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Post by steamer5 on Apr 15, 2020 23:00:04 GMT
Hi Guys,
I seem to remember reading that Doug solved the problem of bending the tubes to get nice tight radi using the 5/32 tube. Of course he never let on as he was in business,
I can’t remember were I read it, likely ME, but he achieved tighter radi than the one you normally get using a former.
Anybody else have any recollection of this? Wonder if Doug would share the how to now that he’s retired & it appears that the new owners aren’t doing the superheaters, well maybe not yet.
Cheers Kerrin
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Post by Deleted on Apr 15, 2020 23:05:59 GMT
Hi Kerrin, I'm sure with the right amount of heat and a little care that it can't be that difficult. I'd probably start with the compact sand trick, to begin with. Not found any 5/32 yet but 4mm seems easy enough to obtain, not cheap at approx £30 a meter but it's there if nothing else can be found...I'm thinking 6 x 2-meter lengths being what I'd need.
No rush, I can look into this more later...
Cheers
Pete
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Post by John Baguley on Apr 15, 2020 23:55:48 GMT
Hi Pete,
Have you tried Southern Temperature Sensors for 316L tube?
They do thin wall tubing down to 3mm and 0.083" dia. They have 5/32" in 0.010" and 0.022" wall thickness.
I've bought 3/16" from them in the past. Unfortunately, they don't give prices on the website so you would need to ring or email them.
John
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Post by steamer5 on Apr 16, 2020 0:24:41 GMT
Hi Pete,
You are probably right, although I think Doug went done the hot route & it wasn’t successful.
Will be very interested in how you get on with the sand when you get there.
Johns source of thin wall tube sounds very promising! Wonder if they post over to here?
Cheers Kerrin
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Post by Deleted on Apr 16, 2020 9:17:00 GMT
Hi Pete, Have you tried Southern Temperature Sensors for 316L tube? They do thin wall tubing down to 3mm and 0.083" dia. They have 5/32" in 0.010" and 0.022" wall thickness. I've bought 3/16" from them in the past. Unfortunately, they don't give prices on the website so you would need to ring or email them. John
Oh wow... thanks for the link John, I can see a plan developing. I may start a separate thread at a later date to get views from the collective and how small can you go re-tube size in a model. A new challenge.. cool.. Yes, Kerrin, I have had a number of successful attempts at forming tube of all types using compact sand, I can't see why this should be any different other than the fact that the tubes will be very long/thin and extra care needed to ensure that the tube is completely full. sorry for taking up space in your wonderful thread Chris. Kind regards Pete |
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Post by Roger on Apr 16, 2020 11:35:03 GMT
Hi Roger, yes it is fortunate that Don Young designed the boiler with 1 1/4" O/D super heater flues to take his favourite concentric tube designs. I am planning on having 2 super heaters in each flue so that should reduce the area for the gasses to flow. I just need to make a slightly smaller radius bending tool to get them in. Interesting thought about the open flues though. I have a Super Simplex with three super heater flues but no super heaters at all, although I am planning at some stage to fit them. But the thing is it is one of the easiest locos to steam and rarely fails me. I regularly passenger haul at Southampton all afternoon with it. Even with the completely open flues I still get a significant amount of ash in the smoke box which I am sure would be coming through the lower fire tubes. I admit I do tend to fire up to the bottom of the door so that doesn't help. But there still must be a reasonable velocity of gasses through the tubes which shows as troughs in the ash, if you know what I mean. Also I run with a flat spark arrestor propped up behind the blast pip/petticoat pipe. After a passenger hauling run you can clearly see three whitish areas in front of the three flue tubes which indicates some high temperature gas flow, so your comment is correct, although it may be because the gasses drawn from the top of the firebox are just hotter anyway due to a more complete combustion in the bigger volume at the top. Anyway tomorrow I hope to make the smaller bending tool and see if I can get two hairpins in each flue. Chris D Hi Chris, That's interesting, I suppose the extra high temperature near those Superheater tubes helps with the amount of heat transferred through them. The flow velocity through the other tubes is presumably reduced and so there's more time for heat transfer. Put together, perhaps this is why you don't seem to have any difficulties. Last year I assisted my neighbour in getting his 4-4-0 American locomotive back into steam. It was almost impossible to keep going without a lot of blower, and the amount of water it was using was astonishing. We discovered that the Superheaters had been removed at some point, but only one of the tubes had restrictors in place. We added one at either end of that one. The boiler used to have to run with a lower pressure too, which didn't help, but that's now been recertified at the proper working pressure. It's a different animal now, far from perfect, but at least not a nightmare to drive. Even when the pressure drops back, it's nothing like as bad as it was, so the Superheater flue restriction appears to have made a big difference. |
