First-Generation US Nuclear Submarines

I find the introduction/implementation of new technologies very fascinating.  When these new technologies are first unleashed, there is a great deal of variety and plenty of experimentation going on before everyone falls into line and starts building very similar things.  The initial deployment of a new technology leads to some really interesting decisions and designs though.

This post is about the impact of nuclear power on submarine design, and on operation. Both were impacted in major ways, and it took several years for builders and sailors to sort things out.  In the meantime, the first generation nuclear boats were somewhat experimental.  There was quite a bit of variety in design and purpose for the new ships.

Until the advent of nuclear power, the best submarine in the world had been built by Germany during World War II.  This was the remarkable Type XXI U-Boat.  These submarines were built from 1943 to 1945, but although superior to any other submarine were plagued by quality control problems, and also by wartime bombing of the production factories.

These submarines incorporated massive storage batteries for enhanced underwater endurance, allowing them to stay submerged at 5 knots for 2-3 days straight.  Additionally, the Type XXI was equipped with a "Schnorkel" (the snorkel mast), which allowed it to remain submerged while running diesel generators to recharge the batteries.  Most importantly, they were fast and quiet, compared to their peers.

Below, Type XXI submarines moored at Bergen, Norway.  May 1945.

There is only one surviving Type XXI submarine, which was scuttled and then re-floated.  It is located at the German Maritime Museum in Bremerhaven.  Photo below.

The advanced technology developed for the Type XXI was not lost on anyone.  After World War II ended, the US Navy tested and Reverse-Engineered two German U-Boats, the U-2513 and U-3008.  As a result, several engineering goals were identified and used in the design of new US submarines.  Those goals were:

1. Streamlining the hull
2. Improving Battery Capacity
3. Installing Snorkels
4. Improving fire control systems

The Navy immediately wanted to begin building a brand new class of submarine with all the new features, but the Bureau of Ships felt that the plethora of WW II submarines could be modified enough to reach most of the goals.  Thus was born the GUPPY program, a series of modifications to improve US Tench, Balao, and Gato class WWII fleet boats, to make them perform more like a German Type XXI.

Below, a Tench Class Fleet Boat, the USS Toro.  The deck guns have not yet been installed for a war patrol.  Note the clutter on the deck and conning tower.

GUPPY mods included rounding the bow, removing the deck guns, and placing a fairing around the conning tower - which was afterwards called a "sail".  Snorkel masts were installed on ships that could accommodate them, and larger capacity batteries were installed.  The last GUPPY conversion was completed in 1963, by which time the WWII ships were no longer able to confront more modern enemy subs.

Below, the USS Tench with Guppy 1 Modification.  Rounded bow, very litle deck clutter.  Antennae and periscopes enclosed in a streamlined sail.

Meanwhile the Navy had managed to fund a few brand-new submarines, starting in 1946, with all of the features from their German Type XXI wish list.  These were the six Tang class submarines.  The Tang class were very capable ships:  The range without refueling was 10,000 miles.  They could run 15 knots surfaced, 18 knots submerged, and could dive to 700 ft.  Far better than anything a WWII fleet boat could do - including a Type XXI.

Nevertheless, all diesel-electric submarines, regardless of their sophistication, need to snorkel and burn diesel fuel to recharge their batteries.  During these periods of charging the batteries (which occur frequently), the submarine is much more exposed to detection than when operating deep. Additionally there is increased danger to a submarine spending long periods at periscope depth from collision with surface vessels, who will be unaware that a submarine is nearby.  The snorkel mast is made intentionally difficult to spot or to detect on radar.  These are the operating limits of a submarine that relies on internal combustion engines to function.

The USS Wahoo, a Tang-Class submarine.

And then suddenly the world changed, and many of the things submarine designers and sailors had always contended with were thrown out the window.

Below: The ship that changed everything - USS Nautilus at her launch on 21 January 1954...  On January 17, 1955 she was "Underway on nuclear power".

The new nuclear propulsion system did several things for ship designers.  No longer did they need to give top design priority to battery capacity, massive multiple diesel generator sets (for quickly charging the batteries), and setting aside space for large quantities of diesel fuel. The new propulsion system allowed engineers to explore the capabilities of a ship that was independent of internal combustion. And explore they did...

