Cutting, Brazing and Rosebud Torch Misconceptions!

This is probably a great time to clear up some misconceptions on Cutting, Brazing and Rosebuds, that alot of welders have.

All the information can be applied to cutting, brazing, fusion or heating, execpt where noted:

Backfire is 99% caused by to much fuel being supplied for a too small of a orifice size, ie; using the wrong sized rosebud or cutting tip for the amount of output heat required. This is the first indication that the mixing chamber pressures are NOT set correct and the pressures are set too high for the given orifice size.

All cutting/heating orifices have a designed pressure rating that's stated from the mfg as the orifice tip body is cooled by the gases flowing from the orifice while in use.

Exceeding the designed orifice pressure rating will cause the ignited acetylene gas to leave the face of the tip body, thus at the same time the flame will add excessive oxygen (oxygen that is obtained from the surrounding air) to the actylene gas that will cause the flame to momentary extinguish, then as the mixed gas cools it reigintes and causes a small explosion as it reignites thus you here the "bang" or poping noise and this condition is called backfire and can be very dangerous.

When the backfire is not corrected by lowering the fuels pressure or volume, acetylene being the fuel in this case, then another EXTREAMLY DANGEROUS condtion will occur called flashback.

Flashback is where the flame that contains oxygen and fuel, is sucked back inside the mixing chamber and will cause a EXPLOSION if not quickly corrected by shutting off the source of oxygen and then shutting of the fuel. Turn off the cylinders in that order as three conditons are generaly considered to cause a explosion, that being oxygen, fuel and a source of ignition.

I added volume to my descriptions as well as pressure because there are some fuels that can explode under the same contions without any warnings as I described above.

Weld Fusion: is where two meatls are joined together by melting a equal amount of molten metal from each piece, either with or without the additon of a compatiable filler metal.

Never run Acetylene above 15psi for any reason!

A drip of liquid black goo from the tip, (ie;runny nose), is usually caused by condensastion mixing with the by-products of combustion then dripping from the tip face. This condition is most likely caused by a air leak into the mixing chamber or tip connections.

Fact: Acetone is a combustitable fuel. You will usually smell acetone while using a touch because the acetylene tank is suppling too much volume of gas for a given tank size for the amount of fuel demand of the mixing chamber and tip OR the the cylinder has been layed on it's side and has not been allowed to stabilize after returning the cylinder to the vertical position. Stablize a vertical acetylene cylinder for 12hrs before using the fuel!

Using too much preheat for the thickness of metal your cutting along with a dirty cutting tip will cause problems.

It's most likely your cutting speed is also too slow but without correcting the first two problems, you will not be able to tell.

What happens when you use too much preheat? The molten metal is very liquid in width and when you try to blow the heated molten puddle with oxygen, the puddle runs to the back of the direction your cutting and reforms a weak bond behind your cutting tip. This new molten puddle is high enriched oxygen and carbon making it very hard and brittle thus when your try to reheat this area it takes longer to preheat as well resist being blown out by the oxygen from the hardness of the metal and will cause molten metal too blow out and back onto the cutter.

With the correct preheat flame temperature the molten puddle will not form as wide thus you will achive a narrow cut without any molten puddle run back.

Using a dirty cutting tip, several problems arise. First with the preheat orifices drity you will not achive a even preheat to start the cut. It will take more preheat to start the cut with a dirty tip than with a clean tip. Second once preheat has been established then the if the center tip orifice is not cleaned then slag will collect on the backside of the base metal and the cut face will be ragged.

The above problems will cause a slower forward cutting speed thus once again cause base metal over heating allowing the harden slag to refrom behind the cutting tip.

The cleanest cut comes from a clean tip. After you clean all the orifice bores in the tip, fire up the torch and set flame for cutting, then depress the cutting lever and observe the flame.

There should be a long very "uniform" inner flame cutting cone. If that inner cone is not "very" uniform then your cut will be ragged just like the flame cone is and the back of the metal will have slag. Reclean the center orifice until it's very uniform.

A cut with a clean tip will have a very smooth cut surface with very little (if any) slag on the backside of the cut. If either one of these is not present reclean the tip.

The center bore orifice can get deformed and the tip needs replaced or cut off. It's really important to hold the cleaning file straight in the bore hole and just removing enough material to clean the bore to make the tip last a long time.

I've never used a new tip that was clean enough for cutting, brazing or heating right out of the box.

Another consideration is as the tip size becomes smaller so does the orifice size and it becomes a bare to clean them ity bity holes. If using an automatic cutting machine then changing tip size would be a production benefit.

Always use a mfg. pressure chart, tip sizing chart and hose sizing chart for setting gas pressures for there brand of mixing chamber and tip combinations.

