, 25 Jul 2011 12:26:04 -0700, Andy Dingley wrote:

On Jul 25, 11:24Â*am, Andy Breen wrote:

Going back to the earlies, the /extremely/ large clearances at the ends
of the cylinders on the two surviving Hedley (Wylam) machines could be
a recognition (possibly by Trevithick, given that the cylinder patterns
are very like ones in his stationary engines, and the cylinders may in
fact be cast from the patters made for the 1805 Gateshead engine) that
they were going to prime.

I'd never considered this as a deliberate measure against damage from
priming, but it's an interesting idea. After all, in loco practice, this
large clearance still hung around until Churchward decided to
deliberately remove it, around 1900. For stationary engines, Stumpf
recognised it as a bad idea, after realising the importance of re-
compression at the end of stroke, for efficiency purposes.

I'm not sure it /was/ a deliberate feature of the Hedley machines -
more the consequence of re-using the casting patterns[1] from a horizontal
-cylinder Trevithick (type?) engine in a vertical position - that
also left them with an immensely long stroke which forced the use
of gearing (the Trevithick locomotive of 1805 was, of course, geared..).
Now, whether Trevithick left that clearance in because he expected
water to be carried over into the cylinder is another question ..
My suspicion is he'd one it as an insurance, expecting boilers to
be over-filled and priming to occur, even with stationary engines
(in all cases a Trevithick engine would be the first high-pressure,
compact engine its operators would have seen - the scope for mis-handling
would be immense...).
OTOH, with the cylinders outside and no real lagging, it's hard to see
how the Hedley machines could have worked (especially on short-railed
plateways, with the resulting violent fluctuations of water level
in the small boiler) without that amount of clearance.

[1] Rather crudely converted to use slide valves in place of the 4-way
cock - the amendation is apparently quite clear in the cylinders of the
two surviving machines..

--
From the Model M of Andy Breen, speaking only for himself

On Mon, 25 Jul 2011 11:54:33 -0700, harry wrote:

On Jul 25, 10:53Â*am, Andy Dingley wrote:
On Jul 25, 6:27Â*am, harry wrote:

No-one in their right mind is going to lose sight of the water level.

A wise idea - mostly because it's very hard to tell if a gauge glass is
full of water or steam, once you've lost sight of the level -
especially on the LMS, where the gauge cocks were linked to a single
handle, so you couldn't blow one at a time.


If you look at a guage glass it has diagonal stripes behind it.

If the glass is full of water they are refracted to the horizontal as
seen through te sight glass.
If the glass is full of steam, they remain diagonal. So you know
whether the water level is above or below the glass.

snip..

There are three cocks to every guage glass. Steam side and water side to
isolate the fitting if the glass breaks and drain to blow down each leg
separately so as to prevent blockages and rings forming on the glass.
There are min. two gauge glasses on ever boiler for redundancy/
camparison reasons
They are all fitted with safety glasses too.

So - what would be the recommended operating method for an early locomotive
with no gauge glasses (and no feed pump - Middleton, early Chapman engines
- or one which might or might not work - Trevithick, Wylam, Killingworth..)?

That's a genuine question - can you, with experience of operating boilers,
cast any light on how such a boiler might be worked best. Because I find
it rather hard to imagine, in spite of reading such accounts as exist from
the time..

--
From the Model M of Andy Breen, speaking only for himself

In message
,
harry writes
There are min. two gauge glasses on ever boiler for redundancy/
camparison reasons
They are all fitted with safety glasses too.
Agreed on the Ell of a mess, but on Gods Wonderful Railway, there was
only one sight glass and two small cocks to open so the top one would
blow a little steam and the bottom one would dribble water.
--
Clive

In message
,
harry writes
And how is watching the chimney (even if visible) going to warn you of
priming?
1. I've never been on a steam engine where you couldn't see the chimney.
2. As soon as the soot starts to streak out of the chimney you now it's
being carried by water, i.e. You've started to prime, and you knock off
the injector/s.
--
Clive

On Mon, 25 Jul 2011 19:40:31 +0000, Andy Breen wrote:

On Mon, 25 Jul 2011 11:54:33 -0700, harry wrote:

On Jul 25, 10:53Â*am, Andy Dingley wrote:
On Jul 25, 6:27Â*am, harry wrote:

No-one in their right mind is going to lose sight of the water
level.