Below, the power plant that started it all.  The S1W prototype reactor in Idaho.  The water tank surrounding the reactor compartment is to absorb gamma radiation and to slow and absorb neutrons. The reactor is well shielded internally and unshielded (except for the pressure hull) exernally.

With all that history out of the way, we finally reached to the subject of this post!

USS Nautilus made a shakedown cruise four months after her first nuclear-powered underway.  Submerged the entire time, she ran 1300 miles from New London Connecticut, to San Juan, Puerto Rico, covering it in less than 90 hours.  This was the longest submerged cruise ever made by a submarine and the highest sustained speed ever recorded.

Nautilus' incredible speed and endurance rendered most of the Anti-Submarine warfare tactics that had been developed during World War II obsolete.  Radar and anti-submarine spotting aircraft were useless against a ship that no longer had to be near the surface and extend a snorkel mast to recharge the main storage batteries.  It could also quickly change position and depth.  A new and difficult adversary, which is difficult to detect and defeat, even today.

Nautilus (SSN-571) against New York backdrop.  SSN stands for Submersible Ship, Nuclear

On October 4, 1957, the Soviet Union placed the Sputnik satellite into orbit, shocking the entire nation.  The implicit message for the US was that the Soviets could rain down nuclear weapons on any US city at any time.

In August 1958, Nautilus was the first ship to reach the North Pole.  She passed through the Bering Strait, and dove under the ice for 2 days before reaching the pole, then continued on toward Greenland.  She did not break the ice during the trip - it was done entirely submerged.

The implicit message for the Soviet Union was that nuclear-powered ballistic missile subs (which were then under construction) could hide under the polar ice and rain down nuclear weapons on any Soviet city at any time.  And thus began the early pieces of what eventually came to be known as "mutually assured destruction"

Nautilus - aside from her novel power source - was not an awesome warship or nuclear deterrent.  The hull and superstructure vibrated so badly that her sonar became useless at anything over 4 knots.  The lessons learned were modified in later designs.

While Nautilus was a ground-breaking ship, in reality she was also a simple old-school Tang-Class diesel submarine with a pressurized water reactor instead of diesel generators.

Let's look at another first-generation nuclear boat.

USS Seawolf (SSN-575) underway surfaced.

Seawolf was similar in many respects to the Nautilus.  She was also a Tang-Class submarine with a nuclear reactor instead of diesel-electric components.  She was commissioned in March of 1957.  This ship used a much more advanced nuclear propulsion system - one that turned out to be overly complex and maintenance intensive.

Seawolf was powered by the S2G liquid-sodium cooled reactor.  By using liquid sodium, the reactor primary coolant system could be operated at higher temperature and much lower pressure.  Also because liquid metal can remove more heat more efficiently than water, steam could be superheated, raising efficiency even further.

The primary coolant system operated at only 15 psig, so the cooling system was quite light.  However... The superheaters suffered from poor tubesheet welds and frequently leaked high pressure steam backwards into the liquid sodium coolant.  This leakage of water into hot liquid sodium created a reaction that caused formation of sodium hydroxide (a strong caustic) and hydrogen gas (explosive when mixed with air).

An additional concern was that the sodium coolant could never be allowed to lose heat.  Dropping below the melting point would freeze the coolant, resulting in a loss of circulation.  Loss of circulation is never a good thing in a reactor core.

In 1960 Seawolf's power plant was converted to an S2W reactor, and with that, the experiment ended!

The Skate (SSN-578) was the third nuclear-powered submarine launched by the US, and the lead ship of only four in that class.  This made the Skate class the first actual production run of nuclear submarines. All ships of this class used the S3W reactor.

Below, USS Skate surfaced at the north pole, August 1959.  Note the steam rising from the warm seawater discharge at the right side of the photo.

Skate was commissioned in December of 1957, and in August 1959, became the first submarine to surface at the north pole.  In August of 1962, Skate and Seadragon rendezvoused at the north pole and surfaced together.  They operated together for another week before parting ways.

The ships of this Class were Skate, Sargo, Seadragon and Swordfish.  Even though the power plant had changed dramatically, this series of submarines was still based on incremental improvements of the German Type XXI diesel boat!

Change was in the works regarding hull design, however.  Importantly for the new nuclear-powered submarines, a prototype diesel-electric submarine had been testing the advantages of streamlining for optimum underwater performance.  This ship was the "Auxiliary Submarine" AGSS Albacore .  Her hull was the result of wind-tunnel testing, and she revolutionized submarine design by using a teardrop shaped hull, thus minimizing drag.

