Building first gas forge

[Straick]

I'm building my first gas forge right now. I'm using firebricks and refractory cement(left over from redoing my oil fired boiler) with a steel angle iron frame(so that I'll be able to move it). I redid my math on the volume, and it came out to 248.625 cubic inches. Originally I somehow originally had come up with about 300, and I'm thinking I miss measured originally. The burned is getting mounted straight into the top and will be sealed around it's opening.

I did build a tee burner following the directions in the sticky at the top. Thank you Frosty for the nice clear write up, it was very easy to follow. The only changes I made to them was that I tapped the 1x1x3/4 tee for the threads on the flare instead of the pipe thread and used the pipe thread for a ball valve, as well as using a ball peen hammer to make my flare(one going inside and hitting it with another). For a regulator, I'm using one of my spares for my oxy/propane scrapping kit. Got it tuned to burn nicely(all the way from about 2 PSI all the way up to around 20 PSI) in open air.

Am I going to have too much burner for this size forge, or will I be okay with the 3/4 one that I have now(I think that I had read that the 3/4 ones were good for about 300 to 350 cubic inches)?

Also, on a single burner forge, is an idle circuit worth doing? I'm already contemplating making a bracket for the control valve to hold it to the side, and it doesn't seem like it would be hard to add a needle valve and associated fittings to give it an idle.

[Latticino]

A lot depends on how you have the forge insulated and how large your door/s are.  Firebrick comes in several flavors.  The big split though is between hard fire brick that is reasonably robust, but a mediocre at best insulator and soft firebrick which is a fair insulator, but it prone to abrasion, cracking and flux damage (not to mention total breakdown at high forging or welding temperatures if you get the type that is only rated for 2000 deg. F).  Having never relined a boiler I don't know what you would have used, but as I doubt you had 2,600 deg. insulating firebrick I'd have some concerns.

IMHO, idle circuits are great, if you use them.  Think about your workflow process with your gas forge.  Ideally once it is up to temperature you could switch to idle every time you aren't actively heating product in the forge and save quite a bit of propane (similar to backing off on the air in a coal forge every time you switch to the anvil).  The key question is will you with your gas forge?

[Frosty]

Please show us how you connected the propane to the jet. Being threaded directly into the T means a much different connection to the fuel. I'm always looking for new stuff for my personal tool kit you know.

I never tune to burn outside a forge, build ad tune them for where you're going to use them. Just turn it down, the 300-350 cu/in volume is a max. rule of thumb for the home builts. I have one golden bullet burner that has no trouble bringing almost 700 cu/in to high yellow with the openings minimized.

Frosty The Lucky.

[Straick]

My firebrick and refractory cement are rated for 3000F and 3500F respectively. The refractory cement was left over from my boiler, and I bought the firebrick for this.

 

Here's how I did the fuel connection on the burner as well as the burner.

 

Here's two shots of it running tonight without the flash and the back end blocked. I did swap the .035 tip out for a .030 tip because I couldn't get rid of the yellow flames from the opening of the forge. It's running with the propane at 25 PSI in these shots. Any less on the pressure, and I couldn't get a shot of the flames coming out of the mouth of the forge.

 

I am planning relocating the gas hookup to low on the side of the forge as well as giving myself an idle circuit. Just need to decide if I want to do the plumbing for the idle circuit in soft copper(flares) or hard pipe(threading). The brick did stay cool enough to touch the sides of the forge in line with the burner without burning my hand after I got everyone to temp, so not sure if these are hard brick or soft brick.

 

P.S. Sorry about the large size of the pictures, I'm still learning this camera and figuring out how to resize stuff. The resizing has not gone smooth yet(they always end up distorted or blurry).

[Frosty]

Ah I wish I'd seen this post before replying in your other one where you posted these pics individually from your gallery. I hope my reply isn't lost.

The forge looks good and hot and the dragon's breath shows the burn is a little rich. A little rich is a good thing it prevents scale forming IN the forge. It could probably be leaned up a little more but if it's getting your stock hot enough it's probably good now.

I cheat my pics from camera, phone, etc. by saving them into Word and resizing them there using the (the ITs are going to laugh at me, go ahead I can take it.) "Save AS" function I just set the file size limit keeping it at 1:1.

Frosty The Lucky.

[Straick]

It's not a problem. No matter how I end up doing my piping, that ball valve is staying put. You can never have enough ways to kill a gas feed in an emergency. Never fails that you end up not being able to reach any of the normal ones, and that one you never planned on using ends up being your saving grace. I still need to add one to the output from my regulator for a fast way to kill the gas if the hose gets damaged.

Would you happen to have a link to what a gas forge running a good mix would look like? I've found several of them running, just not sure of what a good mix looks like(my gas background here is heating furnaces and torches).

Your Word method of resizing sounds as good as any to me, so I'm going to give it a try.

[Frosty]

The first pic is my first NA forge. It's about 500cu/in with a hard inner liner and 1" kaowool outer liner, no kiln wash. I built it a little better than 25 years ago. This is my first functioning and reasonably tuned T burner. It's a 1" T and running pretty rich in this pic. See how the flame is pale and pretty opaque? That's not bad it's short but you can see orange IN the forge, that's unburned fuel in an atmosphere with on free oxy. This old pipe forge is seriously over gunned and easily melted steel if you didn't keep an eye on it. It's not up to temp in the pic it's just been lit.

The second pic is my current shop forge in it's second incarnation running on all 4 burners telling me this is a test firing. You can just see one of the burner flames against the far opening. The flame is well formed but much shorter than the one in the old forge. This would've been about 4 minutes after lighting all 4 burners. The reg is probably set around 9-12 psi but may be higher. Certainly not lower.

I put my shut off valves away from the forge for safety's sake. If something goes so far in the pot I need to jump for a shut off valve the chances most of the fire will be around the forge, reaching through the fire is a B-A-D idea. I also have one right after the regulator so I can shut it all off in a split second.

Frosty The Lucky.