Subject: Thermal Lance (Update)

From: [email-masked] (Yogi Shan)
Date: 21 Mar 1995 23:25:17 GMT

As promised, here are the e-mails I received
on my request for information a little ways
back on the thermal lance/burning bar.

Thanks to those who were kind enough to 
respond or follow-up!

Yogi

****************************************************
In article <[email-masked]>, you write:

<snip>

> Does anyone have any information on this interesting
> device?  Any published information sources or other
> references?  Anyone seen one in use.  What are they
> used for legitimately?

I wish I could provide concrete references, but unfortunately
exact titles slip my mind.  Good books on foundry practice
should have information on oxygen lances (I believe that this
may be a category of thermal lances in general).

(Oxygen lances are used to tap furnaces - or at least they used
to be.  I'm not sure how popular jet tappers have become)

> 
> The only thing I can guess is that the tube is Mg
> or an Mg/Al alloy, with either Mg or thermite as
> the filler.  However, thermite produces a temp.
> of 3000 C., which I wouldn't think would affect
> concrete.

I don't believe the tube material matters all that much.
I believe most oxygen lances are made of iron (which
is consumed during use).  When casting Al, etc., lances
made of the same material as is being cast may be used in
order to limit contamination.

The initial heat is provided with a torch (and the torch
is kept handy in case your fire goes out).  The reaction
between the metal and oxygen is usually self-sustaining.

As for burning through concrete, I believe that the glass
transition temperature for quartz is below 3000 C
(but I could be wrong).

Mark

I recall reading about these, but as I recall, the burning bar was just 
iron.  Not sure how you'd -start- one, but it should burn hot once 
ignited!  I think Mg or Al, though they might burn hotter, would also be 
consumed faster, and probably would tent to melt.

Thermal lances have a number of uses: everything from cutting
blocks of marble to penetrating safes. Yes, I am a locksmith, and
have read much of the legal (and illegal) use of burning bars to
penetrate containers.

The main bit of advice is: Don't use it. :-) The contents will
end up incinerated, most of the time. There have been certain measures
made in the security industry to prevent penetration of containers
through use of two factors: the first is the use of highly conductive
materials to wick the heat away from the burning point. The primary one
seems to be copper, although I suppose aluminum would now be cheaper,
as well as more efficient (although it melts at a much lower point.
Har har har har!).

The other one is plywood. Yup. Wood takes much longer to burn
through with a thermal lance than just about anything else. And, as anyone
who has ever operated one can tell you, the last thing someone has to
do when using a burning bar is think about "what's next?"- the bar burns
too fast! Magnesium... *sighs*. Wood charrs, then turns into a kind of
refractory material (akin to graphite, I would imagine) that becomes
difficult to blast away.

I suppose in theory a device could be made to thwart burning
bars quite readily: anything that emits liquid water. When burning metals
hit water, they form a hydroxide + hydrogen gas, which explodes. Heh.
SafeOwners' revenge, I figure. =-D

Anyway. I cannot point you towards references, as they are all
in kind of discrete locksmithing and vault books and periodicals. The
folks in alt.locksmithing might be able to help more; I do not have
my library at hand (grad school. Heh.).

How about posting a followup back to r.c.m. and the other
groups when it's about "resolved" ...

Focused 3000 C may not melt concrete but seems like it would expand it
enough to disintegrate it, perhaps explosively.

 I got one reference, the intro to 
The Oxy Acetylene Handbook (1960 edition) Union Carbide/Linde Divison

talking about the development of oxygen cutting equipment,
a  method developed for tapping blast furnaces was to
direct a jet of oxygen on to an iron plug.

continuing down the page, they mention the evolution from
oxygen jets in cutting with separate burners to an integrated
welding/cutting tourch 

later, in the chapter on cutting heavy sections, they
discuss the oygen lance  (using black iron pipe)
The key to this is the flow of oxygen, for many purposes
simply burning iron is good enough.
  In the pictures and discussion, they show use
in heavy scrapping (cutting 20 inch thick plate)
cutting in heavy casting, other steel mill operations,

I don't seem to have it, but have also read of its
use for demolition and on concrete... but this welding
book makes the point that it is for ferrous metals due 
to issues with oxide melting points and clearance.

[email-masked] (Yogi Shan) writes:
> 
> I remember reading when I was younger about
> thermal lances, aka "burning bars".  The device,
> consisting of a long metal tube, filled with some 
>... 
> Yogi

   Greetings!

 I have a set of encyclopedia titled "How it works: The Illustrated 
Science and Invention Encyclopedia" published by H.S. Stuttman and Co.
These date back to around '82 or so.  In volume 18, pg. 2397, They have a 
device known as a "Thermic Lance".  Now, these volumes were produced in 
England, and I'm told these devices are still in somewhat limited use 
over there...

