Category Archives: The Power Plant

Building the Engine and Boiler
Below are posts related to the building of Arthur Leak’s marine compound steam engine as originally described in Model Engineer magazine and more recently provided via Camden Books (drawings, manual and castings). It will also include the construction of a oil-fired Yarrow watertube boiler, to designs from John King from the SBA (see links on right of home page)

This is the engine that will power SY-Befur, it is expected to produce 10-14HP. These post cover all the construction from Camden’s castings and the addition of pump and alternator assemblies for our particular installation.

A final video: Everything running on the bench

First Fix the Bugs!

Following on from the Boiler test, and a quick trial we identified just over 20 items that needed some attention. So a week later, with all these items fixed (from leaking valves to painting and plating valve gear components), we are ready to try again.

The Fire-up Plan

We enlist the support of neighbour Micheal Slack (who is also housing the hull) and embark upon a frantic half hour of trying to put the water and steam where we need it and get the plant running properly.

This involves:

  1. Lighting the burner, and raising some steam.
  2. Getting the blue steam pump pumping cooling water thru the condenser to condense the exhaust steam from pump (and engine).
  3. Warming the engine thru with steam to get it ready to start.
  4. Getting the engine to run so that the air pump removes the condensed water from the condenser to create a vacuum.
  5. Getting the boiler feed pumps on the engine running (so Mike can stop with the hand pump).
  6. And get the alternator running to prove that we can provide electrical power for the burner, lights, radio etc.

Getting that lot to happen at the same time took some time and several attempts (and a lot of water on the floor)! It will me much easier when there is a lake providing the cooling feed water, rather than a hosepipe and bucket! But it all worked even the real McCoy lubricator and the whistle!

I was also pleased that the engine does not appear too noisy or knocking, just a bit of noise from the chains. So a good day!

A video of the day

Enjoy the video of edited highlights – with enthusiastic commentary from our “cameraman” Louise!

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Worthington Simpson Pump Restoration

You will have realised that I am a bit of a sucker for ageing lumps of cast iron in need of restoration. So I could not resist a circa 1940 Worthington Simpson Steam Pump that Mark Rudell offered to me. It seemed it would serve well as a boiler feed pump or circulating pump for the condenser. (providing I could ignore the fact that it’s about 5 times the size we need – but hey the designer said I needed 500KG of ballast in the bottom of the boat, and given I can barely lift this beauty it’s all grist to that mill!)

It clearly needed a bit of a clean and a check over, and it took about a week’s work. These are often known as “Donkey Pumps” as they tend to do their work for years with little in the way of maintenance or attention – it seems this one had certainly “done its time” in this mode.

Rather than provide a blow-by-blow commentary on the work it involved, the following pictures will hopefully provide the detail:

  1. Get it apart, Inspect, remove (many) layers of old paint, and clean inside and out.
  2. Reface the mating faces of the pump valve chests.
  3. Reseat/regrind the 8 suction and supply valves (using reciprocating valve grinder).
  4. Repack and adjust the glands on steam and pump cylinders.
  5. Make new packing rings for pump cylinders (in PTFE).
  6. Turn a blind eye to the wear in the pump cylinders (I might re-sleeve these later)
  7. Paint.

It runs well, and the remaining wear in the pump cylinders make it less efficient than it should be, but in it’s planned role as circulating pump it should be fine…. The pictures show some of the steps: (remember you can click to see a full size image…off to watch Strictly !)

 

 

A Boiler Full of Steam

Well the 10th November 2017 marks a major milestone – the boiler passed its initial inspection and steam test, and is now certified for use. (big smiles all round).

Picture of Engine, Boiler Etc. ready for test

Sadly, everything was too frenetic to take pictures during the steam test – but here it is just before we pressed go!

John, our inspector from SBAS Ltd (the SBA’s Boiler Inspecting Company) had been booked to arrive at 3:00pm – at 9:00am I set about final sealing of the try-cocks on the sight gauge – at 1:30pm I nearly called to cancel the appointment as no amount of fiddling and fitting would make them seal, with a constant drip from each of them at anything above 50psi 😦

Finally I made them seal with a combination of shredded graphite string and a binding of PTFE tape to seal the valve stems – dry as a bone at test pressure of 375spi, big sigh of relief. A final tightening of some of the 60+ joints in the steam circuit and we wound up with a boiler that held over 350psi for over one and a half hours without a single pump being needed. (This is a hydraulic test so the boiler is filled to the top (to exclude all the air and thereby minimise any “bangs” resulting from a failure.)

