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Exothermic Welding

06/10/2009 10:39 PM

What is exothermic weld and what is the safety hazard.

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#1

Re: Exothermic weld

06/10/2009 10:52 PM
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#2

Re: Exothermic weld

06/11/2009 3:21 AM

Thermit welding is commonly used to join railway rails together. Welds can be made in gaps of up to 80mm(!). The process is highly exothermic, and once initiated, cannot be stopped until the weld is complete. The safety hazards include:

  • High heat dissipation
  • Sparks ejected from the crucible in all directions
  • Strong light emissions that, if looked at directly, can damage the retina
  • Passing trains on adjacent lines

Contact Thermit GB for an illustration.

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#3
In reply to #2

Re: Exothermic weld

06/11/2009 8:10 AM

GA. Add to that, "Don't breathe the fumes."

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#4
In reply to #3

Re: Exothermic weld

06/11/2009 10:11 AM

<..."Don't breathe the fumes."...>

Quite, though one really wouldn't want to stand that near anyway while it's "going off"....

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#5
In reply to #4

Re: Exothermic weld

06/11/2009 10:40 PM

Ah, but thermite makes such a nice incendiary grenade though.....=b

(been reading "Lucifer's Hammer" again...)

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#6

Re: Exothermic Welding

06/12/2009 3:07 AM

Thermit weld is a process in which coalescence is achieved by chemical reaction heat. Usually a strong reducer (mostly Al) reacts with iron oxide (if you want iron/steel as the final product), reduces it giving Al2O3 and Fe. The reaction heat is enough to melt the iron so it can fill the crucible created surrounding the two parts to weld and the gap between. Resulting oxides usually float as slag in the melt pool.

Safety hazards have been well explained before.

Kind regards

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#7

Re: Exothermic Welding

06/13/2009 10:14 PM

Ronron,

To summarize from the other posts--

  • It is a method of welding in which the energy to create the weld is supplied by the ingredients, instead of an outside energy source such as a flame or generator.
  • Once the reaction has been started, stopping it is virtually impossible until all the components have reacted.
  • It can put out very large amounts of heat quickly, so sparks, flying globs, fumes, intense light, and similar are normal.
  • In abnormal conditions the mold within which the welding reaction is done can melt or shatter, so anything nearby can be damaged or burnt. Very hot parts can fly a considerable distance.

This list is not complete, but I hope it gives you guidance for the more important question of what safety precautions you need to take before doing exothermic welding.

--JMM

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#8

Re: Exothermic Welding

06/15/2009 1:38 PM

exothermic welding is also used to make grounding connections. It is irreversible and makes a very low impedance splice. Cadweld is a brand name

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#9

Re: Exothermic Welding

09/12/2017 4:22 AM

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