Question for the experts about gas welding.

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What kind of rod is used in torch welding?  do you use fluxed rod?  is there a specific material/rod for this type of welding?  can you weld any kind of steel, stainless/aluminum/etc...when gas welding?  I've read about techniques for this kind of welding, just nothing about materials or consumables.  any help is appreciated.  thanks
Reply:Clothes Hanger
Reply:Rubenz, funny reply, but i got a feeling your being serious.
Reply:Originally Posted by babydaddyRubenz, funny reply, but i got a feeling your being serious.
Reply:You can practice with hangers or do non-critical stuff, but you shouldn't do much else.  The quality of the metal is not generally known by the welder or graded in any way.  Some have coatings that will contaminate the weld.  Others are not good steel at all and have very low strength.you can weld mild steel, just flame and filler.You can weld aluminum, but you generally need flux.  You can get flux-cored rods from airgas or other suppliers. I don't know about stainless.  I think maybe no.http://www.key-to-steel.com/Articles/Art97.htmKeep in mind, many folks learned gas welding in school and never did it much afterwards.  There are exceptions, though.  Lots of aircraft builders do aluminum gas welding.  Done well, it's pretty nice...but bad welds are much easier to make, if you know what I mean.  Last time I welded with gas was probably 10 years ago and not by choice...so take this for what it's worth...not from an old pro, but from someone who has done enough oxy/ace welding to choose another method.Last edited by smithboy; 04-18-2006 at 12:54 PM.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Clothes hangers are the worst kind of crap to use . Way to much carbon in  it . If you are to poor to use real welding rod, (wire) & insist on using coat hangers , heat the hanger red hot & let it cool some , before using . when using the hangers , notice all the sparks you get . that's  bad. Sorry, i get pissed when i hear some body saying that coat hangers are o k . They're NOT .
Reply:just to clarify. I never said they were ok to use LOL. just that I've seen people use them.
Reply:so, for clerification, use a standard weld rod for filler(fluxless) for appropriate steel thickness?
Reply:Roy is right...if you are building a candle holder, coat hangers wont hurt anything...if you are building a chair, beware...if you are building a trailer, get ready for an accident and a lawsuit.For steel, standard rod is right.  You can use mig wire also...same stuff pretty much, just floppier.  You can take a long piece of mig wire (not fluxcore), fold it 3 times, hang one end on a stationary object, and twist it with a drill to make a piece of thicker filler.  I know you just got a feeder and this trick might come in handy.  After a day or two of migging, I always end up with a couple of 15 foot pieces of wire that I had to pull out of the gun.  I save them and make a few pieces of tig filler.  Waste not...Last edited by smithboy; 04-18-2006 at 01:06 PM.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Any TIG welding rods work with the gas torch, but there are also gas specific rods.  Any of Lincolns RG rods are forumulated for gas and that is typically what I use.  RG60 will give you comperable strength to the TIG rods and makes a nice looking bead.  RG45 is weak and the bead appearance isn't that great.  I don't know why they make it, RG60 can do everything it can and do it better for the same price.
Reply:The clothes hanger, clean bare metal, is essentially a RG-45 wire.  Mechanically they are pretty much the same.  However, this is only giving you 45,000 psi of tensile strength.  An E6011 or E6013 welding rod for stick has 70,000 psi of tensile, and an E7018 or ER70S-6 like used in mig and tig will produce 70,000 psi of tensile strength.  Therefore you can see there is a pretty good jump between the tensile strength.  Also, having very clean bare metal does make a differnce.  There is a RG 60, and possibly more.  Lincoln I know of makes an RG 60.  This is much closer to the strength gained by a E6011 or E6013 rod.  Of course penetration is totally differnt.  The penetration will probably be closer to that of E6013 which will have a big impact on strength depending on application.  With this all said and done, for most applications without load bearing such as a trailer or automobile structure, the RG 45 would suffice.  Lets say you are puttng on a fender, or making a mail box, or you are welding some art work, the RG 45 would be fine.  If you are welding the frame of a trailer, I would think of nothing less than a E6011 or E6013 depending on thickness, and I personally choose to use E7018.   E7018 is a structural rod and its not always the most user friendly...usually far from it.  Once you learn to use it though youll find it to be a good rod.IF it Catches...Let it Burn
Reply:I don't understand, the question was asked about gas welding wire and you're going off on arc welding electrodes?