So the pressure test is complete. Next the steam and accumulation tests. So we wheel the complete set of machinery (engine, boiler, steam pumps, battery and regulator) outside (with a lot of puffing and blowing), drained the water in the boiler down to operating level, and we light the burner.

The burner needed some adjusting to get it to light and burn fairly cleanly (a little more tweaking needed) and we quickly had 10psi on the gauge (5-6 mins)  – so we turned off the burner and checked round for leaks or other problems and to let the boiler “adjust” to its new state of hotness.

All looked good so we brought it up to 50psi to check the water gauge (sight glass) was reading correctly and all the various blowdows operated correctly – they did! (more smiles).

The next step is to make sure the safety valve opens at the correct pressure and is able to control the pressure within 10% of safe working pressure with the burner full on.

So, burner on and another 10mins to come to working pressure of 250psi (17Bar) – whereupon I got an impromptu (but complete) hot shower. The safety valve did open OK, but as the water was quite high in the boiler. and had been dosed with washing soda to bring the PH up to 11 (and probably because of all the crud left in the boiler) we got a lot of water carried over into the exhaust steam (what is known as priming) which provided the aforementioned hot shower. There was enough showering down on the 240v wiring of the burner that I decided to kill the power while we dried things off….

So with a little less than a litre of diesel left for the burner we lit it once more and went for the accumulation test. By now it’s getting a little cold and dark, so reading the gauge within the billowing clouds of steam was quite hard for John, but after a few minutes he was happy that all was good – we were passed.

Not wanting to waste all this nice steam we tried the Worthington Simpson steam pump (A post on the restoration of this is on the way) in anger, and it performed quite well – supplying feed water at over 200psi….. and then we tried the engine!  after some warming thru this ran too and even the generator seemed to be making 7.5amps at a modest speed – but we highlighted the next (somewhat expected) list of jobs:

  • Two of the relief-drain valves seemed not to want to close (more clouds of steam and investigation needed)
  • The circulating pumps (engine driven) did not deliver enough cold water to the condenser to condense the exhaust steam and create the vacuum. So we are going to revert to the original design of the engine-driven pumps acting boiler feed pumps and the steam pump as a circulating pump.
  • I think I saw a couple pin-hole leaks in the feed pump plumbing which need checking
  • We need to finalise the plumbing from the cylinder drains
  • On the next run we need to get the displacement lubricator running.
  • We need to check the alternator performance to make sure we can generate the 20+amps we need to drive the inverter for the burner.

….then we can think about attempting to install the whole she-bang in the hull!!!! (Spring ’18 Launch – yes,  I think we might make it!)

A Plumber’s Nightmare & a Real McCoy

Over the last few days we have encountered the two items mentioned in the title in real life, in a slightly stressful way.

The Real McCoy

One of Elijah McCoy's displacement lubricators - actually this one was made by the Detroit Lubricator Company.

One of Elijah McCoy’s displacement lubricators – actually this one was made by the Detroit Lubricator Company.

While Wikipedia suggests two origins for the phrase “The Real McCoy”, the most well documented version relates to one of the brass beauties shown here.

It is a displacement lubricator patented by one of Elijah McCoy’ in the 1870s in America.  These devices perform a simple, but vital, role of providing internal lubrication for steam engine cylinders and valve gear, but they do it using an apparently impossible process.

Basically they are attached to a ‘T’ in the steam line supplying the engine. You fill the lubricator with oil, and then via a mechanism which is not at all intuitive, the steam in the steam line to the engine decides it would prefer to be in the lubricator and, as it migrates that way and condenses as it cools, displaces the oil which is forced back into the steam line. So the connection to the engine sees steam heading one way and oil heading the other with nothing obvious causing that to happen!! The lubricator has a number of valves to control the rate that this happens and allow the machine to be shut off and refilled while underway.

Apparently Elijah McCoy’s  lubricators were so good and reliable that companies wishing to purchase steam locomotives were given to checking that it was fitted with a “Real McCoy Lubricator” – hence the phrase 🙂

In my case I purchased this at an auction a few years ago, and prior to fitting it I needed to pressure test this (as with all other pressurised components). As I did this, it revealed a number of leaks and failed seals on the two sight glasses.

Taking it apart revealed seals that may once have been rubber, but in the intervening years (100+?) had turned into something more like wood. I managed to find some replacement ones that just needed shortening, but fitting these is a tense process as cracking the glass would be just too easy.

Anyway, we managed it, and with a little TLC and returning some of the needle valves, we had the Real McCoy: a leak-less displacement lubricator.

The Plumber’s Nightmare

The fwd boiler fittings almost complete.

The fwd boiler fittings almost complete.

The rest of the week has been consumed by attempting to fit the fittings to the forward end of the boiler.

