Burner tube diameter for 12" vertical welding forge?

Salem Straub

Salem Straub

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Oct 20, 2008
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Anyone have input about what size burner tube to use for a 12" dia. vertical welding forge? I have a 10" vertical welding forge with a kaowool and cast liner, that I'm thinking about upsizing from. The 1" burner tube I have on that one even seems a bit small. It's a simple forced air burner, with a pretty good blower and a gate valve. I wonder if I'm wasting my blower by bottlenecking the air/gas too much going into the forge.

Would 1-1/4" be better? Also, I'm thinking about adding a stainless tip to the burner tube. Anyone have a comparable setup to recommend? The new forge will be lined with 2" of inswool.
 
Salem,

Zoe Crist and I use 2" piping and then reduce with a 2x1.5" bell reducer as it enters the forge, with just as much 1.5" nipple as needed to hit the edge of the inside of the forge, with great results. My main forge is 2" of cerachem with 3/4" of kast-o-lite 30. Performance is top notch, and I'm using about half the fuel as his larger chamber does, but you've got to compensate with billet size.
 
If you have a blower that can handle a bit of back pressure 1" if fine. If your blower just produces the amount of air you need then you might have to up size to 1.5". Keep the end of the inlet pipe about an inch back from the inner edge of the forge and it won't burn away too fast.

Wayne Suhrbier
 
Hello Salem,

I'm using 1 1/4 burner tube with a Sticktite burner nozzle #ST 205-28 from --> http://v2.wetdogglass.com/products/detail/287/Burners . Man these tips are worth every penny ~$60. You will have the ability to drop the heat down really low without the burner going out and crank it up with really even flame. So efficent. Bob Kramer turned me onto this a few years ago. Just keep it inside the forge lining by 1/2" or so...
 
I would go to 1.5".
Run 1.5" pipe from the blower, about 2" from the forge shell, add a 1.5/3" bell reducer, a 4"X3" nipple, another reducer, and the nozzle tube in 1.5".
This mixing chamber will really improve the performance of the burner.

I use stainless nozzle tubes, and have been experimenting with titanium nozzles.
 
+1 regarding what Stacy said about mixing chamber. I go 2" pipe from blower then have a 2" to 3" bell reducer connected to a 4" X 3" nipple then a 3" to 1.5" bell reducer before the main 1.5" burner tube. Proper mixing of gas and air is huge. Also, I am running on natural gas rather than propane but have used same setup for both. Just use different gas volume for NG than LP.
 
I know some hate the science talk stuff, but from an engineering point of view, the mixing chamber is probably the most important part of a properly designed forge burner.

Something else I have experimented with ,but have not really done any pro and con testing of ......
is a toroidal insert. It is a spiral twisted piece of thin stainless steel ( or titanium) that fits inside the main burner tube past the gas inlet but before the mixing chamber.. The theory I developed is that it starts mixing the gas/air by rotation, and when it enters the mixing chamber it is swirling around ( toroidal) at a good rate. This passes on to the reduction pipe entering the burner nozzle, and you get high velocity rotating gas that combusts upon entering the chamber. The creation of a hot spot should be much less, and the nozzle should run slightly cooler due to better heat extraction and cleaner burning.

Try it out and let me know what you think...it only will cost about $0.50 in thin scrap stainless sheet. If you don't like it ,you can just pull it out and chuck it in the scrap bucket.

The other thing that makes a burner sing is a properly designed burner flare - AKA nozzle. If you don't have the ability to make one....buy one. It can make a good forge into a great forge.
As said before, I am experimenting with titanium flares/nozzles. More on that after the new shop gets built.
 
Thanks for the advice, guys. Lots of good points there.

I like the mixing chamber ideas. One problem I may have with that is that I'm trying to incorporate a waste oil drip into the burner tube. I have this rigged onto my current welding forge and it works OK. It's just a 1/2" gravity line to a needle valve, reduced to 1/4" tubing brazed onto a hole drilled in the top of the burner tube. I think I'd have to install this downstream of a mixing chamber, as I'd hate to think of oil accumulating in the bottom of a chamber.

The blower I have is a decent size and throws a fair bit of air, no CFM rating I've found anywhere though. It's a squirrel cage type, and so not good in dealing with back pressure like a radial blade-type blower. I do have a better radial blade blower I may use for the new burner. I think its true that my current blower, being a squirrel cage would deal better with larger tube.

I've used SS flares from Zoeller on venturi burners. Don't know if I can get one from him for 1.5" pipe, I'll check out your link Eric, but $60 will hurt my pocket. Hey, I'm just a knifemaker. Definitely not well-to-do. Although, with forge design money invested in efficiency is quickly returned in fuel savings.

Wayne, I'll probably be getting some refractories from you soon. Thanks.

Any further input will be appreciated as well.
 
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