On 25 Jul 2003 09:07:53 -0700, (Joe) wrote:
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
questions:

1. What can't I do with oxy-acetylene? Or, is there something of
comparable cost that would be better for me to use?

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.

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?

Don't know where you're located, but there aren't any regulations
against it where I live.

3. What is the best reverse-flow & flashback configuration ( at the
torch or tank or both)?

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.

4. The Smith booklet takes about '4 preheats' on a tip, what does it
mean?

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.

5. My garage is unheated, would this be a problem in winter when
everything freezes?

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.

Gary