Setting the proper neutral preheat flame, the orifice holes around the center cutting orifice, can be observed by the tip of the inner flame cone:

A neutral flame has a blue colored flame outer sheild with a light blue to white inner cone flame that is slightly rounded at the cone tip.

A oxidizing flame (too much oxygen) has a sharp pointed very white inner cone.

A reducing flame (not enough oxygen) would have a very round to a ragged thrid inner cone.

Examples:

I have found 5psi acetylene and 30psi Oxygen while cutting to be a good all around setting for upto 50ft of 1/4" hose. Your final pressure setting is regulated by the needle valve adjustments on the mixing body.

For brazing or welding a size #0 tip works well with 5psi Acetylene and 20psi Oxygen. Again the needle valves on the mixing body sets the final pressure needed at the tip.

I also use the above settings to preheat 2" round bar without any problems using the #0 size tip or the rosebud tip.

The advantage to using a rosebud tip is that it expands the flame temperature over a wider area vs using a #0 size tip. I very seldom use my rosebud tip. Preheating with LP saves some expensive gas then finish heating with Qxy/Acet.

Altough theres many different tip sizes, I have a found a No3 makes for a all around good cutting tip as it will cut upto 1-1/2" or 18ga sheet metal depending on the preheat setting.

I strongly urge you too research more information for your safety.

T_Bone

Sorry, you need to get the tip charts from Google search as I don't have that info.

T_Bone

T_Bone

When I was a pup, about 11yo, my neighbor had a carbide generator and I was amazed as my dad only used bottle gas.

The neighbor would always come get me to watch the generator as he cut metal and put up with my 1000 questions of "how come it does that or how come your doing it that way, as my Daddy does it this way"... LOL, My Dad told me in latter years my neighbor was impressed that I had such a quest for knowledge at such a young age.

Jerry, I strongly urge you to use the pressures stamped on your rosebud as the design of the orifice could be that it requires a given pressure setting for tip cooling. Always use the mfg suggested pressure settings.

T_Bone

Sorry, but I've never heard of HGX. How about filling us in as I always like learning something new.

I tried several search engines and didn't find anything that applies to torch cutting/heating with HGX.

T_Bone

(Slag inclusion AWS defined): Inclusions are impurites or foreign substances which are forced into a molten puddle during the welding process.
Cause: 1)improper base metal preperation. 2)improper cleaning of slag in a multipass weldment.
3)faulty electrode manipulation. As you can see, all three are caused by welder error. What alot of welders tend to try when inclusions are incurred, is to push the electrode deeper into the weld puddle thus forcing the inclusion out into the slag puddle where it will be removed with the slag. That rarely will happen. What is more likely to occur is the slag will cold fuse to the hole wall, made from the ellectrode, as the electrode is with drawn to noraml arc length thus covering the inclusion with molten metal leaving the welder to believe he has removed the inclusion as the weld puddle will return to look near normal. On a mulitpule pass weldment, the electrode will doposit more slag on top the exisitng slag inclusion but will have a near normal looking molten puddle this time. This inclusion will contiue to grow with-in the weld until the cover pass is put on. During a bend test the slag inclusion will break out and will show the inclusion from the root pass to the cover pass. Under this circumstance this weldment would fail certification.

A welder has a greater risk of a failed weld by not stopping to clean out the inclusion by grinding or other suitable means.

Faulty electrode manipulation is mostly from the welder varrying the arc length or too long of arc length or the reverse too sort of arc length as described above. The best improvement a welder will see in his welds is when he learns to control the arc length. It doesn't matter what process is used, arc length is very important. Ever wonder why a machine weld looks so great? It's because of the precise controll of the arc length and electrode speed!

On x-rays I've see small slag incusions though out the entire weld shown as small specks on the x-ray. These are usually electrode slag deposits not cleaned off during a multipass weldment but also can be scale and other impurities not cleaned off the base metal before welding. There is a myth that a welder does not have to remove all slag between passes on certian electrodes. This is not true and is what causes all the specks that I see in x-rays. If a welder hurries between electrode changes, he can sometimes restart a rod without chipping the slag without worry of slag and porosity inclusions but this no gaurantee there will not be any slag or porosity inclusions. Another good pratice is to start a bead in a different spot on each pass as this will help elimante any inclusions following though each pass. Depending on the size and spacing of the inclusion, some inclusions are acceptable as sound welds and will certify.

Ovehead weldments have a greater tendency to have both slag and porosity inclusions. As an AWS inspector I have seen alot of this and started watching welders during certification tests and found that is from the welder trying to hurry too much as his mindset is the puddle is going to fall if he goes too slow. A overhead weld should be made just like a flat weld with a very slight increase in electrode speed.

