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Thread: Whisperings
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20th Jan 2016, 09:20 PM #856Most Valued Member
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Hi Vann
not really a hijack as we have done a repair on a similar governor handle. I just forgot to take some pics of it in use.
From memory (which isn't flash) the whole centre had fallen out and maybe part of the rim.
I will take some pics tomorrow as the handle hasn't been painted and you can see the repair.
I didn't repair the handle on the one I did as I thought it prudent to leave it to our resident expert who taught at the local TAFE college (recently retired).
In reality it isn't that difficult and push come to shove I would have a crack.
Phil
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20th Jan 2016, 10:15 PM #857Most Valued Member
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Hi all
after a bit of use on the Jones and Shipman surface grinder, the 'Y' screw started to get a bit tight.
I pulled the front cover off and gained access to the lower half of the nut, well the screws that hold the nut in anyway. Between the screws was what looked like a homemade fitting so I decided to pull it out and see if it was blocked.
On the outside of the base of the grinder was a spot where the zerk fitting used to be. The copper pipe that went from this fitting to the homemade fitting was full of grease so first thing was to clean it out.
The rest is in the pics
Phil
IMG_7975.jpg IMG_7954.JPG IMG_7957.JPG
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21st Jan 2016, 01:22 AM #858
Thanks Phil.
Where this thread joins the handle, it is relatively thin and prone to break...and it did
Super welder Raymond wasn't at work that day so I had to have a crack at brazing the two bits back together.
Lets just say that its been a while.
Phil
Attachment 360556
I won't comment about the brazing because it is far better than mine would be.Best Regards:
Baron J.
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24th Jan 2016, 08:28 PM #859Most Valued Member
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Over in the General Metalwork section Ken has asked how a Cornish boiler works so I will give it a crack at explaining.
Remember, I am the explainer from hell so bear with me.
The pressure vessel component of a Cornish boiler consists of a drum that has a hole cut in both ends and essentially a pipe is slid in and riveted.
The actual method of construction isn't that way of course for obvious reasons but...
The drum is then set on brick plinths that give support along it's full length and create a passage for the gas pass in the underflue.
Brick work is then done around the boiler to complete the passages for the gas to pass through the side flues. When I say gas, that is the hot air from the fire.
The gasses run from the fire down the furnace flue, to the back of the boiler then split up and return down either side of the boiler through the side flues heating the outer shell, then join together and go under the boiler through the underflue heating the underside of the outer shell
Some pics might help.
Don't hesitate to ask any questions.
Phil
This pic is of a Cornish boiler in operation
Fire in Thompson.jpg
Next couple of pics are from a smaller boiler we had a new setting put under it
Days 103.jpg Days 105.jpg Days 35.jpg Days 111.jpg DSC_0781.jpg
These are from the last boiler clean we did
Fireside (7).jpg IMG_5335.jpg
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24th Jan 2016, 08:31 PM #860Most Valued Member
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24th Jan 2016, 09:06 PM #861Philomath in training
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Phil, if I understand your Cornish boiler explanation, The fire in the 'tube' heats the water directly but then the flue gases are re-directed to heat the outside too, increasing the efficiency of the boiler? Where do the combustion products (ash/ clinker) go? Are they just scraped out when the boiler is cool?
Michael
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25th Jan 2016, 05:56 AM #862Most Valued Member
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Hi Michael
spot on with your understanding.
Most of the ash and the very occasional clinker as we are burning wood, go through the grate and into the ash pit but the fly ash goes down the passes and has to be brushed and vacuumed out each year at the annual inspection.
The ash in the ash pit is scraped out every morning after the first charge of the fire.
As an aside these boilers are called Cornish 3 pass boilers for obvious reasons.
The only similar style boiler is the Lancashire which has two furnace flues which join together towards the rear of the boiler with the second pass being under the boiler and the third down the sides then onto the chimney.
Phil
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25th Jan 2016, 08:53 AM #863
Hi Phil. Thanks for your explanation. Interesting.
It seems to me to be a lot less efficient than a multi-tube boiler - as, for the second and third pass, the hot gases travel through passages that are not conducting heat directly into the water on all sides. Or does the whole thing stay so hot that losses to "earth" (brick) become negligible? It certainly looks to be simpler (cheaper) to make than a steam locomotive boiler.
Are the three sets of four "rivet heads", visible on the end plate, longitudinal stays? Are there any stays between flue and outer shell/barrel?
