[TheForge] Re: RE: Petrogen Torch Yak

Tue Aug 17 13:48:11 EDT 2004

It OK if you call it an oxygen lance -- for in fact it is a lance.  The term
used may vary by region or industry.  My background always as called them
"burning bars".  We used the term "oxygen lance" to refer to the liquid
(water) cooled lances used in basic oxygen furnaces or electric arc furnaces
used for the production of steel.

Here is a website with information on burning bars

http://www.millerandco.com/products/specialty_items/burning_bars.htm

and here is one on oxygen lances for use in steel production

http://www.berrymetal.com/sales.htm

To confuse the terms even more we would talk about using burning bars to
lance (verb) large chucks of steel scrap.   The largest I have ever seen
being cutting up a plate mill back-up roll that weight over 500,000 pounds
and was 84 inches in diameter.  The working face of the roll was 220 inches
long plus the lengths of the bearing necks.  It had completed it useful life
and was being cut up for scrap.  It filled several rail road cars.  The
company doing the scraping brought in several tank trucks of liquid oxygen
for lancing.  They elected to do the work at night in an area outside of the
plant but still inside of the plant fence.  A lady that lived on top of the
hill about 3/4 of a mile from the plant called 911 and reported that an
airplane had crashed at the plant.  We had fire departments and police on
the way when our plant fire marshal hear the calls on the radio and reported
that everything was under control and that it was a false alarm.  Next time
we cut up scrap rolls we did it on the other side of the plant and in the
day time.

Most likely the correct term to us is "thermic lance" but I have never heard
it called that in my industrial experience.  Here from another website is a
bit of history on the "Thermic Lance"

After the Second World War ended, this process was fully developed in France
to help break up large concrete structures such as gun emplacements. The
device has changed remarkably little since then and the description is
pretty accurate. It consists of a mild steel tube about 3 metres long by 20
millimetres in diameter packed with steel rods. An oxygen delivery hose and
valve are connected to the operator's end of the tube and oxygen is supplied
to the lance via a pressure-reducing valve from large compressed oxygen
cylinders or an oxygen supply line from a liquid oxygen source.

The lance tip can be ignited with an oxyacetylene torch. Once the end of the
steel pipe is red hot, the oxygen supply is turned on and the metal will
burn in a self-sustaining reaction. The lance is then fed slowly into the
concrete and is consumed as it goes, eventually requiring replacement with a
new lance. Besides concrete, this method can also penetrate thick metal.

The principle relies on the fact that iron at a sufficient temperature will
burn in oxygen. The reaction that is produced: 3Fe + 2O2 * Fe304 is highly
exothermic and the temperature it generates--between 1800 °C and 2500 °C--is
sufficient to melt concrete.

The melted concrete is quite fluid. It consists partly of iron silicate
formed by the reaction of the iron oxides, which are produced by the iron
and oxygen reaction, together with the silicon oxides found in the sand and
other siliceous material used to make concrete. This slag is blown back out
of the hole by the pressure of gases within.

This is from http://www.newscientist.com/lastword/article.jsp?id=lw720

Dave Smucker

----- Original Message ----- 
From: "Charle B Vincent" <xlch58 at swbell.net>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Tuesday, August 17, 2004 11:43 AM
Subject: Re: [TheForge] Re: RE: Petrogen Torch Yak

> I think they are commonly called an oxygen lance.   Old welding books
> detail how to make them up from a length of ordinary black iron pipe.
>
> Charles
>
> David E. Smucker wrote:
>
> >Ray,
> >
> >Have you ever seen or used "burning bars" for demolition work.  The are a
> >thin steel tube packed with steel wire.  The small size is about 3/8 dia
and
> >3 feet long and the large size go up to about 1 inch diameter and 20 feet
> >long.  They have a crimp on one end so the wire doesn't fall out.  The
tube
> >is connected to just oxygen -- no fuel gas at all. While they are pack
with
> >wire there is enough space between the wires for oxygen to flow.  You
> >"start" them with a regular torch -- just bring the end up to a hot
yellow
> >heat -- then turn on the oxygen.  The tube and wire are consumed in the
> >process and generate a great deal of heat while excess oxygen is supplied
> >like a oxygen lance.  They will blow through lots of things cutting
steel,
> >rebar and concrete.  They are not for the faint of heart.  Oh, and the
> >quality of the cut is not very good.
> >
> >Dave Smucker
> >----- Original Message ----- 
> >From: <debmiller at fuse.net>
> >To: "Sponsored by ABANA" <theforge at mailman.qth.net>
> >Sent: Tuesday, August 17, 2004 7:47 AM
> >Subject: [TheForge] Re: RE: Petrogen Torch Yak
> >
> >
> >
>
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