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Author Topic: Funnel/Smokestack Questions  (Read 1026 times)

Landlocked

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Funnel/Smokestack Questions
« on: December 31, 2016, 10:12:11 PM »

All,


My steam boat's funnel pierces a deck and a hard awning.  To make reassembly easier post-light off, I'm planning on having the upper deck and awning lift off as a single piece.  There's a heat shield around the funnel between the deck and the awning.  I'm thinking that leaving a gap between the upper and lower stackpipes and relying on the heat shield to be an outer stack should still give me a good draft and make positioning the deck in place much easier.  There's a couple of inches of penetration by the lower stack pipe into the heat shield area.


Is this a good plan?


Second question for which I think I know the answer -- the heat shield has some grills at the top to help dissipate heat.  I'm guessing that adding these cutouts will likely mess with my draft.


Thoughts?


Ken/Landlocked





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Landlocked

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Re: Funnel/Smokestack Questions
« Reply #1 on: January 05, 2017, 03:05:12 AM »

I've gotten a bit lucky.  By chance, I made my lower upper stack long that it penetrates down into the heat shield far enough to overlap slightly with the copper pipe supplied with the boiler.   I had leveled the boiler against the drag of the keel  so the 90 degreeboiler pipe doesn't cant back to be concentric with the upper stack's lean.


Now I'm mulling over making a new lower upper stack that's about an inch longer and/or getting out the big torch and trying to bend the cooper piece about 6 degrees to give it something closer to the right lean.  I have the exhaust pipe plumbed in the stack so I would have to make sure in bent only in the correct plane.


With the stacks overlapping the heat shield becomes more of a shield again and not part of the stack.


I'm also mulling over the idea of dropping the upper stack assembly onto the awing as a separate reassembly step.  Using elastic for the stack support stays would make that step quicker/easier. 


Also, apologies, i didn't include a pic of the prototype earlier (it's the Sabino -- see my other threads).


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derekwarner_decoy

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Re: Funnel/Smokestack Questions
« Reply #2 on: January 05, 2017, 06:00:49 AM »

Hullo Ken.......

I think I understand your quandary....having said this, I don't think the red spanner + bending will be the ideal way to attain that 6 degree tilt...the result would be a crumpled dogs breakfast

1. If you are comfortable with silver soldering, cutting out that annular elliptical wedge and the following mating together & silver soldering may offer a solution

2. You could also consider 3 support strips say 6 wide x 20 long x 1 thick brass strip......drilled with M2 clearance holes at top & bottom....bent to suit the 6 degree tilt.....& having M2 holes drilled & tapped into the copper chimney stack around the joint........these would give you all of the necessary support during the soldering process....they could also be soldered in & wouldn't look out of place

3. Another option could be one of those 135 degree Yorkshire copper tube bends .....cut & shut to achieve the 6 degree tilt

:o Another thought from left of centre

4. This may only be suitable for a vertical [gas] boiler ........place a 6 degree angular cupped round wedge the diameter of the boiler under the boiler base to achieve the 6 degree tilt.... [I cannot see any downside  <*< around the boiler function apart from ensuring the water gauge was on the high side]

Good luck.......... Derek

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Derek Warner

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Illawarra Live Steamers Co-op
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Landlocked

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Re: Funnel/Smokestack Questions
« Reply #3 on: January 06, 2017, 12:08:17 AM »

Derek,


Thanks for your thoughts.  I have a 135 joint that I've been thinking of trying to mostly straighten.  I was thinking heating and stretching the inside of the bend since strength is not critical. If I botch it with heat, I can still cut the wedge and solder.


Tonight's/tomorrow's project is to extend the lower upper stack  (by making a new one).  After I make the skirt for holding the upper section in place, I'll decide if I need to lean back the lower stack or not.


BT BT


Anybody have a sense of what stack temperatures might be?  With the venturi tube effect I'm trying to create?  I have some ceramic wool to line the inside of the lower upper stack but I made my seams with J&B Weld, max temp 500 degree F.  For some reason I thought J&B was good to 900 degree F and now I'm thinking I need to regroup and try to solder the seams w/o blowing through the aluminum flashing. Is soft solder good enough or do I need to go to silver solder for the upper portions as well?