Reply:thanks for the insight guys.  I'm mostly interested in structural welds that my mig machine can't handle.  Anything on a trailer should be able to be got with the mig, but i'd like to fab up a winch plate and mount.  Don't know design on this yet, but i'm thinkin that some 3/8"-1/2" stuff is in order to hold the weight of the winch and the load of the winch pull.  before i get into something structural like that i'll be sure and get more advise from ya'll for design and do a lot more unstructural welding for practice.  thanks again.
Reply:Originally Posted by smithboyYou can take a long piece of mig wire (not fluxcore), fold it 3 times, hang one end on a stationary object, and twist it with a drill to make a piece of thicker filler.  I know you just got a feeder and this trick might come in handy.  After a day or two of migging, I always end up with a couple of 15 foot pieces of wire that I had to pull out of the gun.  I save them and make a few pieces of tig filler.  Waste not...
Reply:so next question, do i have to knock the flux off the RG60 rod before i use it as a filler or can it stay on?  is that a dumb question?  probably not real cost effective to buy sticks and knock 50% of the price off it?  is there a standard steel only rod for this application?
Reply:There is no flux on RG60 or any gas/TIG rod for steel.  Gas welding steel over 3/16" of an inch thick, especially butt welds and T welds is extremely difficult.  Do practice a lot and do destructive testing to ensure you're getting good penetration.  Lay some T welds and butt welds and cut them up to get an idea of the penetration.
Reply:babydaddy, i wouldn't recommend gas welding steel 3/8"-1/2" for your application, stick it if your mig can't handle it.
Reply:thanks for the info guys.  i guess i was under the impression that if i couldn't get my mig to do the beefier stuff than i could use the torch.  After playin with the torch a little, i can see that it will and is difficult to get a consistant melt goin on.  I've said before that i've got a buddy with a buzz box and can use it anytime.  I'd like to have one in my garage though just cuz.  can't ever have enough tools .  thanks again.  ya'll are very kind to give up info that most folks have to go to school for.
Reply:Originally Posted by smithboyYou can weld aluminum, but you generally need flux.  You can get flux-cored rods from airgas or other suppliers. I don't know about stainless.  I think maybe no.http://www.key-to-steel.com/Articles/Art97.htm
Reply:That's good info.  I had never heard of welding stainless with a flame.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Go to your local welding supply and request OA gas welding rods. They sellthem by the pound and in the diameter that suits your application. These rods have deoxidizers incorporated in them and a light copper coating to resist rust. Notice I said resist because bare OA rods will rust over timeunless you take certain precautions.
Reply:Someone can shed more light on the following designations :E means a covered electrodeER means an electrode either wire or rollS means solid
Reply:pretty much got it covered.  The E designation related to stick or flux core wireThe ER being Electrode Rod is either mig solid wire or cut length...since they are mechanically the exact sameThe S as is posted is as opposed to T for tube.  C = coredExamplesE7018       SMAWER70S-6    GTAW/GMAW solid wireE70C-6M   Flux core gas shieldedE70T-3     Self shielded flux coreIF it Catches...Let it Burn
Reply:Originally Posted by TxRedneckpretty much got it covered.  >snip.  C = coredExamplesE7018       SMAWER70S-6    GTAW/GMAW solid wireE70C-6M   Flux core gas shieldedE70T-3     Self shielded flux core
Reply:WoW!!  You guys just flew way over my head with all the rod and wire designations .  I'd like to give the gas welding a shot someday, but for now i'll concentrate on gettin good beads with the new mig.  I found a used red face buzz box and am thinkin of picking it up.  from what i hear and read, you can't go wrong with the red AC225 stick .  thanks for the replies and keep the conversation goin cuz it's very valuable info for us beginners  even if it's confusing.  ive been taking notes and printing out some of the info here for refs. later on. .I would personally not use oxy/acytelene welding for thicker metal - you're much better off having it stick welded as  you will get better penetration.  I have used oxy-acetelene quite extensively, but mainly for tubing and 1/8" or smaller guage metals.Typically you would use the same rod for both TIG and oxy-acytelene.  The exception is when you're using a flux-coated brazing rod - you would remove the flux for TIG (or purchase flux-less rod).Re the weld strength, you're going to have to put a tremendous amount of heat into your metal to try and weld 3/8" or 1/2" steel with oxy-acytelene.  As hot as you'll have to get it, when it cools you'll get a lot of warpage and stress on the weld, with poor penetration.  It will probably crack or break; especially with the kind of loads that a winch will put on it.You can probably pick up a used stick welder for less than $200.00 - a good investment.
