How to Build a Propane Forge Burner





Introduction: 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

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

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

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

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

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.



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

    You're on the wrong website, Gary.

    I doubt that's the case. It's not uncommon for purchasing something to be more financially(or otherwise) sensible than attempting to build your own. I'm a machinist by trade and could probably build a half dozen of these from the scrap pile at work, costing me nothing more than the time to do so. That said, if it takes me more than a couple hours each, then it's cost me more overall than just buying them outright.... Not a wise choice when there are a million other things far more important(and productive) that I could be doing.

    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


    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

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

    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.

    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.