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Old 01-10-2008, 07:41 PM
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Oxy Acetylene Info Needed

I took a welding class and we learned OA welding, so I know how to set the flame to look and sound right to weld. I need to know what to set the PSI at for each. Also, we never learned how to cut using the same set up. Is the flame set the same way? Is the PSI the same? Any help will be greatly appreciated. Thanks

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Old 01-10-2008, 07:55 PM
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Set acetylene at 15 and oxygen at 40. Same for cutting. When cutting you set it a little hotter the thicker the metal you are cutting.
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Old 01-10-2008, 08:25 PM
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Oxy Acetylene welding/cutting

For welding you need a neutal flame, both regs should be set at around 3 to 4 lbs adjust for a neutal flame on your torch. For cutting set the oxygen reg at 40 lbs and the gas at around 4lbs and if you use the rosebud to heat some metal in a hurry the set your gas reg at around 15lbs and oxygen at 40lbs
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Old 01-10-2008, 09:09 PM
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I'll throw mine in the hat to.

8 and 28. 8 on the acetelene, 28 on the oxygen. I've been using that number since I was 20.

I worked with an old welder, and thats the number he taught me. I'm 66, so I guess thats 46 years, because I've always had a set of torches.

On acetelene gauges, they will have a red line at 15 psi, so don't go over that.

If you only use them once in a while, always shut the tanks off and drain the hoses, your gauges will last almost forever.

Before you mount your gauges, just crack the valve real quick, that will get any dirt out of it, and won't get in your gauges.

Rob

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Old 01-10-2008, 09:09 PM
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There really is no simple answer but if you set that Oxygen to 40 PSI for cutting it MAY be right depending on the metal thickness and size of the tip or you may be wasting a lot of Oxygen, for example I just spent the last few days cutting some 1/4" mild steel for a project I am building and with a no.1 tip (Victor J 100) I used 20 PSI on the Oxygen and the Acetylene was set about 5 PSI. As long as the flow volume is high enough the Acetylene pressure is not important but the Oxygen pressure is VERY important! Learning the proper gauge settings is a matter of practice and there simply is no one setting to use all the time, I always set the Oxygen pressure according to the tip size and what I am cutting at the time. You can find charts for your particular torch and tip size that will give approximate settings for different metal thickness and that will be a good place to start but after a short time you will develop a "feel" for what is right. When gas welding the flow volume is what you are concerned with and most of the time about 4 or 5 PSI on the Acetylene and around 10 PSI on the Oxygen is just fine. Pressure settings are not critical to gas welding as long as you have enough volume since the flow will be determined by the valve adjustment on the torch and you simply need enough to supply the flame to the setting you need. My hat is off to you for learning that very respected skill and it is a shame more people don't do the same, Oxy/Acetylene welding is a very useful skill to have and a lot of people might be surprised at what a person can do with a good welding torch.
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Old 01-11-2008, 08:18 AM
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15 and 40? Is someone cutting an aircraft carrier in half?

Acetylene becomes unstable above 15 PSI.

Pressures are determined by the tip size.

Speaking of tips - When you're welding, if you get popping that blows hot metal in all directions, you need to raise the acetylene pressure a bit.

I light the acetylene (Yes Paris, that's is the one that burns), get the flame big enough to stop making soot, introduce the Oxygen and then add more acetylene and then trim the Oxygen to a very slightly sharp inner fame.

Another tip; Plant your corn early.
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Old 01-11-2008, 09:21 AM
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Acetylene is a bomb ready to go off and as stated above, don't raise the pressure any higher than necessary to get the job done. I leave mine at 4 or 5psig all the time. Acetylene is so unstable it must be stored dissolved in liquid acetone inside your cylinders. The free gas will auto explode when conditions are right and you don't want to experiment to find out what those condition are!! When you start using it, it comes out of solution with the liquid. You never want to pressure up the gas any more than necessary.

The oxy setting should be the same as the acetylene setting for welding. This allows adjustment of the flame with the valves on your torch head. If the gasses are at significantly different pressures, it is a bear getting the flame mixture under control. Bump the oxy to 20psig or so for cutting most normal thicknesses of steel. You rarely need more than that. Again, the valve on the torch head are there for the fine tuning.
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Old 01-11-2008, 10:11 AM
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Quote:
Originally Posted by willys36@aol.com
You never want to pressure up the gas any more than necessary.