Albacore at launch, December 1953.  Submerged speed on an electric motor and batteries was a remarkable 33 knots.  Nuclear propulsion would arrive two years later.  The combination of a sleek hull and nuclear propulsion would have to wait for the arrival of the Skipjack class in 1959

The experimental teardrop-shaped Albacore also begat a class of three Diesel-Electric boats called the Barbel Class.  These vessels, which also use a teardrop hull, look nearly identical to modern nuclear submarines.

Below, a Barbel Class submarine, the diesel-powered USS Blueback (SS-581) moored in Portland, Oregon 2004

The Skipjack class is what I would consider a late first-generation nuclear submarine.  It incorporates many features shared by current submarines, such as the teardrop shaped hull, an attack center inside the hull instead of a conning tower inside the sail, and a powerful S5W reactor that became the mainstay of the US navy for decades.

The reason I don't consider Skipjack class ships second generation is because while they were very fast, they weren't particularly quiet. Nor were the hull or piping systems robust enough for these to be deep-diving ships.  You could also argue that they really were second-generation ships, because the hull was finally something not based on a diesel boat. 

Skipjack class boats were very nice looking.  Did I mention they were fast?  The Skipjack class pretty much standardized and finalized attack submarine shape and layout.  In all the decades since the Skipjack Class arrived the basic shape has not changed, although of course every aspect of the operating envelope has improved a great deal.

USS Skipjack (SSN-585) trying to perform a high speed surface run.  Skipjack class boats could run at 15 knots surfaced, 33 knots submerged.

But was the Skipjack Class the last first-generation nuclear submarine the US built?  Heck no!

The US built only one submarine that held two nuclear reactors.  That ship was the USS Triton (SSRN-589).  This ship was a "radar picket submarine".  The purpose of a radar picket submarine was to stay out ahead of an aircraft carrier group, and use radar to spot incoming threats before they got close to the carrier.  This essentially extended the radar detection range of the surface ship(s) in the carrier group.

Apparently, giving away the position of the most expensive submarine ever built by surfacing and sending out radar signals was OK, because that was how they were using her!  Different era, I guess...

USS Triton did not have a teardrop shaped hull, but she did have two reactors.  What she lacked in grace, she made up in punch - she achieved her speed through raw power.  Because she lacked a  teardrop shaped hull, she was slightly faster surfaced (30+knots) than submerged (27+knots).

She isn't very pretty.  Triton launch, August 1958.

Profile shot.  Still not pretty.   ...but two S4G reactors!

The Triton however, having two complete reactor and steam plants, was very reliable.  In 1960, on her shakedown cruise, she followed Magellan's course around the world - submerged the entire time.

The purpose of needing a "radar picket submarine" ended with the introduction of carrier-based early-warning aircraft, and so Triton was converted into an attack submarine.  She lasted about more 10 years in a Navy composed of ships that were increasingly faster, quieter, and less complex - at least from a propulsion and prototype perspective.

There was still another first-generation nuclear submarine.  USS Halibut (SSGN-587), the first US and only purpose-built nuclear-powered guided missile submarine.  With the exception of Halibut, the US Navy did not field nuclear powered guided missile boats until very recently.  The US Navy has retro-fitted four Ohio Class ballistic missile submarines (SSBNs) for cruise missile duty (SSGNs). 

Below, Halibut launching a Regulus guided nuclear missile.

Halibut steaming on the surface.

I discussed Halibut and her diesel-electric cousins in this post, so I won't go into it more, other than to say she was the last unusual design before everything became quite standardized.

Afterward were the Thresher/Permit class (14 boats), the Sturgeon Class (37 boats), and Los Angeles Class (62 boats).  The Thresher/Permit Class had one variant, and the Sturgeon Class had two variants.  You can review them at the links provided.  Interesting variations...

Blog Main Photo

It's time to change the main photo.  The aspen leaves have long since fallen!

What the hell is an SSXBT? Should I buy one off Ebay?

An SSXBT is a Submarine-Launched Expendable Bathythermograph!  Say that three times fast...

Now you probably can't wait to learn ALL about this arcane, but exciting technology.  First let's see if we can figure out what it does by its name.

Submarine-Launched.  Pretty self-explanatory there.
Expendable.  OK: you won't be getting it back after launching it into the ocean.
Bathythermograph. It records the temperature of the ocean.

