Natural Gas Forge?

G L Drew

G L Drew

Knifemaker / Craftsman / Service Provider
Joined
Feb 3, 2005
Messages
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I am in the process of building a gravity type (no blower) forge for my son and could use some advice. He heats with natural gas and would like to hook the forge into that system instead of using propane tanks. Will he get the same heat as propane? Has anyone experimented with a oriface sizes for natural gas?
 
Mr. Drew,
Maybe you could elaborate/clarify a bit.
1) When you say a gravity forge do you mean a venturi/jet ejector burner (naturally aspirated)? That is one in which the movement of the gas entrails with it the oxygen it needs to fully burn within the forge.
2) You mention your son currently uses natural gas but you wish to incorporate natural gas? Do you mean he currently uses propane but you wish to use NG? Or he currently uses a blown burner with NG but you want to use a naturally aspirated NG burner?

I think this will help folks help you out.
Best
Steve
 
STEVO, on #2, i think he means that his son heats his house with natural gas, and he wants to plumb the forge into that instead of lugging propane tanks around. But i could be wrong.
 
A little Googling and it would seem that natural gas (give or take low 3,000's) doesn't burn as hot as propane (give or take mid 3,000's).

Not sure if that will make a big enough difference or not. I was curious about the matter and am simply reporting back what I found. :)
 
Natural gas forges run well, and are the industrial standard. It is far more economical than propane, and will produce enough heat to melt steel.
They don't run on atmospheric burners (venturi) beyond very small flames, because the gas pressure is too low. On that subject, most residential gas pressure is so low that it won't run a forge at all. You need at least 2-3 PSI and a 2" inlet line to the house/shop. Residential gas lines are 3/4" to 1" and the pressure is less than 1/2 PSI ( don't confuse the 5-7 WC pressure rating with PSI). If your son has well head pressure gas, like the folks with gas wells on their property,or commercial gas, then he is in great shape to use NG for his blown forge. At 5-8 PSI ( 150-200 WC), I guess he could even run a venturi burner.

SO:
Yes a forge can run on NG
No, it won''t run a venturi burner.
It will run a blown burner if the supply has enough volume/pressure.
People with well heads get free natural gas and enough pressure - I hate them :)
 
Stacy is correct. I used to run natural gas in town, long time ago... about 4 PSI (I think), 3/4 inch line to the blown forge. As I recall, it was a high volume/low pressure situation. I did a lot of pattern welding with it at that time. It got white hot.
 
stevomiller said:
Mr. Drew,
Maybe you could elaborate/clarify a bit.
1) When you say a gravity forge do you mean a venturi/jet ejector burner (naturally aspirated)? That is one in which the movement of the gas entrails with it the oxygen it needs to fully burn within the forge.
2) You mention your son currently uses natural gas but you wish to incorporate natural gas? Do you mean he currently uses propane but you wish to use NG? Or he currently uses a blown burner with NG but you want to use a naturally aspirated NG burner?

I think this will help folks help you out.
Best
Steve
Click to expand...

Sorry for the confusion. He is using natural gas for he heating and cooking in the house and would like to hook his forge up the that using a venturi system (no blower).
 
It takes around 5psi of well head natural gas to run forge. I operate both blown and a venturi forges on that same 5 psi setting. House pressure is around 8 oz and with the small entry piping will not supply enough gas volume to operate a forge.

Stacy, I feel the hate and it feels sooooo good. ;)

Fred
 
if you dont mind my asking, I am in the middle of a forge build myself, and was wondering how important it is to get the satanite smooth and round, and what the best way of achieving that would be.
 
Put on a pair of rubber gloves and smooth it by hand. A long paint stir stick will work if the chamber is too small for your hand. Just try and get it smooth. It doesn't have to be like glass. The smoother and rounder the better. A perfect circle is not necessary as long as the side and top surface curves. The floor can be flat.

