putting (OA) dangers into perspective

hello folks, after a few months of happily stick welding i am yearning to learn to use OA.
One thing that is bothering is that I am a bit afraid of using OA from
what I read in past posts here, that it spontaneously combusts with oil, flashbacks, tank pressures,popping etc.
on the other hand LPG tanks are part of every day life.i dont lose any sleep about having them around.
is my fear of OA out of proportion? e.g. is having a OA pipe split during welding inheriently more dangerous than having a LPG BBQ pipe split during use? or is operating a LPG blow torch less dangerous than operating a OA torch?
thanks for patiently reading my post, Sam
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I've used OA in commercial, school, and hobbist modes for years. Mind your safety rules and they are just fine.
Lots of places with the full set of rules but basic things like: -Get GOOD regulators, not some el cheapo or dumpster diving versions. -Deal with a reputable supplier for your tanks -transport tanks with the safety caps on -Chain the tanks so they don't tip over -use good torches with the arrestors in the line -weld in a area where the sparks won't start a fire -Do your cutting outside, NOT in a confined space. -Etc, etc but mostly about using some common sense.
I'm partial to Victor torches (Harris are fine too), you can get a brand new set with single stage regulators, hoses, torch and tips, cutting attachment, and goggles for $150 or so. Don't fiddle with used or off brand at that price.
I actually picked up and old but complete Harris outfit for free from a community level shop. The supervisor wanted the older equipment OUTA HERE so he wouldn't have to worry about someone hooking it up when he wasn't watching. Nothing wrong with it but I won't use it until I check out the regulators.
If you do take the plunge, do some hard shopping for the best deal on tanks. You are not likely to use a lot of gas so you want some deal that does not have huge charges for monthly or yearly rental/lease. I lease my tanks, deposit is equal to the cost of the tank, no monthly fees, no recertification costs, bring them in and swap for a full one when I run out. If I decided to quit using the tanks, I bring them back to the store and get a full refund of my deposit.
Cheers.
Sam wrote:

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Great information in above post. I don't consider my OA outfit (gas welding only, not used for cutting) to be particularly dangerous or sensitive. I don't wipe the oxygen tank outlet with my finger to avoid oils. I watch the acetylene regulator to make sure it isn't creeping. I do a leak test each time I change gas bottles. I turn the tank valves off when I leave the room. I let replacement acetylene bottles rest in an upright position for at least 1/2 hour when I bring them home. All these things become automatic after a few weeks. Lastly, because I only weld, I bought a Meco torch from TinmanTech. I like it much better than the Victor 100 I was using. Good luck.
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It is the oxygen that can spontaneously combust with oil, not the acetylene.
Acetylene tank pressure is not high. It is the oxygen tank pressure that is high.
Properly used, acetylene is quite safe. Improperly used, it can be dangerous. The main issue is that it can spontaneously decompose at certain pressures without the presence of oxygen. With a properly maintained tank and regulator it is of little danger. Then tank is filled with a solid matrix. Then it is filled with acetone. When the acetylene is pumped into the tank under pressure, it disolves in the acetone and won't explode. As long as you keep the tank upright and don't use more than about 1/7 of the tank capacity per hour everything should be fine. Break either of these two rules and you risk drawing acetone out of the tank leave room for free acetylene in the tank with the possibility of a subsequent explosion.
As far as leaks go, acetylene is probably safer than LPG. If acetylene leaks, it rises because it is lighter than air and will usually disipate safely. LPG will descend and find the lowest point where it will pool. And if it finds an ignition source on the way, you have a fire or explosion.
Flashbacks are a possibility with any oxyfuel process. You need flashback arresters in the lines. But mainly you just need to recognize one when it happens and shut down before any damage occurs.
Note that acetylene tanks can and do leak from time to time. The problem usually seems to be with the fuse plugs in the tank that are mean to relieve excessive pressure. The result can be anything from a pop, to a bang to an explosion that can destroy a vehicle or building. So, it is best not to store them in your garage and carry them in an enclosed vehicle. But then the same goes for LPG.
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On 5 Feb 2005 03:39:29 -0800, low snipped-for-privacy@yahoo.com (Sam) wrote:

Fear of what ? Consequences or real likelihood of having it happen ?
You can survive an LPG explosion in a workshop. But an oxygen cylinder will take walls down and collapse the building. However this is an extremely rare event and the fact that OA is so commonly used, yet so rarely causes an accident (even with Billy Bob and his "Hey Y'all" approach to safety) should be some reassurance that the _likelihood_ of accident is very, very low.
Your gas supplier will have safety information. Read this stuff and _do_ it. The people who scare me are garage mechanics who've never paid any attention to it, they just picked up a torch and "taught themselves" to use it. Some of the safety hazards just _aren't_ obvious.
Have equipment that's correct, in good condition, and reasonably recent. There are lots of rubber seals and diaphrams in there - they do fail with age and it's not obvious when they've done so.
Use oxygen and acetylene equipment. Don't improvise with some old propane kit you have around.
Keep it clean. You'll want a storage box with a lid, particularly for oxygen kit. Dirt stops metal-metal seals sealing and organic dirt can be a hazard around oxygen.
Cylinders will smash a foot if they fall, even with steel toecaps, even if you don't damage the cylinder. Get a trolley, or else a wall bracket with chains. Move cylinders on a cylinder trolley as much as possible. Rarely can you safely move a full-size cylinder onto the back of a truck on your own. Maybe you _can_ lift it, but you can't control both ends while you're doing so (your arms won't reach) and the damn things are round so they'll roll.
The torch should be in good order. The valves should work, shouldn't require a gorilla to shut them off, and shouldn't have been used by a gorilla so that the seats are mashed and no longer seal. There's a gas mixer inside that should be kept clean of carbon.
You _must_ have check valves on the torch end of the hoses. You mustn't repair damaged hoses with odd bits of copper pipe and Jubilee clips. Hoses don't last forever either.
The regulators should regulate, particularly the propane. Sticky diaphrams or a creeping pressure rise are just not acceptable.
Seals should seal. Don't keep using ones that don't - there's a dozen O-rings in a gas welding set and you need all of them in working order.
Purge the hoses when you start and when you shut down. There's an order to this (your gas / torch supplier's guide will have it) so learn it and follow it.
Learn the right gas pressures for different nozzles / tasks.
If you want to, write this stuff on a piece of paper, get it laminated up and hang it around your cylinders.
Light with a spark or electric lighter, not with a butane gas lighter.
If you're working on a bench, get an economiser (torch hanging hook, with built-in gas shut-off valves and a pilot).
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On Wed, 09 Feb 2005 13:43:19 +0000, Andy Dingley
This is some darn good information....thanks you are 100 % correct about shop mechanics, I was one for over 10 years and worked at high profile multi line dealerhip , and have seen it over and over again about new hires and their use of O/A equipment. zero safety training, just enough to show how to light the torch and how to shut it off. acetylene and oxigen pressure set to 10 Psi , left at this setting day after day , and used with the same setting for everything because nobody knows how to set it correctly. sad......

