3” boiler project.

[DJoksch]

I have room to open the hole and will check to make sure the blow off valve can keep up.

 

[Steamchick]

Good! Well done Doug.
I have crunched a few numbers:
Hoop stress – flue tubes:
s = P D /2t
P = 50psi; D = ID tube = 0.4096”; t = thickness = 0.0452”
So:
s = 50 x 0.4096 / 2 x 0.0452 = 453psi.

Permissable compressive stress in copper: Tc = Ts/3.5: stress @ 50psi: 3950/3.5 psi = 1128psi. (3950 is derived from ASME limit for 50psi tensile strength).

Therefore a FOS of 1128/453 = 2.49 exists. = safe.

ASME stipulation (for USA): - My interpretation:
If the Safety valve is set to lift at 50psi, the NWP shall be declared at 50psi. and the Safety valve shall prevent a pressure of 53psi being exceeded at all times (I.E. outlet valve closed and full fire on normal maximum water level). - You may of course run at any pressure below 50psi. “NWP” is a legal name for the value set on the certification.
Also:
I.E. If the NWP is declared at 35psi, then the Safety valve shall be set to prevent a pressure of 37.1psi from being exceeded at all times (I.E. outlet valve closed and full fire on normal maximum water level).

The “quirk” is that a Safety valve of around 50sq. inches heated surface area, with NWP of 50psi shall have (need) a Safety valve clear passage of typically 9/64” ID. Whereas at 25psi NWP the safety valve passage shall be typically 3/16” ID. This suggests that the safety valve shall probably be good at 50psi lift, when connected to the “whistle” connection in place of the whistle (1/8"ID), but NEEDS a test to prove it. It may need to be opened out to the "next drill size" , in stages, if not adequate...

This boiler has about: 43sq.in. Flue tube surface area and 4.5sq.in base-plate heating surface = just less than 50sq.in of heated surface. BUT the effectiveness of the radiant heated surface and flue gas heated surface makes a significant difference between boilers, as does the nature of the fire. e.g. A meths burner will produce very low power of radiant heat and a radiant gas burner of the same power will produce much more radiant heat, and less Exhaust gas heat for the flue tubes. But the only proof is a test – where the Safety valve is set to some value, and a gauge is used to check the pressure in the boiler at “full-blow”.

I therefore recommend that a test be conducted to prove the safety valve – or otherwise – when situated at that connection.

I should appreciate any further comment from any certified boiler testers who are reading this? - I would feel bad about giving any wrong advice if I am in error. I have learned a lot from "leaping before looking" - then being advised by the "more observant" after they fell off the wall laughing!
Cheers Doug,
K2

 

[DJoksch]

Thanks so much for all the help. This was my first steam project and the thought of a 50lbs steam vessel in front of my face was a bit unnerving. It helps to have someone review point out potential trouble spots and plain screw ups. I will take care of the pop off valve as you suggested and test at full steam. I’ll post the completed project.

 

[Steamchick]

Just glad to study the boiler. I enjoyed design work back between 1978 and 1990. Got a real kick from being able to say "This will work", or "this is right" after doing calculations, and being confident when giving work to the test guys that things would not fail. But boiler calcs are not within that experience so I am enjoying learning about those now. I am grateful to all who share their boilers with me so "I can have a play". Especially when I see both excellent workmanship displayed like yours, added to the imagination that you have applied to use your different skills to resolving various issues that crop-up along the way.
I think the trumpet bell chimney is great! Your interpretation of my guide to making a ceramic burner, and the result, make me feel that I am able to help.
I am simply doing this because it is fun!
And that is what makes retirement worthwhile.
Thank you Doug.
K2

 

[Richard Hed]

Just glad to study the boiler. I enjoyed design work back between 1978 and 1990. Got a real kick from being able to say "This will work", or "this is right" after doing calculations, and being confident when giving work to the test guys that things would not fail. But boiler calcs are not within that experience so I am enjoying learning about those now. I am grateful to all who share their boilers with me so "I can have a play". Especially when I see both excellent workmanship displayed like yours, added to the imagination that you have applied to use your different skills to resolving various issues that crop-up along the way.
I think the trumpet bell chimney is great! Your interpretation of my guide to making a ceramic burner, and the result, make me feel that I am able to help.
I am simply doing this because it is fun!
And that is what makes retirement worthwhile.
Thank you Doug.
K2

In that case, when I needs a calculation you will have to pay me as hereabouts, anything that is "fun" has to be taxed, paid parking fee, fee for this or that. I charge a mere 50$ for "funning".

 

[Steamchick]

Hi Richard, Always glad to hear your comments. For me, "Fun" is what does the happy chemical thing in my brain... and the tax-man has not yet found a way of charging for that!
I know that Elliot Ness used the Tax-man to stop Al Capone's fun... but so far the modern day Elliot Ness is not (Yet!) on my tail!
When I do stuff for "free" - I do not charge, nor pay, so it becomes a zero-value transaction. The Tax on zero is always zero...
On everything else, I guess there is always some tax, and some spare besides, in case he missed something!
Stay safe and happy!
K2

 

[Richard Hed]

Hi Richard, Always glad to hear your comments. For me, "Fun" is what does the happy chemical thing in my brain... and the tax-man has not yet found a way of charging for that!
I know that Elliot Ness used the Tax-man to stop Al Capone's fun... but so far the modern day Elliot Ness is not (Yet!) on my tail!
When I do stuff for "free" - I do not charge, nor pay, so it becomes a zero-value transaction. The Tax on zero is always zero...
On everything else, I guess there is always some tax, and some spare besides, in case he missed something!
Stay safe and happy!
K2

Yes, yes, that is all true, but just for having some "fun", nowadays, you must pay. For most people this talk we have would be "fun", but if it was fun for me, I might get charged (like a tax on breathing which someday someone will figure out how to do that), I might have to pay for it, so instead, this is "work", so I can't mbe charged for it. But for you, it is fun, so I will have to charge you. PLease send your 50$ to . . . .