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Post by coniston on Apr 16, 2020 19:43:42 GMT
Hi Roger, yes it is fortunate that Don Young designed the boiler with 1 1/4" O/D super heater flues to take his favourite concentric tube designs. I am planning on having 2 super heaters in each flue so that should reduce the area for the gasses to flow. I just need to make a slightly smaller radius bending tool to get them in. Interesting thought about the open flues though. I have a Super Simplex with three super heater flues but no super heaters at all, although I am planning at some stage to fit them. But the thing is it is one of the easiest locos to steam and rarely fails me. I regularly passenger haul at Southampton all afternoon with it. Even with the completely open flues I still get a significant amount of ash in the smoke box which I am sure would be coming through the lower fire tubes. I admit I do tend to fire up to the bottom of the door so that doesn't help. But there still must be a reasonable velocity of gasses through the tubes which shows as troughs in the ash, if you know what I mean. Also I run with a flat spark arrestor propped up behind the blast pip/petticoat pipe. After a passenger hauling run you can clearly see three whitish areas in front of the three flue tubes which indicates some high temperature gas flow, so your comment is correct, although it may be because the gasses drawn from the top of the firebox are just hotter anyway due to a more complete combustion in the bigger volume at the top. Anyway tomorrow I hope to make the smaller bending tool and see if I can get two hairpins in each flue. Chris D Hi Chris, That's interesting, I suppose the extra high temperature near those Superheater tubes helps with the amount of heat transferred through them. The flow velocity through the other tubes is presumably reduced and so there's more time for heat transfer. Put together, perhaps this is why you don't seem to have any difficulties. Last year I assisted my neighbour in getting his 4-4-0 American locomotive back into steam. It was almost impossible to keep going without a lot of blower, and the amount of water it was using was astonishing. We discovered that the Superheaters had been removed at some point, but only one of the tubes had restrictors in place. We added one at either end of that one. The boiler used to have to run with a lower pressure too, which didn't help, but that's now been recertified at the proper working pressure. It's a different animal now, far from perfect, but at least not a nightmare to drive. Even when the pressure drops back, it's nothing like as bad as it was, so the Superheater flue restriction appears to have made a big difference. Hi Roger, the pressure will have a very significant effect on the steaming of a 'wet' loco, my simplex runs at 100 psi, even at that pressure there is a lot of condensate exiting the chimney, in less than hot weather it's like driving through a light rain shower!. And yes of course it does use a lot of water, luckily the axel pump is to Martin Evans second design for Simplex which is pretty good, although I do prefer to use injectors so I have a No3 which is more than adequate. As I said I do intend to retrofit super heaters when I get round to a heavy overhaul, maybe next year now. If you are referring to a Virginia then I can see that with such a small boiler and low number of tubes it would benefit from restriction through the open super heater flues, glad you managed to help get it running at east reasonably. Chris |
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Post by coniston on Apr 16, 2020 19:52:46 GMT
Hi Pete, Have you tried Southern Temperature Sensors for 316L tube? They do thin wall tubing down to 3mm and 0.083" dia. They have 5/32" in 0.010" and 0.022" wall thickness. I've bought 3/16" from them in the past. Unfortunately, they don't give prices on the website so you would need to ring or email them. John
Oh wow... thanks for the link John, I can see a plan developing. I may start a separate thread at a later date to get views from the collective and how small can you go re-tube size in a model. A new challenge.. cool.. Yes, Kerrin, I have had a number of successful attempts at forming tube of all types using compact sand, I can't see why this should be any different other than the fact that the tubes will be very long/thin and extra care needed to ensure that the tube is completely full. sorry for taking up space in your wonderful thread Chris. Kind regards Pete Hi Pete, no problem adding more conversation to the thread, all interesting stuff. I would have thought going less than 4mm would create too much pressure drop, pipework in all industries is a juggling act between diameter, length and pressure. I worked many years designing mobile refrigeration and air conditioning systems and know first hand how the wrong pipe sizing can completely ruin the performance of a system. We also have to remember the radiant super heater must withstand the heat of combustion without any cooling effect from the steam inside, i.e. when in the station blowing up or waiting for the off. SO I would err on the side of caution regarding wall thickness. Mine are 1/4" O/D x 20swg i.e. 0.036" wall thickness. But maybe your idea of a separate 'super heater' thread may generate more discussion and save too much heartache when you get to the point of making them? Another possible supplier is www.pipedreamfittings.com/product/seamless-tube-316-stainless-steel-imperial/Chris D |