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thank you all so much for your information and views. Much more confident now. A little fear is good too, keeps the safety aspect fresh in my mind.
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Sam wrote:

For cutting, your acetylene regulator can plug into a normal LP cylinder, be ABSOLUTELY SURE you purge the lines at *low* pressure after you switch to propane, as you'll be using propane at a pressure over the magic 15 for acetylene.
This is good up to about 18ga hot rolled steel, and may help you to get used to the cutting process without having the fear of experiencing heat-assisted deep tissue exfoliation courtesy of wayward acetylene.
It's been so long, I don't remember if one can use LP through a normal torch tip for brazing or if the gas-mixer is Acetylene only.
Good first project is to acquire a hand-truck (One with inflated tires, trust me on this one.) and weld some semicircular tank guides and chain points to it. (and if you're like me, throw a set of stair climbers on it too.) with your torch. (yeah, you could stick or mig it, but why not learn the torch on something simple(I cheated and MIG-ed the rods onto the skis of the climber.).
OA is a very effective way of doing things around the shop that you'd be crazy to do with stick/mig/tig (ever tried putting a cast iron 4 burner woodstove that looked like it was broken to bits by a sledge hammer back together? Braze it!)
And once you have acetylene rod in the shop, it's akin to the proverbial baling wire in it's multitude of uses.(/me glances around and sees 6 different non-welding uses for 3/16 rod.)
If I'm wrong on anything, please please please correct me. I fear my "vacation" from welding has dulled my knowledge slightly.
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On Thu, 10 Feb 2005 18:13:40 -0500, Josh Sponenberg

I can't do this in the UK. My (expensive) acetylene regulator just won't flow anything like the pressure or flow rate that my (cheap) propane regulator can.
--
Smert' spamionam

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I thought (don't know for sure, though) that propane would destroy the rubber seals in an acetylene regulator. Isn't propane corrosive and that is why grade "T" hose is specified for it? Thanks.
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John wrote:

I think it's backwards. Acetylene can contain acetone vapor, which will kill seals that are just fine for propane (N-Buna I think). Maybe someone more versed in this can fill us in on the details.
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Propane will destroy acetylene hoses. For this reason I'd never use it in a regulator either, but this situation just doesn't arise in the UK.
However US practice seems to be radically different and I've no idea what acetylene regulators are made of.
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On Wed, 09 Feb 2005 13:43:19 +0000, Andy Dingley

Excellent post!!
As a side note, this past weekend I helped a fellow weld up a new carport for his RV.
He uses propane oxy for cutting.
Damn I hated it. As far as Im concerned based on those 2 days..propane is for hambergers. Ill stick with OA thankyouveddymuch. And observe the safety rules.
Gunner
Rule #35 "That which does not kill you, has made a huge tactical error"
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A cow-orker insists that the check valves should be placed at the regulator end, in case the hose is torched & a fire started into the hose. It seems that in this case you would want an anti-back flash device in the hose next to the regulator.
I've always run check valves at the torch end. I don't think I have any back-flash devices. How essential are these?
-Jeff Deeney- DoD#0498 NCTR UTMA BRC COHVCO AMA '99 ATK 260LQ-Stink Wheels '94 XR650L-DreamSickle We don't stop riding because we get old, we get old because we stop riding.
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On Wed, 09 Feb 2005 20:00:33 GMT, "Jeff Deeney"

Then he's wrong, for two reasons.
1 - You can't get check valves to fit there (in the UK at least). Ours are a combined hose barb and pipe fitting onto the torch body, with a check valve internal to them. They only flow _from_ the hoses into the threaded fitting, so they're pointing the wrong way for regulator fitting.
2 - The purpose of check valves is to avoid mixed gases getting into the hoses. This is explosive and poorly contained. A mixed gas explosion inside a torch body is unpleasant, but they do happen from time to time (usually when people don't keep their mixers clean).

A severed acetylene hose ? No big deal really - it's no worse than an LPG hose fire, although rather smokier.

You shouldn't ever need them, but if you do you'll be glad you did. They're not the primary safety measure, but they can stop a small incident turning into an accident.
They're damn cheap for reasonably new ones off eBay. You just have no excuse _not_ to have them, although their absence wouldn't stop me from using a welding rig (some faults would).
PS - Congratulations on losing Kali
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