Oxy/acet torch questions

SteveB wrote:


That was a few months ago actually. I drove past there a week or so after and the remains were quite impressive.
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wrote

Thank you for correcting me and making me feel right at home. My wife does that a lot, too.
Steve ;-)
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On Tue, 9 Oct 2007 21:46:00 -0700, "SteveB"

Don't know what he heard or felt, but th' propane truck driver who's loaded tanker blew to kingdom come in this one, is still alive. Critical condition at Harborview, but alive.
http://seattlepi.nwsource.com/local/334588_tacomafire07.html
Preliminary cause is focused on an improper hose connection.
Snarl
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On Tue, 09 Oct 2007 23:18:29 -0400, AWN

They really don't take much "cracking pressure" to open, so multiple checks is not a big problem. I have them at both ends of my 25' hose, sand if I get a 50' I'll get another set for that. Makes it nice when the torch can live in the nice protective "Welding" toolbox, and not have to stay connected to the hose and regs to get beat up, or require a wrench every time.

To avoid BOOM-ness, follow the rules in the book.
First: No copper tubing or components AT ALL in the Acetylene circuit, or any brass that isn't designed for the use and is below the copper percentage that is trouble. Copper Acetylide salts will form, and they are explosive and shock sensitive. (Not a good combination.
And when they say "USE NO OIL" on the Oxygen gauge, they are not kidding. You don't get any oil, grease, thread sealants or any other possible contaminants anywhere near pressurized Oxygen unless they are designed for the purpose. Spontaneous rapid oxidization - fire.
Store the bottles in the shade and keep them secured upright. If they have safety caps (large rental bottles) keep the caps on whenever transporting and when not in use for long periods.
Never transport gas bottles casually in a car or van - you really should use an open truck bed, but not everyone owns a truck... The bottles have to be secured upright, and kept in a well ventilated area - cool and out of the direct sun. If your truck has a shell on the back, leave the door and all the windows open. Go straight home from the welding supply and get the bottles out of the trunk and properly stowed in the shop.
If you must transport them in the trunk of a car, the trunk lid should be wedged open with a cardboard box and a strap to provide lots of ventilation, and the bottle(s) secured upright to a milk crate or the trunk hinge bracket.
You might have to build a 'bottle holder box' with a big 2'x2' slab of plywood on the base, so the bottles drop in the box and are held upright. Then you lasso the top of the bottle and secure to three or four points with motorcycle straps - the trunk hinge points on both sides and the lid latch striker works.
And don't try playing the Anvil Chorus using a big hammer or wrench on the top of the Acetylene bottle as the anvil. And always have the bottles secured to the wall, or secured in the cart, or in a crate so they can't just fall over. It takes a lot of banging and dropping to set off a deflagration, but you don't take unnecessary chances either. Be deliberately gentle when handling them.
That's the biggies - I have to get up early.
--<< Bruce >>--
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I took the liberty of copying and posting your message in sci.engr.joining.welding
Cruise over there and see the posts.
Steve
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Thanks Steve! As to your post on worst case scenarios... I ran into my basement shop today to grab something quickly before dinner guests arrived.... And... I knocked over a cast iron table saw wing right onto my bare foot against concrete. Needless to say, after the smashed metatarsal and 5 hour hospital visit, I have my crutches to remind me of my stupidity for the next 6 weeks or so...
The lesson... Boots in the workshop (ever slippers would have been better than bare feet). Second lesson... Leaning CIRCA 1960 table saw wings against a shop wall rather than installed on the saw or stored properly IS a recipe for eventual disaster.
Thanks again, Andrew.
On 10/8/07 3:16 PM, in article snipped-for-privacy@news.infowest.com, "SteveB"