So we have a device that takes the temperature of the ocean, apparently...  couldn't we just stick a thermometer into the water to figure that out?

Actually an SSXBT does a little bit more than take water temperature in a single place, which is what makes them pretty cool devices :)

The purpose of an SSXBT is to make a graph of the ocean temperature from the surface, all the way down to the maximum operating depth of the submarine that launched it.  The reason for wanting to know the ocean's temperature vs. depth profile is to better understand how sound will carry at various ocean depths, and set your ship's operating depth accordingly.

Colder ocean water is more dense and tends to carry sound further.  Interfaces between warmer and colder layers can reflect sound, keeping surface ships from hearing a submarine.  A cold channel between two warm layers may carry a submarine's sound a great deal further horizontally to another submarine than it would ordinarily go.  Understanding these conditions and using them tactically helps a submarine to remain hidden.

This cannot be emphasized enough:  Remaining undetected is critical for a submarine.  The only advantage (although it's a huge one) that a submarine has is stealth.  Once a submarine is detected, it is no more difficult to destroy than a surface ship.  Probably easier, because as floating targets, surface ships have many, many countermeasures against attack, while submarines do not.

...Which brings us back to our SSXBT and getting a profile of the ocean's temperature vs. depth.

Below is an image of an SSXBT, which is 3 inches in diameter and about 3 ft. long.  It is shaped like a small torpedo, and in fact, these are gently launched with pumped water through tiny 3" torpedo tubes (called "Signal Ejectors") out the top of the submarine.  A signal wire connects the SSXBT to a recorder on the ship (which of course has to be moving very slowly for this to work at all)

In the photo you will notice the SSXBT is made of two pieces.  The piece to the right is buoyant. After launch, the SSXBT floats to the surface, and then the right (buoyant) part separates.  The left part contains a weighted temperature probe with fins, which records water pressure (depth) and temperature as it sinks.  The data is relayed back to the ship via a signal wire, which is wound on a spool in the slotted section of the SSXBT. The buoyant part of the SSXBT scuttles itself after reaching the surface, so there is only brief evidence at the surface that a submarine lurks below.


Below is a drawing of an SSXBT, slightly more complicated than the one above.  This one has a "Lifting Body" (#306) that is buoyant, and helps prevent the signal wire from getting tangled up with the ship.

Just so you don't think I am blathering highly classified information all over the internet:

Here is a Lockheed-Martin advertisement with a drawing explaining how their SSXBT works.

Here is a declassified document (10-20 second .PDF download) explaining all about temperature gradients and how to read and troubleshoot your own SSXBT temperature chart!  Pretty cool stuff.

The photo of the SSXBT above was from someone who was selling it on Ebay.  Unfortunately the auction has already ended.  Truly a Christmas gift for the guy who has everything... I'd be willing to bet he doesn't have one of these :)

A dangerous tree

I took a week's vacation recently, and it wasn't much of a restful vacation.  More like catching up on chores - one big chore in particular.  Ever since moving here, I have been worried about one very large Ponderosa pine tree that was leaning toward the house.  I did not want to attempt to take the tree down myself because it was leaning the wrong direction, and I wasn't sure I could make it fall where I wanted it to.

Notice how the branches on this big leaning tree are the same size as some of the surrounding trees...

It took the tree service several weeks to give me a bid, then another month for them to actually come out and drop that tree (and a couple of others, one of which was leaning toward our power line).

As luck would have it, I had scheduled some time off about the time they got around to felling the big tree.  Good thing too; it was a pretty big job to clean it up.  The tree service would have hauled the tree off, but it would have cost 3x as much.  So I decided to do it myself.  ugh...  Of course it had to be the biggest, fullest tree on the property!

Happily, the tree fell away from the house, but it also blocked one of the driveway access roads.

Here I'm getting ready to start cutting off the limbs.

The first of four burn piles.  The tree is still blocking the driveway, but the lower half has been limbed.  I decided to save logs from the larger limbs.  Somebody will want them for firewood.

The driveway is open again!  Note the addition of more logs from the tree branches to the left.  There are still plenty of limbs remaining on the far side of the trunk.

The final burn pile.  The trunk is mostly sectioned.  There are quite a few more branch logs on the left.  After taking this photo, I stacked out the branch logs behind the house, but probably won't move the sections of the trunk until they dry out.  They are really heavy.

