O/A...arcair...or plasma?

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I just looked at two good size demolition jobs, one is quiet a bit larger then the other it involves removing about 40-50 I beams that are 20ft in the air. like a middle level in a warehouse. the beams are roughly 20 feet long, 18"tall with a web and flange thickness of about 5/8". I think i would kill my powermax 600 with all that maxed out cutting, plus it wouldn't be that fast. So my alternative would be to just torch them all down...but my question is, would an arcair setup blow through this stuff pretty fast? i have only tried out air arcing once and it worked pretty well.  if this is a good idea, what do you guys recommend?-NateMiller Trailblazer 302gMiller Spoolmatic 30aLN-25 x 2Idealarc SP200Hypertherm Powermax 600
Reply:Invest in a thermic lance setup.
Reply:Originally Posted by \\NV.Welding//...So my alternative would be to just torch them all down...but my question is, would an arcair setup blow through this stuff pretty fast?...?
Reply:awesome, i figured that O/A would be the most practical. just figured id see if i was missing out with an arcair setup. thanks for the input-NateMiller Trailblazer 302gMiller Spoolmatic 30aLN-25 x 2Idealarc SP200Hypertherm Powermax 600
Reply:Propane would be cheaper. Invest in the proper tips and spares, and your good to go, for maybe 1/4 the cost of acetylene. I know there are some fans of propane out here so I'm sure there will be more support.Just my  opinion, not from a book, just from the road.Howes Welding Inc.www.howesweldinginc.com
Reply:I have to disagree with the statement about Ox/Acc being the best process for this job.If you have good access to both the web and flange on said I-Beams then a "properly sized" plasma cutter would be your fastest, most cost effective choice.A Hypertherm Powermax 1250 will cut 5/8" steel at more than 30 ipm.  Pre-heat is non-existent.  Cut speed is a lot faster than a gas ax.  If I were doing this job, I'd start my cut on one side of the bottom flange (no piercing), cut the flange, moving up the web.  When that was done, I'd cut the other side of the flange.  Then I'd cut the top flange.  With 80A cutting power, the cut in the flange will penetrate to the previous cut made in the web.  After the first couple of beams, I'd guess each end could be cut in under 2 min. using plasma.On the other hand, if it comes down to using a PM 600 or a torch, I'd use the torch.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:exothermic would be the way i would go or oxy lance but you have to have a big enough air compressor to push a lot of air they have a relly cool video if you are on this websit go weldin theater.com and check out the oxy lance vid
Reply:Gentleman, Plasma and exothermic have their place, but this aint it!Sounds like NV.Welding has a chance at a nice job, but its going to take proven, efficient, and safe techniques for it to pay off for him. The described beams weigh over a half ton each, and are going to require careful safe handling.NV describes the beams as installed as part of a structure, twenty feet in the air.Typically such beam  installations carry heavy paint coats and lots of bolted and welded brackets, clips, connections, etc. for utilities and decking.Most likely the plan will be to do just enough cutting in the air, to allow the beams to be lowered to ground level. Most of the cutting will probably not be to the beam itself, but rather many small cuts to connectors, fasteners,  and the above mentioned attachments, located all over the beams.Monkey-man is going to have to run around and make nips and cuts everywhere. Some of the cuts will only allow less than ideal positioning of the torch, and may require burning through paint, and cutting  away various attachments, such as bolt heads, sprinkler pipes, or conduits full of electrical wire. An oxy-fuel torch will easily handle any of this.I believe that a plasma power-source and its torch and hose lacks the practical maneuverability needed for this job. Also a plasma torch's cut has very limited "reach" and requires careful torch positioning to reach rated cutting capacity.  What if NV should possibly encounter a few heavier members that need to be cut?The nimble and versatile oxy-fuel torch and hose can handle anything likely to be encountered on this job. The torch can work without electrical power or an air compressor, and can easily reach a hundred feet away from the cylinders. But probably the greatest advantage of oxy-fuel is that the operators hands can be 2'-5' away from the cut. That distance means a lot when cutting pieces under unknown tension and loads, which often "jump" when cut.A little off-topic, but when a beam may be holding an unknown load, you should never leave a beam's flange partially cut, with a plan to finish the flange cut after the web is cut. The flange needs to be cut completely, allowing the beam to "peel" to relieve tension if necessary, as the web is cut. By leaving the flange partially intact, as the web is cut, the partial flange could yield with a sudden unpredictable failure.Good LuckLast edited by denrep; 04-26-2009 at 03:56 PM.
