Description: AFM 2% thoriated tungsten electrodes have been designed for direct current applications. They have the thoria content dispersed evenly throughout their entire length. They maintain a sharpened point well, which is desirable for welding steel. They can be used on alternating current work, but a satisfactory balled end, which is desirable for the welding of nonferrous metals, is difficult to maintain.
Should it be desired to use these electrodes for alternating current welding, then balling can be accomplished by briefly, and carefully, welding with direct current electrode positive prior to welding with alternating current. During alternating current welding, the balled end does not melt and so emission is not as good as from a liquid ball on a pure tungsten (EWP) electrode. Tip color is red.
Chemical Composition Requirements (%):
- W - 97.3
- ThO2 - 1.7-2.2
- Total Other - 0.5
Statement of Commission VIII on Health Aspects in the Use of Thoriated Tungsten Electrodes:
ˇ°Thorium oxides are found in Thoriated Tungsten Electrodes up to 4.2% (ISO 6858-WT 40 electrode). Thorium is radioactive and may present hazards by external and internal exposure. If alternatives are technically feasible, they should be used.
Several studies carried out on Thoriated Electrodes have shown that due to the type of radiation generated, external radiation risks-during storage, welding, or disposal of residues-are negligible under normal conditions of use.
On the contrary, during the grinding of electrode tips there is generation of radioactive dust, with the risk of internal exposure. Consequently, it is necessary to use local exhaust ventilation to control the dust at the source, complemented if necessary by respiratory protective equipment. The risk of internal exposure during welding is considered negligible since the electrode consumed at a very slow rate.
Precautions must be taken in order to control any risks of exposure during the disposal of dust from grinding devices.
The above statement is based on a considered view of the available reports.Commission VIII will continue to keep these aspects under review.ˇ±
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