Hello everyone, I'm in the market for an oxy-acetylene welding/cutting
set but I have a few questions before I make my purchase. I have done
some stick welding before but never used gas so I'm a little nervous
about the safety aspects. I want the set for making sculptures out of
scrap metal parts and I wanted the most flexible tools I could get. My
1. What can't I do with oxy-acetylene? Or, is there something of
comparable cost that would be better for me to use?
2. I'm going to have the tanks in my garage at home, which is about 25
feet from my house and my neighbour's. Is this legal, are there any
regulations about residential areas I should know about?
3. What is the best reverse-flow & flashback configuration ( at the
torch or tank or both)?
4. The Smith booklet takes about '4 preheats' on a tip, what does it
5. My garage is unheated, would this be a problem in winter when
Thanks very much in advance for your help.
Depends a lot on your skill and patience. Try to find someone
who can give you hands-on training. As much as I like to
self-teach myself, welding is one field where a little hands-on
help goes a long way.
Your ideal setup would be a MIG, a TIG, and a plasma cutter.
Since that would set you back about $4000-$5000 for new
gear, I suspect it's not an option.
My biggest problem with O/A is that it takes awhile to heat
the material to welding temp and that causes too much warp
and discoloration. My next new toy will be a TIG.
For a beginner at least, O/A will limit you to steel.
Thousands of O/A sets in garages throughout the world.
When I'm done I always: close the bottle valves, bleed
off the pressure in the hoses one at a time, turn the
regulator pressure adjustments CCW until they go slack,
close the torch valves. Just like Mr. Cole taught me
in HS shop class 35 years ago.
I probably should leak-test the acetylene regulator
connection to the bottle each time I put it on.
I don't use them. See your dealer if no one else replies.
Sounds like a cutting torch (or gas axe as we call them).
Cutting torches have multple O/A flames positioned around
a central oxygen jet. You use the O/A flames to get the
metal up to welding temperature then turn on the oxygen.
The oxygen will then burn through the metal. Works well
with steel, works poorly with cast iron, and not at all
with everything else.
I've seen guys thawing pipes with O/A rigs so they
must work ok in the cold.
Joe wrote: (clip) I want the set for making sculptures out of scrap metal
parts and I wanted the most flexible tools I could get(clip)
That would be oxy/acetylene. You can weld, you can braze, you can silver
solder. You can cut and you can heat metal for forging and bending. There
are lots of other tools that are very good for particular applications, but
none of them completely replaces the O/A torch.
On 25 Jul 2003 09:07:53 -0700, email@example.com (Joe) wrote:
I have a Uniweld on my service van. The only time I ever had a
problem was when the plastic trigger guard on the fire extinguisher
broke and I didn't notice it, and I picked up the torch tote and
managed to fire off the extinguisher. White powder went _everywhere_.
I do know that Uniweld at least has optional back-flow
preventers/flame guards which are fitted to the hoses at the torch
handle. Cheap, and work well.
the dash plumber at mindspring dot com
On 25 Jul 2003 09:07:53 -0700, firstname.lastname@example.org (Joe) wrote:
The thing you can't do with O/A, at least you can't do it well, is to
cut non-ferrous materials. A plasma will cut anything conductive,
but O/A works by using a jet of oxygen to burn iron that's been
preheated to ignition temperature. That won't work cleanly with
other metals (doesn't even work with cast iron).
You can weld most anything weldable with O/A, though it is sometimes
difficult, and always slow. You can also braze and heat.
Don't know where you're located, but there aren't any regulations
against it where I live.
The main reason for using these is to prevent fire in the acetylene hose
due to oxygen back flow into the acetylene hose if the torch tip becomes
blocked. So the best place for the check valve is where the acetylene
hose connects to the torch. The checks normally come in pairs, so you
can put one on the oxygen side too, but the likelihood that acetylene
pressures would become so large that back flow could occur into the
oxygen hose is slight.