Reply:Definately go with the O/A. You will be able to cut through most any thickness of material.Go hot, or go home!
Reply:Get a liquid Oxy, a #100 propane tank and have at it. Last time a big liquid oxy was $80, and propane was $75. If you can get a 3 foot long scrapping torch on the cheap you will be much happier as well.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:My #1 choice would be a cutting torch.  Propane would work, but preheat time is kinda slow especially if there are a lot of small cuts to make.  ARC AIR will cut off the old welds if that is how you are taking it apart.  For the arc air, all  you need way up there is + cable and an air line.  No expense for O2 or acet.  Carbon arc rods are about a quarter each ($.25)  What size welder do you have?If you are going to cut the beams in two or cut the ends off, a torch will be faster and easier.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Like denrep and Tozzi said get a scrapping torch, you want to be way back when the beam are cut loose.Tough as nails and damn near as smart
Reply:OA without a doubt. Use a scrapping torch if you want to, if you have one or can get one cheap enough. A journeyman Victor will do the job, though, w/o the extra expense. My opinion.  Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.                                         -Cree Indian ProverbSA 200 LincolnVictor Torches
Reply:You will need oxygen and propane for cutting.  I suspect that you also will require a large air compressor and at least two heavy impact guns to loosen bolts.  The crane time will kill you unless you can salvage quickly.
Reply:lowering the beams down wont be much of an issue, the building is huge and theres enough room to get a wheel loader with forks right under the beams, as of right now there is 6 inches of poured concrete on top of the beams, but thats not my job to take care of. I have a nice victor 3ft scrapping torch i was thinkin about using, looks like that will probably be the route i will travel. When i got my powermax 600 about a year ago i went to my lws intending to purchase the 1250. i was talked out of it mainly because my ranger 9 doesnt have enough @$$ to power it. i havent been looking at purchasing a new engine drive lately, but whats out there that will put out 80amps?-NateMiller Trailblazer 302gMiller Spoolmatic 30aLN-25 x 2Idealarc SP200Hypertherm Powermax 600
Reply:I guess I could have read your sig.  The ranger 9 is a little small to gouge (arc air).Looks like the torch is the only way to fly.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:The Powermax1250....if you decide to use plasma....would be perfect for this job. You can get a 50' torch lead.....or you can put the plasma right up on a scissors lift if needed. If you want to get the job done in the least amount of time....plasma. No preheat, no gases, no special torch expertise needed, and almost 3x the cutting speed of an oxy-fuel. Less fumes as well (if the beams are painted) as the plasma heat does not burn back the paint as much as oxy-fuel.Sounds like for this job I'd sell or trade the Powermax600 up for a Powermax1250.Jim
Reply:thanks for the advice everyone, i appreciate it -NateMiller Trailblazer 302gMiller Spoolmatic 30aLN-25 x 2Idealarc SP200Hypertherm Powermax 600
Reply:Originally Posted by \\NV.Welding//lowering the beams down wont be much of an issue, the building is huge and theres enough room to get a wheel loader with forks right under the beams, as of right now there is 6 inches of poured concrete on top of the beams, but thats not my job to take care of. I have a nice victor 3ft scrapping torch i was thinkin about using, looks like that will probably be the route i will travel. When i got my powermax 600 about a year ago i went to my lws intending to purchase the 1250. i was talked out of it mainly because my ranger 9 doesnt have enough @$$ to power it. i havent been looking at purchasing a new engine drive lately, but whats out there that will put out 80amps?
Reply:All due respect for plasma and its proponents.I don't have time to explain the details right now, but..."It just don't work like that."Last edited by denrep; 04-27-2009 at 11:45 AM.
Reply:Originally Posted by denrepAll due respect for plasma and its proponents.I don't have time to explain the details right now, but..."It just don't work like that."
Reply:Originally Posted by denrepAll due respect for plasma and its proponents.I don't have time to explain the details right now, but..."It just don't work like that."
