Home mad boliers

[Deck Dog]

Recently on Youtube I saw several videos where people made boilers out of old propane tanks, the small kind. Now I know only a little about model boilers but doesn't this sound a bit dangerous? ???Wouldn't a propane tank boiler cause more shrapnell if it exploded than a copper boiler? Everone of these "Home Boiler Makers said "you know it is safe as it can hold the pressure" Still sounds extremely dodgy to me.

 

[bearcar1]

You are wise beyond your years DD. Of course it is dangerous. But because it is being shown on You Tube and the knuckleheads were successful that time around, people think it is safe to do and copy. I get so agitated when I think of the unsuspecting innocent people that sustain physical harm due to these videos it makes me want to do bodily harm to the individuals that post such crap. Unfortunately, there are those that walk among us that are not very bright and will most likely never be harmed by their own stupidity, you know the ones "but judge, I didn't know the gun had bullets in it". There are strict pressure vessel guidelines that need to followed and of course annual inspection and certification of these same vessels, saves lives, not some jerry rig contraption built from what was found in the garage.

BC1
Jim

 

[Springbok]

Jim
I could have not said it better myself have a look at the first post in this forum it says this.(more politely) I sometimes look at the pillocks posts on utube and cannot believe they are serious. Just think if you had some children/grandchildren nearby when it went BOOM. would you ever forgive yourself.... No if you want to build a boiler in no matter what scale get a decent book, do research obtain all the correct materials.
Here in the UK we have very stringent codes of practice thankfully.

Bob

 

[steamer]

Whether a propane tank makes more schrapnel or not is not really the question.

The question is, does a propane tank make a dangerous boiler?.....unfortunately , None of us can probably answer that but I'm sure we all have an opinion!

However, I can garrantee the following, the individual who made the boiler from the propane tank can't prove to anyone that it is a SAFE boiler!

The reason for the rules is to provide guidance and control over the design , materials of construction, and methods of construction so that once complete, there is OBJECTIVE evidence based on Engineering principles that the resulting pressure vessel was safe for its intended use.


Dave

 

[Mainer]

Does anyone know what the design pressure of a propane tank is? I would, at an absolute minimum, want to do a hydraulic pressure test to 2X the anticipated working pressure before even considering something like that. But it's basically a bad idea.

 

[Dan Rowe]

A propane tank for a boiler is a BAD idea.

Even if it can pass a hydro test it is a BAD idea.

Here are two reasons I thought of why it is a BAD idea.

1) Steel for boiler use is designed for many cooling and heating cycles a propane tank is not designed to work over ambient temperature. (Think hot summer day.)

2) A boiler is designed with corrosion allowance. I do not think propane tanks are designed with much corrosion allowance. There are lots of cases where air tanks let go because the water is allowed to accumulate in the bottom and KABOOM there goes the corner wall of the shop. (I have an automatic drain on my air tank.)

There might be even more reasons that building a boiler from a propane tank is a BAD idea.

Did I forget to mention that building a boiler from a propane tank is a BAD idea.

Dan

 

[steamer]

I agree Dan! :big:

Just trying to point out that the code isn't to spoil your fun...its written that way for a reason....Darwin Award Cadidates included!

Dave

 

[ChooChooMike]

I think the thread title says it all Home MAD boilers

 

[Robsmith]

Send in a request to Mythbusters...they love to blow stuff up !

 

[abby]

Some very vociferous comments but have you really considered the matter or are these knee-jerk reactions ?
The first question should be at what pressure would the boiler be required to operate.
Real boilers and large model boilers too are commonly made from steel and I can see no valid reason why a steel pressure vessel should not be used.
I have scrapped many steel boilers in my demolition days and contrary to popular belief they were not rusty or corroded inside , neither were the steel pipes which carried the steam.
Boiled water and steam contain very little air and almost no oxygen.
Any competent engineer should have no problem making a safe boiler from such a starting point.
Any boiler should be hydraulically tested to twice its working pressure and safety valved to suit so what are the objections ?

 

[Mcgyver]

we're talking the small hand held tanks commonly used for plumbing?

whats a bad idea is making a boiler without knowing how to design it or failing that not using a published design. There is nothing inherently wrong with using one of those, although there'd be a lot you'd need to do in execution of the project to be onside with safety. First I'd cut one in half (after removing the valve and filling with water) to measure the thickness of steel. Then you can calculate safe working pressure.

One of the TSME guys once took one these to explosion with steam. Over 2000 psi irrc....but we don't know if the same gauge steel is being used so I'd want to measure.

all the normal boiler rules apply, safety value, safety facto (8x), etc. I have my doubts the utube crowd has much of clue in that regard, so it may be what they are doing is very dangerous...but its not because its a propane tank.

From a legal standpoint though, it sounds on shaky ground, I can't see clubs wanting those fired at their get togethers. iirc steel boilers need to be welded by a pressure vessel certified welder. While the original tank might ok, you're going to have weld in bushings etc.

Note, a boiler is magnitudes more dangerous than an air compressor tank. They are little sticks of dynamite not be trifled with. but the important part about safety is understand the what and why.

 

[rkepler]

Some very vociferous comments but have you really considered the matter or are these knee-jerk reactions ?

I think part of each, really. Most small propane tanks don't seem that they would have the thickness of material for a rated boiler, but then most are below minimum heating surface and water content for ratings. But my gut feel is that the boiler material might be too thin.

The first question should be at what pressure would the boiler be required to operate

Something like this would be expected to stay below 30-40 psi, I would think. In the live steam hobby the larger boilers generally operate at 100-125psi but we build them with 3/16 and 1/4" walls (at least in the 1/8 scale I operate in).