Reply:Originally Posted by lotechmanOops!  You'll find that C-6 is metal core wire as opposed to tubular flux core wires which are designated with "T".  I use C-6 all day long.  "T" designated wires can be self shielded or gas shielded flux core.  I continually have to ask which ones are all position... or figure it out the hard way.  Originally if we tested on any flux core we were good for metal core wire.  Not so any more.  We have to test with metal core and test with the flux core.
Reply:Originally Posted by babydaddyWoW!!  You guys just flew way over my head with all the rod and wire designations .  I'd like to give the gas welding a shot someday, but for now i'll concentrate on gettin good beads with the new mig.  I found a used red face buzz box and am thinkin of picking it up.  from what i hear and read, you can't go wrong with the red AC225 stick .  thanks for the replies and keep the conversation goin cuz it's very valuable info for us beginners  even if it's confusing.  ive been taking notes and printing out some of the info here for refs. later on. .
Reply:You can get fine penetration on thick metal using an acetylene torch.  If you use the right tip and turn your gas pressures up, you can use the inner cone like a gouging torch that gouches the base metal as you lay in new filler.  Leaves an ugly weld compaired to using a nice soft flame, but it gives good penetration.  I may weld on up for you and take some pictures if I get time.  You are right about the excessive heat, though.
Reply:one question that was never answered outright can you O/A weld using stick electrodes ie E6010 or E6011Matt the Alaskan red neck
Reply:Knock the flux off and use the bare steel.
Reply:Geez matt and I could have told you that lolwhy not use a 7018 that got wet though IF it Catches...Let it Burn
Reply:Well, we had some people on this forum telling us about things they do not know about.  I just welded up a small piece of 1/4" plate with a torch to disprove some misconceptions.  A torch can do thick metal and a torch can get good penetration.I made this joint without using any special preperation techniques.  The metal was left as cut with the torch and there was no beveling, gouging, or preheating done prior to the weld.  Now, with steel and gas prices the way they are right now, I can't afford to practice on thick metal a lot so the weld doesn't look good.  But, it did the job with full penetration and no undercutting.  Welding the thick metals is very tricky.  The weld is sound, and with practice could look good as well.The topside of the weld.  I used a backhand technique where the torch faces towards the bead and you feed filler from the side of the bead.The backside of the weld.  Once I got everything figured out, I pretty much had 100% penetation.  I'd like to see you do that with a MIG welder.A disection of the weld reveals 100% penetration and no porosity/The other side had a little less than 100%, but still very acceptable.The welding was done with a Smith medium duty torch using a #208 tip, 3/32" RG60 filler, and a backhand technique.
Reply:I certainly agree that thick steel can be welded with the OFW process.  But when senctioning a weld for visual inspection, you have to get rid of the smears caused by such an agressive saw.  Then, etch it with some acid and you'll be able to see your exact bead profile.
Reply:No offense but from my background thats not considered CJP.   Complete joint penetraion would appear like a small weld on the backside.  This is not what is seen here.   For the most part what was said was that oxy-fuel is not a practical process compared to electric processes for thicker material.   Thats my stance and IM sticking to itIF it Catches...Let it Burn
Reply:if that were a "test plate" , it would be considered 50% penetration , at best . the "red neck" is right . THE issue, i think , is that a person ,when welding , needs to  "KNOW"  what they're doing . Guessing just DOESN"T get it , when the chips are down . I really like to use my short arc, (mig) ; BUT - if if I am NOT  TOTALLY sure( confident)  of it , I know i can trust the 7018 welds from my dc 250 miller dial  arc or even better, my lincoln sa250 diesel generator .