Reply:I have not done this type of job with plasma.....but I did cut 300 holes in I beam webs (mostly 5/8" and 3/4" thick) with plasma. The fab shop forgot the holes until after the erector had the building mostly up. The holes were for electrical conduit, and locations were pre-marked for me.  I did the job with a portable generator, a portable compressor and  Powermax 1000 using a magnetic hole template to guide the torch. The holes were very nice, required virtually no grinding...and the job was done by two guys (only one cutting) in less than 8 hours. We outbid a different outfit that planned to take three days using oxyfuel. I paid for the plasma, the 10kw generator....and a good days pay for two workers.I did another overhead demo job that involved removing the welded sprinkler system from a 30,000 square foot (open ceiling). This was done in an afternoon.....very fast work with plasma...if you have the right equipment.To do this type of work you need a plasma with drag cutting capability and plenty of reserve power. These jobs....of course can be done with oxyfuel.....but the proper plasma will be much faster.....and requires far less skill and expertise.Jim
Reply:denrep,As a former combat engineer, I can assure you I've cut my fair share of steel that is in both compression and tension.  I've used many different approaches to the problem at hand.In fact, in one afternoon (bout 2.6 sec to be exact), I probably cut more steel (in compression and tension) than you have in the last 10 years.  (190' of triple double truss steel bridge).  Bridge was designed for a 5 T load.  Failed when a tractor-trailer rig loaded with 78,000# of powdered milk (per BOL) tried to cross.  Ever tried C-5 sheet?If the beams we're talking about here are still in compression/tension (other than from their own deadweight), we're looking at a whole different set of issues.Really comes down to the guy doing the job selecting the equipment he/she is most comfortable using.  Any of the described processes will "git it done".  How fast, and how much can he make is the issue to decide on.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Jim Colt, the guy has a ranger 9 for power.  It won't have near enough balls for a bigger plasma.  My ranger 250 has 9KW of 220 power (same as a ranger 9?).  It will run my power max 600 and that is all.I agree if he could go BIG, it would be a much simpler task.  He is also a weldor, so I ASSume he is proficient with a cutting torch.  Maybe it would be more cost effective to rent the generator and plasma or trade up.I don't sell much if any of my equipment, I just keep buying. DavidReal world weldin.  When I grow up I want to be a tig weldor.I agree...he definitely doesn't have enough power. The 10kW generator I used with a Powermax1000 was marginal....so a ranger certainly wouldn't power a 1250.I'm just saying....given all the right equipment...the job could be done very well, and of course in my opinion, faster than other methods with plasma!I personally would be nervous about the tension in the beams.....especially after a concrete floor was removed from them. Kind of like that 2 foot diameter oak that the wind tipped at a 45 degree angle on my property last fall...it was leaning against the tops of some big pines.....that first couple of slices with my chainsaw were nerve wracking....kind of wondering which way everything was going to go because the roots were still in the ground. I'm still here and I burned that oak this winter....but it was interesting when it let go!Jim
Reply:I'm not condemning plasma, it's a valuable process, especially for fabrication and shop work. However, there is absolutely no way plasma will match -let alone triple- the production of oxy-fuel in carbon-steel demolition or scrap work. In my opinion, plasma's laboratory rated cut speeds and capacities are not achievable in the field. With oxy-fuel, the laboratory rated cut speeds and capacities can be surpassed in the field, particularly when cut quality is not an issue.How about a little friendly wager... title for title, "pinkslips" if you're from CA.The Match:Rusty used painted beam about the dimensions that NV describes.Regular production equipment - Hand held oxy-fuel vs 80 - 100 amp portable plasma. Cuts to be made freehand, with the beam in some position typically found in the field, not on a bench.Winner takes the runner-up's equipment! To sweeten the deal: If the winner's processes comes in 3x faster, the runner-up not only surrenders his gear, but donates to charity the value of the winner's equipment. To be fair to all, any malfunctions would void a run.Regardless of the outcome, everybody wins -  Plasma engineers may find some insight into why the present process isn't making large inroads into the heavy demolition and scrap cutting market. Also, plasma-shy buyers seeing the test may be converted over to the process. But the real cherry would be if Alfred, or whoever operates  the O/F torch had to shut-up and donate the cost of a plasma machine to charity. Of course if fate should side with Alfred, he would sing praise to his new Powermax 1250 with many rich photo posts. Good LuckPS - I asked Alfred. He said if he won, he'd raffle the 1250 off on WeldingWeb. Any active user, who has previous to this posted a project with cutting pictures, could enter the raffle - except Denrep.Last edited by denrep; 04-27-2009 at 04:32 PM.
Reply:That must be on big wheel loader to reach 20' in the air.