Cutting tips have multiple preheat flames which surround the central
oxygen cutting jet. Their purpose is to heat the metal to kindling temperature
so the oxygen jet can then cut steel by burning. Welding tips will have only
a single flame cone (excess oxygen is a no no when welding). Rosebud
tips also have multiple flame cones, rosebuds are used for heating.
No. Acetylene sublimes from solid to gas at -84 C. It is what's called
a "reluctant" liquid in that you'll never normally find it in the liquid state.
Normally, the acetylene is dissolved in acetone in the tank. Acetone
freezes at -94.7 C. Oxygen liquifies at an even lower temperature.
So unless you live in an *extremely* cold part of the world, you needn't
worry about this.
Hmm. Extremely non-polar molecule. No vanderwalls forces I guess.
Ever make ethanol ice cubes? :)
================================================= please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
Acetylene has a critical pressure (905 PSI), at least theoretically. But as
you know, acetylene is very unstable at high pressures (that's why it is
stored dissolved in acetone in cylinders). So the critical pressure is never
reached in practice.
Not the way you'd cut steel. Hitting the oxygen lever just makes
a godawful mess (aluminum oxide has a *much* higher melting
point than pure aluminum). You can melt through it with a welding
tip, and since aluminum is hot short, it can be convinced to drop
out, but the cut will be ugly and very ragged.
I learned to gas weld (oxy-acetylene) waaaay back in high school, and
every time I have wanted to do something with metals, I invariably end up
looking at gas welding first. It is probably the most versatile metal
modification system you can own. Welding, Brazing, Soldering and Cutting
(ala the old "gas axe" approach) can't be beat for the money in any other
system I can think of, and I own a fairly decent assortment of tools,
including a metal mill and lathe, several cutting/welding systems, and a
host of air and electric metal and woodworking tools as well
With an OA setup, you can cut iron and steel (a 4-preheat tip is
essentially a cutting tip, my current one is a 6-preheat tip, meaning it
has 6 preheat jets surrounding the single cutting jet of the cutting head
tip. A 4-preheat tip sounds to me like a fairly small system.)
You can weld iron and steel in thinner gauges, but can't do a decent job
of welding thick sections without a lot of practice and very large tips,
so I resort to Stick Arc welding (the second type I learned) and which is
pretty inexpensive because you don't have to buy or lease tanks. Third is
MIG welding, but the current MIG I own is set up for flux cored wire so I
can't do very thick sections with it. Though I have the tank for separate
gas and solid wire, I've not taken the time to get the tank filled because
Aluminum and Stainless require different gasses, and I don't have any
projects on my current list that actually _require_ me to use stainless or
Aluminum, particularly in the relatively thin sections my inexpensive MIG
system could handle. (MIG and TIG systems for thick metal sections are
very pricey compared to similar thicknesses in Iron and Steel using OA
and Stick AC or DC arc welding.)
With an OA gas welding setup, you can also braze a wider variety of
metals, Silver Solder, or even solder using standard tin-lead or lead-free
solders if you wish. The only thing to keep in mind is that the flame of
most tips is usually pretty intense and not spread out like a propane
torch, so if you are going to be soft soldering (tin-lead or lead-free
solders for plumbing) you will want to be moving the flame around a lot to
spread the heat or you could burn through the base metal. If you do a lot
of cutting, sometimes OP (Oxy-Propane) may make sense, but it generally
isn't as hot and requires different tips than OA, and I can't recall
anyone actually doing much welding with an OP setup, just demolition or
Learning to gas weld is an art, and like most arts, it is easier if
someone can teach you, or at least watch while you are in the earlier
stages. Once you have the basics, you can pretty much go on your own.