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derekwarner_decoy

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Re: Funnel/Smokestack Questions
« Reply #4 on: January 06, 2017, 02:44:55 AM »

Ken......that 135 number is a popular %)

1. my steam discharge valve on the boiler top reaches ~~135 degrees C [@ 3 Bar relief valve setting]
2. the boiler top plate & chimney flange is ~~ the same
3. the unpainted section of the copper chimney [70 mm from the boiler top] is ~~100 degrees C
4. the chimney top [170 mm from the boiler top] is ~~ 75 degrees C

From this, a soft soldered connection around the boiler top chimney flange would not be recommended >>:-(

These temperatures are reasonably accurate as checked with a $20 digital pyrometer. The chimney is copper....so holds the heat, but is totally open to the atmosphere so dissipates heat as well....remember in OZ, we can have 45 degrees C ambient....all things being equal.....you could knock ~~15 degrees C off the latter two temperature bands with an ambient of ~~ 20 degrees C

Ceramic cloth adhered with JB Weld is fine as the JB W is good for a constant operational 260 degrees C ....

Derek
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Derek Warner

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Illawarra Live Steamers Co-op
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www.ils.org.au

Landlocked

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Re: Funnel/Smokestack Questions
« Reply #5 on: January 06, 2017, 02:58:46 AM »

Derek,
I went downstairs to play tonight and learned some stuff.
Soldering aluminum takes a whole different set of fluxes/solders than than my brass/copper piping world had needed.  Nothing would stick!  After Googling, I understand why.
Seems like the flashing, even though very thin, was pretty resistant to me melting it.  Warping is a whole other storyze]
Need a hardware store run to get some AL specific stuff to continue playing but I think I'm going to go with J&B and keep my fingers crossed.  I may have to rebuild my heat shield because I used 5min epoxy and then shifted to J&B when one end sprang open.
Thanks for the temperature numbers (and you can keep the 45 degree stuff down there -- 30 is hot enough!)
Ken
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derekwarner_decoy

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Re: Funnel/Smokestack Questions
« Reply #6 on: January 06, 2017, 03:16:22 AM »

Sorry Ken.......on a day listed as 30 degrees C here, this is an in the shade temperature.....place the boiler chimney out in the sun & the upper outer shell or chimney would rise to ~~45 degrees C [physical ambient temperature] well before lighting :-X.......Derek
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Derek Warner

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Illawarra Live Steamers Co-op
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www.ils.org.au

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Re: Funnel/Smokestack Questions
« Reply #7 on: January 06, 2017, 03:25:10 PM »

Ken,
It's very difficult, to cut 6deg out of a pipe and S/Solder it.
You would need to scribe a circle around the pipe and cut 3deg either side with a very fine slitting saw otherwise you have 1-circumference larger than the other and S/Solder is not a good gap filler.


Why not pack the pipe with dried sand, if you don't have any put enough builders sand in a flat tray and stick it in the oven at a high temp( advisable when the wife is out ) and keep moving the sand until dry.
Plug one end of the pipe and  fill with the sand, plug the other end when full.
Have a piece of wood, I used an old floor board 7/8" ' thk with a hole bored in it to take the pipe, chamfer the top of the hole in the direction you want to bend to get rid of the sharp edge, place another piece tube of a slightly different bore over the pipe down to the timber and pull over, you will manage 6deg with ease.
You may have to anneal the pipe at the bend point.


If you don't fancy this method try your local Plumber or H&V engineer who will have the bending frame to bend to 6deg.


George. 
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Landlocked

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Re: Funnel/Smokestack Questions
« Reply #8 on: January 06, 2017, 11:49:23 PM »

George,


I had heard of the dry sand technique to avoid kinking in old car forums for exhaust systems.   


I've experienced the balanced corner wedge requirement playing with some PVC tubing I was trying to make something non-strength bearing out of.  A 40ish degree + a 50ish degree miter do not create cross sections that can be chemically soldered/glued into 90 degree corner.


Right now, by extending my lower upper stack a couple of inches, I think I'm going to be able to get sufficient overlap to get a good draft without overheating anything.


Time (probably in the Spring) will tell.  By the way Derek, it's 0 degrees here in the shade today.


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Re: Funnel/Smokestack Questions
« Reply #9 on: January 07, 2017, 12:09:55 AM »

Correction,


Derek, it's minus 17 degrees C here.


Ken
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Landlocked

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Re: Funnel/Smokestack Questions
« Reply #10 on: January 08, 2017, 03:49:40 AM »

All,


I've decided to go with J&B epoxy and ceramic wool and crossing my fingers.  I built a new lower upper stack that gives me about 2 inches of overlap with the copper pipe coming off the boiler.  The heat shield will be just a heat shield. 


Still to be determined if the stack assembly will be fixed to the deck section or will need to be emplaced last.


Pic below shows the dry fit.


Thanks for the input.  I'm declaring this thread closed and resuming documenting progress in my other SABINO threads.


Landlocked/Ken
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