Excerpt from above:

"The Principle on which most thermic lances operate is that when iron 
burns in a stream of pure oxygen a very hot, molten oxide is produced.  
This slag is used to melt concrete and metals and thus bore holes through 
them. 

The most common thermic lance consists of a long steel tube, 
commonly of 3/8 or 1/2 inch diameter, with one end open and an oxygen 
inlet at the other.  This tube is packed with iron core wire which 
provides the fuel for the lance. High pressure oxygen, at approx. 116-174 
psi is injected through the inlet and flows through the space between the 
core wire and the tube.

The lance tip is then held in a flame until the iron starts to 
oxidize in the oxygen stream, and then is put to the work.

They give examples of hot many holes need to be cut in order to 
slice through a certain sized wall, steel plate, etc.  A diagram is 
included, as well as some pictures, but I've given you most of the 
article. 

                                Hope this helps,

In article <[email-masked]>, you write:
|> 
|> 
|> I remember reading when I was younger about
|> thermal lances, aka "burning bars".  The device,
|>...

Hi,

Used them in Alunimium smelters and in a steel mill.
They aren't as exotic as you propose, the bar is a steel tube
usually about 1 in. O.D. with 7 steel wires inside (the
arrangement is a hexagon with a central wire). Normally you
start them with a natural gas/butane bottle and oxygen.
When the tip gets to bright red heat then you switch to 
oxygen only. The heat comes from burning the iron.

The temp of the flame is somewhere around 3000 C (from memory).
You are right that a burning bar will pretty much cut anything,
including concrete, refractories, etc.

I've used them to cut up outsized pieces of scrap Aluminium and
Steel. The disadavntage of them is that they are expensive to operate -
the oxygen consumption is very high and you only get about 5 to 10 minutes
burning out of a 5 meter bar.

The up side is that they are FUN to use - it's a real power
trip using one of these things.

Have seen your lance.It uses magnesium rods in a steel pipe(standard
water pipe).The oxygen is sent threw the pipe after you lite the mg.

Heard about similar thing many years ago. NAVY mechanics used it to burn 
through very thick plate. I believe it was jast a pipe feeding pure oxygen. 
It was not consumed itself. The plate was preheated with a torch. At that 
point pure oxygen was "blown" onto the surface. The steel itself was 
partially "burned", the rest was melted and flow away.

Could be I am totally wrong, but that is what I remember.

In article <[email-masked]>, you say:
>
>I remember reading when I was younger about
>thermal lances, aka "burning bars".  The device,

 Um ,I read a post posted to rec.pyro about a year ago about the 
 thermal lance ,apparently It's a hollow tube of magnesium about 
 6 or so feet long ,with an ordinary welding adapter at the end .
 it's screwed on to an oxygen tank ,and pure oxygen blasted through
 it. The tip of the lance is then ignited with a blowtorch ,and 
 starts merrily burning away at a pretty damn high temperature 
 which can slice through practically anything without a seconds 
 hesitation.
 The article I read also mentioned it slicing rather neatly through
 concrete blocks ,It's meant to be one of the uses It's put to.

Oxygen lances and burning bars are commonly used in the steel industry.

Oxygen lances, a steel (or stainless steel if you don't want the pipe
to be consumed) pipe through which oxygen is passed, work real good on hot
steel.  Once you light the pipe you can burn through any steel object
fairly quickly (with the exception of stainless of course).

Applications: opening ladles (when the default method doesn't work), opening
tapholes in furnaces when it gets plugged, burning off hot skulls off various
objects.

Burning bars are basically an oxygen lance with the pipe filled with Mg wire.
Here, you get some serious burning power.  You now do not have the safety net
of just being able to burn steel, you can burn holes through your refractory
as well.

We routinely use 1" and 1/2" diameter oxygen lances and 3/4" burning bars. 

Regarding your enquiry about thermal lances, i have seen them in 
operation for legitimate purposes.They are used in foundries and
metal casting operations for clearing pouring spouts. They are also
used for cutting large section ferrous or non ferrous metals that are
unsuitable for classical methods(saws, oxy cutting).They are 
particularly advantageous because they operate on non ferrous 
materials that are not usually able to be cut by the oxy acetylene
torches which rely on the rapid oxidation process eg steel. They 
rely on the heat of the reaction of the oxidation of the core to melt
the material.The disadvantage is the cut edge is untidy and the gases given off during the oxidation
of the Mg core wires are highly toxic.

More accurate information can be obtained from a welding materials
supplier eg Lincoln.