 

[Steamchick]

Your cheque is in the post. Be careful not to drop it, it will bounce!
Incidentally, as you are being paid for "work" I must inform the IRS... just so they understand why I am sending them their share, as you will of course!
K2

 

[Steamchick]

Oh. I just realised. As for me it is "Fun" - and has no value to another, it carries no "value added tax" - so I won't have to pay the tax-man anything! - You do it all.
K2

 

[Richard Hed]

Oh. I just realised. As for me it is "Fun" - and has no value to another, it carries no "value added tax" - so I won't have to pay the tax-man anything! - You do it all.
K2

I might laugh, but that might be proof of "funning" so I won't. But it is very late here on the Left Coast of USA, are you up early or are you looking at the stars?

 

[Steamchick]

I am in the UK - where all time starts and ends. I can't help it if you are running 9 hours late or 15 hours early, or however it works...
The only star visible now is called the Sun.
Good-night Richard. Sleep soundly.
K2

 

[DJoksch]

Just gotta ask. These things are copper brazed with silver. I have some stainless steel and a tip from a cappuccino coffee maker wand. I would think such a boiler would be safe for food.

 

[Steamchick]

Probably, but I am not a chemist. The house is full of copper pipes, so that's OK. As long as the silver solder alloy does not contain Cadmium, or other toxic metal, I guess it is OK? But it is too hot for coffee. The aromatic oils will boil-off if too hot. But you should be using de-mineralised water in the boiler to avoid contaminating the inside. That tastes horrible compared to normal "mineralised" water. And I wouldn't use the steam as it is at much higher temperature and pressure than the coffee maker! (IT WILL COOK YOUR FLESH INSTANTLY).
It's just not an appropriate use of your boiler. Use a kettle - designed for that job!
K2

 

[Richard Hed]

Just gotta ask. These things are copper brazed with silver. I have some stainless steel and a tip from a cappuccino coffee maker wand. I would think such a boiler would be safe for food.

Like aluminum, you wouldn't want to cook with ANY aluminum, but some aluminums are worse than others. Those cast aluminum pots that one finds in the 3rd world are the worst kind of aluminum. So with copper, proper copper is no where near as dangerous as alu but silver, if used for long periods, can give you heavy metal poisoning. and as Steam Ken says abouve, if the silver is mixt with other metals . . . ? Personally, I would not do it. Why not try stainless? You can tig stainless.

 

[DJoksch]

I was basically making fun. I posted a Facebook photo and I was asked if it was a cappuccino machine so of course I could not resist saying yes. My next project will be the horizontal version of the Clarkson vertical I posted and a 3” horizontal boiler. I’m deciding if I should go with a fire tube or water tube design.

 

[Richard Hed]

I was basically making fun. I posted a Facebook photo and I was asked if it was a cappuccino machine so of course I could not resist saying yes. My next project will be the horizontal version of the Clarkson vertical I posted and a 3” horizontal boiler. I’m deciding if I should go with a fire tube or water tube design.

Naughty.

 

[Richard Hed]

I have 4 years to go.

You are retiring at 40? Your photo looks 35.

 

[DJoksch]

I’m a software and electrical engineer. We live in cubicles protected from the elements. Coupled with the fact that my hair does not turn gray, but rather falls out in shame makes 60 look pretty good. Oh yes,... my pop made mom a frying pan from melted down automotive pistons. Nothing like breakfast with a little beryllium and food preservatives to keep a youthful appearance.

 

[Richard Hed]

I’m a software and electrical engineer. We live in cubicles protected from the elements. Coupled with the fact that my hair does not turn gray, but rather falls out in shame makes 60 look pretty good. Oh yes,... my pop made mom a frying pan from melted down automotive pistons. Nothing like breakfast with a little beryllium and food preservatives to keep a youthful appearance.

OMG, I won't use alu for cooking even without the beryllium. I can taste it. 60 or 16? You should show us a close up without the hat. Jeez, I'm trying to work in a joke about your doglette, but It just escapes me. I had one last year about that size but my son and I took her on a walk about 11:00 at nite, someone, somehow snatched her as we didn't have her on a leash. There was NO-ONE to be seen anywhere. We don't know how they did it.

 

[Steamchick]

Hi Doug,
I have been doing some slightly disturbing calculations on copper tube in compression. E.g. The same as a flue tube. The answer is "not domestic water pipe - use thick thick thick-walled".
Or use water tubes. The Stuart boiler is very effective and simple, if it is simply a " low-maintenance steam supplier " that is needed, but I'm sure you would make it a "work of art" because you can!
My boilers are purely functional - hence shy of being photographed!
But if you want a "more visible" boiler, a marine boiler is less hidden by the fire-box.
Personally, I avoid the complexity of the firebox of locomotive-style boilers. I don't need to do all that work for stationary boilers.
But a very efficient/powerful "stationary or marine" boilers is the 3 tube with multi-water-tube Yarrow type of boiler. I have a book with about 50 designs in it... the best I have read - by K.N. Harris. But there is another highly recommended that I have not bought yet... by Alex Wise.
Worth getting one or both to help you make the decision,
Regards,
K2