Vertical up welds are best made with good consentration on the molten puddle. This can best be observed welding in the flat position. The weld puddle will be very shinny and will have some swriling action within the molten puddle. The slag looks dull and lumpy will roll to the back of the weld puddle as the puddle moves forward. As the weld puddle forward speed slows the slag will recombine with molten puddle causing the puddle to splatter and gather inclusions and encase the electrode tip causing the electrode to stick to the base metal. The weld puddle width should be about 2 times the electrode diameter. AWS code calls the maxmium weave bead width of 8 times the electrode diameter in any position as any more width than this will cause slag inclusions because the slag cools too much before the electrode returns to deposit more weld.

The best way that I've taught people to weld is have them try what too many amps does, turn down the amps, move too fast, too slow, too long of arc length, too short of arc length, with stopping inbetween each change to see what the weld looks like. This way the welder learns what each wrong effect has. Then when they make a weld that looks wrong, they will know what caused it and how too correct it.

A interesting note, a long arc length with have more uncontrolable heat than a short arc!

Back to verical up welding. Now that you've studied weld puddle control, pay close attention to the molten puddle shape and size. There's going to be slag running around the out side edges of the molten puddle but don't pay attention to it as it will go where it goes and the slag distracts your consentration away from the molten puddle. Don't bother to look where your going as that will come with time as you have to look above the electrode to see where your going and at the same time consentrate on the molten puddle. A weld puddle of 1-1/2 times electrode diameter is much easier to consentrate on when first learning vertical up welding.

Veritcal down welding should be avoided if possible. AWS code does allow a maxmium 2" of vertical down weld on most electrodes. There is a high risk of slag and porosity inclusions while vertical down welding.

The slang "gap rod" will not certifiy under any circumstance. Too wide of a root opening will cause slag inclusions and porosity within root pass of the weld. The proper root opening is 2/3 of electrode diameter with a land thickness 1/4 of electrode diameter.

(Land): the flat area between the back of the base metal extending just to where the bevel starts.

(Porosity): Porosity is the formation tiny pinholes generated by atomspheric contamination or gas entrapment during solidification.

(Root Opening): The gap between the base metals to be welded.

(Root Weld): The first weld bead of a weldment.

6010 and 6011 have very different penetration characteristics with 6010 having the best penetration of any stick electrode. All carbon base metals will weld very simular weather old or new depending on how they are prepared. Alot of welders forget steel on equipment will work harden from viberation thus changing to a tighter grain structure or take on stress. You have to relieve this stress before welding or the weld will soon crack or brake away from the base metal. The easiest way to remove the stress is to heat the base metal to approx 1100F (dull red) and let it cool before welding. This will allow the grain sturcture to return to near normal before welding. As I've stated before, Lincoln 6010 is the finest 6010 I've ever used.

Welding galvanized is an art all to it's own. Technique has every thing to do with making a sound weld. As I stated previously 6010 ran DCEN (straight polarity) is a great electrode for welding glavanized. I have ran hundreds of certification tests over the past 35yrs with 6010 and yet to have a test fail because of the electrode. However, I have seen alot welds fail due to welder error.

T_Bone

I thank GOD for my wife's effort on my numerous threads, as I'm truly blessed with the most warm, loving woman that I ever met. :)

This is probably a great time to clear up some misconceptions on welding that alot of welders have.

(Slag inclusion AWS defined): Inclusions are impurites or foreign substances which are forced into a molten puddle during the welding process. Cause: 1)improper base metal preperation. 2)improper cleaning of slag in a multipass weldment.
3)faulty electrode manipulation. As you can see, all three are caused by welder error. What alot of welders tend to try when inclusions are incurred, is to push the electrode deeper into the weld puddle thus forcing the inclusion out into the slag puddle where it will be removed with the slag. That rarely will happen. What is more likely to occur is the slag will cold fuse to the hole wall, made from the ellectrode, as the electrode is with drawn to noraml arc length thus covering the inclusion with molten metal leaving the welder to believe he has removed the inclusion as the weld puddle will return to look near normal.

On a mulitpule pass weldment, the electrode will doposit more slag on top the exisitng slag inclusion but will have a near normal looking molten puddle this time. This inclusion will contiue to grow with-in the weld until the cover pass is put on. During a bend test the slag inclusion will break out and will show the inclusion from the root pass to the cover pass.

Under this circumstance this weldment would fail certification.

A welder has a greater risk of a failed weldment by not stopping to clean out the inclusion by grinding or other suitable means.

Faulty electrode manipulation is mostly from the welder varrying the arc length or too long of arc length or the reverse too sort of arc length as described above. The best improvement a welder will see in his welds, is when he learns to control the arc length. It doesn't matter what process is used, arc length is very important. Ever wonder why a machine weldment looks so great? It's because of the precise control of the arc length and electrode speed!