A wise idea - mostly because it's very hard to tell if a gauge glass
is full of water or steam, once you've lost sight of the level -
especially on the LMS, where the gauge cocks were linked to a single
handle, so you couldn't blow one at a time.


If you look at a guage glass it has diagonal stripes behind it.

If the glass is full of water they are refracted to the horizontal as
seen through te sight glass.
If the glass is full of steam, they remain diagonal. So you know
whether the water level is above or below the glass.

snip..

There are three cocks to every guage glass. Steam side and water side
to isolate the fitting if the glass breaks and drain to blow down each
leg separately so as to prevent blockages and rings forming on the
glass. There are min. two gauge glasses on ever boiler for redundancy/
camparison reasons
They are all fitted with safety glasses too.

So - what would be the recommended operating method for an early
locomotive with no gauge glasses (and no feed pump - Middleton, early
Chapman engines - or one which might or might not work - Trevithick,
Wylam, Killingworth..)?

Illustration: there's a picture of the preserved 'Locomotion' at
Darlington North Road taken in July 2008, showing the back of the
boiler (fire-hole end) and what I'm pretty sure is the driving side
of the engine. As you can see - no gauge glass, neither for fireman
nor driver (the feed pump and pet-cock to bleed the pump are low on
the back of the boiler, out of shot in this). There is a drain-cock on
the back of the boiler which I would guess was used to estimate water level
- if all you get out is water the level is too high, if all that comes out
is steam it's too low, if you get a sputtering mix it's right?
I need to go back to the texts and see if anyone mentions how it was used,
but if you have any ideas from experience of more recent boilers it'd be
much appreciated.

http://users.aber.ac.uk/azb/images/locomotion.jpg

Locomotion, as it survives, seems to have an original (or at least early)
boiler shell, and its condition is essentially that after an early restoration
to running-on-rails status after retirement as a stationary engine in 1850.
It seems likely that it was working without a gauge glass of any sort when it
ceased work (plausible, given what's known of practice at the time).
The 1845 Derwent locomotive, as preserved, has a gauge glass, but it looks
very much like one crudely retro-fitted:

http://users.aber.ac.uk/azb/images/derwent.jpg

Given that Derwent was working regularly until 1898, and was restored to run
under its own steam in 1925, retro-fitting of a gauge glass somewhere in
its later life is very likely.


--
From the Model M of Andy Breen, speaking only for himself

On Jul 25, 8:40*pm, Andy Breen wrote:
On Mon, 25 Jul 2011 11:54:33 -0700, harry wrote:
On Jul 25, 10:53*am, Andy Dingley wrote:
On Jul 25, 6:27*am, harry wrote:

No-one in their right mind is going to lose sight of the water level..

A wise idea - mostly because it's very hard to tell if a gauge glass is
full of water or steam, once you've lost sight of the level -
especially on the LMS, where the gauge cocks were linked to a single
handle, so you couldn't blow one at a time.

If you look at a guage glass it has diagonal stripes behind it.

If the glass is full of water they are refracted to the horizontal *as
seen through te sight glass.
If the glass is full of steam, they *remain diagonal. So you know
whether the water level is above or below the glass.

snip..

There are three cocks to every guage glass. Steam side and water side to
isolate the fitting if the glass breaks and drain to blow down each leg
separately *so as to prevent blockages and rings forming on the glass..
There are min. two gauge glasses on ever boiler for redundancy/
camparison reasons
They are all fitted with safety glasses too.

So - what would be the recommended operating method for an early locomotive
with no gauge glasses (and no feed pump - Middleton, early Chapman engines
- or one which might or might not work - Trevithick, Wylam, Killingworth...)?

That's a genuine question - can you, with experience of operating boilers,
cast any light on how such a boiler might be worked best. Because I find
it rather hard to imagine, in spite of reading such accounts as exist from
the time..

--
From the Model M of Andy Breen, speaking only for himself- Hide quoted text -

- Show quoted text -

I think many early boilers operated at such a low pressure (5 or 10
PSI) that water levels and even furnace uncovering was less critical
than in a high pressure boiler. The accidents started to happen when
high pressure steam was introduced. There must have been a lot of
operator guesswork.

