Shay Plumbing VIII - Steam
Turret & Associated Plumbing
Nelson Riedel Nelson@NelsonsLocomotive.com
Initial: 11/24/03 Last
Note: This page has been revised several times to reflect
advice from readers and experience from initial tests. The more
significant changes are noted in the text.
The layout of the steam, water and burner controls on and
around the boiler backhead proved to be quite a challenge. A number of different
live steam locomotives were examined and probably 50 different
variations were sketched (a good way to kill time on long
flights). Near the end of this process an organization of the controls and gauges into functional
groups evolved. The following lists this organization.
The steam turret is located on the top rear of the boiler. The turret contains cutoff valves that supply steam to
the whistle valve, to the steam brake valve, and to a
manifold for the blower and atomizer valves. There is
also a port for the steam pressure gauge and spare ports for possible
later use to supply steam to a steam water pump and/or
The water controls are on the left side of the
boiler. These controls are a
valve to adjust
the axel pump output and a test valve to verify that the axle pump is
working. The water
gauge is on the left side of the backhead and the steam pressure gauge
is in front of the backhead next to the water gauge.
The blower & atomizer valves are mounted on a
manifold near the
floor to the right of the boiler. The blower pipe runs through the right stay tube to the
smoke box. The atomizer valve serves an on/off function to supply
the atomizer regulator located under the platform that covers the
reversing gear lever. The manifold is fed
steam through a cutoff valve from the steam turret. The
manifold is also fed compressed air via a quick connect fitting under the right side of the cab floor.
There is a cutoff valve and check valve in series with this air
supply. There are pressure gauges for both the blower and atomizer
located above the platform that covers the reversing gear lever.
The steam brake valve and whistle valve are located on
the shelf above the rear cylinder.
The oil feed valve is located in the oil tank with the
knob at the top of the tank.
|Cass 10 Turret: This is the steam turret on Cass No
10. The turrets are hard to photograph on the
operating locomotives because of all the clutter. The turret
shown here is very similar to Kenneth's design.
|Turret Layout: This photo shows the turret layout.
The ports in the back and right end are 1/4" MTP and the two
ports at the front are 5/16" MTP. The port on
the left end is 3/16" MTP.
The initial plan had been to put a cutoff valve between the
boiler and the turret as recommended by Jim Buchanan.
However, I didn't like the looks of that arrangement.
This is a revised layout; the earlier version has the top of
the water gauge connected to the turret.
|Blower & Atomizer Manifold: This is the manifold with the compressed air feed. The
manifold is made from a 1/4" pipe nipple. A plug was
silver soldered in the top and the bottom was
tapped 1/8' NPT. The blower and atomizer ports are
5/16" MTP and made like the ports on the side of the
turret. The valve outputs are 1/4" MTP. The air feed components across the bottom of
the photo are all 1/8" NPT.
The support bracket is silver soldered to the elbow to the
right of the compressed air valve. The bracket screws into the reverse
lever mounting bracket.
|This shows the installed manifold and associated compressed air
hardware. The reverse lever bracket was moved out
3/8" and up 3/8" to give a little more room for the
valves. The quick connect and compressed air valve are
under the cab floor. The rest of 1/8" pipe and
fittings are under the platform covering the reversing gear lever.
The compressed air valve is rated for 250 degrees F (McMaster-Carr
4264K44) and the check valve is rated for 400 degrees
(McMaster-Carr 7775K61). The check valve will normally
prevent steam from exiting via the quick connect after the air
line has been disconnected. The hand valve
serves as a backup for the check valve. (That green knob has
|This photo was taken with the cab and cab floor in position. The
bottom of the manifold is about 1/4" off the floor. The right
side water feed pipe will come out of the floor and over the frame
I beam under the manifold.
The manifold is along the edge of the cover for the back side
of the rear cylinder making it more or less inconspicuous.
|Pressure Gauge: Initially the pressure gauge was
located in the top left front corner of the cab.
When I got to looking at the possible roof lines I realized very
little roof would be possible with the gauge in that
position. Then I remembered that Dan Staron had said that he
was going to position his pressure gauge in the top center
of the backhead. Then I remembered that Cass No 11 had the
pressure gauge in the center of the backhead as shown in photo on
the right. So, decided to move the pressure gauge to top of
|This shows the second ( and hopefully final) location of the
pressure gauge. The pipe from the turret to
the gauge is 3/16". The union at the turret end is a
SuperScale with a male end on the turret side. The street
elbow between the union and the pipe is TrueScale. The
fitting on the gauge end is 3/16" compression to female
1/8" NPT. The pipe was formed by heating red hot and
then quenching and then bending around a steel rod.