We had so much rain and a little snow, that I had to buy a weed burner to ignite the last pile.  I wasted a few gallons of gasoline and diesel, with no lasting fire to show for it.  This little sucker got it going after about 3 minutes of roaring and howling flame.  It's noisy, but it works.

America's fastest locomotive

M-497, nicknamed "The Black Beetle".  This was the fastest locomotive to operate in the US.  It was an experimental locomotive build and tested by the New York Central Railroad.  The locomotive was actually a Budd Rail Diesel Car (RDC-3) powered by two second-hand GE J47-19 turbojet engines. These engines had originally been mounted on a B-36D Peacemaker for take-off assist and dash speed over the bombing target.  The B-36 was active from 1946 to 1959

Below:  B-36 Peacemaker.  Note the outboard engines are a pair of turbojets...

Below is a photo of a Budd Rail Diesel Car.  These were individually powered rail cars, i.e. passenger or mail coaches that also contained two small diesel engines.  These single cars were used in rural areas where passenger traffic was light.  Photo courtesy of Bevis R. W. King.

Below is a photo of our hybrid of the Budd Rail Diesel Car and the B-36 turbojets.  The M-497 in 1966, with the B-36 engines mounted up front.  An aerodynamic nose was added to the locomotive, and the diesel engines were removed.

M-497 on one of the test runs, which took place between Butler, Indiana and Stryker, Ohio.

Another picture of M-497, clearly moving at high speed.

This testing was done on straight track in good condition and with no modifications.  The top speed was measured at 183.68 mph - a record that was set in 1966, and which unfortunately has not been broken since in the US.  A passenger train going that fast would certainly be awesome.  I'm pretty sure it could be done....

Steam Turbine Outage

This may or may not be an interesting topic to the random readers that drop by here.  I honestly don't know.  I've been around steam turbines my entire adult life, and have never given the shaft sealing system much thought - until we had a seal failure that ended up with the accumulation of a bit of new knowledge, which I share here.

As you would guess, steam tends to leak out of a steam turbine at the high pressure end, where steam enters the turbine, and air tends to leak in at the exhaust, where the final stage of the turbine is at 1-3 inHg Absolute pressure (25-27 inHg vacuum).  Steam turbines are not sealed like pumps.  Pumps use flexible packing or mechanical seals, that actually come in contact with the shaft.  Steam turbines do not seal this way, due to large swings in operating temperature from cold to running.  Instead turbines are sealed using steam!

I took a quite a few photos while the steam turbine was apart for the seal repair, and thought they were interesting enough to put up.  The steam turbine is a General Electric model A-10.

Most modern steam turbines are what we call "self-sealing".  What that means is that they only need to be supplied with sealing steam during startup and shutdown.  After the turbine reaches a certain load (5-20%), leak-off from the turbine supplies the seal steam, and external sources can be shut down.  If there is any excess leak-off, and the seal steam supply pressure gets above the setpoint, a seal steam dump valve opens, and dumps the excess steam into the main condenser.

The symptoms of a failed steam sealing system are these:  

• The seal steam dump valve is 100% open, and yet the seal steam header pressure is still too high.
• Water vapor and condensation coming from the Lube Oil System vents.  
• Increasing Lube Oil Tank level due to steam ingress and water contamination/condensation.
  

Note:  Water enters the lube oil system because the turbine shell is very close to the bearing housing.  So as steam leaks out along the shaft of the turbine, it can leak right into the adjacent bearing housing.  The lube oil system is kept under a light vacuum so that air will leak into the bearing housings, rather than oil leaking out.  This will help pull in steam if the steam seal is leaking.

First of all, before any work can begin, the steam turbine must be shut down and allowed to cool.

Following the shutdown, the steam turbine has to be continuously rolled at low speed (typically 4-10 RPM) for about 3 days.  Steam turbines operate at very high steam pressures and temperatures, and as a result, the turbine shell is very thick at the high pressure end.  The shell is also insulated for thermal efficiency as well as for safety.  For these reasons it takes several days before the turbine is cool enough to stop turning.