This seemed as though it would be a simple process, but pushed me to the edge of serious depression.

Due to the temperature and pressure of this assembly (250psi and 200+ degrees Centigrade) all of this needs to be in steel pipe with screwed fittings.

The problem is that while one can imagine how it all goes together, the reality is more complex, principally because you can’t actually screw all the parts together as the end points are fixed and so you can’t tighten everything.

Moreover it appears to need a certain sort of brain/thinking to figure this out – my respect for plumbers has been raised considerably! This was born out by half an hour in Penrith at the sales desk of a pipeline and hydraulic supplier while the staff demonstrated considerable fortitude (and difficulty) in “rummaging” through their stock to find the combination of bits we needed. (Actually I found this quite encouraging – if they couldn’t sort it out, perhaps I was not being a complete klutz.)

The net of this story is that what you need are “cone unions” – and I think the ones provided by Bessegers (like these) are by far the best design. These allow you to assemble the screwed bits, and then attach the assembly to the component you are plumbing without needing to move the joints you have made.

The second take away, is that sometimes you need to opt for an indirect path for the piping to allow you to accommodate the offsets in all three dimensions.

Onwards!

Boiler Gauge Glass and Boiler Fittings

Boiler Gauge Glass

Finished Gauge Glass

Finished Gauge Glass

We decided to make the sight glass for the boiler following John King’s design, with slight modifications. Ian Cross of the SBA was very helpful and modified some existing patterns he had for “normal” reflex gauge glasses to suite rear-entry installations, and had 3 sets of these cast for our “boiler making syndicate”.

As it happened he made the castings with larger/longer mounting “lugs” so I decided to try to make the gauge with the cocks integrated into the body (as opposed to separate valves as drawn by John). This was a quite stressful decision as the cocks are not easy to make, and any errors result in a scrapped casting, but none-the-less I am quite pleased with the result.

The design is unusual as the lower cock is made as a three-way cock to allow the two cocks to be set for normal operation, isolation of the glass (in the event of failure of the glass) and to allow blow-down of the glass and drum – a neat and innovative solution.

Manufacture

The manufacture was quite simple:

    • The flat faces of the casting were all faced on the shaper (using stop-pins) to hold it to the shaper table. This approach allows the complete faces to be machined in one pass.
  • Milling the Glass Recess

    Milling the Glass Recess

    The body and cover castings were then attached to the mill table and the recesses were cut for the glass (a B2 Klinger Reflex Glass from Heritage Steam Supplies).

  • At the same time the holes (ports) to connect the drum to the gauge glass space were drilled. This required some careful measurement as I made my usual mistake of not really understanding how the gauge fitted into the casting (it’s a bit like the sculptor finding the subject hidden in the stone) and so had not realised that the pre-cast slot for the glass was not actually arranged to be at the longitudinal centre of the casting – so the ports to the glass slot had to be offset from the threaded holes for mounting the gauge. As all these holes had to also mate with the taper cocks taper part it needed to be done carefully.
  • The next process was to drill and bore the holes for the taper cocks. Firstly, the cocks themselves have to be turned with the correct taper – the important thing is that the cocks and the holes are turned at exactly the same setting, so one sets the top-slide to the 10-degree angle and then locked in place while both parts are made. Here are some pictures of the parts and video of setting up for the the boring using a sharpened rod (located in a dot-punched mark at the centre and a closed up tailstock chuck, which provides a female centre point) and dial gauge to get the casting correctly positioned on the face-plate. This is a very off-set operation so large amounts of junk have to be bolted to the face-plate to attempt to balance everything.
  • Boring the drain port

    Boring the drain port

    The last operation is to drill and centre-bore the drain hole from the bottom of the casting to the taper-cock bore. This needed to be accurate, so I drew it up in ViaCad to ensure I had accurate dimensions and angles. Then a digital angle gauge allowed the head on the Rambaudi Mill to be set over to drill the hole (rather a “tall” set-up).

  • The final assembly showed that the handles on the cocks clashed with the dome nuts on the steam drum ends, this could probably have been avoided by shortening the shafts of the cocks, but this would have required bent handles (as described in the drawings) but I did not have any suitable material. So I made two spacers to lift the gauge clear of the end-plate. these have o-rings installed on both sides to seal the assembly.

Boiler Fittings

The next stage of the process is to attach all the boiler fittings and then assemble the steam/exhaust/feed-water components to the engine so that we can complete the boiler test and check everything operates before installing into the boat.

plumbing diagram

plumbing diagram

plumbing Bill of Materials

plumbing Bill of Materials

En-route I drew up a plan for this to choose the appropriate fittings and a bill of materials to match.