After curing the satanite by letting it dry a few days, complete the cure by a slow and low firing . the next day, ) assuming there are no cracks to repair), paint a layer of ITC-100 over the satanite. Let it dry for a day or two and fire at low heat for 15 minutes, then medium for ten, then at full heat for 5 more minutes. Let cool off and insect for any cracks. Once fired and hard, the liner will last a long time.
 
I'm currently running a 6 in of WC Natural Gas Forge, the gas company had to come and change the meter in order to flow enough, and we plumbed 1 1/2" line from the meter to the forge, we t'ed of that to feed the furnace. The forge has no orfice just a 3/8" hole inside a 1" pipe. I can take pictures of it if you like.
 
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R.Rock said:
I'm currently running a 6psi Natural Gas Forge, the gas company had to come and change the meter in order to flow enough, and we plumbed 1 1/2" line from the meter to the forge, we t'ed of that to feed the furnace. The forge has no orfice just a 3/8" hole inside a 1" pipe. I can take pictures of it if you like.
Click to expand...

A photo would be greatly appreciated.
 
The Tag says 450,000 btu its a MIFCO it runs 6in of Water Column not psi, my mistake.
http://www.mifco.com/slotforg.htm
mine is a 826 and when I get home tonight i'll get you the pictures, is there anything in particular that you want photos of?
 
there was a guy on here, i cant remember his name but seems like he made one that ran on residential natural gas. blonde guy according to his avatar lived in florida i think? does real nice work built a press too i think....... its buggin me i cant remember is name. maybe i'm wrong, ring a bell to any of the older folks around?

jake
 
Would a natural gas compression system like those used at ng filing stations be feasible in a home setup? How complicated is this type of compression system?
 
You might want to look at Eric Fleming's forge. It is forced air (not atmospheric/aspirated) with natural gas. He easily gets forge welding temps out of it. The gas is real low pressure but he makes up for it with volume via wider pipes and a large orifice.

Whoops, looks like this has already come up. Oh well, in that case just consider this a ditto.

I visited with Eric a few years back. We did a bit of forging together. I can attest to the efficacy of his natural gas forced-air temp-controlled forge. It runs great! (He's in San Diego.)
 
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As you see by those examples, a NG forge will run just fine. It does require a large size gas inlet line ( which requires a different meter), and a good size blower. There isn't any way to run a normal size forge from a standard residential NG inlet line.

The problem is the volume of gas needed. With propane, we deliver the volume by running it at pressure through a 1/4" hose.
In a venturi forge, 3-10 PSI is choked down from the 1/4" hose to about .030" at the orifice to create a high velocity jet of gas, which creates the venturi and draws in enough air ( oxygen) to efficiently burn the gas.
We can run a blown propane forge at about 2-5PSI, and get enough gas, because there is no orifice .
Natural gas is delivered at around 7"WC, which is about 1/4PSI ( 27"WC = 1PSI). That won't deliver enough volume unless the pipe is large. A large 1.5" inlet pipe is 35 times the size as a 1/4" propane hose, so at 1/4 PSI it will deliver about the same volume as running a propane forge at 9 PSI. A standard 3/4" inlet pipe to a residential meter will only deliver the equivalent of about 2PSI in a propane forge. That won't sustain a venturi, and would only supply a very small blown forge. It might work for HT, but not for forging or welding.
 
Wow Stacy, that's a lot of data. Not sure I understand your conclusion though.

bladsmth said:
A standard 3/4" inlet pipe to a residential meter will only deliver the equivalent of about 2PSI in a propane forge. That won't sustain a venturi, and would only supply a very small blown forge. It might work for HT, but not for forging or welding.
Click to expand...
My understanding is Eric forge welds billets with his natural gas forced air forge on his residential feed (no special meter). As I recall (back before his new press and welding) his forging (non-welding) gas consumption didn't even raise his bill past his base gas fee. Granted that pretty light forging then (he has another career). Given his success, it sure seems doable with basic residential gas service and a blower.

 
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