New Zealand Yarrow boiler

[NilochParticipant @niloch]

Beautifully complicated boiler with at least 176 tubes

[NilochParticipant @niloch]

I've been struggling with an all copper Yarrow boiler to the design of Terrence Holland's for about eighteen months but my efforts are completely insignificant compared to this large one by Kiwi Noel:

**LINK**

Not many of the images have captions and I can't work out how the small diameter tubes are joined to the steam and mud drums.

[JasonBModerator @jasonb]

The tube expander on the end of that long extension is a give away

[nigel jones 5Participant @nigeljones5]

they look to be expanded in, bet that was awkward!

[NilochParticipant @niloch]

Hey Jason, I thought maybe that was a de-burring device.

[John OlsenParticipant @johnolsen79199]

I'm also in New Zealand, and am building a three drum boiler to a different design. Mine has steel tubes. The top drum is eight inch and the mud drums are five inch. There are 126 tubes. It is rated to work at 250 psi and is built to the ASME (American Society of Mechanical Engineers) specifications. I only plan to run to a maximum of 170 psi, I am not sure that the plain bearings in my Leak compound would thank me if I put too much pressure on them.

My water tubes are also expanded into the drums. With steel this is even more difficult than with copper. One extra difficulty was that there are actually three specifications of tube that are approved for the design I am using. I managed to end up with two sorts, which meant reaming the holes in the drums out to suit the very slightly different outside diameter. Also the one with the thicker wall was much harder to expand. The wall thickness is around an eighth of an inch. My tube expander gadget, invented entirely independently of Kiwi Noel, is rather similar to his except that it is driven by a battery electric drill. It took four different sizes of expanders, two for each size of tube, to get enough expansion. When you expand the tube, you can see it growing on the outside part near the drum, and if you have a free hand you can feel it get warm. The pressure must be quite intense. For those unfamiliar with tube expanders, they have tapered mandrel down the centre which is driven. Around that is a cage with slots for three rollers. The slots are angled very slightly so that when you drive the taper one way, it pulls the taper into the rollers expanding them outwards and rolling the inside of the tube outwards.

My boiler has downcomers to each mud drum at each end. They are not strictly necessary in a Yarrow design, but the design would not have got past the approval without it. It has had a hydraulic test but is not mounted in its housing yet.

The plant is to go in a thirty foot boat. Progress has been held up for the last year or so as I am getting ready to move house, which has involved putting lots of stuff in storage so I can redecorate ready for selling. I hope that will be all over in a few months and maybe I can have her in the water within a couple of years.

So Kiwi Noel seems to be building two. Mine is the second example of this design to be built. There is also a replica of a Herreshoff steam launch nearly finished here in Auckland, with a Yarrow boiler. That makes five that I know of in steam launch sizes here in NZ now. There are of course other boats with different types of boilers.

John

Putting in the tubes was a major effort. Getting three or four in during an evening was about enough.

The engine under steam. At that time I was experimenting with having separate control over HP and LP cutoff, but decided it would be too complex. So now is has a simple locomotive style Johnson bar and quadrant. The copper drum is an experimental oil separator. Seems promising but not tried in service yet.

The boat. Thirty feet long, six feet beam.

[NilochParticipant @niloch]

kiwinoel posts here, see his Achilles Wheels post under General Chat

**LINK**

[Noel Muirhead 1Participant @noelmuirhead1]

Hi a friend told that Kiwinoel was mentioned on this site and as I am he I thought I had better register and take a look.The boiler is a John King design from the Steam Boat Association of G B my friend John in Ashburton and myself brought the plans and permission to build two boilers we chose them as they are weldless so could do all the work ourselves they are the short version 186 12mm cupro nickel tubes connecting 2 100mm scd 40 mud drums to 1 150mm scd 40 steam drum the outer tubes are the downers the inner tubes do the heating, 27sq' heat of heating surface 250PSI working pressure. The chain driver is not my idea I saw something like it in a photo of some boiler builds sent to us by John King our one has 1/4" squares in the sprockets we used it with a countersink driven by a battery drill to deburr the holes inside the mud and steam drums then wound it by hand to turn the tube expander it worked a treat. John has gas fired his and is using it to power all his model steam engines mine well I haven't got a boat so might use it just to run the Hasbrouck No 5 for demos, I think the other half would like to see it on E Bay or Trademe. I have started on an Achilles Loco it was brought in from the UK part, built excellent workmanship however there are a few things to put right and even after years in earthmoving and diesel engines I have to learn a new language. If any one has built or had something to do with an Achilles I would like to hear from them

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