If you look at these old boilers, there is a lot of space between the
top of the boiler and the top of the furnace so there was bags of
lattitude in water level.
Modern boilers have a lattitude of only a few cm.

Cast iron boilers would be less affected than wrought iron by an
overheat of the metal.
How would they make the glass tube in the very early days? Must have
been a major problem.

On 26/07/2011 08:35, harry wrote:
How would they make the glass tube in the very early days? Must have
been a major problem.

Glass working is a very ancient technology, making the gauge glasses
would have been relatively simple compared to the problems of
constructing a high pressure boiler. It was the sort of job you'd
happily sub-contract to the local glassworks and think no more about it.

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at www.greywall.demon.co.uk/rail

On Tue, 26 Jul 2011 09:02:44 +0100, Graeme Wall wrote:

To tackle a couple of Harry's points first (for some reason his post wouldn't
allow commenting directly.. odd)

1.
Most boilers were low pressure back then, but all "Trevithick" engines (to
an early 19th century steam engineer a "Trevithick" was any engine working
by steam pressure as opposed to vacuum - it was as generic as "diesel" is
today..) worked at 25psi or above. All the early locomotive boilers I have
found a figure for were intended to work at 50psi - though one has to remember
that the (a) the boiler couldn't sustain pressure when the engine was working
- pressure would be dropping as the engine ran, to be recovered at halts (b)
the safety valve would be fixed down while the engine was running (because a
deadweight valve would otherwise bounce and cost steam that was needed - and
tying the valve down was safe[1] because the boiler couldn't supply enough
steam to maintain pressure when the engine was working - boiler capacity being
defined more by water requirements than steam requirements in the earlies..).

2.
There was much greater latitude for water level variations in those boilers than
modern ones - had to be, I would think, if they were to work at all. However,
the large single flue tube would be horribly vunerable to water surges in
such a small, short boiler as the engine rocked wildly on the short rails (3'
rails, no suspension on the locomotive, short wheelbase..). Really, these
things were working on the very edge of practicality, and must have been
horribly prone to all kinds of disarrangement..

On 26/07/2011 08:35, harry wrote:
How would they make the glass tube in the very early days? Must have
been a major problem.

Glass working is a very ancient technology, making the gauge glasses
would have been relatively simple compared to the problems of
constructing a high pressure boiler. It was the sort of job you'd
happily sub-contract to the local glassworks and think no more about it.

There must have been an issue there, given how long it took for gauge glasses
to appear - it's not as if there wasn't a major glassmaking centre (Sunderland)
just down the way from the collieries where the Tyneside pioneers were working,
after all..

As it was, it doesn't seem to have been until the middle 1840s at the earliest
when they started to appear, and they don't seem to have been universal until
well after that. Making glass that you could be sure was stable and flawless
enough to resist that pressures involved (it's that "could be sure" bit...)
at a reasonable cost (because they'd always managed without up until then,
after all...) would have been the thing. In the first days of gauge glasses
I suspect they ordered from the glassworks and then /did/ think about them.
Extensively. Often at about 2am...

--
From the Model M of Andy Breen, speaking only for himself

On 26/07/2011 11:03, Andy Breen wrote:
On Tue, 26 Jul 2011 09:02:44 +0100, Graeme Wall wrote:
On 26/07/2011 08:35, harry wrote:
How would they make the glass tube in the very early days? Must have
been a major problem.

Glass working is a very ancient technology, making the gauge glasses
would have been relatively simple compared to the problems of
constructing a high pressure boiler. It was the sort of job you'd
happily sub-contract to the local glassworks and think no more about it.

There must have been an issue there, given how long it took for gauge glasses
to appear - it's not as if there wasn't a major glassmaking centre (Sunderland)
just down the way from the collieries where the Tyneside pioneers were working,
after all..

No one thought of it initially perhaps. After all, as you point out,
there was plenty of water space available and a gauge glass would do
little to help with the problem of surging.


