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Converting Propane forge to Natural Gas


Dave Stephens
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My Chileforge is awesome, but goes through propane like a college freshman goes through beer.

 

Anyone converted their propane forge to natural gas?

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"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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If it is a venturi, then you need to go up in orifice size, but I don't know how much. The other problem, if I remember correctly, is line pressure. NG comes into your house at something like 5psi, and you need 15-20 to run a venturi, so you need a way to bump the line pressure.

 

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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The other problem is that going to natural gas means a decrease in available BTUs, hence the bigger orifice.

 

Are you getting advertised temperatures, or satisfactory working temperatures for what you want to do? How much propane are you going through in a day (8 hours)?

There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves. Will Rogers

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If it is a venturi, then you need to go up in orifice size, but I don't know how much. The other problem, if I remember correctly, is line pressure. NG comes into your house at something like 5psi, and you need 15-20 to run a venturi, so you need a way to bump the line pressure.

 

Geoff

 

i think its 0.5 psi for natural gas around 11 inches wc

 

also can add a boost pump http://gas-tec.com/products_2.html

Edited by john marcus

infinite edge cutlery

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If it is a venturi, then you need to go up in orifice size, but I don't know how much. The other problem, if I remember correctly, is line pressure. NG comes into your house at something like 5psi, and you need 15-20 to run a venturi, so you need a way to bump the line pressure.

 

Geoff

 

Well, that pretty much answers my question. My forge needs at least 12 PSI to reach welding temp.

 

I have a buddy who converted his propane BBQ to run on natural gas from his house, which is what gave me the idea. Didn't know what the PSI to the house was though.

 

Thanks Geoff.

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"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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Are you getting advertised temperatures, or satisfactory working temperatures for what you want to do? How much propane are you going through in a day (8 hours)?

Mike --

 

Yeah, the Chile Forge is great to work with. Reaches welding temps w/ only about 15 minutes warm up.

 

I go through a full 30 lb propane tank in a weekend of forging (maybe 8 hours total). I should probably get a bigger tank, but they're more of a pain to haul down to the gas station to refill.

 

-Dave

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"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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If you have a amerigas dealer near you go there i went from paying 47 to fill my 40 tank at the hardware store to 67 to fill a 100# tank there and they lease you the tank with the first fill up!

 

~~DJ

 

PS i tired Nat. gas and wasnt happy with it on a forced air blower..... it works well for HT but not forging.

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Thanks DJ

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"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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I looked into building some natural gas forges for a local community college. In the end, we went with propane instead. Unless you have an industrial source of natural gas already available, you simply don't have a large enough pipe coming into most residential areas to supply the volume that you will need for a forge.

 

I will say that when I was thinking about it, the local gas company rep that I talked to was very willing to assist me in getting a higher volume line installed pretty much anywhere I wanted. He did feel like the forge would have needed to go through the engineering department at the gas company to get approved, but he made it sound like it wouldn't be that hard.

 

If I remember correctly, Olsen's "The Kiln Book" http://www.amazon.com/Kiln-Book-Materials-...n/dp/0873419103 was very helpful in making the calculations for the necessary volume of natural gas vs propane. It's pretty calculation intensive, tho. I'm not great at math, but I'm not terrible. I had to seek assistance from a friend with an engineering degree to make heads or tails of some of the notation for gas and temperature. :blink:

Edited by josh powell
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  • 2 weeks later...

Hey guys,

 

This is my first post here. Might as well use it on something I know a thing or two about. I'm a natural gas pipeline engineer with a chemical engineering degree, so at least I'm not a complete newbie to things of this nature. :D

 

It is entirely possible to run a forge on house pressure NG. I just finished one this weekend that handily burnt a 1/2" O-1 drill rod in 5 minutes from a warm (refractory drying temp) start. How's that for hot? I have a 60cfm leaf blower for power, 1 1/4" burner body (no flare... it's not meant to burn outside the forge), 1 1/4" full port ball valve for air control, 1/2" full port ball valve for gas control, 1/2" gas line at 0.5psi. My forge is about 6" diameter inside and 18" long. It's lined with 2600° firebrick with thin set concrete topper mortar, perlite, and furnace cement to fill the gaps. Body is galvanized flashing. Don't worry, I burnt the zinc off the parts that will get hot. So, at least a forge of this size with this insulation WILL get to a steel burning temp.

 

If I'm judging stoichiometric mixture correctly, I'm probably flowing about 5-6cfm of gas going flat out, which would cost about $21 per 8 hours of run time. Now, I only have to run it at about 1/4 of that to keep a forging heat... maybe even welding. I don't know. I don't have a thermocouple and it was too bright outside to get a good read on the temp. In either case, it's a good performer, it's economical, and it's ready to go all the time.

 

To convert a propane to a NG forge, just add a blower and a big burner. You should be good to go!

 

Taylor

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Taylor Coleman Knife Works

 

"Trust, but verify." - Ronald Wilson Reagan

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It is entirely possible to run a forge on house pressure NG. I just finished one this weekend that handily burnt a 1/2" O-1 drill rod in 5 minutes from a warm (refractory drying temp) start. How's that for hot? I have a 60cfm leaf blower for power, 1 1/4" burner body (no flare... it's not meant to burn outside the forge), 1 1/4" full port ball valve for air control, 1/2" full port ball valve for gas control, 1/2" gas line at 0.5psi. My forge is about 6" diameter inside and 18" long. It's lined with 2600° firebrick with thin set concrete topper mortar, perlite, and furnace cement to fill the gaps. Body is galvanized flashing. Don't worry, I burnt the zinc off the parts that will get hot. So, at least a forge of this size with this insulation WILL get to a steel burning temp.

 

Taylor

 

Thanks for the post Taylor. How about some pictures of the forge?

 

Cheers,

 

--Dave

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"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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OK... here are some pics and videos. You can see in both where some hot spots had developed, and they were fixed. Galvanized is a good indicator of such things. As it is now, it's not exactly comfortable holding your hand on the exterior while it's running... it's not 200 degrees either. I would guess about 130-140 degrees.

 

I ended up cutting off the excess flashing, not being content with just burning off the zinc and leaving it. It makes for a cleaner look.

 

The videos show me jacking around with the air and fuel. Basically, I like a good crisp relight, and controllability down to very low fires. I can't quite hold a candle flame, but I can get close. You see full and half throttle in the videos.

 

Sorry about the mess in the shop. It's not like that when I'm forging. Promise :)

 

100_3644.jpg

100_3643.jpg

 

Video 1

Video 2

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Taylor Coleman Knife Works

 

"Trust, but verify." - Ronald Wilson Reagan

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Cool!

 

Thanks Taylor.

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"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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Nice work, Taylor. Thanks for posting the pics and videos. I contemplated converting to NG to eliminate freeze-up problems I was having and eventually ended up with a 100# propane tank to solve the problem. I assumed that the low pressures of NG along with the lower BTU content would result in a burner that would not suit my needs.

 

After seeing yours in action, I think my next forge will be fueled with NG.

Have you ever thought about the life of steel? It's interesting to think that you can control the fate of a piece of metal.

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Very nice! I've thought about doing this, but I was under the impression that I'd need to have a larger NG line installed to do it. (AFAIK the line upstream of a typical household regulator/meter like mine can provide plenty of BTUs; it's the downstream size that actually comes into the house that's relatively anemic.) But it sure doesn't look that way based on those videos!

 

Thanks for posting, Taylor.

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