Reply:Originally Posted by \\NV.Welding//They got a Kawi loader, its a little smaller then a cat 980. I was told it would reach high enough. i sure hope it does.dont worry.. the thought has crossed my mind a few times, if the economy was better and i knew i had enough work, id go get a 1250 and probly rent a generator I know my way around an O/A torch pretty well, and i already have the equipment. so i would make the most money that way...maby with the pay from this job ill get a pm1250im gonna see if i can get down to this job in the next few days and take some pics
Reply:Originally Posted by jdh239I would like to know.  I was thinking about picking up a plasma cutter, and I would like to hear the cons.  I won't ever be cutting a beam with it, but still curious.
Reply:I'd be more than happy to go side by side with an 80 or 100 amp plasma (Hypertherm, not import!) on 5/8" to 3/4" carbon steel...the dirtier the better! I won't go for pink slips.....but I'd be happy to cut steel...and see who finishes first.I fully agree that there are locations where a longer, skinnier torch will go where plasma won't....but if someone wants to come up with a good scrapping / demolition test that's somewhat fair....what the hell....let's do it!  And if you can cut 5/8" steel at 30 ipm (not maximum speed or "laboratory" speed....but the optimum speed for best cut quality and angularity at 80 Amps)  with a pierce time of 1 second with oxy-fuel....then we'll all learn something!We should also then put a plasma torch and an oxy-fuel torch in the hands of someone that has never used either.....and see how long it takes each one to pick up the skill to cut some 5/8" or 3/4" steel.My company could certainly learn something from this....this is the type of feedback that helps develop new technology...if there is a market for a different torch shape...or some different technology to do a task...we would be happy to participate and learn.....especially with the chance of winning a few speed races. When do we start!Jim
Reply:haha, this is turning into one heck of a thread, didnt think it was gonna get going like this.Denrep brings up some very good points, so does everyone else. Im a fan of plasma cutting just as much as the next guy, but different jobs call for different tools. thats why i was asking.The next issue is heavy power and air supply. Typically when a structure is having floors and beams extracted, as NV describes, grid power and shop air are long-gone; so a generator and compressor, and long reach umbilical cords must be factored in to the plasma equation. Of course any engine exhaust must be vented outdoors, and traffic must be kept away from the leads.
Reply:The more i think about it, im not positive its 20ft in off the ground, im gonna try and get over there tomorrow afternoon and measure it up and take a few pictures-NateMiller Trailblazer 302gMiller Spoolmatic 30aLN-25 x 2Idealarc SP200Hypertherm Powermax 600
Reply:For once  I think denrep is in trouble.  I think a 1250 could out cut a torch any day.  No preheat time....... Just pull the trigger and go.I had to scrap a complete 55' aluminum trailer.  All I had was an OLD transformer Linde 30 amp plasma.  I had no power at the site, so I used my weldman power G7 (7Kw) and a gas air compressor.  I had to use the sawzall where there was structure.  I tried the sawzall on the flat good going stuff, but the plasma beat the pants off that.  It was MUCH easier on my ears too.Denrep, I have a HT600, I can do a race in my shop with that and an oxy torch.  maybe 1/2" plate?  I think the plasma will win.  I don't know about 3x the speed, but if the torch is propane instead of acet, probably because preheat is slower yet.  The more the corners, paint, crappy welds and "stuff" in the way, the more starts with the oxy torch.I think this requires a new thread.  No pink slips, what would I do with another oxy torch?David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Jim,To a degree I understand denrep's concern for a "standoff" provided for by a scraping torch.  Maybe something Hypertherm would consider looking into.  An extended reach torch may have an application in the scrap business.  I think I read a thread a while back where one operator running a scrap business, was transitioning from using O/A to plasma.On the other hand, if I was cutting the said beam, even with O/A and I wasn't relatively sure I could support the cut end to prevent it from "jumping/bucking", I'd probably cut a temp hole in the web and secure the I-Beam to the existing support with a short length of chain.  