Propane forge critique

[M3F]

Hello all. I have not posted much so I apologize in advance if this isn't in the correct area.

I'm xxxx bent on getting my propane forge to reach welding temp. The goal is to weld canisters and billets of 1084 w/15n20 which from what I've read is anywhere from 2100F to 2500F. Everyone seems to want to talk colors when i'm looking for temps. 

The forge has 2" of kaowool, 4 thin coats of satanite rigidizer, and 4 thin coats of ITC 100HT. All layers were properly cured before the next was applied and the burners tips are roughly 1" up into the lining. My laser thermometer read 2100F but I don't trust it's accuracy so a thermocouple is on order as well as a ceramic kiln shelf.  I think I've done all I can and would like a critique. If this setup doesn't hit the temps I need the next step is either buy an efficient 1 burner forge like a Chile or buy an air blown forge.  Again the goal is to weld 4-6" billets and canisters. 

In the 1st pic I'm running 9psi with about 3/4 choke and in the last 3 pics I'm running 20psi and about 1/2 choke. From what I understand this seems to give me what I think is a neutral flame and proper flame coming out the doors. Any input is appreciated. Thank you.

 

 

[Frosty]

How much forge welding have you done? 

Who sold you Satanite and ITC-100? Satanite is NOT a flame contact refractory it is mortar for cementing bricks together. ITC-100 is okay but there are much better products available. You have what you have now, go with it.

Forget about psi and listen to the flame. As much as I hate videos for their near utter lack of useful information yours does provide confirmation for what I see. Your burners are running rich. Listen to your video the flame is a breathy almost roar, a whooshy sound. Turn the psi down and start opening the chokes a little at a time until the flame is almost shrieking. You want a breathy almost scream. 

Put a piece of steel in the fire and watch for scale forming IN the forge. If it scales close the choke a LITTLE and test again. repeat until the flame is screaming but not forming scale in the forge.

Do this ONE adjustment at a time, test, observe and make notes. If you start changing lots of things at once you' never know what works even if you stumble onto the right settings. Once you get a good strong neutral flame MARK THE CHOKE POSITION!

THEN, after you find the neutral tune point  for your burners start adjusting the psi. Use the same technique, adjust it a LITTLE, test, observe, make notes. Do NOT adjust the chokes during the psi tests!

Give that a try and let us know how it goes. We'll help you get it working. 

Frosty The Lucky.

[M3F]

Thank you I will try tuning that way, I believe I'm close to understanding the propane forge setup. I thought i was nuetral but what you said makes sense.  I've done a small quantity of canisters and mild steel welds in my coal forge and that's it. The satanite mixture and ITC was purchased on Amazon from Mr. Volcano. 

[Frosty]

Next time order some Plistex 900 from the IFI store, the link's at the top of the page. Glenn sells small quantities for not too much. It will serve better than Satanite and ITC-100 combined. It is high alumina and is very resistant to chemical erosion from molten flux. It will fire hard like a ceramic cup to resist mechanical erosion from being poked by cold sharp steel and does a good job of re-ratiating IR.

Those forges work well, they're worth the money you spent, they just need a little tweaking and we're pretty good at helping folks through it.

Frosty The Lucky.

[Mikey98118]

Good advice, Frosty.

M3F, I think you have a plenty good enough forge, and mainly need to get used to fine tuning it.

[M3F]

Ok round 2...

Full 20lb tank with psi at 25, chokes wide open produced a ton of scale. As I slowly closed them and watched the scale, brushed it off, and readjusted I found that just around 1/2 choke on the front burner and 3/4 on the rear burner the scale was at a minimal. With those settings the laser thermometer reached 2500F. (Again I don't trust it so the thermocouple is on order) It was a good lemon yellow bordering on white color that I could barely look at. 

After that I turned the psi down to 15 and the temp was 2300F. As far as the sound I really couldn't tell much of a difference.

 

 

 

Listened to both videos. Now I hear a difference. 

Also does the Dragon's breath indicate anything with the results I've got?  Thank you. 

[Mikey98118]

Looking at how high your forge temperature is getting (yellow to yellow-white incandescence is consistent with your 2500 F thermal reading), tells me that you don't have a problem with burner performance. You might want to try running the rear burner considerably hotter than the front burner. I do think you simply have too much combustion going on for the forge size to contain. Also, the orange color of your exhaust flame looks suspiciously like excess calcium burning out of the refractory binder; it should go away by and by.

[M3F]

Ok. Next issue. What causes the burners to flame out at the burner tip up through the choke?

And the brass fittings where the propane get so hot after shutdown it melts the lines.

[M3F]

So heres what i have so far...I removed those burners and put the set in that came with the forge. (Hell's Forge)  I never get blow back or lines melting with them. I installed the thermocouple in the center through the side, level with where a billet would be. It reached 2300F with the 1st burner running. I'm waiting on a the mig tip for the second burner.  The color showed lemon yellow almost white and difficult to look at. 

I was able to maintain that temp at 15psi with the choke wide open. If I closed it at all or reduced the psi the temp dropped. Throughout all these trials the scale was minimal. In the future I think I will purchase a 1 burner forced air or a 1 burner Chile Forge for forge welding and keep this one for longer blacksmithing type jobs. So my goal was reached but I have some questions to close this out.

1. What does that flame out indicate on a burner?

2. When the 2nd burner is running is it accurate to say the temp will increase over 2300F?

Thank you again for all your input. 

[Frosty]

25psi Holy MOLY!! Why do YOU think you have so much dragon's breath? One of the burners flames out? So which one stops burning, front or rear?