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Post by coniston on Apr 16, 2020 20:19:24 GMT
Spurred on by the success of my first experiment I spent a bit of time yesterday evening checking the maximum bend radius I could get away with to have twin super heaters in each flue. It turns out to be 1/2" inside radius giving 1" overall width. So today I made a second former for my bender, didn't get many photos but here I am roughing the groove before plunging in with the newly ground radius tool. First I went to 1/2 depth and full width, then full depth in the middle with my 2mm wide parting tool.  Then parted the piece off  After adding a pipe support it was ready to use. Here you can hopefully see the pen mark for the mid point of the tube and the tube support block which is pinned to the back of the former with a couple of 1/8" dowels to stop it moving.  Then with the bender assembled it is a simple matter of pulling the handle and the tube is bent, this is half way round.  And the complete bend.   And all six bent in less than half an hour.  Fitted into the flues nicely without any resistance. Poking nicely out into the firebox.  And the ends at the smokebox end, yes the boiler is upside down.  For comparison here are the original super heaters taken out of the steel boiler, they are typical of the era, being made at the end of the 1960's and are copper tube with return bend blocks. With the new ones I have 50% more tubes, they are 50% longer and they are radiant so if the loco steamed well before then it can only be better now, especially with a copper boiler with bigger firebox and grate area.  Now to sort out the smoke box arrangement for wet and dry headers and steam pipe. Bearing in mind the Clarkson design has slide valves there is only a single steam pipe to connect to, quite different to Don Youngs layout with each super heater feeding a separate cylinder. Chris D |
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kipford
Statesman
Building a Don Young 5" Gauge Aspinall Class 27
Posts: 575 
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Post by kipford on Apr 16, 2020 22:31:13 GMT
Chris
Looks promising, it is sure going to be a real spaghetti inside their. It has spurred me to revisit the superheaters for the Aspinall. I had already changed them from the Concentric type Don designed. But I like the idea of no joints in the fire box plus the added bonus of better flow. I reckon you have reduced the 'k' factor on the bend loss by about 5 compared to a spear end, which has to be the worst shape for pressure loss I have ever seen.
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Post by steamer5 on Apr 17, 2020 0:42:20 GMT
Hi Chris,
Great result!
Now for the fun part, making the headers, going to be fun seeing how you sort that out.
Cheers Kerrin
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Post by Deleted on Apr 17, 2020 8:20:28 GMT
Excellent work Chris, more so for myself, as you have the same size flues....it looks to me that you managed to bend them without heat, am I correct in this? I agree with the comments above, a neat bend will always be better than a join, after all, full size have no joints.
Cheers
Pete
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Post by Roger on Apr 17, 2020 8:51:04 GMT
This is definitely the way to go with the Superheaters if you have room in the tubes, that's a great result with very little heartache.
I used 5/16" x 22 gauge 316L tubing from Steel Express, I couldn't see it anywhere else. Although the tube was fine, the way they shipped it was dreadful, with it overhanging the end of a piece of wood that was miles too short. I've had two lots from them, and neither was undamaged. Fortunately it didn't matter, but it's not ideal.
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Post by Roger on Apr 17, 2020 8:53:26 GMT
Hi Chris, Great result! Now for the fun part, making the headers, going to be fun seeing how you sort that out. Cheers Kerrin Hi Kerrin, It's not quite as bad as it looks. When you come to weld them into the header pipes, you can stretch and move the tubes apart so you can get in there with a small torch. |
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Post by coniston on Apr 17, 2020 9:18:39 GMT
Interesting comments thank you all. to answer a couple of points:
1. Yes Pete they were bent cold, actually no real problem and it certainly paid off making a tool to make sure the tube is properly supported and doesn't deform (much). In fact I think it could be bent with a 3/8" internal radius, maybe an experiment for the future?