Reply:I do like 7018, but the penetration is considered low.  Not sure exactly where or how they obtain figures on these things.  However, they say 6011 or 6010 is deep penetrating.  That it is.  I guess if you compare the two, the 7018 is low penetrating compared to 6011.  6011 is deep penetrating.  BUt if Im really concerned about the root penetration ie CJP root pass pipe weld I use a 6010 and then will it up and cap with a 7018.  The 7018 is a high strength rod that offers great ductility and strength.  Its a great rod for a lot of applications.IF it Catches...Let it Burn
Reply:76GMC, I think that we're comparing apples to oranges here.  The request made early on was to weld a winch mounting plate from either 3/8" or 1/2" steel.  Your demo was 1/4" - significantly different than welding 1/2"...Yes, you can weld them with oxyacytelene, but like the others I maintain that all things being equal, you will get a superior weld from stick (6010 root pass, with a 7018 cap) versus gas on thicker metal.That's not to say that the gas weld won't be adequate - my point is about which is superior.Good dialog from all.Scott
Reply:What is different about gas than any other welding process?  You have a heat source and a shield.  The source is a little cooler than an arc welder's, so more heat goes into the metal before it gets to its melting temperature.  While this is usually a fault, it does provide a rudimentary PWHT because it takes longer for the weld to cool and produces a more ductile weld.  The shielding gas is CO2.  The fillers are the same, except in this case as I used an OFW only filler.  The point of my post was that an OFW is entirely capable of producing good penetration in thicker metals.  Using a #209 tip, I could have probably produced the same results on 3/8ths inch metal.After reading MAC's post, I did take a smooth file to the cross-section.  I didn't have any phosphoric acid, so I tried muriatic.  I couldn't get any porosity or lack of fusion to show through.  I would have liked to sand it with 220 wet, but someone used all of my wet/dry paper so I was stuck with what the smoothe file left behind.I see nothign wrong with the joint that was produced.  It's a 60ksi weld bead on 45ksi steel and the bead nearly equals the thickness of the material and should not fail before the material.  These are perfectly acceptable conditions for a hobbiest weld.  Now, in an engineered structure where safety factors are low and costs of failure are high (dollars and lives), then maybe it is best to use another process with lots of NDT.  But, I would feel very confident in this weld holding together a trailer or a winch plate.I admit OFW welding is dirty and has a lot of inclusions of carbon and oxides that would show up in an X-ray test, but for the hobby welder, microscopic imperfections are the least of our worries.Finally, I wasn't trying to say OFW was superior to modern arc processes, I was just trying to say that is still a viable and flexible process that has more applicatoins than people realize.Last edited by 76GMC1500; 05-01-2006 at 12:29 AM.
Reply:tx redneck : you worry about 7018 , that it might have shallow penetration. Remember , welding instructors  will tell you that a good weld does not need deep penetration . It just needs perfect FUSION . I see what the concern is , so many guys do NOT have a decent  D C  welding machine . I happen to despise 6011. it sucks. (compared to just about any other rod, except maybe 6013. ) before i got D C machines , i used 6011 for a root, then covered it with 7024 or 7014 . they are nice and smooth , like lo-hi . 7014 all position , 7024 , flat only .
Reply:I did a lot of O/A welding on a couple of traliers a few years ago.  I also repaired a tractor once.  I also repaired a deck on a house. I've even installed rails.  All  items except the deck are still holding.  All different customers all still customers.About 7 years ago that is the only portable welder I had.  Nothing like standing in 98 degree weather with a torch welding some metal.  Everything around you gets hot.  Wood burns decking, light/brake wires melt and tanks get sucked dry.  It is expensive.  The noise is deafening with large tips.  On a hot day you really do not know how much Acetylene is in the tank so you might run out in the middle of the job. I like to gas weld.  I now reserve it for small gauge cosmetic stuff.  I really like to watch the puddle just flow it is so easy to control.  I recently (3 wks ago) built a Valet Box of 14 g sheet metal I have about 2 hours of actual gas welding in it.  A couple of months ago I replaced the deck mentioned earlier.  I used an mobile electric welder.
Reply:Originally Posted by 76GMC1500Well, we had some people on this forum telling us about things they do not know about.  I just welded up a small piece of 1/4" plate with a torch to disprove some misconceptions.  A torch can do thick metal and a torch can get good penetration.
Reply:Originally Posted by Roy Hodgestx redneck : you worry about 7018 , that it might have shallow penetration. Remember , welding instructors  will tell you that a good weld does not need deep penetration . It just needs perfect FUSION . I see what the concern is , so many guys do NOT have a decent  D C  welding machine . I happen to despise 6011. it sucks. (compared to just about any other rod, except maybe 6013. ) before i got D C machines , i used 6011 for a root, then covered it with 7024 or 7014 . they are nice and smooth , like lo-hi . 7014 all position , 7024 , flat only .