As it was, it doesn't seem to have been until the middle 1840s at the earliest
when they started to appear, and they don't seem to have been universal until
well after that. Making glass that you could be sure was stable and flawless
enough to resist that pressures involved (it's that "could be sure" bit...)
at a reasonable cost

There's the rub, fine, accurately made glassware had been around for
centuries but at a cost. I don't think there was any intrinsic problem
with producing the glass at that time. It just needed someone to think
it was needed.

Have a look at the Turnbull collection of 18th Century glasses at
Mompesson House. Absolutely flawless with lots of intricate effects
worked into the stems. Such glasswork had been around since the mid
16th Century when Venetian glassmakers were enticed to London to improve
the local product. Such people would have found producing a simple 8
inch tube a doddle.

(because they'd always managed without up until then,
after all...) would have been the thing. In the first days of gauge glasses
I suspect they ordered from the glassworks and then /did/ think about them.
Extensively. Often at about 2am...


Probably once they started working with pressures greater than 50psi and
more limited waterspaces above the firebox.

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at www.greywall.demon.co.uk/rail

On Tue, 26 Jul 2011 12:12:12 +0100, Graeme Wall wrote:

On 26/07/2011 11:03, Andy Breen wrote:
On Tue, 26 Jul 2011 09:02:44 +0100, Graeme Wall wrote:
On 26/07/2011 08:35, harry wrote:
How would they make the glass tube in the very early days? Must have
been a major problem.

Glass working is a very ancient technology, making the gauge glasses
would have been relatively simple compared to the problems of
constructing a high pressure boiler. It was the sort of job you'd
happily sub-contract to the local glassworks and think no more about
it.

There must have been an issue there, given how long it took for gauge
glasses to appear - it's not as if there wasn't a major glassmaking
centre (Sunderland) just down the way from the collieries where the
Tyneside pioneers were working, after all..

No one thought of it initially perhaps. After all, as you point out,
there was plenty of water space available and a gauge glass would do
little to help with the problem of surging.


As it was, it doesn't seem to have been until the middle 1840s at the
earliest when they started to appear, and they don't seem to have been
universal until well after that. Making glass that you could be sure
was stable and flawless enough to resist that pressures involved (it's
that "could be sure" bit...) at a reasonable cost

There's the rub, fine, accurately made glassware had been around for
centuries but at a cost. I don't think there was any intrinsic problem
with producing the glass at that time. It just needed someone to think
it was needed.

Have a look at the Turnbull collection of 18th Century glasses at
Mompesson House. Absolutely flawless with lots of intricate effects
worked into the stems. Such glasswork had been around since the mid
16th Century when Venetian glassmakers were enticed to London to improve
the local product. Such people would have found producing a simple 8
inch tube a doddle.

(because they'd always managed without up until then, after all...)
would have been the thing. In the first days of gauge glasses I suspect
they ordered from the glassworks and then /did/ think about them.
Extensively. Often at about 2am...


Probably once they started working with pressures greater than 50psi and
more limited waterspaces above the firebox.

And also, possibly, once (to use the term obligatory in uk.r)
elfandsafetymadness stepped in in the form of regulations on construction
and inspection of boilers (when government started to impede industry with
red tape/legitimately question the number of people getting blown up - choose
one explanation according to dogma or sense...)

--
From the Model M of Andy Breen, speaking only for himself

On 26/07/2011 12:17, Andy Breen wrote:
On Tue, 26 Jul 2011 12:12:12 +0100, Graeme Wall wrote:

(because they'd always managed without up until then, after all...)
would have been the thing. In the first days of gauge glasses I suspect
they ordered from the glassworks and then /did/ think about them.
Extensively. Often at about 2am...


Probably once they started working with pressures greater than 50psi and
more limited waterspaces above the firebox.

And also, possibly, once (to use the term obligatory in uk.r)
elfandsafetymadness stepped in in the form of regulations on construction
and inspection of boilers (when government started to impede industry with
red tape/legitimately question the number of people getting blown up - choose
one explanation according to dogma or sense...)


When did mandatory boiler inspections come in?

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at www.greywall.demon.co.uk/rail

On Tue, 26 Jul 2011 12:23:14 +0100, Graeme Wall wrote:

On 26/07/2011 12:17, Andy Breen wrote:
On Tue, 26 Jul 2011 12:12:12 +0100, Graeme Wall wrote:

(because they'd always managed without up until then, after all...)
would have been the thing. In the first days of gauge glasses I
suspect they ordered from the glassworks and then /did/ think about
them. Extensively. Often at about 2am...