Real boilers and large model boilers too are commonly made from steel and I can see no valid reason why a steel pressure vessel should not be used.

I don't have a problem with steel, just with the steel being used in a boiler vs. a propane tank. Heat does odd things to steel and welds, and it's possible that something happy with a couple hundred psi at 100degF would be unhappy with 50psi at (280degF?)

I have scrapped many steel boilers in my demolition days and contrary to popular belief they were not rusty or corroded inside , neither were the steel pipes which carried the steam.
Boiled water and steam contain very little air and almost no oxygen.

I've seen hobby boilers that needed tube sheet replacement from corrosion. There's a big difference between commercial boilers with treated water and maintenance and someone filling a propane bottle with air-entrained tap water and boiling it dry only to refill.

Any boiler should be hydraulically tested to twice its working pressure and safety valved to suit so what are the objections ?

Most of my objections are just gut feel, maybe contaminated by some of what I see on youtube. Here's one of the first results searching youtube for "propane bottle boiler":

https://www.youtube.com/watch?v=yoUfwBfJhPA

Heating over a grill, no (visible) safeties, plastic tubing from the boiler, I can't be sure but it looks like soft solder connecting the tanks (unless it's silicone or something goopy). At least he's got a pressure gage but it's inside the grill.

Here's one done a lot more "right", but still hardware store components:

https://www.youtube.com/watch?v=WQ_mBwyTaiM&feature=related

I think you could make a proper boiler from a propane bottle but the ones I see on youtube don't seem to be able to do so. If I were to make a boiler that size I think I would start with spec materials - the effort is about the same by the time you get everything you need hung on it.

 

[abby]

All of the comments are valid but actually more related to the idiocy of some people who like to post videos to youtube , and of course those people have nothing to do with our type model making.
When I read propane bottle I was thinking of the 47kg bottles that I buy for my foundry not the little cans.
What I was really trying to say is that we are often restricted by club rules etc , which although existing for sensible reasons , can deter progress in design and construction , which is what engineering is all about.
Most club boiler codes insist on over-engineering , with heavy gauge copper and silver solder , only recently have TIG welded copper boilers become acceptable and even then with strict rules.
Ultimately you can build what the heck you like as long as you don't use it in a public place or try to sell it .
Perhaps some clever member can invent the total surround air-bag that contains the steam in the event of a boiler burst
Dan.

 

[ronkh]

http://www.google.co.uk/url?sa=t&rc...gWz6TyStvFcfSUNWg&sig2=WVPQiL0rV19n6z-4MMIe8Q

Just one of many fools!

 

[Allen]

Some random thoughts. The ASME code IS NOT the only "safe" way to construct a boiler. It IS a hodgepodge of actual physics and materials testing, blended liberally with kneejerk reactions and sometimes conflictory rulings made by a private, for profit, trade association given the weight of law.... in a way that vastly further enriches said private, for profit, trade association.

THAT said, yes there are sound engineering principles that DO need to be followed. Just like you can't simply toss an old pressure canner in the fire and call it a "boiler", you can't build a safe one from odd bits of materials which you don't know the properties of, either.

Safety SHOULD be first, last and foremost. SOME builders seem all to willing to cut dangerous corners

But, on the other side of the coin, some ruling bodies seem to put CYA over the actual product. ie You can do EVERYTHING by the (ASME code) book(s) and STILL have a problem getting it accepted without spending just as much on a lawyer as you did on the boiler... especially in the Communewealth of Pennsyltucky.

 

[Ryker Carruthers]

I have seen boilers for model traction engines that WERE code welded etc. I also have a friend that made a non code boiler for their model and honestly I trust that boiler very much more than the code one. It does scare me to see some of the weld beads on code boilers because many I know I could do a better job. Tuesday thru monday next week I will be at a show with a code and non code boiler. I will post pictures on here of some of the weld beads and tube sheets and what not.
Ryker Carruthers

 

[gus]

My two cents worth from my 32 years of air receiver manaufacturing and ASME Code design.

A weld that looks very good outside does not mean you have a welded joint that will pass radiography, tensile test,Izod & Harpy test,root bends---root bend & face bend.

Test two specimens.
Specimen A.Looks good by visual inspection,height and width of weld meets specs.
Radiography showed cracks and porosity inside weld.
Specimen B Looks not to good by visual inspection.Weld heigh,width meet specs and no
undercuts.

My weld inspector advised Specimen B would fail Radiography.

He was wrong. It was a sound weld as shown by Radiograhy shots.He had to prove me wrong by doing all the destructive test.Weld stood up.

As long as welder certification is valid. We can trust welder. By all means do a NDT to audit his welding. I keep my welders on their toes.I would go into the shop and take out 10% of WIP
jobs for Spot radiography. No weld defects!!!

 

[Allen]

So, Gus, what do you do with state inspectors who says multiple (passed) destructive tests on sample joints, magnaflux on the actual joints, the required code material paper trail and calculations for a Section I part PMB construction, AND a weldor who had ASME certification, and did the welds under the watchful eye of not one, but TWO ASME code welding instructors means.... bupkis?
The responses were rather telling,
"How do I know you did the calculations correctly?" (without even looking at them, Apparently there is a $100/hr fee to have someone at the dept of Labor and Industry even consider revueing them... with a 3 hour average)
"The sheets aren't stamped with the paperwork numbers." (except stamping is NOT required for part PMB construction, there IS however a photographic trail, and I could produce those weld instructors as witnesses willing to swear the material in the paperwork was the material used, if needed)

and the most telling... "I'm sure it's safe, I'm just not going to be the first guy to sign off on it"

All this to NOT get a 100psi ticket on a boiler that the calcs say is good for 400psi......