Introduction: How to Build a Propane Forge Burner

Picture of How to Build a Propane Forge Burner

In this Instructable I show how I was able to build a propane burner/torch from scratch using common plumbing fittings from Home Depot or hardware stores. The regulator might be the only part that you will need to source that might be harder to find. Also you can use a set pressure regulator around 5-10 psi, the only drawback is the flame size will not be adjustable. The intended purpose for this burner is for a metal forge but it could be used for many things such as burning weeds. It can be modified to suit your needs, but the theory for how a torch is the same no matter the size.

Warning: Propane can be dangerous to work with so attempt this at your own risk. I accept no responsibility for any damage to yourself or property. Also burning propane will produce carbon monoxide, only use propane appliances in a well ventilated area, including this propane burner.

Step 1: The Parts and Tools

Picture of The Parts and Tools

The parts and supplies:

WATTS brand pipe parts from Home Depot:

  • Steel Pipe Nipple(s) or Pipe 1/2" MIP (at least 10" long)
  • Brass Pipe Coupling 1/2" FIP LFA-810
  • Brass Pipe Cap 1/8" FIP A-708
  • Brass Pipe Nipple 1/8" MIP x 2" A-717
  • Brass 1/2" Flare x 1/2" MIP Union A-277
  • Brass Pipe Hex Busing 1/4" MIP x 1/8 FIP A-738
  • Brass Pipe Coupling 1/4" FIP A-732

Other parts:

  • Low Pressure Propane Quick Release Plug 1/4" MIP
  • Low Pressure Propane Quick Connect Socket with Ball Valve
  • 1-15 psi Adjustable Propane Regulator
  • Pipe Tipe or Pipe Thread Sealant
  • Sheet Metal
  • Self Tapping Screws

Common Drill bits including but not limited to:

  • 1/4" Drill Bit
  • 1/32" Drill Bit (or smaller depending on how large you want the flame)


  • Drill
  • Center Punch
  • Adjustable Wrenches
  • Plumbing Solder and Flux
  • Blow torch

Step 2: Video of Build

Here is an in depth build of the burner. This serves as an addendum to the Instructable write up.

Step 3: What Not to Do

Picture of What Not to Do

I started the build using a brass pipe nipple that was too short, you can see in the pics it works but the problem was the whole burner got too hot since the pipe was too short. I recommend using black iron pipe at least 8-10" long instead, it doesn't conduct heat as well either. I was unable to get black iron pipe and in the length I needed so I got some galvanized pipe instead (it's what Home Depot had) and used a coupler to make it the length I needed.

Also there is an issue with using galvanized pipe, when it is heated it can release toxic zinc fumes, the way to get around this is remove the galvanization by soaking it in vinegar overnight. This will break down the coating, you can see it in the pics.

Step 4: The Build

Picture of The Build

Ok I will try my best to describe what was done to make the torch, the video does a better job at covering the aspect for how the "Brass Pipe Nipple 1/8" MIP x 2" is soldered to the Brass 1/2" Flare x 1/2" MIP Union and how all the parts fit together. Be sure to use pipe tape or pipe thread sealant on the joints.

Here are some high level instructions:

  1. Drill a hole for the orifice in the "Brass Pipe Cap 1/8" FIP", I used a 1/32" bit.
  2. Drill 4 holes around the steel pipe where the threading ends, I used a 1/4" drill bit.
  3. The "Brass Pipe Nipple 1/8" MIP x 2" is soldered to the "Brass 1/2" Flare x 1/2" MIP Union", this centers the nipple when we screw this part to the "Brass Pipe Coupling 1/2" FIP" and aligns it down the pipe of the steel pipe, we will call this the "aligned nipple assembly".
  4. Screw the 1/8" Brass Pipe Cap with the drilled orifice hole to the end of the "Brass Pipe Nipple 1/8" MIP x 2" that is now part of the "aligned nipple assembly". You will want it screwed to the end that has the 1/2" MIP threads., we will now call this the "orifice assembly".
  5. The "orifice assembly" is then screwed into the "Brass Pipe Coupling 1/2 FIP"
  6. The steel pipe with the 1/2" holes is screwed into the other end of the "Brass Pipe Coupling 1/2 FIP"
  7. Screw the "Brass Pipe Coupling 1/4" FIP" to the other end of the "orifice assembly"
  8. Screw the "Brass Pipe Hex Busing 1/4" MIP x 1/8 FIP" into the "Brass Pipe Coupling 1/4" FIP"
  9. Screw the "Low Pressure Propane Quick Release Plug 1/4" MIP" into the "Brass Pipe Hex Busing 1/4" MIP x 1/8 FIP"