Probably once they started working with pressures greater than 50psi
and more limited waterspaces above the firebox.

And also, possibly, once (to use the term obligatory in uk.r)
elfandsafetymadness stepped in in the form of regulations on
construction and inspection of boilers (when government started to
impede industry with red tape/legitimately question the number of
people getting blown up - choose one explanation according to dogma or
sense...)


When did mandatory boiler inspections come in?

Not sure. Boiler insurance and inspection was very common, even of stationary
ancillery colliery plant (which always lagged on investment) by the 1860s
- 'Agenoria', now at York, was inspected by such a company in her last working
years, and it was the same inspector who rediscovered her remains and persuaded
the owners to put her back together and donate he to the Patent Office Museum.
That implies inspections were routine (and, if they were checking something
like Agenoria, probably mandatory) by the 1860s.

--
From the Model M of Andy Breen, speaking only for himself

On 26/07/2011 12:29, Andy Breen wrote:
On Tue, 26 Jul 2011 12:23:14 +0100, Graeme Wall wrote:

When did mandatory boiler inspections come in?

Not sure. Boiler insurance and inspection was very common, even of stationary
ancillery colliery plant (which always lagged on investment) by the 1860s
- 'Agenoria', now at York, was inspected by such a company in her last working
years, and it was the same inspector who rediscovered her remains and persuaded
the owners to put her back together and donate he to the Patent Office Museum.
That implies inspections were routine (and, if they were checking something
like Agenoria, probably mandatory) by the 1860s.


That probably gives a latest date for the introduction of gauge glasses.

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at www.greywall.demon.co.uk/rail

On Tue, 26 Jul 2011 12:35:10 +0100, Graeme Wall wrote:

On 26/07/2011 12:29, Andy Breen wrote:
On Tue, 26 Jul 2011 12:23:14 +0100, Graeme Wall wrote:

When did mandatory boiler inspections come in?

Not sure. Boiler insurance and inspection was very common, even of
stationary ancillery colliery plant (which always lagged on investment)
by the 1860s - 'Agenoria', now at York, was inspected by such a company
in her last working years, and it was the same inspector who
rediscovered her remains and persuaded the owners to put her back
together and donate he to the Patent Office Museum. That implies
inspections were routine (and, if they were checking something like
Agenoria, probably mandatory) by the 1860s.


That probably gives a latest date for the introduction of gauge glasses.

Agenoria, as far as I can seen, has never had, since restoration in the
1880s), a gauge glass:
http://www.stourbridge.co.uk/agenoria.htm
so inspections may not have originally required such things (possibly
an "are there any obvious holes?"[1], "is there a safety valve that works"
kind of regime at the start - still probably regarded as unwarrented
interference by many...).
Wylam Dilly, which worked into the 1860s, still didn't have a gauge glass
when photographed at Craghead in the 1880s (though she was an exhibition
piece by then):

http://www.scienceandsociety.co.uk/r...reenwidth=1004

Stephenson's Billy, now at North Shields museum, got a new boiler in the
1870s (after 1862?). The photograph in ER2 taken of the machine at Killingworth
post-rebuild (certainly the same machine as is now at Shields) shows what
looks like a single gauge glass on the LH side of the backhead. This suggests
that when the new boiler went on such things were required, at least on new
boilers...

We may be looking at the very late 1860s/early 1870s for such things becoming
mandatory. Annoyingly, my copy of Ahrons' 1825-1925, which would have given
the answer quite quickly, has turned coy and hidden itself.

--
From the Model M of Andy Breen, speaking only for himself

On 26/07/2011 13:29, Andy Breen wrote:
On Tue, 26 Jul 2011 12:35:10 +0100, Graeme Wall wrote:

On 26/07/2011 12:29, Andy Breen wrote:
On Tue, 26 Jul 2011 12:23:14 +0100, Graeme Wall wrote:

When did mandatory boiler inspections come in?