The oxy setting should be the same as the acetylene setting for welding. This allows adjustment of the flame with the valves on your torch head. If the gasses are at significantly different pressures, it is a bear getting the flame mixture under control.
Right, especially the part about never going higher than necessary!

It is a common mistake to turn up gas pressure in an attempt to get the torch to stop popping but this will not help. The control valve is nothing more than a "choke" valve that simply restricts the amount of gas that can squeeze by at any given pressure so the size and intensity of the flame is determined by how much the valve is opened (more for low pressure, less for high), the flame will be the same no matter what the pressure as long as it is high enough to adjust the flame to where you want it. A simple way to envision this would be to, using a welding tip, adjust the flame until it just breaks away from the tip using 5 PSI then set the gauge at 10 PSI and adjust the flame until it again just starts to break away-the two flames will be identical but with the higher pressure the valve will not be opened as far. The higher pressure would allow you to adjust the flame higher than the low setting but since the 5 PSI gauge setting will supply more than enough volume for most welding tips there simply is no reason to go higher than that. With a higher pressure, as you pointed out, the valves will be "touchier" (Did I just invent another word?) which will make the torch harder to adjust plus raising the possibility of forcing Oxygen into the lower pressure fuel line which can cause a hazardous condition, backflow valves should aways be be used but unfortunately they are often not used.
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Old 01-13-2008, 07:00 PM
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15 and 40 as oldred says,the torch is the adjustment you need..not the regulators.
The Tip size is what's important as in the thickness your cutting.

One thing they may or may not of told you since your new to this but im gonna throw it out there for those who may not know..NEVER..and i do mean NEVER!!..put oil or grease on ANY fittings,torch,hoses,regulators,tanks..etc..INSTAN T ignition,
If the threads are screwed up on it,either use a thread file to repair or replace it..I mean this in a SEVERE way..its not IF it ignites..it WILL ignite,lots of people have been severly injured and killed from it,exploding regulaters..torches..etc
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Old 01-13-2008, 08:36 PM
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Quote:
Originally Posted by oldred
As long as the flow volume is high enough the Acetylene pressure is not important but the Oxygen pressure is VERY important! Learning the proper gauge settings is a matter of practice and there simply is no one setting to use all the time, I always set the Oxygen pressure according to the tip size and what I am cutting at the time. .
Oldred is right on regarding the oxygen pressure with respect to cutting. In fact, the acetylene isn't involved in the cutting. It is only used to raise the metal to it's ignition temperature. When you push the oxygen trigger to cut, the metal actually becomes the fuel. I used to win bets by turning off the acetylene while cutting and use only oxygen to continue the cut. Wonder if my hands are still steady enough to pull that one off today?
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Old 01-14-2008, 08:44 AM
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Quote:
Originally Posted by redsdad
I used to win bets by turning off the acetylene while cutting and use only oxygen to continue the cut.

LOL, I have won a couple of bets doing the same thing! It is surprising how many welders, sometimes ones with years behind them, that have no idea what is actually happening when they trigger that Oxygen. Most of the time the argument starts when someone makes the age-old statement that "the Oxygen pressure needs to be high so it can blow the molten metal out of the cut". It may surprise some to know that the metal does not have to actually melt before it will cut, it will start to cut just before it reaches the melting point if it is clean and there is no mill scale on it. The metal is not "blown out" by the Oxygen stream it actually begins to burn and will create enough heat to continue the cut far past the point the flame can reach and, theoretically at least, once the cut is started the Acetylene would no longer be necessary. This of course is not practical and conditions would have to be absolutely perfect with a perfectly steady Oxygen stream but it can be done to a point and in some cases Oxygen is used without fuel other than the steel itself, a lancing rod for instance does not use fuel gas once the burn is initiated. Using too much Oxygen pressure to make a cut will cause excess dross (slag) on the bottom of the plate making it hard to separate the pieces plus requiring more clean up effort along with a couple of other more minor undesirable characteristics. Just as there is no one size of cutting tip for everything there simply is no one pressure setting that will do everything so the welder must learn from experience what works and the Oxygen pressure must be adjusted to the task at hand and it is not at all practical to try to rely on any one pressure setting. As a rule of thumb (whatever that means ) for the cleanest most efficient cut use the smallest tip that will easily do the job for what you are cutting and lowest Oxygen pressure that will easily cut through the material, a tip that is too big and pressure that is too high will cause wasted fuel and material along with a ragged cut and excess metal warpage. If the tip is too big and/or the pressure too high it is easy to use 2-3 (or more!) times as much gas as is necessary which can get quite costly in addition to a poor quality cut.