Thanks again for taking the time to add to this great thread of yours.
Cheers, Vann.Gatherer of rustyplanestools...
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25th Jan 2016, 09:46 PM #864Most Valued Member
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Hi Vann
I appreciate the thanks and I can't see this thread ending anytime soon, especially as I have just started on a full restoration of the inverted vertical engine in the blacksmiths shop. This engine was made in Buffalo New York which means all the threads are National form. Should be fun as someone has used 1/2" Whit 12 TPI and jammed them into 1/2" NC 13 TPI.
The rivets are for the longitudinal stays but no stays like the 'firebox stays' on a locomotive style boiler are used as the circular shape is perfect for a pressure vessel.
The loss of heat in the bricks only really comes into play when firing from cold, once they get hot they hold the heat very well as they are fire bricks.
They also assist in giving better draught.
Cornish boilers are made for their particular application, slow(ish) to respond but massive capacity. A locomotive style boiler is designed for very rapid steaming and very rapid non steaming. For example, a locomotive needs a lot of steam at the bottom of the hill so a good fire and air is needed but when it gets to the top it instantly doesn't need that so the dampers are shut and the boiler goes off the boil almost immediately.
A locomotive boiler has a large heating area relative to the quantity of water whereas a Cornish boiler is the opposite.
Halfway in between is another style of land boiler called the UFMT or Under Fired Multi Tubular boiler which gives you the best of both worlds, quick to steam and good capacity.
I have put in 3 pics as they aren't great focus wise but you should get the idea.
Phil
IMG_5361.jpg IMG_5362.jpg IMG_5354.jpg
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25th Jan 2016, 09:57 PM #865Philomath in training
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Thinking about the two styles of boiler, I would have thought that the Cornish was also slightly safer - if a loco boiler tube developed a hole, steam pressure would be lost but the fire would probably continue going as the flue gases etc would tend to push the water/ steam away and up the chimney but if a Cornish developed an internal hole then the fire would likely be doused?
Michael
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25th Jan 2016, 10:20 PM #866Most Valued Member
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Hi Michael
The safety of a pressure vessel is normally directly proportional to the skill of the operator
Boilers don't normally get holes, they split, which becomes a rent, at which point the only thing to do is open your eyes real wide as it is the last thing you are ever going to see.
The size of the furnace tube in the Cornish boiler will let go with enough force to (in our case) dump 17 tons of boiling water under pressure into the atmosphere which will then flash off into steam. Imagine a 1 litre milk carton of this water, it's going to give you 1600 1 litre milk cartons of steam in less than a second, obliterating everything in its path.
They still use steam to throw jets off aircraft carriers due to its explosive qualities.
If a tube lets go on a locomotive, it is still fairly well contained to a relatively small tube and only deadly if the fire doors are open.
Phil
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26th Jan 2016, 03:23 PM #867Most Valued Member
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Thanks for all this Phil, you are a wealth of information. . Where did you learn all this, as well as being able to rebuild such fantastic machinery?
KrynTo grow old is mandatory, growing up is optional.
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26th Jan 2016, 04:01 PM #868Senior Member
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What happens when a boiler goes bang.
http://www.ipemaritimes.com/bxpl.pdf
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27th Jan 2016, 06:21 AM #869Most Valued Member
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Outstanding stix
I am teaching the young bloke at work about this at the moment (he is going for his ticket) and I often get asked why I strip every nut and bolt off the boilers at inspection time and thoroughly inspect and repair or replace anything that is just a little suspect. That's why!
Standing in front of these things on a regular basis you end up with a lot of respect for them. One of the most important things to learn is when it is safe to put water in and when it's not. Obviously the guy in the report didn't.
I learnt on the same boiler as that one, a Cleaver Brooks 400HP and they weigh in around the 20 ton mark so that's a fair punch to get it to move that far.
I still find it hard to believe the lack of maintenance that went on there, it beggars belief and to my mind they deserved everything they got.
(a still alive) Phil
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14th Feb 2016, 04:46 PM #870Most Valued Member
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Hi all
I'm pretty confident everyone knows of the Ingersoll Rand air compressor at work. My favourite engine, got quite a workout over the Christmas holidays running nearly every second day. For a while now I have wanted to have a crack at re-setting the main valve so it would be easier to start and run a lot smoother.
I got the go-ahead and am pretty happy with the results.
This is the video of the test run.
https://www.youtube.com/watch?v=LvmsOXYd2cY
Phil
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