Step 5: Nozzle Flare

Picture of Nozzle Flare

Use some sheet metal and shape a nozzle flare. All I did was cut out some sheet metal and through some trial and error, kept bending it into a shape of a cone with pliers. It is attached to the end of the steel pipe by drilling some holes and held in place using self tapping screws. I would recommend using stainless steel to make the nozzle once you are happy with how the burner works.

The torch is now built!

Step 6: Test Burn

Picture of Test Burn

Hook up the propane regulator to the propane tank and connect the quick connect to the propane burner.

Test for leaks around the joints using some soapy water. Fix leaks as required.

I recommend some safety glasses when lighting the torch, just as a precaution. Turn on the propane and light with a bbq lighter.

I like running the torch around 6-8 psi and adjust as needed.

The flame for this torch is around 6-10 inches long. If you wanted a smaller or larger flame you could use a smaller drill bit for the orifice and adjust the size of the intake holes as needed. The nozzle flare also can be adjusted for refining the torch.

February 8, 2016 - Update
I have posted a follow-up video on a small modification made to the burner to make it more adjustable.


GaryA83 (author)2017-06-01

thinking of making a forge for knife making. Just looking for some input before i cut it up. Will this work well, old air compressor...think can leave wheels and handle on to make it a little mobile to pull in and out on my garage

GaryB25 (author)2016-05-26

by the time you have paid for all the parts needed you could buy one off ebay for less.

pdub77 (author)GaryB252017-02-05

You're on the wrong website, Gary.

ChristopherO16 (author)2016-12-27

what's your temp range in the forge. I love this build and thinking about using this in an outdoor wood fired pizzaoven for those dreaded no burn days

ronald.ferreira.39 (author)2016-09-25

how much propane must be blowing out before we light it wouldent want to light it and then the tank blows up

ronald.ferreira.39 (author)2015-11-10

will this be hot enough to melt asphalt to make it smooth

Will this produce enough heat to melt asphalt concrete (pavement/tarmac). Yes it will melt the asphalt cement in the concrete.

How smooth it becomes is entirely dependent on the aggregates in the concrete. Heating it may even make it less smooth as the warm cement loosens and sinks deeper between the aggregates.

You'll likely have to roll the hot concrete to smooth it out, the roller size also depends on a lot of things. Anywhere from 300lb to 3ton roller could be required.

incensedpanther (author)2016-03-27

Okay popped over to check this out. now I understand the air intake. your using the air intake as a choke. if you close off all the holes does it shut the flame down? anyway I need to turn this into a reality for me. let you know how it goes.

No if I close all the air holes it does still burn but not well at all, the air doesn't get a chance to mix until the nozzle. Good luck.

borentpa (author)2015-11-20

Thanks.... I too like the way you instructed.... What not to do.....

wrecks135 (author)2015-11-16

Is this basically a Reil type burner?

DIY Hacks and How Tos (author)2015-11-15

All manufacturers of teflon cookware recommend that you never take it about 500F. This usually isn't a problem unless you leave an empty pan on the stove or you try to broil with it.

DIY-Guy (author)2015-11-14

Glass melts around 1200+ F.
I never expected anyone to mistake the mere burning of food (much less than 600 F) with the doubly high temperature of melting glass. Give me a little respect before you bash me, ok?
If a little factoid is so offensive, it would be better to read it again and drop the attitude before replying next time. I'm not worried about burning tape at fittings far away from the flame and I never implied that those would burn either. My caution was intended for wise people who choose to continue to learn as much as possible about subjects they are interested in.

