Gas torch as a burner?

[Ash1]

Hi hope everyone had a good weekend,  

I'm planning on building a small gas forge with a single burner and would really appreciate some advice.  Ideally I'd like to use a propane torch as the burner but I'm struggling with working out which one will work best. Would something like this be suitable? 

Like I said, advice really appreciated. 

[ThomasPowers]

Depends on how you build your forge and what you want to do with it; which you didn't tell us.   It's sort of like me asking you Will this set of tires fit my truck?"

[Ash1]

OK thanks Thomas. I'm much more familiar with solid fuel but I'll do my best! 

I'm going to weld up a small box insulate it with fire bricks (two for the top and bottom and one on each side)  and run the burner in the top. I'll use it for  small projects in steel, some forge welding but not smelting. 

Let me know if I've left anything out. 

[Mikey98118]

If you are xxxx bent on using a propane torch, instead of a burner, you will have to use one with the #3528 stainless steel nozzle; at least it won't melt down in the forge, which makes it feasible, but not your best choice, for sure.

[timgunn1962]

Assuming from the link that you are in the UK, I would not advise using a torch unless you have (or need to buy) one anyway.

The Sievert stuff is quality, but it's worth checking whether the burner on that one is brass, steel or stainless steel.  There's a pretty good chance that brass will become a dribbly mess when trying to get useful forge temperatures.

You can buy a 1/2" long-Venturi Amal Atmospheric Injector (a commercial Venturi mixer) for around £50 delivered. Either the 354/12BLV (with a 60 jet) or 354/12PLV (with a 70 jet) will work. If you are mainly working hot, with welding the priority, the 60 jet is probably best. The 70 jet might be slightly better if precise temperature control down at Heat-Treating temperatures is important to you.

You'll also want a 6" (or longer) 1/2" pipe nipple for the burner. The injector incorporates a 1-in-12 tapered section and you don't usually need anything else on the end in a forge.  

You'll need a regulator, hose and fittings to get you into the 1/4" BSPF port in the injector. A gauge is optional and will fit in the other 1/4" port in the injector if you want to use one. The regulator should be a 0-30PSI (0-2 bar: adequate) or 0-60 PSI (0-4 bar: overkill).

Don't get a 0.5 bar-minimum (8 PSI) regulator, they are horrible to use in a forge.

The Amal burners turn down well and provide for exceptionally fine adjustment of the mixture/temperature. 

Fire bricks come in 2 main types: "Hard" and "Soft" or "insulating Fire Bricks". You'll almost certainly want IFBs. Hard bricks do not insulate to any useful degree and you'll probably need to step up to a 3/4" burner if you use them.

IFBs are not flux-resistant. Read the stickys for ways to protect them. 

Bricks are expensive to ship so we tend to get different ones over here to those in the US. My preferred IFBs for forges are marked LW23GRD. They don't seem to break up as badly with heat cycling as others I have used and, despite the 2300 degF rating, do not melt at temperatures I can readily obtain with the Amal burners. They also insulate better than anything else I have tried except the JM23s from Thermal Ceramics. I once used a JM23 to reduce the opening of a forge built from LW23GRD and the JM23 melted to a puddle. JM23s are my first choice for electric Heat-Treat ovens but I avoid them for forges.

I weld up a frame from 1" angle, rather than a sheet metal box.

I also take the burner in the side to reduce the chimney effect on the burner when the forge is shut down.

[Frosty]

Good info Tim and regional to boot! 

Over here we're just starting to see insulating fire brick that will take the thermal cycling and high temps gas forges develop so I'm having to rethink my usual gas forge build thinking. 

Frosty The Lucky.

[ThomasPowers]

Yes if you use hard firebrick you will need a bigger burner and more gas and watchout as the forge will stay HOT for hours after it finally comes up to temp. Insulating firebrick is better. but you may want to look into one of the fibrous refractories likes kaowool.

Smelting is taking ore and turning it into metal --- is that what you meant; or were you wanting to say melting which is taking metal(s) and turning it/them into liquid?

[Mikey98118]

Tim,

I would love to see you copy your post on either the Forges 101 thread, the Burners 101 thread, or both. Good sources and other advice for your end of the pond shouldn't vanish into old thread files at the end of the month

[Ash1]

Thanks Tim that's really helpful. You've saved me loads of trial and error (mostly error probably!). If you could copy that post somewhere permanent I'd recommend it, it's one of the most helpful explanations I've seen. Anyway I'll let you know how I on. 