Last edited by oldred; 01-14-2008 at 11:44 AM.
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Old 01-26-2008, 06:19 PM
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Here is a chart to follow. All this other stuff is BS and going to get someone hurt. As someone said acy is a bomb waiting to go off. Do it right or leave it to a pro.

http://www.hoopersupply.com/tipchart.html

Also read the warnings on this site about using acy too fast out of the bottle.

http://www.hoopersupply.com/weld.htm
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Old 01-26-2008, 09:53 PM
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Quote:
Originally Posted by RPM
All this other stuff is BS and going to get someone hurt.

What was said that was BS and going to get someone hurt? In fact what the majority said, with the exception of a fixed setting recommendation for everything, is pretty much right on and in fact inline with your chart. I even suggested to use a chart as a starting point for any particular tip/metal combo until the operator becomes accustomed to the torch and can set it for the particular task at hand from experience, that chart is certainly a good guideline to follow but even those figures do not have to be absolutely adhered to (within reason) and tuning the torch for the job is just part of what the welder has to learn. Since you think ALL everyone said was BS would you care to explain what was said that is going to hurt everyone? Maybe you can point out all the things that was mentioned that is so terribly wrong.
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Old 01-27-2008, 07:23 AM
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Set acetylene at 15 and oxygen at 40. Same for cutting. When cutting you set it a little hotter the thicker the metal you are cutting.


15 on the acy is way too much. It "COULD" run the bottle out too fast and couse a problem.

15 on the acy is enough to cut 12" thick plate with, As somebody else said you going to cut a battle ship in half.

I have a pantograph and cut 3/8 and 1/2 all the time. I run about 4 on the acy and 20-25 on the ox. Looks like it was cut with a band saw.
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Old 01-27-2008, 09:57 AM
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I agree that 15 PSI Acetylene is borderline (however it is still inside the permissable range) and rarely would there be a need for it although it is no more inherently dangerous whether you are cutting 1/2" plate or 12" plate nor would it cause the tank to run out any faster, just that like any pressurized gas the lower the setting that can adequately do the job the better and this was pointed out more than once and by more than one person. The amount of gas you use is measured in volume and unless you turn up the flame higher the amount used will be the same regardless of the gauge setting, 5 PSI would yield the same usage rate as 15 PSI assuming the torch is adjusted to the same flame intensity the difference would be that with the higher pressure the valve on the torch would not be opened as far, not true for Oxygen when cutting however since the cutting circuit is wide open. 15 and 40 as a setting for welding is way to high and this was pointed out repeatedly also it is quite unbalanced even for cutting although there are a great many situations where 40 PSI on the Oxygen would be called for. Acetylene pressure determines the flow POTENTIAL not the absolute amount of gas being used that is determined by the valve setting, higher pressure will yield the same flame as a lower pressure but with less valve opening (assuming the low pressure setting is high enough to supply the volume required to produce the desired flame). There is nothing wrong with your advice but to say that all everyone else offered is BS is just plain BS in itself and in fact is hardly different from what you are suggesting, most of it anyway. Personally I am well familiar with torches and torch settings since I have made my living with the darn things for nearly 40 years and besides the usual steel plate in various thickness I have cut a great deal of metal (in the form of alloy steel castings) in excess of 14" thick, this was done by hand since it was always on-site. Take a good look at what is said before you tell everyone that ALL they have offered is BS because there was some sound advice offered and if you can't recognize that then you better keep that chart handy because you obviously are no pro.
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