On x-rays I've see small slag incusions though out the entire weldment shown as small specks on the x-ray. These are usually electrode slag deposits not cleaned off during a multipass weldment but also can be scale and other impurities not cleaned off the base metal before welding. There is a myth that a welder does not have to remove all slag between passes on certian electrodes. This is not true and is what causes some the specks that I see in x-rays. If welder hurries between electrode changes, he can sometimes restart a rod without chipping the slag without worry of slag and porosity inclusions but this no gaurantee there will not be any slag or porosity inclusions. Another good pratice is to start a bead in a different spot on each multi-pass weldment as this will help elimante any inclusions following though on each pass made.

Depending on the size and spacing of the inclusion, some inclusions are acceptable as sound weldments and will certify.

Ovehead weldments have a greater tendency to have both slag and porosity inclusions. As an AWS inspector I have seen alot of this and started watching welders during certification tests and found that is from the welder trying to hurry too much as his mindset is the puddle is going to fall if he goes too slow. A overhead weldment should be made just like a flat weldment with a very slight increase in electrode speed.

Vertical up weldments are best made with good consentration on the molten puddle. This can best be observed welding in the flat position. The weld puddle will be very shinny and will have some swriling action within the molten puddle. The slag looks dull and lumpy will roll to the back of the weld puddle as the puddle moves forward. As the weld puddle forward speed slows the slag will recombine with molten puddle causing the puddle to splatter and gather inclusions and encase the electrode tip causing the electrode to stick to the base metal.

The weld puddle width should be about 2 times the electrode diameter. AWS code calls the maxmium weave bead width of 8 times the electrode diameter in any position as any more width than this will cause slag inclusions because the slag cools too much before the electrode returns to deposit more weld.

The best way that I've taught people to weld, is have them try what too many amps does, turn down the amps, move too fast, too slow, too long of arc length, too short of arc length, with stopping inbetween each change to see what the weldment looks like. This way the welder learns what each wrong effect has. Then when they make a weldment that looks wrong, they will know what caused it and how too correct it.

A interesting note, a long arc length with have more uncontrolable heat than a short arc!

Back to vertical up welding. Now that you've studied weld puddle control, pay close attention to the molten puddle shape and size. There's going to be slag running around the out side edges of the molten puddle but don't pay attention to it as the slag will go where it goes and the slag distracts your consentration away from the molten puddle. Don't bother to look where your going as that will come with time as you have to look above the electrode to see where your going and at the same time consentrate on the molten puddle. A weld puddle of 1-1/2 times electrode diameter is much easier to consentrate on when first learning vertical up welding.

Veritcal down welding should be avoided if possible. AWS code does allow a maxmium 2" of vertical down weld on most electrodes. There is a high risk of slag and porosity inclusions while vertical down welding. (Edited: 11/13/07)

(Edit:) "I have just read on the Lincoln's website that Lincoln now makes several certifyable electrodes for vertical weldments on both pipe and plate."

The slang "gap rod" will not certify under any circumstance.

Too wide of a root opening will cause slag inclusions and porosity within root pass of the weldment. The proper root opening is 2/3 of electrode diameter with a land thickness 1/4 of electrode diameter.

(Land): the flat area between the back of the base metal extending just to where the bevel starts.

(Porosity): Porosity is the formation tiny pinholes generated by atomspheric contamination or gas entrapment during solidification.

(Root Opening): The gap between the base metals to be welded.

(Root Weld): The first weld bead of a weldment.

6010 and 6011 have very different penetration characteristics with 6010 having the best penetration of any stick electrode.

All carbon base metals will weld very simular whether old or new depending on how they are prepared. Alot of welders forget steel on equipment will work harden from viberation thus changing to a tighter grain structure or take on stress.

You have to relieve this stress before welding or the weldment will soon crack or break away from the base metal.

The easiest way to remove the stress is to heat the base metal to approx 1100F (dull red) and let it air cool before welding. This will allow the grain sturcture to return to near normal before welding. As I've stated before, Lincoln 6010 is the finest 6010 I've ever used.

Welding galvanized is an art all to it's own. Technique has every thing to do with making a sound weld. As I stated previously 6010 ran DCEN (straight polarity) is a great electrode for welding glavanized. I have ran hundreds of certification tests over the past 35yrs with 6010 and yet to have a test fail because of the electrode. However, I have seen alot weldments fail due to welder error.

T_Bone

My personal prefference is 1/8" as it's very easy to control the weld puddle in any position on plate, pipe or open root welds.

Most welding employers will not let you use anything but 1/8" electrodes as the certified welding codes make a welder retest when increasing or decreasing the electrode size more than 1/32" from the code WPS (weld procedure specification).

I also like Lincoln 6010,(old name 5P), and Chemtron 1/8" 7018, as it's the finest 1/8" 6010 &7018 electrodes that I've ever used and over 40yrs welding, I've tried many different electrodes.

T_Bone

KEH

T_Bone