Trying to learn from a book or video is usually pretty frustrating, but
having someone that is a good welder (or good welding teacher) can get you
into decent territory in a couple of hours. It doesn't take a long time
to learn, so having someone else stand by while you get the basics usually
isn't too long or even that expensive if you have to pay someone to teach
you. A night class or community college extension course could be really
helpful because they tend to also bring up a lot of other subjects and
expand your horizons a bit... (like AC Arc (stick) welding and other metal
fabrication skills. ... but I digress ....
To directly answer your questions:
1) nothing can really touch the versatility of gas welding, and it is
pretty inexpensive overall. If you buy/lease larger tanks, your gas costs
per job will be considerably less than if you get smaller tanks. If you
are refilling your tanks in six months or so, you probably have big enough
tanks for your typical use. If you don't go through all the gas in a set
of tanks within a year, you probably have a tank set too big for your
typical use. However, if you are going down for a refill every month or
two, you might think about upgrading to a bigger tank size. Generally
speaking, the bigger tank size, the less per cubic foot you pay for the
gasses. If you do a lot of cutting, get the next bigger size Oxy tank.
If you mostly do straight welding/brazing and such, get tanks of similar
physical (dimensional) size. Cutting takes a lot of extra oxygen compared
to regular welding/brazing/heating, so if you do a lot of cutting, you
will be running down for Oxy refills a lot more often than Acetylene.
Typically, if you start with the standard paired sizes, you can watch and
decide what to do later, particularly if you lease tanks. If you do buy
your own tanks be aware that many suppliers now charge an exchange fee
when you refill them, because tanks have a finite life span, and someone
has to pay for the obsolescence of old tanks. You can either pay it in
the gas cost, or directly in a fee per refill/exchange. By the way, most
places will exchange tanks when you go in for a refill. They don't
actually refill _your_ tank when you come in, but give you another tank
that is a "lease" or a "owner" tank. If you don't do much welding or
cutting, you can end up with a tank that is near it's re-certification
time, and if you're not watching, you might end up with a higher
refill/recertification charge than you expect. (It has happened to me,
even though I bought new tanks, refilled them once, and got caught because
the hydro-test expired on the tanks I had at my home at the time. Many
vendors keep decent track, but some don't and you might end up getting
charged more than you might expect. As a result of past problems with
this, I currently lease the tanks I now use, and the supplier/owner takes
care of obsolescence. It costs a bit more than owning tanks, but I don't
have any unpleasant surprises when I refill..
2) Most places pressure tanks aren't heavily regulated. The Acetylene
tank is actually full of a filler (like balsa wood) that helps keep the
acetylene stable at high pressures inside the tank. When you are using
Acetylene, keep your pressures in the 7 to 12 pound range for most uses.
(Avoid higher pressures, Acetylene becomes dangerous above 15 PSI, which
is why an Acetylene gauge is red above that pressure. Oxygen is typically
more dangerous, especially if you don't realize that a bit of grease on
the threads or mating surfaces of an oxygen regulator could cause a very
nasty fire or explosion. (If you are cutting something with an
Oxy-Acetylene torch that has oil or grease, don't try to "blow it out"
using the oxy jet. It'll only get much worse. DAMHIKT <smile>) Of
course in some areas, nearly everything is illegal that you'd want to do
except sleep, so your mileage and local regulations may vary. However,
I'd hazard a guess that even in the inner city, there is at least one
Oxy-Acetlyene rig for every 10 or 20 homes, certainly a lot more in the
suburbs, no matter how close the homes are. You are more likely to have
problems from setting something on fire from other causes than from the
inherent danger of the high pressure gasses. Of course, you should always
observe proper fire safety, and be aware that making something hot with a
torch may cause other things to catch fire, and be ready for the
consequences. If you have gas heat or a gas hot water heater, be
particularly careful that you don't have any Acetylene leaks, because the
pilot can start a larger fire if the Acetylene is leaking. However, you
will definitely smell Acetylene before it gets anywhere near a
concentration that could cause an explosion from such an ignition
source.... If in doubt, take the safe approach and keep the tanks away
from any ignition sources.