Not sure. Boiler insurance and inspection was very common, even of
stationary ancillery colliery plant (which always lagged on investment)
by the 1860s - 'Agenoria', now at York, was inspected by such a company
in her last working years, and it was the same inspector who
rediscovered her remains and persuaded the owners to put her back
together and donate he to the Patent Office Museum. That implies
inspections were routine (and, if they were checking something like
Agenoria, probably mandatory) by the 1860s.


That probably gives a latest date for the introduction of gauge glasses.

Agenoria, as far as I can seen, has never had, since restoration in the
1880s), a gauge glass:
http://www.stourbridge.co.uk/agenoria.htm
so inspections may not have originally required such things (possibly
an "are there any obvious holes?"[1], "is there a safety valve that works"
kind of regime at the start - still probably regarded as unwarrented
interference by many...).
Wylam Dilly, which worked into the 1860s, still didn't have a gauge glass
when photographed at Craghead in the 1880s (though she was an exhibition
piece by then):

http://www.scienceandsociety.co.uk/r...reenwidth=1004

Stephenson's Billy, now at North Shields museum, got a new boiler in the
1870s (after 1862?). The photograph in ER2 taken of the machine at Killingworth
post-rebuild (certainly the same machine as is now at Shields) shows what
looks like a single gauge glass on the LH side of the backhead. This suggests
that when the new boiler went on such things were required, at least on new
boilers...

We may be looking at the very late 1860s/early 1870s for such things becoming
mandatory. Annoyingly, my copy of Ahrons' 1825-1925, which would have given
the answer quite quickly, has turned coy and hidden itself.


A photo of the GW broad gauge single Sultan seems to show a gauge glass
on the boiler backplate. The photo isn't dated but the loco was built
in 1847 and withdrawn in 1874. Sultan is the loco depicted in Frith's
painting of Paddington Station. The painting itself is at the Royal
Holloway College in Egham.

However what appears to be an offical broadside picture of Lord of the
Isles, built 1851, doesn't have one.

Supplementary question, when did the railways start taking 'builders'
photos' of new engines?

Bulkeley, built 1871 definitely has one.

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at www.greywall.demon.co.uk/rail

On Tue, 26 Jul 2011 13:52:54 +0100, Graeme Wall wrote:

On 26/07/2011 13:29, Andy Breen wrote:
On Tue, 26 Jul 2011 12:35:10 +0100, Graeme Wall wrote:

On 26/07/2011 12:29, Andy Breen wrote:
On Tue, 26 Jul 2011 12:23:14 +0100, Graeme Wall wrote:

When did mandatory boiler inspections come in?

Not sure. Boiler insurance and inspection was very common, even of
stationary ancillery colliery plant (which always lagged on
investment) by the 1860s - 'Agenoria', now at York, was inspected by
such a company in her last working years, and it was the same
inspector who rediscovered her remains and persuaded the owners to
put her back together and donate he to the Patent Office Museum. That
implies inspections were routine (and, if they were checking
something like Agenoria, probably mandatory) by the 1860s.


That probably gives a latest date for the introduction of gauge
glasses.

Agenoria, as far as I can seen, has never had, since restoration in the
1880s), a gauge glass:
http://www.stourbridge.co.uk/agenoria.htm so inspections may not have
originally required such things (possibly an "are there any obvious
holes?"[1], "is there a safety valve that works" kind of regime at the
start - still probably regarded as unwarrented interference by
many...).
Wylam Dilly, which worked into the 1860s, still didn't have a gauge
glass when photographed at Craghead in the 1880s (though she was an
exhibition piece by then):

http://www.scienceandsociety.co.uk/r...reenwidth=1004

Stephenson's Billy, now at North Shields museum, got a new boiler in
the 1870s (after 1862?). The photograph in ER2 taken of the machine at
Killingworth post-rebuild (certainly the same machine as is now at
Shields) shows what looks like a single gauge glass on the LH side of
the backhead. This suggests that when the new boiler went on such
things were required, at least on new boilers...

We may be looking at the very late 1860s/early 1870s for such things
becoming mandatory. Annoyingly, my copy of Ahrons' 1825-1925, which
would have given the answer quite quickly, has turned coy and hidden
itself.


