If you’re wondering about an oxy acetylene welding pressure settings chart, you’re diving into a topic that’s super important for getting strong, clean welds. I’ve been welding with oxy acetylene for years in my shop, and setting the right pressures has been a game-changer for my projects.
When someone asks me, “What’s the deal with oxy acetylene welding pressure settings?” I love sharing what I’ve learned from trial and error, burned tips, and plenty of practice. Let’s sit down together, and I’ll walk you through everything you need to know, based on my own hands-on experience.
Oxy acetylene welding uses a mix of oxygen and acetylene gases to create a hot flame for joining metals. The pressure settings for these gases are critical—they affect the flame’s heat, stability, and how well your weld turns out.
I’ve messed up welds by setting pressures too high or too low, so I know how important it is to get this right. I’ll explain what oxy acetylene welding is, why pressure settings matter, how to set them correctly, and provide a practical pressure settings chart.
What Is Oxy Acetylene Welding?
Oxy acetylene welding is a process that uses a flame created by mixing oxygen and acetylene gases to melt and join metals. The flame can reach temperatures up to 6,300°F (3,480°C), hot enough to weld steel, cast iron, or even braze dissimilar metals.
I’ve used oxy acetylene to weld everything from car frames to custom art pieces, and it’s versatile because you can control the flame precisely.
The setup includes two gas cylinders (oxygen and acetylene), regulators, hoses, and a torch with a welding tip. Regulators control the pressure of each gas, and the torch mixes them to create the flame.
Getting the pressures right is key to a stable flame and a strong weld. I learned this the hard way when I set my acetylene too high and got a sooty, unstable flame that ruined a weld.
Why Are Pressure Settings Important?
Pressure settings determine how much oxygen and acetylene flow to the torch, which affects the flame’s type and quality. There are three main flame types:
- Neutral Flame: Equal parts oxygen and acetylene, ideal for most welding. It’s clean and precise, with a sharp blue cone.
- Oxidizing Flame: More oxygen, hotter but can burn the metal. I’ve used it for cutting but avoid it for welding.
- Carburizing Flame: More acetylene, cooler and sooty. It’s good for brazing but messy for welding.
Incorrect pressures can cause problems. Too much acetylene makes a sooty flame that deposits carbon on the weld. Too much oxygen can oxidize the metal, weakening it. I’ve had welds fail because I didn’t balance the pressures, so I always double-check my settings. The right pressures ensure a stable flame, clean welds, and safety.
Oxy Acetylene Pressure Settings
Pressure settings depend on the welding tip size, material thickness, and type of welding or brazing. Regulators have two gauges: one for tank pressure (how much gas is left) and one for working pressure (what’s delivered to the torch). I focus on the working pressure, measured in PSI (pounds per square inch).
Oxygen pressures are typically higher than acetylene because oxygen supports combustion. Acetylene pressures are kept low to avoid instability—never go above 15 PSI for acetylene, as it can become explosive.
I’ve always stuck to this rule to stay safe. The exact settings vary based on your torch manufacturer and tip size, but I’ll share a general chart that’s worked for me.
Oxy Acetylene Welding Pressure Settings Chart
Here’s a pressure settings chart I use for oxy acetylene welding, based on common tip sizes and material thicknesses. These are guidelines I’ve refined over years of welding steel in my shop. Always check your torch manufacturer’s manual for specific recommendations.
| Tip Size | Material Thickness | Oxygen Pressure (PSI) | Acetylene Pressure (PSI) | Best For |
|---|---|---|---|---|
| 000-1 | Up to 1/16” (1.5mm) | 3-5 | 3-5 | Thin sheet metal, light welding |
| 2-3 | 1/16” to 1/8” (1.5-3mm) | 5-7 | 5-7 | Medium sheet metal, small parts |
| 4-5 | 1/8” to 1/4” (3-6mm) | 7-10 | 7-10 | Thicker steel, structural welds |
| 6-7 | 1/4” to 1/2” (6-12mm) | 10-15 | 8-12 | Heavy steel, large repairs |
| 8+ | Over 1/2” (12mm) | 15-20 | 10-15 | Thick plates, heavy-duty welds |
Notes:
- For brazing, use slightly lower pressures (1-2 PSI less for both gases) for a softer, carburizing flame.
- For cutting, increase oxygen pressure significantly (20-40 PSI) with a cutting tip.
- Never exceed 15 PSI for acetylene to avoid safety risks.