Reply:So you just said OFW produces an acceptable weld, but it isn't an efficient process.  Not all of us have a Miller Dynastywhatever.  In fact, some of us don't even have 220v.  If you take into consideration start-up costs, OFW is a very efficient process.  Sure it takes me 5x as long to lay a bead as a stick welder, but for $500 I was able to purchase a set-up and enough gas to have lasted a year and a half and still going.  I can weld thicknesses to 1/2" (theoretically as I haven't tried it yet), I can weld as thin as 22 guage, I can weld mild steel, stainless steel, aluminum, monel, etc... all without buying expensive reels of wire.  I don't need to switch back and forth between shielding gasses.  Everything is portable.  I can cut, I can braze, all for $500 initial start-up cost.  What is so inefficient about that?No, I am not a welder, I am a student.  As a student, I have very limited funds, I can hardly work during the year because of location and hours.  I can't work during the summer because I am away on training cruises.  I am a mechanical engineering student.  I am studying mechanical engineering.  I know what makes a proper joint and what testing is performed on joints.  I know about alloys and I know about the effects of heat on steel.  Who knows, maybe I'll be the guy telling you you're joints suck one day.  I may not be able to weld, I'm not a "weldor", but I still know what makes a joint.  I don't have a lot of experience yet and can't throw numbers at you, but I have a solid foundation to build upon.  I am hear to learn the specifics and I am hear to gain experience.  I don't have a teacher, I have taught myself everything I know using resources like this.  Sometimes I have some input from my own experiences.  Most of it is with OFW, so that is why I speak of it.  I am sick of you saying everything has to be done with TIG.  OFW has been used for years in some very critical applications such as the aviation industry.  Only OSHA regs on fluxes brought the end of gas welding on aircraft, not the introduction of the all-mighty TIG.Last edited by 76GMC1500; 05-01-2006 at 02:50 AM.
Reply:Well, you'll still need a selection of fluxes and expensive filler rods (instead of expensive wire and shielding gases) for OFW of some of those alloys.For most welding, OFW will be more expensive in a short long run based on fuel costs versus electricity costs.  Not to mention regular transporting and time in getting more gas.Some hellacious things have been welded with OFW, no question.  And it's a good process today for things like aircraft chrome-molybdenum and other applications, too.  But arc welding is more economical for the vast majority of welding.As a student, are you using school-owned equipment, or personally-owned?  That might be tainting your view of economics, if school-owned.Summer training cruises?  Navy ROTC, USNA, or something else?  That's interesting, too!
Reply:It's my personal equipment.  Though you are right about my school's equipment affecting my judgement.  I hate MIG as a result of using school equipment.  Every time, I start off laying perfect beads, but after about 6 inches of bead everything gets all weird on my and my beads go ugly.  this has happened on several machines.  Either that or I was just trying to do something they weren't up to like thicker aluminum without preheat.  Though, part of the reason my OFW setup was only $500 was that I was able to aquire some tanks at no cost.  Not everything my school has is bad, though.  Miller donated a welding lab to us with all of the latest and greatest equipment with the stipulation that they be allowed to use it to train their regional reps.  So there is some good stuff in there like a Syncrowave and my favorite, the XMT-304's.  I love the hot start on them, no stuck rods.Part of the degree I get at school is a Coast Guard 3rd Engineer's License, unlimited horsepower steam, diesel, and gas turbine.  I need to have a certain amount of sea time before I graduate in order to get the license so I go on training cruises on commercial ships and my school's training ship.  It is for commercial shipping.  I am actually off for a short time this summer and would like to get a shore side internship, but it is hard to find one for only 1 1/2 months.Think you're so hot, let's see you weld up tubes on a superheater header.Or how about this crankshaft, it's made from more than 20 pieces.  Of course none of the welding was done with OFW.Last edited by 76GMC1500; 05-01-2006 at 03:13 AM.