Sorry you misunderstood HariKarier11.

HariKarier11 (author)DIY-Guy2015-11-15

I'm sorry you took that as bashing, so I apologize for doing that. Ive built a few forges and burners for branding irons and the point of ignition is approximately 1" to 2" from the orifice and that is the last fitting the teflon tape was used on. Depending on the temperature of where you live, the propane vapor temperature varies, but because it's colder then the ambient temperature, it cools the pipe, the fittings and the teflon tape as it makes it way to ignition, unless you have an uninvited ignition deep inside the burner, then you just shut it off and fix the problem. Safety first should always be the first topic that we put in place while we work on our project, or in a teaching situation. So whether you're welding, doing foundry work, blacksmithing, gas or coal, glassblowing, woodworking or whatever you're into, you should always be mindful of your surroundings and what your breathing. Hopefully your workspace is well vented and if it is you don't worry about it.

plantprof (author)2015-11-10

Nice project! I especially like your "what not to do" and sharing the "fails" with us to help us avoid those. You mentioned using gas rated yellow teflon tape for this project, but it looks like your regulator, feed hose, and quick release connections all have white tape around the threaded connections [beginning at ~5.00 minutes on the video]. Does it really matter?

HariKarier11 (author)plantprof2015-11-10

Plumbers have been using white Teflon tape for years and for what you're doing you don't have to run to the hardware store to get the yellow one, unless you're building a structure that is inspected and they specify it the plans. White tape is single density, yellow is double density, pink is triple density and green is for the oxygen lines like you find in a hospital. And I think the green is made petroleum free. If you're worried about it, just wrap some more tape around it, but for what you're doing I wouldn't worry about it.

DIY-Guy (author)HariKarier11 2015-11-12

In college, we were told in glass blowing class that burning Teflon (could be Teflon tape too) creates a type of cyanide gas. We were always VERY careful with heat around Teflon.

MaxPower1977 (author)DIY-Guy2015-11-14

Interesting, the joints that require tape all are well below where the nozzle is.

MaxPower1977 (author)plantprof2015-11-10


Yeah it looks white but that tape is 8 years old and been in and out of the sun, so it went from a yellow to a white from the sun. It does make a difference as yellow is gas rated and white is the regular stuff for plumbing (general rule).

Chipper Bert (author)2015-11-09

Nice build. Have you thought of adding a compressed air feed (a lá Benson Burner) to beef up the heat?

Thanks!, Interesting idea for the compressed air, I haven't since I think with propane I can bump up the pressure to get more flow, so it's working well. But I have seen other people use compressed air with natural gas, since I think the pressures are lower or there is less BTUs per same volume of gas.

Back in the stone age (when I was in college) we had burners in the civil engineering lab that were set up like this. As you say, you can't push up the btu content of the gas but the idea is to concentrate a lot of gas into a small area and get it to burn fully by force feeding the oxygen. Sort of similar to a turbocharged engine. But hey I'm a civil engineer not a mechanical one. Please experiment on my behalf. I'm too scared of blowing myself into the next dimension to try it myself...

Chipper Bert (author)2015-11-09

Bunsen! Not Bunsen! Accursed predictive text is worse than Cheque Spell....

thansen871 (author)2015-11-08

i made mine very similar to this, for the nozzle on the end, i just used a reducer, i believe i have a 3/4 black pipe for the main, and it steps up to 1 1/4 for the nozzle.

crabapple0001 (author)2015-11-08

You said drill a cap & skip the other parts????

All you need is a reducer from the larger pipe to the smaller pipe.

Flaky_Jay's (author)2015-11-08

I really enjoy seeing a well written able' so good job. also at most home Depot's you can get pipe cut and threaded to size, I like to get a pipe twice as long as I need than have them cut n thread it to size. I look forward to see what you make next.

OldGuy52 (author)2015-11-08

Very nice! Appreciate the experiences of the first attempts. I would have tried the same.

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