Once the beam is "free floating" the chain could easily be removed.I think that what you're running into here, in large part, is the mentality that "we've always done it this way".I had seen the larger 260A Plasma cutters work on a CNC table and was always amazed at what they could accomplish.  With that said, the first time I picked up the torch for a PM 1250 and lightly drug the tip across a piece of 3/4" steel, rather quickly, I may add, I was even more amazed.  My thoughts were, "How the heck did that little 90# box just do that?"  The more you use them, the more uses you find for them.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:I get the feeling that many here are thinking of old school plasma......like a T-D Pak10xr or a Hypertherm Max100. They were top of the heap for hand cutting about 12-15 years ago...today our 45 Amps system will do as much....and weighs 1/10th...and provides 10x the consumable life. If anyone hasn't tried a 1250 (80 Amps) or a 1650 (100 amps) plasma....maybe they should. 12 - 15 years has made a huge difference in performance.If it is just severing these beams.....and I have a 1250 against anyone with oxyfuel...I will cut it at least twice as fast......maybe a little more. Granted, getting power and air is necessary.....1 3/8' hose and one cable...thats the same number as the hoses for the torch!Let's have a run off...determine advantages and disadvantages.  There are some things that plasma does better and there are some things oxy-fuel does better.....let's figure it out. Who wants to come up with a cutting comparison challenge.....I'll bring a 1250!Jim
Reply:One of my friends salvage yards just switched over half of his cutting equipment from O/A to  1250's and he is more than happy with the results so farCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:Originally Posted by jimcoltI'd be more than happy to go side by side with an 80 or 100 amp plasma (Hypertherm, not import!) on 5/8" to 3/4" carbon steel...the dirtier the better! I won't go for pink slips.....but I'd be happy to cut steel...and see who finishes first.I fully agree that there are locations where a longer, skinnier torch will go where plasma won't....but if someone wants to come up with a good scrapping / demolition test that's somewhat fair....what the hell....let's do it!  And if you can cut 5/8" steel at 30 ipm (not maximum speed or "laboratory" speed....but the optimum speed for best cut quality and angularity at 80 Amps)  with a pierce time of 1 second with oxy-fuel....then we'll all learn something!We should also then put a plasma torch and an oxy-fuel torch in the hands of someone that has never used either.....and see how long it takes each one to pick up the skill to cut some 5/8" or 3/4" steel.My company could certainly learn something from this....this is the type of feedback that helps develop new technology...if there is a market for a different torch shape...or some different technology to do a task...we would be happy to participate and learn.....especially with the chance of winning a few speed races. When do we start!Jim
Reply:How about the run-off/test/demolition-demo be over Herehttp://weldingweb.com/vbb/showthread.php?t=30006  The best laid schemes ... Gang oft agley ...
Reply:I've spent a bit of time running a 1250, and torches of course...I dunno, The 1250 is bad a$$. Almost every time I use the thing I am amazed at what it does.Could it out perform the gas axe on a demo? Tough one. I'd love to see the test.
Reply:The one aspect of the plasma that is an advantge a good portion of the time but can be a negative at others is the fact that it doesn't discriminate between multiple layers, rust, crud or small gaps. When you are trying to cut close, remove one piece and save one untouched the plasma makes you wish you'd gotten out the torch. Anything in the way of the plasma arc is a goner. Besides the fact the big head makes it more difficult to get in close. No such thing as splitting a nut off a bolt with a plasma. With a torch you can get in and cut something off right close to the original bead. A plasma makes it tough to get in that close and you still have a big flag to remove somehow. With a plasma you come in at an angle with a lot of power and you'll be cutting into the part to be retained.  Tabs in corners and attachment plates, with a torch you can split 'em or shave 'em. Plasma will cut or gouge everything it touches. I dunno. I wouldn't want a bunch of gouges in columns to be retained. I wouldn't want a bunch of one inch tage ends sticking out that still had to be ground off or cut with a torch anyway.  Each one has its place I guess. Hopefully the whole job here is bolted up on the big ticket items.
Reply:I have to read up a minute, see if they found the pink slip yet.Did you check the glove box?
