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How should we hang the superheater?
Posted by: Mike Clark (---.glfd.adsl.virginmedia.com)
Date: October 14, 2009 02:25PM

Just taken the burner off for the boiler inspector and see that the superheater has once again wriggled free from the two brackets which hold it. These are fixed to two long studs hanging through boiler tubes and form a three point mounting with the exit point at the back of the burner.

Is there a consensus about how the superheater should be mounted? I think it needs to be a bit freer to allow for expansion, after all it is a bit like a giant bourdon tube. I was thinking of just providing a sort of shelf to support it at the front and fixing it only at the back where it goes through a clamp outside of the burner casing.

What do you think?

Mike

Re: How should we hang the superheater?
Posted by: johnhennessy (---.plus.com)
Date: October 15, 2009 06:02AM

Mike
The superheater on my little Locomobile is only attached outside the burner to its own pipework; although it is only one turn. I would aggree with you that a good deal of freedon is required. But take a look at the superheater on Terry Fry's EX It was once circular!!
Kind regards
John H

Attachments: Terry Fry\'s superheater.jpg (119kB)  
Re: How should we hang the superheater?
Posted by: Rolly (---.hsd1.ma.comcast.net)
Date: October 15, 2009 09:25AM

Mike you did not say how your superheater was attached to the rod hanging through the tube. J- hook I bolt or what.
My 1920 Stanley super heater was hung from brackets outside the burner box from brackets attached to the boiler support frame.
I take it your super heater enters and leaves the burner box from the same side so you need to support the other end. Any exterior hanger outside the burner would require another notch in the jacket.
On my EX Iím going to make a separate ring to go up against the boiler to support the super heater and primarily make a seal so the burner pan will not have any notches in it when removed and reinstalled. I also had done this on my 1920 Stanley boiler.
Rolly

Attachments: Burner box.jpg (20kB)   super heater.jpg (42kB)  
Re: How should we hang the superheater?
Posted by: les nelson (---.dynamic.dsl.as9105.com)
Date: October 15, 2009 11:08AM

Hi All I have had to replace my superheater once in 12 years due to the fact it came out as a Pretzel and eventually was easier to make a new one than try and reform the original, there is no support (on mine) except the end fixings and where it rests on the vaporiser and heat sink (pilot), the original shape was two circular loops, the poor old super heater has to survive red heat (starting up and coasting when the burner is operating) then gets a shot of steam up one end creating the thermal shock causing the distortion we are now familiar with, I have seen s.heaters having the tubes welded together and supported but the stress from thermal shock had destroyed the welds and the fixings so I am firmly convinced that NO suport is best, thereby allowing the tube to find its own configuration as needed, at least this will not influence/damage any other part of the burner assembly.

Re: How should we hang the superheater?
Posted by: Mike Clark (---.glfd.adsl.virginmedia.com)
Date: October 15, 2009 05:49PM

Happy afternoon spent straightening (or maybe bending!) the superheater. Like the one you show John it had gone all out of shape.

Queer how the out of shape pipe went from a steady curve to two much sharper bends with absolutely straight bits in between. It's schedule 40 3/8 stainless steel pipe so is quite hard to manipulate - but as usual there is a trick which avoids heat. This is to make a former by bolting a large disc (in this case a10" face plate) onto the bench with a couple of strategically placed pillars to bend against - then with a good heave you can tweak the pipe to where you want it, either reducing or increasing the curve as needed until it is back to shape. I learnt this when making a steam loop for my car which had to be about 12" diameter to lie horizontally under the pump pit.

Considering how hard it is to bend the pipe cold it must get pretty damned hot in service to change its shape so much - near enough white hot I would think. Just shows that the saturated steam, as soon as it gets into the vaporiser must be kept off the walls of the pipe so it doesn't really cool the pipe much. Or like Les said it cooks when the burnerís on but the throttle shut.

Anyway now I have to decide how to support the front end as I put it back together. I had a pair of simple ďwĒ shaped double clamps holding it from the stud but I think this was too constraining. I heard somewhere that Stanley used a couple of wire loops hanging through two boiler tubes to give support but not constrain the pipe - has anyone done this? Otherwise I may just put a couple of L shaped brackets from the inner wall of the burner to support the superheater so it can float about but not drop.