A photo of the GW broad gauge single Sultan seems to show a gauge glass
on the boiler backplate. The photo isn't dated but the loco was built
in 1847 and withdrawn in 1874. Sultan is the loco depicted in Frith's
painting of Paddington Station. The painting itself is at the Royal
Holloway College in Egham.

However what appears to be an offical broadside picture of Lord of the
Isles, built 1851, doesn't have one.

Supplementary question, when did the railways start taking 'builders'
photos' of new engines?

Bulkeley, built 1871 definitely has one.

I suspect they may have been common on main lines before they became universal.
I'd expect locomotives in industrial use to be among the last the get such
things - and only retrofit them when absolutely required to (I think Colin
Mountford produced some figures to the effect that investment in colliery
railway locomotives and stationary engines lagged that in "primary production"
equipment by several decades - thus the long lives of many locomotives,
including some of the earliest)

--
From the Model M of Andy Breen, speaking only for himself

On Tue, 26 Jul 2011 13:52:54 +0100, Graeme Wall wrote:


Supplementary question, when did the railways start taking 'builders'
photos' of new engines?


I think the answer there would be "as soon as there was a photographer
in the town", or at least one who charged rates they were prepared to
pay. They were a powerfully good way of advertising a product, and
emphasised that firm/company was right on top of new technology. Modern,
and all that..

--
From the Model M of Andy Breen, speaking only for himself

On 26/07/2011 14:15, Andy Breen wrote:
On Tue, 26 Jul 2011 13:52:54 +0100, Graeme Wall wrote:


Supplementary question, when did the railways start taking 'builders'
photos' of new engines?


I think the answer there would be "as soon as there was a photographer
in the town", or at least one who charged rates they were prepared to
pay.

In places like Swindon, Crewe, Doncaster and so on I suspect any
enterprising photographer would have been keen to quote special rates to
a customer who was going to be good for repeat business for a long
period of time.

They were a powerfully good way of advertising a product, and
emphasised that firm/company was right on top of new technology. Modern,
and all that..


Having looked at a photo of a South Devon Pearson loco I'm not so sure :-)

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at www.greywall.demon.co.uk/rail

On Tue, 26 Jul 2011 15:32:10 +0100, Graeme Wall wrote:

On 26/07/2011 14:15, Andy Breen wrote:
On Tue, 26 Jul 2011 13:52:54 +0100, Graeme Wall wrote:


Supplementary question, when did the railways start taking 'builders'
photos' of new engines?


I think the answer there would be "as soon as there was a photographer
in the town", or at least one who charged rates they were prepared to
pay.

In places like Swindon, Crewe, Doncaster and so on I suspect any
enterprising photographer would have been keen to quote special rates to
a customer who was going to be good for repeat business for a long
period of time.

I'd expect so, too. Even more so in Manchester where they could tap into
work for Beyers, Sharps, the M&SL.. or on Tyneside, where they could
do jobs for Stephensons, Hawthorns, the NER at Gateshead, the N&C at
Blaydon - and the S&D at Darlington weren't that far away. Similarly
for other big industrial concentrations.

Actually, it'd be interesting to see whether the private builders or
the companies were the first to make extensive use of photographs.
I can see it being a real advantage to a builder, being able to show
pictures of their product off to new clients...

Not a locomotive builder's photograph, but the Stockton and Darlington
were evidently proud enough of their new viaduct at Hownes Gill in
1858 to have it photographed (with a Hackworth vertical-cylinder-
and-countershaft locomotive on it..). I'm looking at the picture in
Tomlinson right now. The S&D also had their 2-4-0 Rokeby photographed
after its 1860 rebuild.
AFAIK the first photograph of any industrial artifact is one of Brunel's
ship "Great Britain", taken in 1844 when she was fitting out:

http://en.wikipedia.org/wiki/File:SS..._by_Talbot.jpg

I'd say we're looking at a date somewhere in the 1850s..

They were a powerfully good way of advertising a product, and
emphasised that firm/company was right on top of new technology.
Modern, and all that..


Having looked at a photo of a South Devon Pearson loco I'm not so sure
:-)



--
From the Model M of Andy Breen, speaking only for himself

On Tue, 26 Jul 2011 15:32:10 +0100, Graeme Wall wrote:


They were a powerfully good way of advertising a product, and
emphasised that firm/company was right on top of new technology.
Modern, and all that..