The gauge is supported only by the 3/16" tube. It
seems very stable since the left side of the tube rests against
|Water Gauge: Jim Buchanan had advised
that the water gauge not be connected to the turret because the water level would fluctuate when the steam supplied to other turret ports
varied. I decided to try it on the turret anyway. (This reminds
me of a story told by a female engineer colleague. She said
that male engineers are like little boys, about 5% will listen to
good advice while the other 95% will pee on an electric
Murry Curtis of Melbourne sent along a couple comments after
this page was first posted. He says that the small boiler
code down under specifies a separate boiler port for the water gauge
because even small pressure differentials can cause a large change
in water level (remember that atmospheric pressure at ~ 15 psi
will raise a water column ~ 30 feet). He also said
that the pipe from boiler to water gauge must be straight so that
a rod can be pushed through it to show it's not plugged by
I also found that when testing with compressed air, opening the
blower valve caused the water level to increase maybe 25% of the
glass height giving a very false reading. So, I moved the
top to a dedicated boiler port..
The photo shows the redone water gauge. The bottom of the water gauge screws
directly into a 1/8" NPT in the backhead. The top port
of the gauge is threaded 1/4"-40 but apparently not tapered; otherwise it
matches MTP 1/4"-40. The cutoff valve (LSM 1/4")
connects to the boiler via a 1/4"
nipple. The pipe between the valve and top of the
gauge is also 1/4" tube threaded MTP each end. The
connection at the top of the gauge didn't leak even though only
the male part was tapered. Maybe the Permatex No2 used on
all the joints helped. The union that is part of the
valve together with the valves at each end of the gauge permits
the glass to be replaced without reducing boiler pressure.
The test cock at the bottom permits both pipes from the boiler to be
|Safety Valves: The last thing before pressure testing was
to install the pair of safety valves in the top of the steam
dome. The holes were tapped 1/8" NPT. These
valves are brass body with stainless steel ball intended for air
service. It's not clear if the spring is stainless
steel. It'd probably be wise to buy a package of
suitable stainless steel springs.
Murry also had some comment about the exhaust
capability of the safety valves. He describes a test of the
safety valves as follows (both safety valves working) : For the
coal fired locos weíre required to build up a good fire, water
at the top nut and put the blower full on. The pressure (on a
calibrated gauge) must not exceed the working pressure by more
than 10% for the time it takes the water to reach the bottom nut,
5-10 minutes. Itís interesting that a lot of the designs
published in England will fail on this requirement I've been told.
Usually because the steam can get past the valve seat fast enough
but then can't get out of the safety valve body. Some designs call
for a couple of nicks in the side of the adjusting nut, thatís
all! No wonder the steam can't get out.
Update 4/24/04: The safety valves worked OK in a number
of steam tests. One problem is that about 15 psi pressure
drop is required before the valves shut off. At some point
I'll make least least one valve that requires only a couple psi
drop to shut off. I made the deflectors shown in the
lower photo to deflect the relief steam upward. The bottom
of the deflector has a hole for the 1/8" pipe safety
valve and the inside is just large enough to clear a 1/2"
deep socket. The outside is slightly less than
7/8". The valves could have been located a little
further apart such as on 1.25" centers. End
|Testing With Air: The next step was to connect the air
line as shown in the photo. The regulator has quick connects
on both sides. The pressure was set for about 50 pounds and
then the most obvious leaks fixed ------ a few open valves
and drain holes not plugged. The pressure was then increased
to 100 psi and the safety valves adjusted to go off at 100
psi. The throttle was opened and the engine
tested. The air supply to run the engine is limited
since it must go through the 1/4" OD tube between the air
input and the steam manifold. The engine did run but
Testing For Leaks: The next step was to brush a
soap solution (liquid dishwashing detergent in water) on the
joints. The photo shows a few problems. (There seems
to be bubbles everywhere ---- did every joint leak? That's
an unknown since all haven't been tested yet.) The joints
were tightened a bit and the leaks stopped. There are also
leaks around the steam dome top and two of the upper heads.
Those joints have gaskets but will try a bit of Permatex No 2 to
see if that helps. One pretty significant leak is the test
cock at the bottom of the water gauge. That cock
uses a tapered plug. Think I'll test it in boiling water
---- friend Dan Staron says those cocks seal better when
hot. Of course, there is some hope that steam is
thicker than air and won't leak as easily.
Another comment from Murry Curtis: Testing any steam
appliance with air is sure to give you heart ache. Air
squirts past things that hot steam/water won't even dribble out
of. I first tested my copper boiler under water with air pressure
and nearly died when the water bubbled like a spa. The boiler
inspector just laughed at me and pumped up the boiler with water -
not a drop.
From Murray's comments it appears that steam is thicker than
air. Now need some steam which requires water and fire so it's on to the water
plumbing and burner.