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It's just a peace of mind thing. We all do lots of jobs with no/minimal/incorrect PPE. (Personal Protective Equipment) This is not in the same category, but the point is similar. You're trying to prevent for the worst situation. I have had slag fly from where I was welding and set things afire. If the hoses were near them, they would have ignited, too. But, with the positive pressure, they would have just spewed. It's when you have a blowback, and the gas INSIDE the lines gets on fire that you're in trouble.
I don't know any statistics on injuries or fatalities without the arrestors. I have never heard of any, and I've been welding since 1974.
I bought a torch set recently, too, and I'll go spend the $$$ to get a set, but that's just the way I am. I have a tendency to have regular worst case scenarios.
I suggest that you Ping Ernie in the sci.engr.joining.welding group and ask him. He knows more about welding than the sum of the entire population who knows anything about welding.
You can take what he says as gospel.
And the sci.engr.joining.welding is one great newsgroup.
Steve
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AWN wrote:

The purpose of the backflow preventer is to prevent oxygen being forced into the fuel cylinder (at times when the fuel cylinder pressure is below cutting oxygen pressure) and vice versa. It's likely to be a bad thing if this happens, especially if you're using acetylene. In my opinion, safe working practices, adhered to scrupulously, are nearly good enough to get by without bothering with backflow preventers on your torch.
I see flash arrestors as more of a personal choice, I don't feel that I need them nearly so bad as the backflow preventors but I sure ain't gonna ridicule anyone over them.
You can weld with coathanger wire, no problem there as long as you're not expecting too much. Pretty unpredictable alloy but adequate for an exhaust job that nobody is going to look at.
I don't know about welding with mapp, it's not advised to weld with propane (because it's not possible to control the amount of oxygen and carbon available to the puddle). I suspect mapp to be the same but nobody says you can't try and see what happens, especially with an exhaust system.
As others have advised, careful with the torch, Eugene, 'specially under the car. Setting your stuff on fire in the driveway is sure to make the authorities soggy and hard to light..
John
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Coat hanger wire is maybe good for welding coathangers. Proper mild steel gas filler rod is cheap, has consistent analysis, can be had in many sizes and you don't have to worry about weld contamination from the coating or the mystery metal's strength. Bought by the pound, you change sizes when you change tips for material thickness. One size doesn't do it all. Visit your welding supply, you're going to become VERY familiar with them with small tanks. They should have flashback arrestors as well as quick connects. Unless you're begging in the streets, cost isn't that high.
Small tanks are cute and handy, they'll leave you flat on a Sunday afternoon with no gas, though. Just not very much gas in those small bottles and they cost almost as much to fill as larger bottles. Transport and handling is the main cost for bottled gases, along with insurance. Check your tip chart, it should tell you what tip size is to be used for what thickness of steel and the gas flow rate. From that you can figure out how long your gas bottles are going to last on a project before a refill is needed. No tip chart? Visit a welding supplier that sells Victor equipment, they hand them out gratis.
Air/MAPP is nowhere near hot enough to melt steel, maybe do brazing on small stuff.
Most pros I know don't use gas for welding up exhaust systems, they either use stick or MIG. What O/A is good for is cutting loose the rusting bits of what's left of the original pipes and heating stuck nuts. Small tanks are no good for that, you'll get maybe one or two cuts before the oxygen goes flat.
Stan
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On Thu, 11 Oct 2007 06:27:10 -0700, snipped-for-privacy@prolynx.com wrote:

The "B" acetylene (~40 CF) and '50 Cubic Foot' Oxygen are the smallest practical size bottles for home use - and even at that, you really do need to have two sets of bottles if you want to get work done. One set in use, and one set of full spares to finish off the weekend project. And if you are doing any torch cutting, two spare Oxygen, you go through it fast when you hit the cut valve.
The "Porta-Torch" size bottles - "MC" Acetylene (originally for motorcycle headlamps) and 20CF Oxygen - are only really practical for Air Conditioning & Plumbing repair work where you have to take the torch up a ladder to the roof or drag it under the house. Try doing anything other than silver brazing with the smallest tips, and they run out FAST.
Myself, I leave the B and 50 in their little cart outside, and connect more welding hose to reach the work.
Or I just take the B alone and use a Prestolite Air/Acetylene handle - it gets plenty hot for plumbers' solder, and can silver braze up to 1-1/8" copper A/C suction lines if you know what you're doing.
--<< Bruce >>--
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