Oxy-acet (thermal cutting)

[hotspurs]

Can anyone help me!

Where can I find valuable information on the www regarding 'Thermal Cutting' using oxy/acety. I am looking for literature for a total beginner, inclusive of pictures if possible.


My request is for cutting carbon steel plate & pipe.

many thanks...new to this site 13/09/09......the info is superb...excellent website!!

 

[Weldingartisan]

Do you mean 'thermal cutting' as in a thermic lance or oxy-acetylene cutting as in carbon steel fabrication? W/A

 

[GeorgeB]

I didn't know much about thermic lances until I just checked wikipedia and or or two other sources. Then I found the following video. How irresponsbible can you get?

Sorry I can't preview my post or check that the embed video works, due to my pre=mod status.

http://www.youtube.com/v/mKZtb6dTWSY

 

[snowcat]

I'm guessing you meen Oxy-fuel cutting, Thermic lances have a very limited field of use....

what do you need to know? BOC site and Murex would be good places to start..

 

[GeorgeB]

I'm guessing you meen Oxy-fuel cutting, Thermic lances have a very limited field of use....
what do you need to know? BOC site and Murex would be good places to start..

I don't know what the OP needs to know but I became interested in the subject of thermic lances last night when I came across an old video tape about putting out the oil fires after the Gulf War in 1990. They were using thermic lances as some part of the process of sealing the well heads. Why burn money as acetylene when you can burn iron, steel and aluminium instead, I'm thinking? If you have a flashback arrestor fitted to the oxygen line, is it still very high risk? I couldn't help wondering if it's worth the risk of trying to make a crude DIY version, but not with spaghetti, like in the video.

 

[snowcat]

thermic larces were popular around the 70-80s, they are only of any use burning through massive amounts material, 4" by foot long pins is the sort of work, and blasting concrete, and foot+ thick sections of steel plate...

They have little use apart from that, there not controllable and just gouge at whatever your trying to cut, the end user also needed to enjoy burns, or wear the sort of kit that F1 drivers would envy...

In oxy fuel cutting, fuel is a non cost, fuel pressures are always very low, even on big nozzles, I use "empty" propane cylinders when they no longer have the pressures for other things such as heaters, and the dregs of a 47KG will last me a good couple of oxegens....

For these reasons I wouldn't bother with any kind of lance.....

 

[Paul.]

When I used to teach we had to demo a thermic lance as part of the course, students were only allowed to watch while we destroyed con blocks and hacked holes in lumps of scrap, in the end the college authorities banned it as too dangerous, (we did it in the car park) and bought a video to show, good fun though while it lasted.

 

[runnach]

Paul, it is even more interesting using underwater, if topside forget to turn off knife switch once fired up, is a test to dental filling as they slowly begin to taste not too nice

 

[GeorgeB]

They have little use apart from that, there not controllable and just gouge at whatever your trying to cut, the end user also needed to enjoy burns, or wear the sort of kit that F1 drivers would envy...

Thank you and others for some very interesting insights.

I now consider that building a DIY thermic lance would be a risk too far, especially as it has no real use or application (at home), like you point out.

 

[rory1]

i use a lance regular in work, and like snowcat says you do get burned quite a lot even with a nice thick stovers jacket on.

the lance leaves any workpiece really messy, even with the most experienced of operators but they are invaluable when you need to remove pins that havnt seen a bit of grease for twenty years.

the lancing rods are also quite expensive, i think the last pack i bought from boc were 90 + the vat for 20 (about 3 foot long and about 1/2 diameter)

i have been led to believe that they use a similar setup to a lance but on a larger scale when the tap into the bottom of a blast furnace when producing steel

 

[pedrobedro]

We used a thermic lance to cut a skull from a furnace that had shut down and set during a melt when I worked in a local foundry in the 70s. From what I can remember of it it was like a conduit pipe filed with iron filings with oxygen blown through it and we had to use an oxy/propane torch to light it. It was very dirty and vicious and I worked on an arcair machine at the time which was not too clean either but it made that look tame.

 

[GeorgeB]

Here's another video which shows the sheer power of a thermic lance, which they are using to almost cut a car in half, in just a few seconds:

http://www.youtube.com/watch?v=kzlb1nTnaKM

 

[runnach]

This vid will blow you away George, and it will and can if not careful

http://www.youtube.com/watch?v=d_58wnEYjLs

 

[GeorgeB]

This vid will blow you away George, and it will and can if not careful

http://www.youtube.com/watch?v=d_58wnEYjLs

runnach - interesting. Are the rods effectively small thermic lances or more like arc welding rods? He seems to ignite them like with arc welding, rather than by using an oxy-acetylene ignition source. Also, the earth clip suggests arc welding.

 

[runnach]

runnach - interesting. Are the rods effectively small thermic lances or more like arc welding rods? He seems to ignite them like with arc welding, rather than by using an oxy-acetylene ignition source. Also, the earth clip suggests arc welding.

Yep small thermic lance, there are two lengths of rod available, I have some examples at work, I'll take some pics next week.

What looks like an earth lead carries the current for firing up lance, once fired up, power should cease (keeps dentist bills down) On the few occasions I have used them, I have a nice new piece of shiny 6mm copper plate for striking up, if burning an old submerged rusty hulk, firing up is a problem on rusty matl.

Broco is used by civils companies too, MOD also use them, for firing up topside, no power source is required, CDI capsule is required, CDI is basically a chemical start, dip lance into chem liquid (reacts with oxygen) while gently squeezing trigger to release small amount of oxygen, once fired up, remove from CDI and full on with oxygen to burn almost any material known to man, Broco burns at over 10.000F at tip!!

 

[Bigjoe]

Don't think id fancy doing that!

Do the divers have a reactive screen in their dive helmet or a flip down type shield?

 

[runnach]

Tis always gloomy/dark Joe, basic flip down lens adapted to suit whatever hardhat diver uses. Actually it is an interesting process, fine doing it occasionally, I couldn't, fancy doing it too often meself, too many factors making it too bloody dangerous!

You been to Hamish new place yet?

Cheers...........

 

[Bigjoe]

Not had a chance yet, he was'nt in the last time i was in town but im going to try and get up ther very soon...have you been to see him?

 

[runnach]

Nope not been yet mate, bloody time is very short at the mo!!

Back on topic, some pics of Broco Ultrathermic Cutting Rods, link explains process. Pics show one full rod clad in what is basically insulating tape, I cut back outer tube casing to allow full view of alloy core wires, O2 flows through centre of rod, apologies for pic quality, phone cam used.

Cheers............

http://www.strongweldingproducts.com/broco/c_ultrathermiccuttingrods.html

 

[GeorgeB]

Broco is used by civils companies too, MOD also use them, for firing up topside, no power source is required, CDI capsule is required, CDI is basically a chemical start, dip lance into chem liquid (reacts with oxygen) while gently squeezing trigger to release small amount of oxygen, once fired up, remove from CDI and full on with oxygen to burn almost any material known to man, Broco burns at over 10.000F at tip!!

This is so interesting and it's very good of you to post the photos and web link. If these short rods are so easy to ignite, though, as seen in the underwater video, then why are normal thermic lances started with an oxy-acetylene torch, which seems like a lot more hassle.

They say: "Our Ultrathermic Cutting Rod readily ignites from a spark generated by a 12 or 24 volt auto or marine battery and will continue to burn with electrical current removed until the flow of oxygen is stopped or the rod is consumed. The need for expensive support equipment is reduced while a safer diving environment is maintained. "

Is the battery-start an alternative to a CDI capsule, and do these same rods work just as well in air, rather than underwater?