 

In reply to Thomas, Yes I did mean melting.

 

[Mikey98118]

Tim,

I recommended that burners be positioned vertical down at a tangent for the last eighteen years; this was because I liked the flame to impinge on high alumina kiln shelf floors, as the most durable position in the most energy efficient forge designs.

But circumstances alters cases. With better insulating and reflecting materials having recently become available at sane prices, it is time to turn away from the vertical down position.

[Frosty]

I have to dito Mike on this one. Things are changing all the time and some of them fast. We're seeing burners producing beautiful flames I would've been trying to fix not long ago. Some of the guys out there have some really nice build plans that are easier and frankly better for less. 

The current experimenting with bentonite and veegum bound zirconium silicate as a kiln wash or flame face is about to seriously change what home built gas forges are. 

What Mike says about burner alignment is as true as it gets, I'm back to trying to figure out what works best powered by the NARB with my piles of fire bricks and the jury is still hearing opening arguments.

I'm really digging this. 

Frosty The Lucky.

[Hans Richter]

Gents,

I actually use torches like above and his nozzle #73 + part of the original burner head for my venturi twin. Preferred that above a self-made burner from galvanized plumbing stuff.  Combined the assembly with a flashback valve, 50 psi pressure reducer, hose breaking valve and a 26 lbs propane cylinder.

Only build the burner body from SS 316 Ti and later the choke sliders. Here some specifications, venturi  inlet Ø 2 in, 4 in long, burner lance Ø 1,5 in, 12 in long.

Since I use the choke there is a significant reduction of gas consumption but still 2,2 lbs propane gas an hour. Reach temperatures till 1750°F on the work piece and have to figure out if this is enough for welding. During running the forge the burners are cool and steady, but after forging I always disconnect the torches because of the heat of the forge crawls up true burners after shut down.

Don’t talk about freezing gas bottles or else already spoken on other threats.

If there are any ideas to improve my burners please let me know.

[Mikey98118]

Your burners are running with reducing flames (fuel rich), but not badly so; if you reduce the gas jet's orifice size a little, that should clear up. Your main problem is that one of your burners is way too close to the exhaust exit, and that the exit is wide open. You are literally dumping most of that burners heat straight out the opening.

[ThomasPowers]

not to mention that re-running exhaust through a burner really really really spikes the CO production---which is a bad thing.

[Hans Richter]

Hi Mickey & Thomas,

Please find the final setup and configurations on the new pictures. Also thanks about the feedback around the flame pattern this was very useful.

As you see on the first pictures the forge wasn’t assembled and welded off and the chokes not mounted. Thanks for the hint about CO too, till now the shop is fortunately good ventilated!

In the meantime I forged several pieces, and running out of gas, no wonder with an average of 2.2 lbs of gas for each burner on a 26 lbs propane cylinder L

Thank you in advance and keep your comments coming.

Hans   

[Mikey98118]

The new exhaust opening puts the front burner in a much better position. I like the ceramic blanket cowling; you need to protect it with colloidal silica rigidizer, and then seal coat it afterward. Rigidizing and seal coating will help preserve this structure and guard your health.

 

[Mikey98118]

BTW, that cowling presents an entirely new direction in forge construction; congratulations.

[Hans Richter]

Hi Mikey, the crawled fibre matt is only placed to avoid further crawling of the roofing above, actually the exhaust heat is to hot and affect the bitumen/transparent PU-wave roof plates . The mat spread the heat and prevent further deformation or burn on the roof above. Don’t want to decrease the exhaust opening more because of putting in work pieces and have an eye on the burners. Consider to place the forge outside the shop like I see quit often, or make an extra shield between the forge and the roof. Any suggestions? Bye Hans

[Mikey98118]

You need more area between the front burner and the exhaust opening, whichever way you choose to do that.

[Ash1]

Hi everyone, 

Just wanted to say thanks for all the advice (especially timgunn1962). I got the forge running a couple of weeks ago and it's been working very nicely. A bit of a change from solid fuel but I'm really enjoying learning some new skills. 

Cheers, 

Ash