Having looked at a photo of a South Devon Pearson loco I'm not so sure
:-)

Just think how old-fashioned, bizarre and quaint a smartphone or an iPad
will look in 20 years, never mind 150...

--
From the Model M of Andy Breen, speaking only for himself

On Jul 26, 4:50*pm, Andy Breen wrote:
On Tue, 26 Jul 2011 15:32:10 +0100, Graeme Wall wrote:

They were a powerfully good way of advertising a product, and
emphasised that firm/company was right on top of new technology.
Modern, and all that..

Having looked at a photo of a South Devon Pearson loco I'm not so sure
:-)

Just think how old-fashioned, bizarre and quaint a smartphone or an iPad
will look in 20 years, never mind 150...

Indeed, just watch a movie from the late '90s and wonder how we ever
managed with such bricks of phones. Go back to the mid '90s and even
top end phone still had things like extendable aerials. That's not
even 20 years ago. Even more recently, CRTs were still commonplace,
but these days they are already starting to look dated.

Robin

On 26/07/2011 15:47, Andy Breen wrote:
On Tue, 26 Jul 2011 15:32:10 +0100, Graeme Wall wrote:

On 26/07/2011 14:15, Andy Breen wrote:
On Tue, 26 Jul 2011 13:52:54 +0100, Graeme Wall wrote:


Supplementary question, when did the railways start taking 'builders'
photos' of new engines?


I think the answer there would be "as soon as there was a photographer
in the town", or at least one who charged rates they were prepared to
pay.

In places like Swindon, Crewe, Doncaster and so on I suspect any
enterprising photographer would have been keen to quote special rates to
a customer who was going to be good for repeat business for a long
period of time.

I'd expect so, too. Even more so in Manchester where they could tap into
work for Beyers, Sharps, the M&SL.. or on Tyneside, where they could
do jobs for Stephensons, Hawthorns, the NER at Gateshead, the N&C at
Blaydon - and the S&D at Darlington weren't that far away. Similarly
for other big industrial concentrations.

Actually, it'd be interesting to see whether the private builders or
the companies were the first to make extensive use of photographs.
I can see it being a real advantage to a builder, being able to show
pictures of their product off to new clients...

My money would be on the private builders leading the way.


Not a locomotive builder's photograph, but the Stockton and Darlington
were evidently proud enough of their new viaduct at Hownes Gill in
1858 to have it photographed (with a Hackworth vertical-cylinder-
and-countershaft locomotive on it..). I'm looking at the picture in
Tomlinson right now. The S&D also had their 2-4-0 Rokeby photographed
after its 1860 rebuild.
AFAIK the first photograph of any industrial artifact is one of Brunel's
ship "Great Britain", taken in 1844 when she was fitting out:

http://en.wikipedia.org/wiki/File:SS..._by_Talbot.jpg

I'd say we're looking at a date somewhere in the 1850s..


There's actually quite a few photos of Great Eastern building, looks
like the yard, or someone (Russell?) commissioned a photographic record
for posterity. Possibly another first.

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at www.greywall.demon.co.uk/rail

In article ,
Nick Leverton wrote:

In article
,
The Real Doctor wrote:
On Jul 15, 11:20*am, Nick Leverton wrote:

Melting of fusible plugs (thus releasing boiler pressure steam into the
firebox) has occurred a couple of times in preservation, but the RAIB
don't seem to have reports on them for some reason.

There was also a case (Nene Valley Railway?) where the wrong taper
thread was cut for a fusible plug, which, held in by a minimal amount
of thread, came out at pressure. I think that killed someone.

I think that's the example I was trying to recall. Certainly dropping
a fusible plug can lead to serious injury in the wrong circumstances,
so I'd hope it would come within the gambit of the RAIB (pace D7666),
but it's not there !

I remember being told about a fusible plug coming away on a preserved
Black 5 on the S&C some years ago. IIRC correctly the plug had been
cross-threaded and no one noticed. The loco wasn't fitted with a
rocking grate and I was told the crew had to shovel the fire out through
the cab rather than just being able to drop it.

Sam