This chart is a starting point. I adjust slightly based on the torch brand (like Victor or Harris) and the specific job. Let’s dive into how to set these pressures and use them.
Tools and Materials You’ll Need
To set up and weld with oxy acetylene, you need the right gear. Here’s what I keep in my shop.
- Oxy Acetylene Torch Kit: Includes torch handle, welding tips, and cutting attachment. I use a Victor-style torch for reliability.
- Oxygen and Acetylene Cylinders: Full tanks with at least 1000 PSI (oxygen) and 250 PSI (acetylene) to start.
- Regulators: One for each gas, with dual gauges for tank and working pressure. I check for leaks before every use.
- Hoses: Red for acetylene, green for oxygen. I inspect them for cracks regularly.
- Welding Tips: Different sizes (000 to 8) for various material thicknesses. I keep a range on hand.
- Flint Striker or Spark Lighter: To ignite the flame safely. I prefer a flint striker for simplicity.
- Filler Rods: For welding or brazing. I use mild steel rods for steel and bronze rods for brazing.
- Flux: For brazing to clean the metal and help the filler flow. I use borax-based flux.
- Safety Gear: Welding gloves, tinted safety glasses (shade 5 or 6), and a flame-resistant jacket. Sparks and UV light are serious hazards.
- Soap Solution: To check for gas leaks. I mix dish soap and water in a spray bottle.
- Wrench: To adjust regulators and open cylinder valves. I keep an adjustable wrench dedicated to my torch setup.
- Fire Extinguisher: For safety, especially with acetylene. I keep a Class B extinguisher nearby.
Step-by-Step Guide to Setting Oxy Acetylene Welding Pressures
Here’s how I set up my oxy acetylene torch and dial in the pressure settings for welding, based on what’s worked for me.
Step 1: Set Up Your Workspace
Safety is my top priority. I work in a well-ventilated area, away from flammable materials like oil or paper. My cylinders are chained upright to a cart or wall to prevent tipping. I set up on a fireproof surface, like a steel table or firebricks, to handle sparks. I wear my safety gear—gloves, tinted glasses, and a jacket—because acetylene flames are bright and hot.
I keep a fire extinguisher nearby and clear the area of rags or other flammables. I also check that my hoses are free of cracks and my regulators are in good shape.
Step 2: Inspect and Connect Equipment
Before setting pressures, I inspect my gear. I check the oxygen and acetylene cylinders for tank pressure—oxygen should be above 500 PSI, acetylene above 100 PSI. Low tanks can cause unstable flames. I connect the regulators to the cylinders, ensuring the threads are clean and tight.
I attach the red hose (acetylene) and green hose (oxygen) to the torch and regulators, checking for secure connections. I use a soap solution to spray the connections and look for bubbles, which indicate leaks. I once had a small leak that caused an unstable flame—checking saves headaches.
Step 3: Choose the Right Welding Tip
The tip size depends on the material thickness. I use the chart above to pick the right tip—small tips (000-1) for thin metal, larger tips (4-7) for thicker steel. I screw the tip onto the torch handle and tighten it with a wrench, making sure it’s secure but not over-tightened.
Step 4: Set the Pressure Settings
Here’s how I set the pressures using the regulators:
Acetylene: Open the cylinder valve slowly (1/4 to 1/2 turn). Turn the regulator T-handle to set the working pressure based on the chart (e.g., 5 PSI for a #2 tip). Never go above 15 PSI—acetylene can become unstable.
Oxygen: Open the oxygen cylinder valve fully. Set the working pressure higher than acetylene (e.g., 5-7 PSI for a #2 tip). Oxygen supports the flame, so it needs a bit more pressure.
I double-check the gauges and make small adjustments while testing the flame. If the flame is too weak, I increase both pressures slightly; if it’s too wild, I lower them.
Step 5: Light and Adjust the Flame
Open the acetylene valve on the torch slightly and light the flame with a flint striker. You’ll get a yellow, sooty flame at first. Slowly open the oxygen valve until the flame turns blue with a sharp inner cone—this is the neutral flame I use for welding. If it’s too pointy (oxidizing), reduce oxygen; if it’s too soft and green (carburizing), reduce acetylene.
I practice on scrap metal to fine-tune the flame before welding. A stable neutral flame is key to clean welds.
