A WATERTUBE BOILER FOR MY TRIPLE EXPANSION ENGINE

[simplyloco]

I already have a nice vertical boiler that I could use, but it is very large, the operating pressure is only about 60 psi and and I want at least 100, and it is not a marine type boiler, hence the need for a new boiler.
There is a Yarrow type water tube boiler listed in KN Harris's excellent book on boiler making. These high pressure boilers powered many ships in the past, but they were a bit more complicated than the one I'm going to make! #
Some pics.



A former to fashion the flat on bottom headers.



A teak former to support the 22mm tube and former.



After about five minutes healthy beating I landed up with this shape. Just what I wanted!



Ta Daa!!! The 6mm tubing and the 54mm barrel arrive on Tuesday. Onwards and upwards!

[crueby]

Great start!  Will be following  this one closely...   

[cnr6400]

 

[tghs]

I'll be watching this one!!!

[Kim]

This looks like a fun boiler project!  I'll enjoy following your progress.  And a great start on it so far! 

Kim

[steamer]

That looks like a great start!!

A bit of operational advice, with small watertube boilers

Keep your feedwater VERY clean.
And a engine driven feed pump that will keep up with the demands of constant feed.

Small water tube boilers are VERY touchy....and can be tough to control, and a engine driven pump that pumps a little all the time I have found to work the best.

Additionally, if you can fit a feed water injector it would awesome! it is wonderful for those times where you have more steam than you need and rather not lift the safety.   Fire off the injector and that works great as a calming a raging water tube boiler down long enough to close the dampers or turn the fuel feed down.

.....ask me how I know this.....

Dave

[crueby]

Dave, side question on the injector idea - I've seen them used on full size engines and down to ride-behind sized locomotives - how small can they be made and still work? Is there a physics limit?

[steamer]

Dave, side question on the injector idea - I've seen them used on full size engines and down to ride-behind sized locomotives - how small can they be made and still work? Is there a physics limit?

I have a Superscale Locomotive works economy injector for the boat, which is fine up to 13.5 square feet of heating surface and 160 psig.  It's a small injector and It has a capacity,  IIRC, of 33 oz a min, and fits in the palm in my hand.   That said I've seen much smaller 3/4 scale ( 3 1/2 gage or Kim's switcher size) sold in the UK fairly readily.    That's probably the limit on how small they can get.   I'm not sure how small this boiler is, but it might be big enough for it.    Getting the combining cones machined accurately enough and small enough is probably the limiting factor here

Water circulation on a very small watertube boiler is violent, and they really want a constant water level, if possible.

Sabino has a water tube boiler with 960 square feet of heating surface 55 gallons of water, and 64 square feet of grate area, and will lift the safety in 17 minutes from striking the match...but, with that responsiveness, comes sensitivity to draft and water level.

Dave

[uuu]

Commercial injectors in the UK can work, but there are plenty of unreliable ones out there.  The trick is to make your own.  The book to get, which goes into all the necessary procedures is by D A G Brown.  (Simplyloco - you'll know this already)
 Nothing will be beyond a person of your skills.  You can go really small - although it gets more tricky as you go smaller.  11oz and smaller are the devil's work.  Here's an account of someone doing a 4oz/min one! 

https://www.modeng.johnbaguley.info/injectors/injectors1.htm

Wilf

[simplyloco]

Wilf is quite correct, there are small injectors out there that can be made to work. I also have the DAG Brown book. I have known John Baguley since 2005: he got me into this!!!!
However, has anyone noticed that this boiler will be fed by the twin cylinder positive displacement Edwards pump on the Bolton Triple? I have every confidence in it, and the associated bypass valve...
Luv
JB

[steamer]

Wilf is quite correct, there are small injectors out there that can be made to work. I also have the DAG Brown book. I have known John Baguley since 2005: he got me into this!!!!
However, has anyone noticed that this boiler will be fed by the twin cylinder positive displacement Edwards pump on the Bolton Triple? I have every confidence in it, and the associated bypass valve...
Luv
JB

Like I said, engine driven pump is perfect....
Dave

[simplyloco]

Creating (!) the End Caps.

Just a hand beating job really, but I'm out of practice as my good lady will testify! 😱😍
BTW, proprietary 54mm end caps are available, and if I can't get these to fit properly then that is the way to go! Cheap too!

https://ondemandsupplies.co.uk/54mm-endfeed-end-cap/...

6mm profile tool and a bit of filing to make the former.


Nothing beats a sophisticated oven. Fred Flintstone look out!


First go at making ash trays. These needed annealing four times to achieve the desired shape.


Excess removed by careful hacksawing.


Glued onto the former with Loctite, left overnight, and carefully machined to 0.1mm undersize.


Perhaps I don't ned to buy commercial end caps after all!


Bronze end caps for the bottom headers with 3/8" x 32 tapped holes in one end for drain plugs.

[Laurentic]

The bottom headers - how many times did they need annealing between hammering before you were able to get that large flat face for the tubes?

Chris

[Kim]

The end caps look great!   

Kim

[simplyloco]

The bottom headers - how many times did they need annealing between hammering before you were able to get that large flat face for the tubes?

Chris

Hi Chris. The short answer is none, as I wanted a hard surface for when drilling the holes. Soft copper snags on tools, well it does for me...
John