If you're asking about flame blowing out of the air intakes or at the end of the jet (mig tip) that is called "Burning back or Back Firing." "Flame Out." means the flame goes out.

Running 25psi through 2 burners in a forge that small is literally forcing the flame from one burner back up the mixing tube until it reaches the jet where it disrupts the fuel stream so that burner stops operating properly thus relieving the pressure in the forge. 

A couple posts ago I suggested turning the psi DOWN and adjusting the chokes a LITTLE AT A TIME until the flame was burning neutral. You are adjusting psi AND the chokes AT THE SAME TIME by big whopping GOBS and wondering why it's doing what it's doing. The difference between 25-15 psi should have negligible effect on the fuel air mix. The beauty of naturally aspirated burners is once they're tuned you don't have to mess with them. I don't put choke on T burners, EVER and if someone does it's because they built it wrong.

Once you have those burners tuned you should be able to tighten the set screw so the Choke can NOT move and snap it off.

If you can't weld at incandescent yellow you don't know how to weld. Buying instruments to tell you things that don't matter isn't going to help. 

I don't understand your question 2. Accurate to say the temp will increase over 2,300f? How do you expect us to know that? That small a forge should reach welding temps with one burner once you get it tuned. I've been welding in a forge since the 70s and have NEVER known what the temperature in the forge was, low yellow and up is good. Spring steel to spring steel wants high yellow or an aggressive flux.

Now, put a piece of tape or something over that gauge and go back to tuning your burners a LITTLE at a time, ONE THING at a time. PSI means nothing except to duplicate a particular temperature without having to do it by eye. That's what the note book is for.

Frosty The Lucky.

 

[M3F]

I did adjust the burners like you suggested and was able to find a great neutral flame for general forge work. Now i know how to run the forge efficiently at a low psi.  I marked the location of the chokes and can duplicate that environment. 

What that didn't achieve was forge welding temp.  I increased the psi only but could not increase the temperature enough.  25psi was part of that test. 

I continued to tune the forge as suggested (chokes independent from psi) and found that at 15psi and a wide open choke the temp hovered at 2300F.  If I'm understanding you correctly the chokes stay put and more psi would increase the temp. I didn't find that as the case. 

After finding those settings I shut down both burners and they got hot enough to melt the gas lines. (Just poorly made IMO) After I let them cool both burners backfired starting at 1psi hence my 1st question.  Just curious what causes it at 1psi NOT 25psi. I assume the heat left in the forge. So those were removed and the old ones put back.  I went through the adjustments again as suggested with the one working burner. It's settings were close to what I found with the 1st set of burners. 

As for my 2nd question is it not reasonable for a beginner to think you would know the answer to if the second burner running would add heat?  Theres 15" of forge body left behind that 1st burner. If the 1st burner brought the entire thing to 2300F my newbie brain says well the 2nd burner running should increase the temp but I'd rather confirm with knowledgeable people.

No I cannot forge weld adequately. Spending money on instruments is my effort to control as many variables as I can. Knowing a temp and then associating it with the color I SEE makes sense to me. 

[Frosty]

Okay, you adjusted the burners and they didn't achieve welding temps. Did the weld you try fail. You DID try to weld in it didn't you? If not how do you  know it didn't reach welding temperature? (the word you're looking for is attain or reach. Achieve relates more to human accomplishment than a machine function. That's not a criticism, it's more of a FYI)

When you shut the burners down the chimney effect caused forge HOT air to flow up through the burners. That is an issue with top mounted burners and the reason my burners fuel circuits are 1/8" copper tubing so rubber hoses don't get damaged. The solution is to close the chokes completely when you shut it off. I guess you don't have a choice with that forge burner set up. 

Why did you light your burners at 1 psi? Especially if you have to run it between 15-25psi, that makes no sense. Is there a reason to try starting it that way?

Sorry, I didn't know what to think. It never entered my imagination anybody would ask if doubling the heat input in a furnace would raise the temperature. I assumed you worded a question poorly, the answer was just too obvious to take it seriously as worded. 

You need to take a breath and step back from this, you're getting frantic. This isn't some sort of emergency, it's a pursuit something you WANT to do, maybe get good enough at making blades to make money at it. Yes? Getting in a rush is only going to cause mistakes and make it hard to straighten them out. Don't make an adjustment and expect everything to work the way you expect it to. Even if you got it working perfectly it's a forge it doesn't care about your expectations, it will work as well as it works. 

You are aware cannister welding is significantly more difficult than simple faggot welding. Yes? Clean and Stack some stock, tack weld or wire it together, war it up till flux melts, pull it from the forge, flux it and put it back in until it's yellow hot and set the welds, brush, flux re-heat, set them a little harder, repeat and refine the welds. Make it a small stack, say a San Mai billet, mild HC mild. Once you get good at welding cannister isn't a big deal but it is harder, you can NOT see if the material inside is hot enough, it's out of sight. 

Forget the instrumentation, it's only confusing you. You're reading it and wondering why it isn't reading what you want instead of trying the forge and seeing if it's hot enough to weld. Looking at instrumentation won't help you read the temperature, regardless of the color if it welds it's hot enough. What could be more simple? The numbers don't weld anything, they're just a meter. 

Mike is better with high speed burners, I don't build burners you have to choke. I may be wrong maybe those burners do need to be adjusted every time you change psi. If that's the case Mike is the guy to help, I'll follow along because I'm out of my depth.

Frosty The Lucky.