Reply:Hmm  a student who knows it all.  Oh wellAs far as youre sick of me talking about tig all the time,  I actually rarely speak of GTAW.   I am personally much more apt to speak of SMAW.    As far as being a mechanical engineering student, you are a student.  You are not an engineer.  More importantly, you may think you understand welding, but until youve been out there and experience the world, and this goes for engineering too, you aint see nothing yet.    As far as your assessment of the osha fluxes...where exactly do you base this?  Are you not aware the almighty GTAW process was developed in around 1942 as a more practical method for joining aluminum and magnesium for building aircrafts in world war two.    Nope had nothing to do with fluxes or osha.  Had to do with needing a more efficent and better method for joining these materials.  I am not saying aluminum can not be welded with oxy fuel, but the costs and the skill level are much higher.  GTAW produces very excellent results in these areas.   Although I am experienced in this process, it is not one I use much.  Therefore I speak little of it.  By 1948 GMAW was established and was found as a faster method for joining metals like aluminum or steel than SMAW or GTAW.  The FCAW process was derived and then the SAW process.  Since then we have many other processes which are much more uncommon, but still have their places.  Electric processes have been around a very long time, dispite what you may think.   SMAW has been around since the 19th century, although until the development of the coated rod was not very reliable.   This occured around the 1930's.  Now, I will let you know since I know you think youre already better than me, you need to ask your teacher or instructor or whatever you call him to explain to you what CJP is and show you pictures.  I encourage you to show pictures of what YOu posted for us and if you compare the two you will find nothing similar.  KNowing theory and understanding practical application are way differnt.  But if you dont actually know the theory part thats dangerous.   You need to understand what you showed was not close to CJP.  ITs called PJP....Partial Joint Penetration.  Its acceptable under certain conditions, but if you call out for a weld to have CJP and it has PJP thats an instant bust.  Its your call, but if you are only going on what youve self taught and mostly from welding forums...I think you ought to first get first hand reassurance of what you think you know by folks who do before you go passing on telling people its ok.   I sure do hope you get this figured out before you get your degree.IF it Catches...Let it Burn
Reply:I didn't say I knew everything, I said I had a foundation and understand what makes a good joint.  GTAW was used for aircraft welding during WWII because of the oil shortage, not necessarily because it was a more efficient process.  I know a little of the history of welding, I have the big black book of Arc Welding by Lincoln Electric.  If I had a weld that needed CJP, I would have beveled/gouged it or welded from both sides, but this was just a coupon to demonstrate that OFW can indeed produce penetration.  I haven't had much practice with OFW on thick metals so my welds looked like chicken ****, I admit that.  Just as soon as we got Metal Sculptor off his high and mighty throne and being helpful, you seem to have taken his place.  I may have said some things outside of the realm of my knowledge, but you got me all flustered with your pompous attitude.  I still stand by the fact that OFW is a viable process with many applications.
Reply:Sorry Junior but I had a big hand in working ole metal vulture down from the get go.  I have been the same ole boy I always was.  Theres nothing high and mighty, but you go and say stupid stuff about what is acceptable and what isnt regarding public safety yeah I got something to say about it.  There are no hidden messages, no secrets of welding.  Im not even referring you to a seasoned welder on rye.  Im telling you that crap like that aint good for a trailer or for a hitch or for any other load bearing members.  I have not a pompous attidude.  I am a weldor, proud and steadfast.  There is a code of ethics and I cant just stand by and allow someone to make false statements of what is good and not when I know its not.  I am not here to insult or be rude.  However, hopefully you will hopefully understand the error of telling follks something like that was acceptable, tis not.   You did say btw it was CJP.  That came from you  once I got everything figured out, I pretty much had 100% penetation. I'd like to see you do that with a MIG welder.
Reply:76GMCYeah, the versitility of O/A is attractive.  When I started I was in no hurry to get a portable welder, I let the jobs pay for my equipment. I figured if they built the Panama Canal with O/A process, then I could do small stuff.  I really like the look of o/a bead: tight, uniform with no cleanup.    I have several welders now.  However, use my 110v 80amp dc stick a lot. It works off 15 amp.  I got it for 100 dollars.  They cost 300 new.  It weighs 7 lbs and is very small.  You can tig (scratch) with it.  While I have the tig set up.  O/A is easier than scratch start tig and tungsten grinding, hence I will o/a weld instead of tig.  One real negative to o/a is the volume of heat.  While you do not the sparks of some electric welding the heat travels and with the time spent welding spontaneous combustion and melting can occur far away from the weld area.  So if you are working around wood plastic or flammable substance beware.  Keep those lighter out of pockets. Keep water near by.