Reply:Denrep,Have you ever used a Hypertherm 1250 or 1650?I've been using an O/A torch since my uncle (hardhat diver/welder WWII) taught me the principles in 1953.About three years ago, I bought my first plasma cutter, a Powermax 600.  I thought I'd died and gone to heaven.  Faster and much cleaner cuts in up to 1/2" mild steel.  Cuts aluminum, SS, you name it.Then, last year, I bought a Powermax 1250.  That machine is a BEAST.  Cuts 3/4" steel like my 600 cut 1/4".  The fact that no pre-heat and the overall travel speed during a cut are what puts it head and shoulders above the torch.  Since I've gotten the 1250, I bet I haven't used the torch for cutting on more than half a dozen occasions.  Pre-heat, yes.  Cutting, very seldom.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Personally I would use both, as they both have functions that the other does notI make O/A torches 3 meters or so long with either an 90deg head or a 180deg head.Have actually made an extension handle for a customer to work on his Plasma and 180deg head on it. Also build torches that will cut up to 750mm for steelworks to cut through billets on Oxy/PropaneIn short they both have there place and doubt that one will take over from the otherAs far as fumes and gases go Plasma I believe is more harmful to breathe in.Cheers
Reply:Regarding fumes:The fumes are essentially the same between both processes....as they are fine particles of the material you are cutting. Plasma often seems worse....because it removes 3 to 6 times tha amount of metal in the same time frame....therefore 3 to 6 times the apparent fumes. Of course if you match the nozzle size and power level to what your cutting...and your ability to move the plasma torch (cutting by hand on gauge material at 450 inches per minute is difficult!)...then there is very little smoke/fumes from the plasma.Jim
Reply:Originally Posted by SandyThe one aspect of the plasma that is an advantge a good portion of the time but can be a negative at others is the fact that it doesn't discriminate between multiple layers, rust, crud or small gaps. When you are trying to cut close, remove one piece and save one untouched the plasma makes you wish you'd gotten out the torch. Anything in the way of the plasma arc is a goner. Besides the fact the big head makes it more difficult to get in close. No such thing as splitting a nut off a bolt with a plasma. With a torch you can get in and cut something off right close to the original bead. A plasma makes it tough to get in that close and you still have a big flag to remove somehow. . . .
Reply:Moonrise is right, this thread is getting muddy. I'm going to stick to \\NV.WELDING//'s cutting process decision here, and the "cut speed only" race can go on in another thread.The cut speed challenge would be fun, and I'm game, but for now I'm waiting to see if a plasma proponent will bring the pink slip. The claim is that plasma is at least two, (maybe close to three) times faster cutting a typical beam connection. I don't believe it, and I've offered to back-up my skepticism with a more than fair "everyone wins" offer.But back to NV's reality - Cutting speed does not matter! It is an insignificant part of the equation. Plasma's speed (or lack thereof)  did not cross my mind when I dismissed all processes other than O/F back in post #3.If any one process should be twice as quick with the beam cuts, it's not going to make NV's job. There may be a total of about 100, 18" beam connections to cut. Let's just say 1800 inches of cutting. That's 60 minutes @ 30IPM vs 120 minutes @ 15IPM. That's a total of ONE HOUR DIFFERENCE on the whole job!Somebody please calculate how long it's going to take each day to set up, fuel,  tear down, maintain and secure: a generator, compressor, plasma power source, and long cords and hose. To be fair, calculate how long it will take to pull two O/F regulators and to roll up a torch hose.As far as O/F gas costs go, I would estimate that one liquid tank, and one 100# propane wouldprobably drop this whole structure. That includes many miscellaneous nips and cutting the anchor bolts or bases flush. There would be plenty of O2 left over for sizing scrap. About $200 would cover the gases. When cutting stops and the torch is shut off,  the costs stop. No engines continue to run on standby. Oxy-fuel is a stand-alone system, which could complete this job without the help of a plasma system. No support equipment or their fuels, would be required if using O/F.I'm not sure how to estimate the recommended plasma's  costs. I'm also not sure of consumable life, or how forgiving the plasma torch parts are to shorts, bumps, and drops. Maybe someone with that knowledge could estimate. Plasma is not stand-alone and somehow compressor and generator costs would have to be calculated. At least some oxy-fuel equipment would most likely still be necessary on the job, due to plasma's limited range.How about cutting tips?  O/F could do the job without wearing out a single tip, but the torch head is bound to take a bump or two, and that could damage a tip. Same goes for the plasma drag cups. I'm not sure how forgiving the plasma tips or torch are, but since your hand is right there with it, it shouldn't take but another second or two of extra care to protect the plasma torch, when moving your hand away from some sudden danger.Despite due caution, there's a mishap? No worry, the cost of an O/F hose repair or torch handle repair is negligible. There is virtually nothing that can go wrong with the O/F system that can't be repaired on-site in minutes, at minimal cost. Even to replace the complete system wouldn't be a great setback. I'm not sure how much a damaged plasma cablehose or torch repair costs.O/F still too slow? About $175 equips another worker with another torch, the two torches can simultaneously cut. I'm not sure how much to equip an additional plasma operator. Please advise.I know 50' of torch reach sounds like a lot, but it gets short fast on a job like this. If we need to make a couple cuts up at the roof, thirty bucks adds a nice stretch to the O/F hose. How much $ to extend the plasma's reach?I'd rather not share a moving manlift with a power source and a 240 or 480 volt extension cable. Is there something safer we could do? Maybe we can get another work platform for the power source?We just found some 1.5" plate on the job, and some 4x4 solid bar at the docks. Will the plasma cut a few very heavy sections?Now do you see why my vote is for oxy-fuel? It's not the few minutes of alleged cut time savings, it's the low cost, fast set-up, mobility, versatility, and safety factor that allows O/F to make the cut.If that's not enough, maybe soon we'll see if O/F will also out-cut plasma on a structural demo job.Good LuckLast edited by denrep; 04-28-2009 at 11:06 AM.