Mike

Attachments: Bent superheater.jpg (110kB)   straightened superheater.jpg (106kB)   superheater in situ.jpg (114kB)   bender.jpg (107kB)  
Re: How should we hang the superheater?
Posted by: Rolly (---.hsd1.ma.comcast.net)
Date: October 16, 2009 08:13AM

Seamless pipe as well as welded pipe have a lot of internal stress already introduces into them. When you bend and roll it into another shape your putting more stress into it.
Then when you start to introduce heat, the pipe will start to change shape till all the stress is released and it becomes totally annealed.
If you roll the pipe into shape and strap some heavy angle iron to it with a lot of U-bolts and send it out to be annealed. It will tend to stay that way through future heating and cooling cycles.
When you rebend it cold your just introducing more stress back into it.
Rolly

Re: How should we hang the superheater?
Posted by: (---.wavecable.com)
Date: October 16, 2009 11:33AM

Mike, I have tried it, and I have seen others "hanging the super heater from wires threaded through the fire tubes". Apparently no one has found a wire that will stand up to the burner's heat as the wires quickly melt away leaving just the wire ends sticking out from the bottom ends of the fire tubes, and the super heater laying on the burner plate. I have since made props that look like chess men that bolt around the super heater and holds it up off of the burner plate. The props have about a 3/4" diameter foot that rests on the burner plate. The props move with the super heater as it grows and moves about with the burner heat. Another method I have seen are "J" hooks that are mounted from the burner side wall. They reach out and support the superheater from sagging onto the burner plate. That has been successful too. SSsssteamer

Re: How should we hang the superheater?
Posted by: (---.armstrong.com)
Date: October 16, 2009 06:06PM

David,

Could you tell me a bit about your firing-up technique? The good folks I've learned from have always said to leave the throttle & drip valve cracked during the long initial pressure-raising burn, so that there is something passing through the superheater & cooling it a little.

Yet I recently spoke with one of the highest-mileage Stanley drivers I know of, and he said he never does this, and has replaced exactly 2 superheaters in 30-odd years, both of which failed at a place that turned out to be a weakness in the fabrication. (His firing-up process is therefore faster and a good deal quieter than mine.)

Now I'm curious about peoples' experience with firing-up-bleed vs. superheater life. (Vs. metallurgy, too, perhaps.)

Kelly

Re: How should we hang the superheater?
Posted by: (---.wavecable.com)
Date: October 17, 2009 12:19AM

Dear Kelly, I didn't see a David in the previous posts. I only have been operating our Stanleys for 25 years but I have over 30,000 miles of experience behind the wheel. As per firing up, the throttle should be cracked open and the steam chest should also be openned slightly when first firing up from cold. The openned throttle permits boiler water to cool the super heater and the openned steam chest vents the steam line for the boiler water to escape the steam chest. On non condensers, the boiler blow downs should be used to bring the boiler water level down to a servicable level. On condensing cars, you would use the surface blow down valve to lower your water to the correct level. The eventual steam arriving in the steam chest helps preheat the engine. Once steam is about up to pressure, the throttle is then closed and the driver is seated in preparation to steaming off. The throttle is openned ever so carefully in anticipation of slugs of water possibly doing damage to the engine as you first start rolling. Some people first start out by rolling both forward and then backward. I have always started out by just carefully rolling forward, which clears out the water just as easily. As soon as the Stanley is under way and without having anymore threats of water in the engine, the steam chest valve is then closed. Do not leave the steam chest open any longer than necessary to get rid of the excess water. Leaving it open unnecessarily too long will be steam cleaning your steam cylinder oil out of the steam chest and putting the oil onto the ground. Pat Farrell

Re: How should we hang the superheater?
Posted by: Mike Clark (---.glfd.adsl.virginmedia.com)
Date: October 17, 2009 06:01PM

Pat,

I like your superheater support idea because it ties the support to the pipe so the only chafing is at the bottom on the burner plate so that is what I am going to do.

As to firing up - yes that is just what I do. I generally turn off the burner at about 400 psi and move off at that pressure, letting it get up to 600psi once we are moving, hopefully thereby reducing the cooking of the superheater while only small amounts of steam are going through. I also suspect that when the throttle is opened the extra bubbling due to the drop in pressure improves the circulation over the bottom tube plate so the full force of the burner is less likely to do harm. I think full burner while the throttle is closed and the car standing is the most stressful time for the firetube bottom ends, apart from a dry boiler!!

One useful idea I have found is to open the boiler blowdowns over a bucket as soon as the main burner is turned on and leave them open until steam starts to come out. That way I clear out about a gallon and a half of water to make steam space and the water in the bottom of the boiler to which the blowdowns are connected is being thoroughly stirred up by the boiling action. A lot of crud comes out that way, possibly more than by just blowing down normally at the end of the day. I also do a small blowdown when putting the car away.

Mike

Mike

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