2. Kerrin, as Roger say the heads etc. are not too much of a problem as the tube doe spring a lot, just need some simple fixtures to hold them in the right place for joining. I cheated a little with the photos, my hairpins are a little too short, unfortunately all I had were 4' lengths, really they could have been better with 5' before bending. My intention is to extend the smokebox ends with copper pipe, then to join each pair into a 5/16" pipe so I only have three pipes to join into the wet and dry headers. But I haven't schemed that out yet.
3. Looking on the internet there are a number of suppliers, some only show metric and others both imperial and metric. There is a massive price difference so it is worth doing some research. So far I have used material I have to hand so it hasn't cost me anything yet, but depending on how things turn out I may have to buy some more at some stage.
Chris D
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Post by steamer5 on Apr 17, 2020 9:28:52 GMT
Ha ha Roger,
I’ve been there played this game..........AFTER melting the first brass Bush for the regulator header fitting, I figured I better get sorted!
I was silver soldering the stainless tube into the brass.....got carried away with the heat. 2nd time round after some instruction by dad, .......it’s amazing what he had learned after I turned 21..( well so he tells me).....I was successful.
The interesting bit was bending the tube so that it fitted into the bush it took a bit of careful tweaking to get the fit right so there was minimal tension on the them. Like Chris, Nigel Gresley’s superheater layout looked like his. I’ve since seen where guys use brass tube to go from the bush to the stainless tube which looks like a far better option.
Hope some of this make sense!
oh woops cross posts!
Cheers Kerrin
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Post by coniston on Apr 18, 2020 20:02:29 GMT
Just a short update today, yesterday and today I made a start on the 'wet header' it is predominantly to the Don Young design for his 'Doncaster' with the exception that my snifting valve is made as a separate item so not connecting directly into the header. There fore I will have a union silver soldered in to connect a 1/8" pipe from the header to the snifting valve, you can probably see it on the sketch above the part. The main body is machined from a piece of cast gunmetal. I have added a short spigot to the face that joins to the pipe/bush from the regulator, this is to aid alignment when fitting as well as providing a bit of a labyrinth seal so the gasket doesn't see full boiler pressure (That's the theory and it seemed to work in my Manor and it is how the existing one is done on the A3). The three unions will be silver soldered into the body for steam distribution to the super heaters.   More tomorrow hopefully. Chris D |
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Post by springcrocus on Apr 19, 2020 7:51:14 GMT
Hello Chris, going back to your superheater tube design, I know you will already have thought of this but I'm going to try something similar to the sketch below. If the tube bends well, it should be possible to have a single tube rather than doubled-up connections at the headers. The cross-format is what Roger was referring to, I think. This also allows a couple of cruciform supports to be easily incorporated.  Regards, Steve |
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jma1009
Elder Statesman
Posts: 5,917
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Post by jma1009 on Apr 19, 2020 20:17:14 GMT
Hi Steve,
I don't think your scheme will achieve anything apart from simplify the header arrangements, which in any event are not insurmountable.
The radiant end - if indeed that is what you have in mind, will get red hot, and there is no point cooling it down again for a further re-heat.
In any event, Chris D's Clarkson loco has slide valves, and you shouldn't over do radiant superheat on a slide valve loco.
With a decent loco valve gear properly set, and no dustbin cylinders ala Greenly and others, you want enough superheat to gain from expansive working when 'notched up' (the valve gear), without condensate forming, and with the exhaust still being 'fluid'.
Cheers,
Julian
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Post by coniston on Apr 19, 2020 20:24:44 GMT
Hello Chris, going back to your superheater tube design, I know you will already have thought of this but I'm going to try something similar to the sketch below. If the tube bends well, it should be possible to have a single tube rather than doubled-up connections at the headers. The cross-format is what Roger was referring to, I think. This also allows a couple of cruciform supports to be easily incorporated. Regards, Steve Hi Steve, yes I think this would be possible. I did consider it but decided not to go this way in order to keep the pressure drop as low as possible. I would have only one super heater in each flue of 1/4" O/D which I feel is too small for the passage of steam. So I have opted for two super heaters giving about the same cross sectional area as one at 5/16", this keeps the area similar through the steam circuit down to the cylinders. As a matter of interest here is the super heater design that Neville Evans came up with for his Penrhose Grange, two super heaters (one for each cylinder) in 5/16" tube double backed on themselves, this would be a good solution for the A3 but complicated to make. ![]()  Chris D |
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