3) Reverse-Flow and Flashback protection is pretty much up to the
individual, but I prefer a set of flashback valves just before the torch
handle. That way, I don't have to worry about the additional capacity of
the hose set, or of destroying a hose set during a big flashback. That
said, I've never had a flashback that was more than a small pop in the
actual tip, but then I'm pretty careful and have been using Oxy-Acetylene
rigs on and off for something around 35 years... Even so, I wouldn't use
a rig without a flashback arrestor somewhere in the system. They are cheap
4) Preheats are the number of fuel gas holes (jets) on the cutting head.
Most larger capacity systems have 6 preheats, and some have 8 or more. 6
seems to be the most popular of the rigs I've used over the years. The
preheats get the Fuel/Oxy mix and are used (as you might expect) to
preheat the metal to prepare it for cutting with the oxygen jet. The
central hole is usually larger and puts pure Oxygen through the tip, which
will actually burn the iron or steel, and blow slag (unburned metal) out
of the cut. If I were buying another torch, I'd tend towards 6 Preheats
because you can typically cut thicker steel with one, and you can
typically get smaller tips for the big torches, but not usually big tips
for the small torches. Bear in mind that if you are cutting much at all,
you will use a lot of Oxygen, and the torch will get pretty hot. A
smaller, shorter, lighter torch will get the handle hotter much quicker
than a larger system will, however, the heavier handle of a heavy duty
torch set will be more tiresome if you only do small, detail work. You
will need to decide what kind of work you want to do before you purchase a
torch set. Of course, if you have the extra cash, a big, heavy duty set
and a small, lightweight torch, each on it's own hose set with a siamese
(Wye) setup is sort of best both worlds...
5) Where I live, it wouldn't be any problem at all, because the lowest
temperature I've ever seen here in the middle of the winter is about 59
degrees.... Of course, I live near sea level in Hawaii, and your
temperatures probably vary a bit more than mine. When I lived on the
mainland, I have used Oxy/Fuel rigs in temperatures down to about 10
degrees F, though Acetylene tends to do better at lower temperatures than
Propane, unless about all you are doing is thawing pipes... You can
probably do ok at pretty low temperatures, but you will have to allow more
time for preheating if you are cutting iron or steel, and regular welding,
brazing and soldering processes will take longer in cold temperatures.
There are probably an incredible number of OA rigs in garages across the
US, many of which don't get used very often. If you are a tinkerer or
artist, you are likely to use them more than the occasional use "just in
case" mechanic type. Since I've moved to Hawaii, my costs for cylinder
lease have been much higher each year than the cost of the gasses. (sigh)
I guess I've moved to other things (though I do spend more for stick
welding rods.... Even so, I wouldn't give up either of the OA rigs I have
in my workshop, though I may drop back to smaller tanks soon if I don't
get more cutting/gas welding projects in my hopper soon...
There was something else I wanted to say, but the ol' brain just went in
to neutral, so I'm going to close....
Take care, learn how to weld properly, always weld or cut on a fireproof
surface, and enjoy yourself. If you do much iron/steel welding, get an
arc (stick) welder next, then if you have the extra money, maybe a MIG or
TIG rig. Given a limited budget, you can do a lot with no more than an
Oxy-Acetylene rig for welding thin sections (to perhaps an eighth of an
inch, pushing it to maybe a quarter of an inch occasionally unless you
have a really heavy duty rig), Cutting to about an inch or so depending on
your rig capacity, and with a relatively inexpensive AC Arc Welding (stick
welding) rig, you can weld up to about an inch thick without too much
trouble. For many years, that was about all anyone used anyway. DC arc
welding helps for control and overhead welding, and MIG and TIG are good
for welding thin sections and other metals (such as stainless steel and
aluminum), however, getting an real capacity for welding Stainless and
Aluminum thick sections costs an arm and a leg, and probably another arm,
depending upon where you live.
Good Luck, Stay Safe, and enjoy yourself!
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