The purpose of rolling the turbine is to prevent warping the rotor.  If the rotor is allowed to stop, it will develop a bow.  Once a bow develops, it may sometimes work itself out when the steam turbine is returned to service; the rotor, reheated by steam, becomes ductile again and the bow mostly disappears.  Other times, with severe bowing, the machine cannot even be started due to increased vibration caused by the off-center mass of the rotor.  The damaged rotor will require machining and the addition of balance weights to compensate for the bowing, if not complete replacement.  Needles to say, it's preferable to keep the steam turbine on the turning gear until it cools down.

Interestingly, a steam turbine rotor does not sag if it cannot be rolled during cooldown.  Instead it humps up in the middle, because of the temperature differential between the top and bottom of the turbine shell.  It is not unusual to have a 200 degree temperature differential between the top of the shell and the bottom.  As heat rises inside the shell, the bottom part of a motionless rotor will contract more quickly than the top, which then bows the rotor upwards.

Onward now to the bits and pieces of a smallish high pressure steam turbine outage...

Below, a worker uses a sledge hammer to remove a nut from a through-bolt on the high pressure turbine shell.

Just above the worker's hard hat, is a black bundle of tubes.  This bundle is the power supply for an inductive heater.  The inductive heater fits down inside the through-bolt (which is hollow), and heats it up.  As the bolt heats up, it stretches out, making it much easier to remove the nut.  The same thing takes place during installation, except when the bolt cools, it shrinks, which draw the upper and lower half of the turbine shell very tightly together.  Note the insulating blanket on top of the shell.  Workers didn't want their feet to get burned while removing auxiliary piping.

Below: The top of the High Pressure turbine shell.  The far end (burnt off paint) is the high pressure steam inlet.

Below, two workers removing the high pressure inlet steam seals.

Below: Another image of the high pressure turbine.  At the bottom left corner on the rotor, are holes for balance weights.  Next is the steam sealing section, then a series of discs with tiny blades at the end.  These discs are the 10 stages of the high pressure steam turbine.  The generator is the big thing to the right.  Notice how thick the steam turbine shell is - This is why it takes three days to cool the steam turbine down from 1050 degrees F.

This is a close-up of the high pressure steam sealing section, with the packing (or labyrinth seals) removed.  High pressure (up to 1800 psi) steam enters the turbine just to the left of the disk on the right hand side, and then flows off to the right. At 1800 PSI, steam would tend to leak out along the shaft and be a hazard for everyone around, as well as causing a loss of efficiency.  To prevent this, steam turbines use labyrinth seals.

Below: Side view of a labyrinth seal.  These segments slide into the grooves in the sealing section of the shell, sitting very close to, but not rubbing on the rotor.  The purpose is to make the steam pass through a "labyrinth", or a series of very tight passages, losing a little pressure with each ridge.  At the left end of the seal in the photo above, a small fan draws off the tiny amount of leak-off steam and condenses it for re-use.  Clever!

Below, labyrinth seals (or packing) installed in the grooves on the high pressure turbine.  Interestingly these are held in place by springs that are merely short flat pieces of steel These springs press against the inside of the packing gland and the outside of the labyrinth seal.  Several of these springs were found to be broken during this outage.

The picture below shows a part of the steam turbine that is contained within the lube oil system.  At the right is a journal bearing.  This supports the aft end of the high pressure turbine (which is just off the picture to the right).  You can see a wire coming off this journal bearing, which is used to transmit the temperature of the bearing metal.  To the left of the bearing is a flat metal flange on the shaft.  This is used to determine rotor expansion.  The shaft expands quite a bit as the steam turbine goes from a cold condition to the normal operating temperature of 1050 degrees F.  The coil of blue wire connects the rotor expansion position sensor to the monitoring system. The big gear is for rolling the rotor when the steam turbine is not in operation.  The big round flange with all the holes in it is the coupling which connects the generator to the turbine.

Below, the bearings at the other end of the high pressure steam turbine.  In the center is a journal bearing, with thrust bearings to either side.  The journal bearing supports the shaft, and keeps it from moving in a radial (side to side or up and down) direction.  The purpose of the thrust bearing is to keep the shaft from moving axially (left to right) .  The shiny flanges with no holes in them are a part of the rotor called thrust collars.  The shiny things just inside them are the thrust bearings.  This section of the steam turbine is continuously supplied with oil to cool and lubricate the components.

One of the pads from the old thrust bearing... not in very good shape at all.

These looked in pretty bad shape as well.  Obviously there had been some heating and breakdown of the oil into carbon deposits.