Step 6: Weld and Monitor
With the pressures set and flame adjusted, I start welding. I hold the torch at a 45-degree angle, heat the metal until it forms a molten puddle, and add filler rod as needed. I keep an eye on the flame—if it starts to sputter or change, I check the pressures or tank levels. I’ve had welds go bad because a tank ran low mid-job, so I monitor closely.
After welding, I let the metal cool naturally to avoid cracking. For brazing, I use a slightly carburizing flame and apply flux to the joint.
Common Mistakes to Avoid
I’ve made plenty of mistakes with oxy acetylene welding, and I want you to skip them. Here are the big ones:
Wrong Pressure Settings: Too much acetylene makes a sooty flame; too much oxygen burns the metal. Stick to the chart and adjust for your torch.
Exceeding 15 PSI Acetylene: High acetylene pressure is dangerous and can cause explosions. I never go above 15 PSI.
Dirty Tips: Clogged tips cause unstable flames. I clean my tips with a tip cleaner regularly.
Ignoring Leaks: Gas leaks waste fuel and are a fire hazard. I always check connections with soap solution.
Poor Flame Adjustment: Welding with an oxidizing or carburizing flame ruins the weld. I practice getting a neutral flame every time.
Skipping Safety: No gloves or glasses can lead to burns or eye damage. I wear full safety gear, no exceptions.
Safety Tips for Oxy Acetylene Welding
Oxy acetylene welding is safe if you’re careful, but it’s easy to get hurt if you’re not. Here’s how I stay safe:
Wear Safety Gear: Welding gloves, tinted safety glasses (shade 5 or 6), and a flame-resistant jacket protect against sparks and UV light.
Work in a Ventilated Area: Acetylene and oxygen fumes can build up. I work outside or use a fan to keep the air clear.
Secure Cylinders: Chain cylinders upright to prevent tipping, which can damage regulators or cause leaks.
Check for Leaks: Use a soap solution to test connections. I spray every joint before lighting the torch.
Keep a Fire Extinguisher: Acetylene is highly flammable. I keep a Class B extinguisher within reach.
Turn Off Valves: When done, close cylinder valves and bleed the hoses to release pressure. I do this every time to avoid leaks.
Suggestions for Oxy Acetylene Welding
Here are some tips I’ve picked up to make welding with oxy acetylene easier and more effective:
Practice on Scrap: Weld on scrap metal to dial in your pressure settings and flame before starting your project.
Clean Tips Regularly: Use a tip cleaner to keep the torch’s flame steady. I clean after every few welds.
Check Tank Levels: Low tanks cause unstable flames. I check gauges before starting to ensure I have enough gas.
Use the Right Tip: Match the tip size to the material thickness using the chart. It saves gas and improves welds.
Learn Flame Types: Practice adjusting to a neutral flame. It’s the key to clean, strong welds.
Keep a Log: Note the tip size, pressures, and results for each weld to repeat successes.
Start Small: Begin with thin metal and small tips to build confidence before tackling thicker steel.
Inspect Hoses: Check hoses for cracks or wear before each session to prevent leaks.
Conclusion
Oxy acetylene welding with the right pressure settings is a skill that can transform your metalworking projects. It’s a versatile process that lets you weld, braze, or cut with precision, and getting the pressures right makes all the difference.
I still remember my first clean weld with a perfectly set neutral flame—it was smooth, strong, and something I was proud of. With the pressure settings chart and these steps, you can achieve the same results. Grab your torch, double-check your regulators, and start welding. You’re on your way to creating strong, beautiful welds, and I’m rooting for you to nail it!
FAQs
What are safe pressure settings for oxy acetylene welding?
For most welding, set oxygen at 3-15 PSI and acetylene at 3-12 PSI, depending on tip size. Never exceed 15 PSI for acetylene.
How do I know if my flame is set correctly?
A neutral flame is blue with a sharp inner cone. If it’s pointy, it’s oxidizing (too much oxygen); if it’s green and soft, it’s carburizing (too much acetylene).
Can I use the same pressure settings for brazing?
Brazing uses slightly lower pressures (1-2 PSI less) than welding for a softer, carburizing flame. Check your torch manual for specifics.
Why is my oxy acetylene flame unstable?
Unstable flames can come from wrong pressures, clogged tips, or low tank levels. Check your settings, clean the tip, and ensure tanks have enough gas.
Is oxy acetylene welding safe for beginners?
Yes, with proper safety gear, ventilation, and leak checks. Start with low pressures and small tips, and practice on scrap to build confidence.