Reply:Just a few points to defend "new" plasma capability.- If you need to use a generator and compressor...set up involves turning them on and plugging in the air hose and power cord. If the job takes oxy-fuel two days.....and plasma one day...then the set up is the same (liquid cylinder of 02, 100 lb propane)...have to be set in place and hoses / regulators connected. Many commercial construction sites have power/air available...at least most that I have been on. Make sure that 02 doesn't vent out on you on a hot day!- Bumping a Powermax torch to the plate does not harm the nozzle/consumables (there is no "tip") Drag it all day long if you wish.....and you'll likely use one set of consumables (maybe two if you want better edge quality). Older plasma's....and some brands...cannot be drag cut, will eat a lot more consumables.- You can bring the plasma power supply up on the scissors lift with you. Just one air hose and a power cord lead to it.....same as oxy-fuel.- Want to gouge out a weld? Put the gouging nozzle in the torch (15 seconds) and have at it.- I beg to differ on the speed does not matter statement. 30 ipm is 30 ipm. Not 12. And a pierce time of 1 second is less than 10 seconds! Multiply these advantages by the number of times they will come into play...and hours come off the plasma job.- A 1250 will sever 2". Steel, Aluminum and Stainless. I have a picture of my 45 Amp torch severing 1-1/2" steel if you'd like to see it!- Nuts can easily be split off bolts with proper technique with a plasma torch.- got some ductwork in the way? Turn the plasma down to 25 amps and cut it cleanly out of the way.I would bring both oxy-fuel (a portable set) and plasma. I'd use the plasma on 80% or more of the cutting....Plasma is not the fragile bulky, heavy equipment it once was. If you do damage a torch lead.....a new one plugs in with no tools....and does not allow flammable gas to escape while somone runs to shut off the propane. A laborer can use a plasma torch with ease.I totally agree that plasma has a higher purchase price....and needs power and air (of course you can get bottled air if you wish).....however it has inherent advantages that certainly can make you more money if it is matched to the job. Plasma will never get reid of oxy-fuel...but I'm looking forward to comparing them for demo and scrapping jobs. I'll try to help arrange this test on the other thread......and the main reason I am not interested in the pink slip challenge....I already have two oxy-fuel sets in the shop....don't need another. I suppose though....I could donate it to the local vo-tech school....Jim
Reply:Denrep is right, cut speed is only one factor.I've done plenty of demo jobs in my time,,,,,   easy enough to put together a few hundred feet of oxy-fuel hose,,,,   do the whole job from one location, don't have to move the tanks.   Working in the air, 50' is not really a whole lot.  You will either be spending a lot of time, climbing up and down the ladder, rerouting your line, or paying somebody to sit there and move the power source as necessary.Then suppose something drops, and cuts the hose????  oxy-fuel, just splice it back together.   Plasma??????????And I have no problems, climbing around stuff, with a couple straight tips, a couple scarfing tips, a wrench, and a striker, changing tips as necessary, and as appropriate for whatever cut.ANOTHER factor to consider,,,,,   using a plasma, you need full-welding hood protection. You are essentially blind, to everything but the arc.  Using a torch, #5 glasses is good enough.   How much can you see thru a #10 lens?????   I can see things perfectly fine, thru a #5 lens, especially when working with things under possible pressure,,,,  visibility is very important.   Torchwork, you can see much better what's happening, as it's happening, and stop or change strategies as you are going along.   Sometimes the forces and stresses aren't what you expect, do you want to know now, as you are cutting, or do you want to know as you are falling, two stories down??????All of this, of course, is much different once you are back working at ground level ....
Reply:Actually....# 6 glasses are good for 80 Amp plasma. Do not need a full shield...but I would use a lighweight flip down visor just to keep slag from hitting the face....as you should with oxy-fuel on a job like this.