Replacement labyrinth seals installed on the high pressure turbine lower half.  Note the serpentine path that leak-off steam must travel.

High pressure steam turbine back together and being fitted with brand new insulating blankets.

One of the things you run into while starting a cold steam turbine is rotor growth.  The rotor does not contain as much material as the turbine shell, and it is completely surrounded by steam (although the steam temperature is kept as low as possible during start up).  At the same time, the turbine shell is also cold, but only has steam warming the inside of a *very* thick piece of steel.  As a result, the rotor heats up much more quickly than the turbine shell, and it therefore expands much more rapidly.

Because one end of the rotor is held in place by the thrust bearing, the other end of the rotor grows as steam heats it.  It's quite possible to have rubs if the expansion of the rotor gets too far ahead of the shell.  That's why you will find rotor expansion proximitors (Below). These little pucks monitor exactly how much the rotor has expanded.

This is one of the few outages I have had time to take pictures and learn a few things, because on scheduled outages, I usually have assignments that keep me too busy for that.  Was fun to learn, fun to share.

NOTE: There is a continuation to this post with some further useful information HERE.

Heating the shop: Step 1

The house we purchased recently has a really nice shop.  The shop is 40ft x 40ft, with a 13 foot ceiling.  It is insulated, has a tall insulated roll-up door, and is wired for 230V throughout.  It even has a small bathroom with a deep sink.  The bathroom is wired and plumbed for a hot water heater, but one was never installed.

The shop has a massive work bench with overhead lighting, and a large mezzanine area for storing stuff that you might not want cluttering up the main floor.  It has windows up high on two sides to bring in natural light.  In short, it's a really nice building!

What the shop doesn't have right now is heat, and that makes it unpleasant and impractical to use for several months of the year.  It also makes the diesel tractor very difficult to start.  The previous owner used the shop as a business, and because he was out there every day, he heated the building with a wood stove. There is a penetration in one wall where the duct for the wood stove once passed through.

I like the idea heating the shop with a wood stove for a couple of reasons:

1. I have plenty of dead trees available for fuel, and many more living ones that I need to clear for fire safety reasons.  
2. All of these trees are free.  

However there are a couple of very solid reasons that have convinced me not to install one:

1. My homeowner's insurance will go up, because wood stoves tend to be fire hazards.
2. Inconsistent temperature control, because I won't be using the shop every day.

Inconsistent temperature control is really THE issue.  When we bought the house, it was unoccupied, and a company had "winterized" the plumbing, filling all the water supply lines with an environmentally-friendly anti-freeze.  The shop still has antifreeze in the water supply to keep the pipes from bursting during the winter months.  I would like to be able turn on the water supply again and use the toilet and the deep sink, and to finally install that hot water heater.

If I were to install a wood stove, I would need to maintain a fire all winter in the shop to keep the temperature above freezing, or risk burst pipes.  Rather than have to deal with that, I thought it would be preferable to install a propane furnace with a thermostat to regulate the temperature.  I only want to keep the shop from freezing, and increase the temperature on those few times when I need to work there.

For the past couple of years I watched the Craigslist ads, and finally found what I was looking for.  In fact, the sellers were getting rid of two furnaces.  I purchased one, and a friend purchased the other. These units came from a logging company's maintenance building.  The logging company stopped using them because they got tired of paying the propane company for tank rental.  I intend to buy a small tank, so that won't be an issue for me.

My Craigslist treasure!  It even came with some exhaust duct and a cap.

The installed version, with horizontal ducting, should look something like this:

Not the same model heater, but you get the idea...

Next, I need to locate a 100 gallon propane tank.  This particular size is nice because the fire code allows you to put a fairly large tank right next to the building.  Anything larger would have to be 50ft away from the shop, which would necessitate digging a deep trench, running a lot of pipe, and having to rent the tank from the propane company.

This is the size that I have in mind (no that isn't me)

After that comes the infrastructure.  I will need to pour a slab for the tank, run some gas pipe, install the exhaust duct, add an electrical circuit for the heater, and install a thermostat.

I was a little concerned about finding a thermostat that has a temperature range as low as I need to go, but I located a digital garage thermostat that looks perfect for the task:

So, with a little time off (Heh. good luck with that!!!!) and some luck finding a propane tank, I may soon be playing...
in hot water,
in the deep sink,
in the shop :)

UPDATE:

I did get this project accomplished about 9 months later.  That post is HERE.