This single sentence hides many hundreds of pounds of components and hours of hand-wringing and frustration!

PTFE – one lesson that has been learnt is that PTFE seals in clacks and valves will not work at 250psi, as their maximum operating temperature is about 190C  (saturated steam at 250psi is at 207C or 406F) and at that pressure the operating pressure limit is very low – so PN32 valves are no-go and PN40 or above is what is required. (So I have quite a stock of ball and globe valves which are going to need to go to eBay 😦 ).

Here are a couple of pictures showing the current state of play…

Boiler Fitting in progress

Boiler Fitting in progress

Boiler Fitting in progress

Boiler Fitting in progress

 

All Pumped up!

Well a definite milestone was reached today; the boiler passed its official initial hydraulic test at 500psi conducted by our Boiler Inspector.

It will never need to be pressed that hard again, next we have a 375psi test with all the ancillaries fitted (gauges, valves, plumbing etc.) then we put some fire in its belly and prove that the safety valves will stop the pressure going more than 10% higher than its 250psi operating pressure – then we will be allowed to insure it and use it in anger!!!

This might seem like a bit of a palaver, but a boiler failure will typically kill everyone within many feet – so it pays to take care.

When you consider that the pressure trying to force each end cover off during the test is equivalent to a large African Elephant standing on it, you can see why it uses a bunch of M16 and M20 studs to hold everything together!

Boiler sitting at test pressure.

500psi on the clock

500psi on the clock

A Few Notes

It took three attempts to get everything perfect, and here are a few notes for other builders:

  • The dome nuts needed to be skimmed, as the imperfections in their surface were enough to produce a significant shower at 200psi as they prevented the dowty seals from working.
  • One of the tubes had not been expanded into the mud drum – that started leaking without any pressure!
  • The stays on the steam drum needed shortening by about 200-thou to stop them bottoming in the dome nuts (it’s a bit of a fiddly dimension, as you must ensure enough thread is engaged with the nuts even with one end completely screwed up to the limit.)
  • The upper end of some of the tubes were a bit long and clashed with the lower stays in the steam drum, resulting in an hour or so with a Dremmel and air-driven countersink, to provide the necessary clearance.

Either way, an important day on the route to launch day!

Boiler Insulation and Funnel

Just a quick note on recent days’ work. We have been insulating the inner boiler casing and installing the funnel (at a jaunty angle)!

The boiler has two casings- one surrounding the burner, tubes etc. (the hot stuff) and an outer one of wood, with an air-gap in-between to keep passengers safe. This also includes a double skinned chimney (also to keep people safe – Lou has quite a scar from another steamboat where the funnel was not lagged or double skinned).

We are using “ceramic fibre board” from Vitcas This is quite expensive, but robust, capable of standing 2,300F (1,250C)  and capable of being cut with a knife or jig saw.

However, the mental gymnastics required to think about how it all fits together inside the boiler I find quite hard. However, after a deal of cutting and trial and error it’s almost done.

Tube nest

As we needed to remove the casing, I also took some pictures of the “tube nest” which shows the 200+ 12mm tubes all expanded into the steam and mud drums.

This lot totals about 30sq-ft of heating surface which is capable of producing about 300lbs of steam at 250psi per hour!

Funnel

This is formed from some 7-inch stainless steel liner and enamel outer flue. This is what you would find attached to your average AGA.

Boat aesthetics required that this is attached at a jaunty angle (5-degrees) to provide an impression of dashing speed etc. However, making things at an angle is often more difficult than making things straight.

We have made the casing from 3mm steel and this has provided a solid foundation for mounting the funnel.

The inner liner is  178mm dia, so I bored out the hole in the top plate of the casing to size with the head of the mill set over 5-deg to get the required oval (a bit OTT I think).

I opted for a set of 20mm square blocks with their base machined to the aforementioned 5-degree angle and then M5 screws are used to attach these to the roof of the boiler casing to provide a “socket” for the liner.. The inner liner also has a “bulge” about 15mm above it’s lower end, so I machined notches in these blocks to engage with this bulge and thus provide vertical (or jaunty angle) support to.

The outer face of these blocks was then machined to fit the outer funnel, again with the steps providing the angled support. M5 screws thru the outer into these blocks secure the outer funnel. Lastly, a set of three blocks were made to secure the inner and outer funnel together at the upper end, and then an air-nibbler used to chop the inner to length.

Milling at 5-degrees

Milling machine set over to machine oval hole in cover, and inner funnel resting in said hole at required “jaunty” angle!

Funnel mounted on Boiler Cover

Funnel mounted on Boiler Cover