Thoriated Electrodes

Unimig Tungsten ElectrodesPreviously, all Tig welding was performed by using 1 of 2 types of electrodes: Thoriated for DC welding of steel, stainless steel, copper, brass etc and Zirconiated for AC welding of aluminium.

Over the past 15 years or so, studies have been made regarding the use of Thorium in DC welding electrodes.  Thorium is a radio active substance and although there was only 1.5-2% used in the manufacture of Thoriated tungsten electrodes, it was deemed a high carcinogenic risk to the user and special safety procedures were recommended.

Because Thorium is almost impossible to penetrate the skin, the primary concern was inhalation of particles during the grinding preparation of the tip and in the fumes released during the welding process.  It was suggested that dust and fume extraction systems be installed to prevent or at least minimise the risk involved in using Thoriated tungsten electrodes.

About a year ago, Thoriated tungsten electrode production was dramatically reduced and most suppliers were only going to supply whatever stock they had of them and from that time on, these electrodes would be no longer available by retail outlets.  This was nearly a worldwide decision.

An alternative was called for prior to this time and 3 alternate compositions were made.

The alternatives they came up with are:

  1. 5% Lanthanated which was found to closely mirror the characteristics of the Thorium electrodes and performed equally as well in AC mode.
  2. 2.0% Ceriated which also performed on both AC and DC mode but depending on who you talk to was not as good as Lanthanated. This fact has been disputed for years and probably will never be resolved due to the differences in operator skills, preferences and even to variations in materials.
  3. Finally, “Rare Earth” electrodes. This is really a misnomer as they are either Lanthanated OR Ceriated as both come under the banner of Rare Earth.

Zirconiated electrodes are still available for AC welding however the introduction of these “Rare Earth” electrodes has virtually eliminated the need to have two different types for different applications.

And once again, debate rages over the use of Rare Earth electrodes in the AC process. Some operators are happy with them, some will say they much prefer the Zirconiated.

My personal belief is whatever you prefer. I’ve had no problems using Rare Earth electrodes in the AC process.

IBS carries Rare Earth, Ceriated and Zirconiated tungsten electrodes.  We have access to Lanthanated if they are requested but really can’t see the logic or necessity to carry both when there is virtually no difference in them.

Dave Dowley

About Dave Dowley

Dave is a member of our Sales Team and joined us in 2015. He specialises in welding and has a number of years of experience as former welder.

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